WO2012060285A1 - Granulated body of silica sand and production method therefor - Google Patents

Granulated body of silica sand and production method therefor Download PDF

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Publication number
WO2012060285A1
WO2012060285A1 PCT/JP2011/074898 JP2011074898W WO2012060285A1 WO 2012060285 A1 WO2012060285 A1 WO 2012060285A1 JP 2011074898 W JP2011074898 W JP 2011074898W WO 2012060285 A1 WO2012060285 A1 WO 2012060285A1
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Prior art keywords
silica sand
silica
alkaline earth
earth metal
weight
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PCT/JP2011/074898
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French (fr)
Japanese (ja)
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誠司 今澄
福山　良樹
藤波　恭一
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株式会社トクヤマ
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Priority to JP2012541829A priority Critical patent/JP5875523B2/en
Priority to CN201180052701.4A priority patent/CN103201220B/en
Publication of WO2012060285A1 publication Critical patent/WO2012060285A1/en

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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/62605—Treating the starting powders individually or as mixtures
    • C04B35/62695—Granulation or pelletising
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • C01B33/023—Preparation by reduction of silica or free silica-containing material
    • C01B33/025—Preparation by reduction of silica or free silica-containing material with carbon or a solid carbonaceous material, i.e. carbo-thermal process
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Definitions

  • the present invention relates to a novel silica sand granule. More specifically, the present invention provides a silica sand granule that has properties that can be handled in the same way as silica stone that is normally used as a raw material when manufacturing metal silicon, and that can replace silica in the manufacture of metal silicon, and a method for manufacturing the same. To do.
  • metallic silicon is obtained by reducing silica at about 2000 ° C. in an arc furnace using silica, which is a silicon source, and charcoal, coke, coal, wood chips, etc. as a reducing material.
  • silica which is a silicon source
  • charcoal, coke, coal, wood chips, etc. as a reducing material.
  • the silica stone is usually 5 mm to 200 mm in size. This is to ensure air permeability in the furnace. That is, in the arc furnace, carbon monoxide (CO) gas and silicon monoxide (SiO) gas are generated as a gas phase in the process of the reduction reaction of the silica, so that all or a part of them is used as the raw material layer. Need to escape through.
  • CO carbon monoxide
  • SiO silicon monoxide
  • SiO 2 silicon dioxide
  • the reaction is complicated and is decomposed into the following elementary reactions, and these elementary reactions are considered to occur in parallel.
  • the condensed phase in the arc furnace temperature range is SiO 2 , C, SiC, Si, and the gas phase is CO, SiO.
  • SiO gas is generated from the high temperature portion near the tip of the in-furnace electrode by the reaction of formula (2). In the upper part of the raw material layer, when the SiO gas or CO gas that generated the gap between the layers rises and is discharged, precipitates adhere to the wall surface of the gap that is the passage by the following reaction.
  • quartz sand has abundant resources compared to quartz stone, and in addition, it is easy to mine, so it can be a great advantage to replace quartz stone as a raw material for metallic silicon.
  • the number of voids is smaller than that of silica stone, and when deposits are deposited due to the reactions of the above-described formulas (10) and (11), the voids are significantly reduced compared with the above-mentioned silica stone. It is feared that it is difficult to escape the gas of CO and SiO generated in the reaction. Further, as can be seen from the formulas (2) to (8), if the CO stays, the progress of the reaction is hindered. That is, SiC is deposited on the bottom of the furnace and causes operational troubles.
  • silica sand as a raw material for metallic silicon to be supplied to the arc furnace to have a size and strength equivalent to that of silica stone.
  • Patent Document 1 silica sand is mixed with a non-sintered carbon carrier such as petroleum coke and a pitch-containing binder and hardened to obtain green pellets, which are cured and heat-treated to give an arc furnace. It is described to form a charge pellet.
  • a non-sintered carbon carrier such as petroleum coke and a pitch-containing binder
  • the present invention replaces the silica usually used as a raw material in the production of metal silicon, and has a silica sand granule having a size and strength that can be handled in the same manner as silica. It aims at providing the method for manufacturing efficiently.
  • the present inventors have achieved this object according to the silica sand granule having a specific average particle diameter and crushing strength, If an inorganic substance having reactivity with SiO 2 is interposed between silica sand particles in the granule structure, the strength can be increased even by heat treatment at a relatively low temperature, and the problem of strength reduction at a high temperature can be solved.
  • an alkaline earth metal compound typically a calcium compound or a magnesium compound as the inorganic substance
  • the above object is achieved, and the use of the alkaline earth metal compound When this was used as the raw material for silicon production, it was found that the purity of the metal silicon obtained can be remarkably improved, and the present invention has been completed.
  • the silica sand granule of the present invention is formed from silica sand and has an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N.
  • the silica sand granule is preferably molded using an alkaline earth metal compound as a binder.
  • an alkaline earth metal compound a calcium compound, a magnesium compound or a mixture thereof is preferable.
  • the ratio of the alkaline earth metal atom to the Si atom is 0.001 to 0.04. It is preferable in order to increase the purity of the silica sand granule itself while maintaining the high strength.
  • the ratio of calcium atoms to Si atoms is 0.001 to 0.04 to maintain the high strength of the silica sand granule.
  • SiO 2 content of silica sand constituting the silica sand granule is preferably at least 97% by weight.
  • the said silica sand can use a thing with a particle size in the range below 1400 micrometers suitably.
  • the use of silica sand having a relative particle amount (weight) of 25% to 70% within a particle size range of less than 75 ⁇ m is due to the action of the binder and a high-strength granule by heat treatment at a low temperature. Is particularly preferable.
  • the relative particle amount is in the range of 150 ⁇ m or more and less than 1400 ⁇ m and the relative particle amount is 10% to 50%
  • some silica sand is used as raw material silica sand by unpulverized or mild pulverization. Can be economical.
  • the relative particle amount in the range of less than 1400 ⁇ m is 100%.
  • the ratio of alkali metal atoms to Si atoms (M1 / Si) contained in the silica sand granule is preferably less than 0.01.
  • the silica sand granule can be produced by granulating silica sand to have an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N.
  • the above-mentioned silica sand granule can be preferably produced by bringing an alkaline earth metal compound such as a calcium compound into contact with the surface of the silica sand for granulation.
  • the silica sand is obtained by granulating by contacting the silica sand with an alkaline earth metal compound such as a calcium compound in the presence of water, and then heating the granulated body to a temperature of 100 ° C. to 1600 ° C. This is preferable for further improving the strength of the granulated body.
  • alkaline earth metal compound calcium compounds such as calcium hydroxide, calcium carbonate, calcium oxide and calcium sulfate, magnesium compounds such as magnesium hydroxide, magnesium carbonate, magnesium oxide and magnesium sulfate, or a mixture thereof are suitable. Used for.
  • an alkaline earth metal compound such as a calcium compound is 0.1 to 5 parts by weight with respect to 100 parts by weight of silica sand.
  • silica sand used in the present invention can be adjusted to an average particle diameter of 1 ⁇ m to 200 ⁇ m by pulverization.
  • the silica sand granule of the present invention is suitably used as a silicon source in the production of metallic silicon, ferrosilicon or silicon carbide.
  • a method for producing metal silicon a method in which the silica sand granule of the present invention is supplied to an arc furnace as at least a part of a silicon source and a reduction reaction is suitably employed.
  • a step of forming silica sand to form a silica sand granule having an average particle size of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N, and the silica sand granule examples thereof include a method including a step of performing a reduction reaction by supplying at least part of a silicon source to an arc furnace.
  • the silica sand granule of the present invention achieves a crushing strength of 200 N or more, and when loaded into the raw material layer in the arc furnace with such strength, it does not collapse due to the load from the top even if handled in the same manner as silica stone, It is possible to ensure the voids in the layer. In addition, even at high temperatures, the strength is not significantly reduced, and the reaction can be performed stably.
  • the strength of the above-mentioned silica sand granule is increased by granulating using an alkaline earth metal compound such as a calcium compound or a magnesium compound as a binder, so that the alkaline earth metal is present on the surface of the silica sand particle. It is presumed that calcium silicate which is a reaction product reacts with the SiO 2 component and strongly binds the silica sand particles.
  • the silica sand granule obtained in the present invention is used as a raw material for metallic silicon
  • the metallic silicon reduced and melted in the arc furnace is easily separated when discharged from the furnace and solidifies, and has high purity.
  • Metallic silicon can be produced.
  • an alkaline earth metal compound typically a calcium compound or a magnesium compound
  • metallic silicon reduced and melted in the arc furnace is more easily separated when discharged from the furnace and solidifies.
  • higher purity metal silicon can be produced.
  • the purification mechanism is such that metal silicon obtained by reducing and melting the alkaline earth metal compound in an arc furnace is removed from the furnace. Since it is easily separated when discharged and solidified, the purity of the metal silicon is suppressed, and advantageously, the calcium compound acts as a scavenger to capture and remove phosphorus and boron in the metal silicon. It is estimated that the impurity concentration of phosphorus and boron can be reduced.
  • the effect of removing phosphorus, boron and the like is, for example, applied to semiconductors, solar cells, etc. in which impurities such as phosphorus and boron adversely affect the obtained metal silicon (for example, polycrystalline silicon obtained by further refining the silicon). It is effective when used for applications.
  • the silica sand granule having the above-mentioned excellent characteristics can be efficiently produced with low energy by a simple method.
  • the silica sand granule of the present invention is formed from silica sand and has an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N.
  • the silica sand granule of the present invention has a crushing strength of 200 N or more while mainly containing silica sand.
  • the crushing strength is less than 200 N, the strength as a substitute for silica is insufficient, and, for example, in a raw material layer of an arc furnace in metal silicon production, there is a risk of collapsing due to a load from the top due to the deposition of the raw material. I can't.
  • the range of the crushing strength is preferably 500 N to 50,000 N, more preferably 1,000 N to 50,000 N, and preferably 1,000 N to 10,000 N. Also good.
  • the average particle size of the silica sand granule of the present invention is 5 mm to 200 mm. If the average particle size is less than 5 mm, a sufficient space for the gas to pass through the raw material layer in the arc furnace cannot be secured. It is disadvantageous in terms of cost and productivity to produce a granulated product.
  • the average particle diameter is preferably 5 mm to 150 mm, more preferably 30 mm to 150 mm, and still more preferably 50 mm to 150 mm.
  • the average particle size may be preferably 5 mm to 100 mm, more preferably 10 mm to 70 mm, and still more preferably 15 mm to 50 mm.
  • the average particle size of the granulated material of the present invention is a number average particle size obtained by sampling 50 randomly extracted granulated materials and calculating the arithmetic average of the particle sizes.
  • the SiO 2 content is preferably 90% by weight to 99.9% by weight. That is, when the SiO 2 content is less than 90% by weight, an excess of an alkaline earth metal component, for example, a calcium component or a magnesium component, which acts as a binder used as necessary, as described later, and other impurities. For example, when used as a raw material for producing metal silicon, there is a concern that the purity of the obtained metal silicon may be reduced.
  • an alkaline earth metal component for example, a calcium component or a magnesium component
  • organic components such as a resin added as a binder component also remain as impurities. There is. Such an organic component impurity is also considered to be a problem when used as a raw material for producing metal silicon, for example, so it is desirable to consider it as the above-mentioned impurity.
  • an alkaline earth metal compound as described later typically a calcium compound or a magnesium compound
  • the SiO 2 content is preferably 90% by weight or more and 99.9% by weight or less. . A more preferable range of the SiO 2 content is 94% by weight to 99.5% by weight.
  • the silica sand granule of the present invention contains alkali metal atoms derived from impurities contained in the raw material to some extent, cristobaliteization progresses during the heat treatment described later, resulting from a density difference.
  • the granulated body itself tends to self-destruct due to expansion. Therefore, the ratio of alkali metal atoms to Si atoms (M 1 / Si) contained in the silica sand granule is preferably less than 0.01.
  • the method for producing a silica sand granule according to the present invention is characterized in that silica sand is molded and granulated.
  • the silica sand used in the above production method of the present invention is not particularly limited as long as the silica sand can be molded. However, considering that the silica sand granule obtained by the present invention can typically be used as a raw material for metal silicon, the silica sand
  • the SiO 2 content is preferably 97% by weight or more, particularly preferably 98% or more, more preferably 99% by weight or more, and further preferably 99.5% by weight or more.
  • the average particle size of the silica sand is preferably 1000 ⁇ m or less, more preferably 200 ⁇ m or less, and even more preferably 150 ⁇ m or less.
  • the average particle size of the silica sand is preferably 5 ⁇ m or more, more preferably 20 ⁇ m or more, and even more preferably 50 ⁇ m or more.
  • the average particle size of the silica sand is particularly preferably adjusted by pulverization or the like so as to be preferably 1 ⁇ m to 200 ⁇ m, more preferably 5 ⁇ m to 150 ⁇ m.
  • silica sand particle size is reduced, silanol groups on the particle surface increase, and the interparticle bonding force in the granulated body structure tends to increase accordingly.
  • the smaller the average particle size the more energy is required for grinding.
  • the said silica sand can use what has a particle size in the range below 1400 micrometers from a viewpoint of improving granulation property.
  • the use of silica sand having a relative particle amount (weight) of 25% to 70% within a particle size range of less than 75 ⁇ m is due to the action of the binder and a high-strength granule by heat treatment at a low temperature. Is particularly preferable.
  • the particle size of the silica sand combined with the above-mentioned small particle size particles is not particularly limited, but as a raw material silica sand, from the viewpoint of being able to use uncrushed or lightly crushed silica sand, A particle having a relative particle amount in the range of 150 ⁇ m or more and less than 1400 ⁇ m is preferably 10% to 50%.
  • the total relative particle amount of the fine silica sand and the silica sands having a particle size of 150 ⁇ m or more and less than 1400 ⁇ m is more preferably 60% or more, particularly 70% or more.
  • the silica sand whose average particle diameter is adjusted to 200 ⁇ m or less, more preferably 150 ⁇ m or less by pulverization can also exhibit high strength.
  • the average particle diameter of silica sand is a median diameter determined on a volume basis determined by laser diffraction / scattering particle size analysis measurement.
  • the relative particle amount and the particle size distribution of the silica sand were determined with a sieve as shown in the examples.
  • the pulverization of the silica sand can be carried out using a known pulverizer.
  • the pulverizer include a screw mill described in Tables 1 and 10 on pages 503 to 505 of the powder engineering manual (edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun).
  • Powder layer striking crushers such as stamp mills, high speed rotary impact crushers such as disc mills, pin mills, screen mills, hammer mills, centrifugal classification mills, roll rolling crushers such as roller mills, ball mills, vibrations Ball mills such as ball mills and planetary pulverizers; tower pulverizers, stirred tank pulverizers, flow-tube pulverizers, annular pulverizers and other medium agitation pulverizers, and jet pulverizers.
  • a pulverizer that requires less energy for pulverization and contains fewer impurities during pulverization is preferable.
  • Examples of such a pulverizer include a medium agitating pulverizer, a ball ball mill such as a vibration ball mill, a rotary ball mill, and a planetary pulverizer, and a roll rolling pulverizer such as a roller mill.
  • the ball medium mill can be finely pulverized and is suitable for mass processing, and the roll-rolling pulverizer has little contamination and a large processing capacity. Therefore, each pulverizer may be used in accordance with the intended pulverized product.
  • the silica sand is preferably molded using an alkaline earth metal compound as a binder.
  • a silica sand granule using such an alkaline earth metal compound as a binder can be produced by bringing an alkaline earth metal compound such as a calcium compound or a magnesium compound into contact with the surface of the silica sand for granulation.
  • Silica sand granule obtained using an alkaline earth metal compound, for example, calcium compound or magnesium compound as a binder is mainly composed of silica sand, and the alkaline earth metal compound is bound by a reaction product of the binder between them. It is a thing.
  • a reaction product is presumed to be an alkaline earth metal silicate, such as calcium silicate, produced by reacting an alkaline earth metal compound with the SiO 2 component on the surface of the silica sand particles.
  • alkaline earth metal compounds calcium compounds, magnesium compounds, and mixtures thereof are preferable in that they are more easily available than other alkaline earth metal compounds in consideration of industrial applications.
  • Examples of the calcium compound include calcium hydroxide, calcium carbonate, calcium oxide, calcium sulfate, and mixtures thereof. These calcium compounds are suitable for increasing the strength of the granulated product obtained by the present invention. Among these, calcium hydroxide, calcium carbonate or a mixture thereof is preferably used. These exhibit alkalinity upon contact with water, increase the reactivity with SiO 2, and contribute to increasing the strength of the granulated body.
  • magnesium compound examples include magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium sulfate, and mixtures thereof.
  • magnesium hydroxide, magnesium carbonate or a mixture thereof is preferably used. These are suitable for increasing the strength of the granulated product obtained by the present invention by exhibiting alkalinity upon contact with water and increasing the reactivity with SiO 2 .
  • the particle size of the alkaline earth metal compound such as calcium compound or magnesium compound is preferably 0.001 ⁇ m to 20 ⁇ m, more preferably 0.001 ⁇ m to 10 ⁇ m.
  • the particle size of the alkaline earth metal compound such as calcium compound or magnesium compound is particularly preferably 0.1 ⁇ m to 20 ⁇ m, and more preferably 1 ⁇ m to 10 ⁇ m.
  • alkaline earth metal compound particles, typically calcium compound particles or magnesium compound particles are agglomerated, a part or all of the agglomerates can be released in the mixing process described later, so that they can be used without problems. it can.
  • the addition ratio of the alkaline earth metal compound is preferably 0.1 to 5 parts by weight, and 0.5 to 3 parts by weight with respect to 100 parts by weight of silica sand. It is more preferable.
  • Alkaline earth metal compounds, typically calcium compounds or magnesium compounds need only be added in an amount sufficient to cover the surface of the silica sand, and the use of higher amounts may increase the amount of impurities. Moreover, even if the amount of the alkaline earth metal compound used is increased, even if a silica sand granule having a crushing strength exceeding 100,000 N is obtained, not only the quality is excessive, but a great deal of energy is required in the production. It is not industrial because it requires it.
  • silica sand is mainly used.
  • the ratio of alkaline earth metal atoms to Si atoms (M 2 / Si ) Is preferably 0.001 to 0.04, more preferably 0.004 to 0.03.
  • silica sand is mainly used.
  • the ratio of calcium atoms to Si atoms (Ca / Si) is 0. 0.001 to 0.04 is preferable, and 0.004 to 0.03 is preferable.
  • the ratio of the alkaline earth metal atom (for example, calcium atom) to the Si atom is within the above range, the purity of the silica sand granule itself can be increased while maintaining the high strength of the silica sand granule.
  • the means for bringing an alkaline earth metal compound, typically a calcium compound or a magnesium compound, into contact with the surface of the silica sand in the production method of the present invention is not particularly limited, but the alkaline earth metal compound is brought into more uniform contact with the silica sand surface.
  • an alkaline earth metal compound typically a calcium compound or a magnesium compound
  • the above mixing and granulation can be performed at room temperature, and heat treatment can be performed in a dryer or a kiln described below.
  • heat treatment can be performed in a dryer or a kiln described below.
  • granulation and heat treatment can be performed simultaneously.
  • a binder may be added to a mixture of silica sand and an alkaline earth metal compound, typically a calcium compound or magnesium compound, and water in order to improve granulation properties.
  • the binder is preferably a water-soluble organic substance.
  • water-soluble organic substances include, for example, carboxymethyl cellulose (CMC) described in Tables 1, 3, and 4 of the Granulation Handbook (edited by the Japan Powder Industry Association, published on May 30, 1975, Ohmsha).
  • CMC carboxymethyl cellulose
  • PVA Polyvinyl alcohol
  • sugar, dextrose, corn syrup and the like can be mentioned.
  • binders composed of organic substances that can be used include other starches such as dextrin, corn starch, and rice cake; proteins such as glue, casein and soybean protein; natural rubbers such as gum arabic; pitch, Tars such as processed tar and paving tar; asphalts such as straight asphalt and blown asphalt; other thermoplastic resins such as acrylic polymers, polyamide, polyethylene, and other cellulose; urea resin, melamine resin, phenol resin, furan resin And thermosetting resins such as epoxy resin, thermosetting polyester, and thermosetting polyurethane; and elastomers such as neoprene, nitrile rubber, styrene butadiene rubber, butyl rubber, and silicone rubber.
  • starches such as dextrin, corn starch, and rice cake
  • proteins such as glue, casein and soybean protein
  • natural rubbers such as gum arabic
  • pitch Tars such as processed tar and paving tar
  • asphalts such as straight asphalt and blown asphalt
  • other thermoplastic resins
  • usable inorganic binders include cements such as Portland cement, blast furnace cement, silica cement, alumina cement, fly ash, white cement, jet cement; sodium silicate 1 and sodium silicate 2 , Sodium silicate No. 3, sodium silicate No. 4, water glass such as metasilicic acid, and minerals such as clay and bentonite.
  • Granulation of a mixture of silica sand and an alkaline earth metal compound, typically a calcium compound or a magnesium compound, and water is carried out by a known method, for example, granulation manual (edited by the Japan Powder Industry Association, 1975 5). Of the methods classified in Part 1, Sections 1 and 4 (issued on May 30, Ohm), the general methods of rolling molds, compression molds and extrusion molds can be suitably employed. Since each method has a different granulation process, the best mode of each method will be described below.
  • each component of the silica sand, alkaline earth metal compound, typically calcium compound or magnesium compound, water, and optionally added binder is a.
  • each powder of silica sand, alkaline earth metal compound, and binder to be added as necessary can be generally performed using a known mixer.
  • powder engineering handbook powder engineering society, issued on February 28, 1986, Nikkan Kogyo Shimbun
  • horizontal cylindrical mixer shown in Fig. 9.1 on page 610 (with internal blades) , V-type mixers (with stirring blades), double-cone mixers and other container rotating mixers; ribbon mixers, conical screw mixers, high-speed fluid mixers, rotating disk mixers, airflow mixers
  • Examples thereof include a container-fixed mixer such as a mixer and a non-stirring mixer; and a composite mixer such as a stirring mixer (with a vibrator).
  • a kneading machine such as a powder engineering manual (edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun) 644 Various kneaders listed in Table 13.6 on page can also be used.
  • Rolling type granulation is, for example, drum type granulation described in Part II, Sections 2 and 6 of Granulation Handbook (edited by Japan Powder Industry Association, published on May 30, 1975, Ohmsha). It can be carried out by adopting a machine or a dish type granulator.
  • the dish-type granulator is preferable because the control of the granulation process is easy.
  • the dish shape of the dish-type granulator includes ordinary dish type (basket type), multi-stage dish type, spherical dish type, truncated cone type, etc., but multi-stage dish type, spherical dish type, truncated cone type, etc. Since the granulator automatically classifies the granulated material according to the difference in centrifugal force because the radius of rotation differs along the rotation axis, the granulated material having a uniform particle size is grown from the outer peripheral side of the rotating dish. Suitable for selective removal.
  • the supply of the mixed powder to the granulator is classified, for example, in Table 5.1 on page 567 of Powder Engineering Handbook (Edited by Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). However, it is preferable to use a vibration feeder, a shaking feeder, a screw feeder, a belt conveyor or the like in terms of easy control of the supply amount. In addition, the supply of the mixed powder may be performed continuously or intermittently.
  • the amount of water is a solid / liquid / gas system classified in Table 8/3 on page 599 of the Powder Engineering Handbook (Edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). It is preferable to add so that it becomes a policy area in the structure (hereinafter referred to as a filling area). This is because when the filling area is in the policy area, water intervenes between the particles and acts as a crosslinking liquid. The filling area is affected not only by the ratio of water added to the silica sand but also by the particle size of the silica sand.
  • the average particle diameter is within the above range, 10 to 30 parts by weight of water can be added to 100 parts by weight of the silica sand. It can function as a crosslinking liquid.
  • an alkaline earth metal compound such as a calcium compound or a magnesium compound or a binder is added, the addition amount is preferably 5 to 20 parts by weight with respect to 100 parts by weight of silica sand.
  • the proportion of the intermediate granule having a particle size of 20 mm or more present in the first-stage rolling granulator is preferably 30% by weight or less, more preferably 20% by weight or less, and further preferably 15% by weight. It is preferable to grow the grains so that
  • the first-stage rolling granulator By performing granulation so that the ratio of the intermediate granule of 20 mm or more existing in the first-stage rolling granulator is in the above range, it is supplied to the first-stage rolling granulator. Generation of new nuclei and grain growth occur from the mixture composed of silica sand and binder, and the number of granules can be reliably increased. In order to make the ratio of the granulated body having a particle size of 20 mm or more present in the first stage rolling granulator within the above range, the particles grown from the rolling granulator are selectively and continuously grown. You can take it out.
  • the granulated material that has undergone grain growth is present on the outer peripheral portion of a rotating dish, and therefore, an intermediate granule having a predetermined size existing on the outer peripheral portion may be taken out.
  • the intermediate granule is taken out from the first-stage rolling granulator so that the proportion of the granulated body having a particle size of 20 mm or more present in the rolling granulator becomes lower. It is desirable to do this.
  • the particle size of the granulated body existing in the first stage granulator is taken out in an excessively small state, the granulated grains are grown when further grain growth is performed in the next stage rolling granulator.
  • the intermediate granulated body may be destroyed by the body, and the production efficiency per unit granulator may be reduced.
  • an intermediate granule having an average particle diameter of 10 mm or more, more preferably 15 mm or more, and further preferably 20 mm or more from the first stage rolling granulator it is desirable to take out an intermediate granule having an average particle diameter of 10 mm or more, more preferably 15 mm or more, and further preferably 20 mm or more from the first stage rolling granulator.
  • the particle size of the intermediate granule taken out from the first-stage rolling granulator is too large, the ratio of the granulated body of 20 mm or more in the granulator tends to exceed the above range.
  • the condition for taking out the granulated body of the specific size from the first stage rolling granulator is that the ratio of the granulated body of 20 mm or more is within the above range, preferably the average particle size of the intermediate granulated body is the above What is necessary is just to set beforehand extraction conditions, for example, the inclination of a cone of a rolling granulator, a rotation speed, etc. so that it may become a range by experiment.
  • the intermediate granule taken out from the first-stage rolling granulator is supplied to the subsequent-stage rolling granulator, and further, silica sand and a binder are added to promote grain growth.
  • a quartz sand granule having a desired average particle diameter for example, an average particle diameter of 20 mm or more, preferably 30 mm to 200 mm, more preferably 30 mm to 100 mm can be obtained.
  • the handling property tends to be further improved, and there is a sufficient gap for the gas to pass through the raw material layer made of this silica sand granule in the arc furnace. It tends to be secured.
  • the average particle size of the silica sand granule is 200 mm or less, it is more advantageous in terms of cost and productivity to produce the granule.
  • the amount of water is the moisture absorption area in the filling area classified in Table 8.3 on page 599 of the Powder Engineering Handbook (Edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). It is preferable to add so that it becomes. If the average particle size is within the above-mentioned range, it is preferable to add 1 to 20 parts by weight of water to 100 parts by weight of silica sand because the strength after molding is increased. In addition, when the binder is added, the addition amount is preferably 5 to 20 parts by weight with respect to 100 parts by weight of silica sand.
  • silica sand, alkaline earth metal compound, typically calcium or magnesium compound, water, and optionally added binder is the same as in the case of the rolling granulation described above. (The Society of Physical Engineering, published on February 28, 1986, Nikkan Kogyo Shimbun)) It can be carried out using the mixer shown in FIG. 9.1 on page 610.
  • a cylinder is filled with powder, tableting compressed by a piston, and briquetting compressing powder between two rotating rolls.
  • a granulated body can be produced using any of these methods.
  • a granulator a single tableting machine described in Part II, 4/5 of Granulation Handbook (Edited by Japan Powder Industry Association, published on May 30, 1975, Ohmsha); 1 point Examples of the rotary tableting machine include a compression type machine, a multipoint compression type machine, a multistage compression type machine, and an inclined roll type machine, and the briquette machine described in Sections 4 and 6 above.
  • the mixed powder can be supplied using a vibration feeder, a shaking feeder, a screw feeder, or the like as in the case of the rolling granulation.
  • Extrusion mold granulation Since extrusion pressure is applied in extrusion mold granulation, the amount of water is classified in Table 8.3 on page 599 of Powder Engineering Handbook (Edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). It is preferable to add so as to be a suspended region in the filled region. If the average particle size is within the above-mentioned range, it is preferable to add 5 to 25 parts by weight of water to 100 parts by weight of silica sand since the strength after molding increases. In addition, when the binder is added, the addition amount is preferably 3 to 15 parts by weight with respect to 100 parts by weight of silica sand.
  • Extrusion mold granulation is an extruding granulator classified into, for example, Part II of the Granulation Handbook (edited by the Japan Powder Industry Association, published on May 30, 1975, Ohmsha), Tables 2.3.1. Can be implemented. Specifically, screw type extrusion granulators such as pre-extrusion type and vacuum extrusion type; cylindrical die horizontal granulator, cylindrical die vertical granulator, disc type die horizontal granulator, etc.
  • Examples thereof include a roll-type extrusion granulator; a blade-type extrusion granulator such as an oscillating granulator; a self-molding extrusion granulator such as a gear-type granulator; a ram-type extrusion granulator.
  • the mixed powder can be supplied using a vibration feeder, a shaking feeder, a screw feeder, or the like as in the case of the rolling granulation.
  • the granulated body obtained by the above granulation method is preferably subjected to a heat treatment in order to further increase the strength.
  • the heat treatment temperature is preferably a temperature at which the silica sand granule is not less than the temperature at which the desired strength is exhibited and the silica sand does not melt.
  • the said heat processing temperature is 700 degreeC or more, for example, Preferably it is 1000 degreeC or more.
  • the heat treatment temperature is preferably 1600 ° C. or lower, more preferably 1300 ° C. or lower, and a temperature higher than that is economically disadvantageous.
  • this heat processing temperature can be lowered more.
  • the heat treatment temperature when the alkaline earth metal compound is used in combination may be, for example, 50 ° C. or higher. However, when water is further used in the production of the granulated body, the temperature is preferably 100 ° C. or higher, more preferably 200 ° C. or higher, from the viewpoint of efficiently removing water. Therefore, the heat treatment temperature may be appropriately determined in the range of 50 to 1600 ° C. according to the composition of the granulated body obtained by the granulation method.
  • Examples of the apparatus used for the heat treatment include a kiln described in Section 5.1 of the ceramics operation (Ceramics Reading Variety Committee, issued September 20, 1973, Ceramics Association). Specifically, as such a kiln, a flame flame corner kiln, a flame flame type round kiln, a shuttle kiln, a bell kiln discontinuous kiln; a ring kiln, a continuous chamber kiln, a continuous kiln of a tunnel kiln; a rotary kiln; An electric furnace such as a resistance furnace may be mentioned.
  • a suitable apparatus used for drying for example, a box-type dryer, a rotating machine, which is classified in 591 page of Powder Engineering Handbook (Edited by Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun) Examples include dryers.
  • the atmosphere for the heat treatment and drying may be an inert gas such as nitrogen, but may be air.
  • a known drying device or the like can be used as the heat treatment device. In this case, drying and heat treatment can be performed simultaneously.
  • the silica sand granule obtained by the production method of the present invention can be used for production of metal silicon, ferrosilicon, and silicon carbide, and is particularly suitably used for production of metal silicon by an arc furnace.
  • a silica sand granule which is a silicon source
  • silica stone which is a silicon source
  • charcoal, coke, coal, wood chips, etc. are mixed as a reducing material in an arc furnace.
  • a method of reducing and melting is mentioned.
  • the arc furnace is thoroughly mixed so as not to segregate, and the required amount is charged.
  • the tip of the electrode reaches the highest temperature due to arc discharge, and the silicon source is reduced by energization so that the ultimate temperature is 1900 ° C. to 2000 ° C., and the metal silicon melt accumulates at the bottom of the furnace.
  • the metal silicon melt collected at the bottom of the arc furnace is extracted into a ladle by opening the spout with oxygen gas or the like.
  • impurities such as calcium compounds are separated as slag by the difference in specific gravity.
  • a metallic silicon mass is obtained.
  • the method for producing the metal silicon includes a step of forming silica sand to produce a silica sand granule having an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N, and the silica sand granule. Also preferred is an aspect in which the step of supplying the arc furnace as at least a part of the silicon source to perform the reduction reaction is integrated.
  • the former requires adding a predetermined amount of iron source so as to have a desired composition.
  • the reducing material is made of carbon. A large amount is added so that the molar equivalent is 3 times or more that of silica.
  • the heating temperature also needs to be adjusted according to the object.
  • the crushing strength (N) was measured with an electric universal compression tester (MIS-225-1-16, manufactured by MARUI) having a maximum pressurization weight of 100 kN. A columnar granule was erected and placed in a compressor, and loaded in the vertical direction. The load was set to a speed at which 1% of compressive strain was generated per minute.
  • MIS-225-1-16 electric universal compression tester
  • the weight of the particles passed through the 75 ⁇ m sieve and the weight of the particles passing through the 150 ⁇ m sieve and not passing through the 75 ⁇ m sieve was measured, and the weight was measured as a ratio (% by weight) when the whole was 100% by weight.
  • Example 1 Silica sand (average particle size: 245 ⁇ m, SiO 2 content: 99.4 wt%, Na 2 O content: 0.0 wt%) was pulverized to an average particle size of 130 ⁇ m with a planetary ball mill. To 100 parts by weight of this silica sand, 1.0 part by weight of calcium hydroxide (special grade of Wako Pure Chemicals) and 16.7 parts by weight of water were added and mixed well in a mortar. This mixture was transferred to a mold having an inner diameter of 20 mm and granulated under pressure at a pressure of about 6 MPa. The columnar granule taken out from the mold was dried at 150 ° C. in a blower dryer.
  • calcium hydroxide special grade of Wako Pure Chemicals
  • the weight of the obtained cylindrical granule was weighed, and the diameter and height were measured. And the average particle diameter and apparent density of the granulated body were calculated from these values. Furthermore, after measuring the SiO 2 content by elemental analysis, the crushing strength was evaluated. The results are summarized in Table 1.
  • Example 2-5 In addition to the 150 ° C. heat treatment of Example 1, a granulated body was obtained in exactly the same manner as in Example 1 except that the heat treatment was carried out in air in an electric furnace at the temperature shown in Table 1. The obtained granule was subjected to the same measurement as in Example 1. The results of various measurements are summarized in Table 1.
  • Example 6 and 7 A granulated material was obtained in exactly the same manner as in Example 3 except that the addition ratio of calcium hydroxide was changed as shown in Table 1. The results of various measurements are summarized in Table 1.
  • Example 8 Pressure granulation was performed in the same manner as in Example 1 using silica sand ground to an average particle size of 7 ⁇ m with a planetary ball mill. This cylindrical granule was subjected to various measurements similar to those in Example 1 by heat treatment only at 150 ° C. in a blower dryer. The results are summarized in Table 1.
  • Example 9-12 In addition to the heat treatment at 150 ° C. in Example 8, a granulated product was obtained in exactly the same manner as in Example 8, except that the heat treatment was performed in air in an electric furnace at the temperature shown in Table 1. The results of various measurements are summarized in Table 1.
  • Example 13 A granulated product was obtained in exactly the same manner as in Example 9, except that the addition ratio of calcium hydroxide was changed to 0.1 parts by weight as shown in Table 1. The results of various measurements are summarized in Table 1.
  • Comparative Example 4 A granulated body was obtained in the same manner as in Example 9 except that the calcium compound was not added. The results of various measurements are summarized in Table 1.
  • Example 14 Granules that were not pulverized by a planetary ball mill, that is, heat treated at 1500 ° C. in exactly the same manner as in Example 5 except that silica sand (average particle size 245 ⁇ m, SiO 2 content 99.4 wt%) was used. Got. The results of various measurements are summarized in Table 1.
  • Example 15 A granulated product was obtained in exactly the same manner as in Example 14, except that the addition ratio of calcium hydroxide was changed to 5.0 parts by weight as shown in Table 1. The results of various measurements are summarized in Table 1.
  • Comparative Example 5 A granulated body was obtained in the same manner as in Example 14 except that the calcium compound was not added. The results of various measurements are summarized in Table 1.
  • Example 16 Silica sand (average particle size 245 ⁇ m, SiO 2 content 99.4 wt%, Na 2 O content 0.0 wt%) was pulverized to an average particle size of 138 ⁇ m with a planetary ball mill. To 100 parts by weight of this silica sand, 1.4 parts by weight of calcium carbonate (special grade of Wako Pure Chemicals) and 20.8 parts by weight of water were added and mixed well in a mortar. This mixture was transferred to a mold having an inner diameter of 20 mm and granulated under pressure at a pressure of about 6 MPa. The columnar granule taken out from the mold was dried at 150 ° C. in a blower dryer, and subsequently heat-treated at 1100 ° C.
  • calcium carbonate special grade of Wako Pure Chemicals
  • Example 17 Granules were obtained in exactly the same manner as in Example 17 except that the heat treatment temperature was changed to 1300 ° C. as shown in Table 1. The results of various measurements are summarized in Table 1.
  • Example 18 Evaluation was performed in the same manner as in Example 3 except that the binder was 1.8 parts by weight of calcium sulfate. The results are summarized in Table 2.
  • Example 19 Evaluation was performed in the same manner as in Example 4 except that the binder was changed to 1.8 parts by weight of calcium sulfate. The results are summarized in Table 2.
  • Example 20 Evaluation was performed in the same manner as in Example 3 except that the binder was changed to 0.8 parts by weight of magnesium hydroxide. The results are summarized in Table 2.
  • Example 21 Evaluation was performed in the same manner as in Example 4 except that 0.8 parts by weight of magnesium hydroxide was used as the binder. The results are summarized in Table 2.
  • Example 24 Evaluation was performed in the same manner as in Example 3 except that the silica sand used was silica sand (average particle size 252 ⁇ m, SiO 2 content 98.2 wt%, Na 2 O content 1.5 wt%). The results are summarized in Table 3.
  • Examples 25-33 Silica sand (average particle size 245 ⁇ m, SiO 2 content 99.4 wt%, Na 2 O content 0.0 wt%) was pulverized to an average particle size of 18 ⁇ m with a planetary ball mill. It was mixed with unground crushed silica sand at a predetermined ratio and evaluated. The results are shown in Table 4.
  • Example 34 The silica sand granulate produced in Example 4 and calcined coke having an average particle diameter of 5 mm were mixed at a weight ratio of 2: 1, and a total of 30 kg of raw materials were used in an ER type arc furnace (manufactured by Ando Kogyosho). Heat treatment was performed. The internal temperature during operation was measured with a radiation thermometer and operated at 2000 ° C. for 6 hours. After completion of heating, cooling was performed for 16 hours, and a sample was taken out. 5 kg of high-purity metallic silicon lump was obtained at the bottom of the sample.
  • silica sand granule of the present invention can be effectively used for the production of metallic silicon, silicon alloys such as ferrosilicon, and silicon carbide as an alternative to silica stone.

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Abstract

In order to substitute for silica stone that is usually used as a material when metallurgical silicon is produced, provided are a granulated body of silica sand that has a sufficient size and strength to be treated in the same manner as in the silica stone, and a method for efficiently producing the granulated body. The granulated body of silica sand is characterized in that the silica sand is formed by using a calcium compound as a bonding agent, and the granulated body has an average particle diameter of 5 to 100 mm and a crushing strength of 200 to 100,000 N. The granulated body of silica sand can be obtained by bringing the calcium compound into contact with the surface of silica sand to granulate.

Description

珪砂造粒体およびその製造方法Silica sand granule and method for producing the same
　本発明は、新規な珪砂造粒体に関する。詳しくは、金属シリコンを製造する際に原料として通常使用されている珪石同様の扱いができる性状を有し、金属シリコンの製造において、珪石と代替が可能な珪砂造粒体およびその製造方法を提供するものである。 The present invention relates to a novel silica sand granule. More specifically, the present invention provides a silica sand granule that has properties that can be handled in the same way as silica stone that is normally used as a raw material when manufacturing metal silicon, and that can replace silica in the manufacture of metal silicon, and a method for manufacturing the same. To do.
　一般に金属シリコンは、原料にシリコン源である珪石、および還元材として木炭、コークス、石炭、ウッドチップなどを使用し、これらの混合物をアーク炉内約２０００℃で珪石を還元することによって得られる。上記珪石は、通常５ｍｍ～２００ｍｍのサイズのものが用いられる。これは炉内の通気性を確保するためである。即ち、上記アーク炉においては、珪石の還元反応の過程で、気相として一酸化炭素（ＣＯ）ガスおよび一酸化珪素（ＳｉＯ）ガスが発生するため、それらの全部または一部を、上記原料層を通して逃がす必要がある。 Generally, metallic silicon is obtained by reducing silica at about 2000 ° C. in an arc furnace using silica, which is a silicon source, and charcoal, coke, coal, wood chips, etc. as a reducing material. The silica stone is usually 5 mm to 200 mm in size. This is to ensure air permeability in the furnace. That is, in the arc furnace, carbon monoxide (CO) gas and silicon monoxide (SiO) gas are generated as a gas phase in the process of the reduction reaction of the silica, so that all or a part of them is used as the raw material layer. Need to escape through.
　上記珪石の主成分である二酸化珪素（ＳｉＯ２）の還元反応は、総括的には次の式（１）によって進行する。
ＳｉＯ２＋２Ｃ→Ｓｉ＋２ＣＯ　（１）
　しかし、実際には反応は複雑であり以下のような各素反応に分解され、これらの素反応が併行して起こっているものと考えられる。 The reduction reaction of silicon dioxide (SiO 2 ), which is the main component of the silica, generally proceeds according to the following formula (1).
SiO 2 + 2C → Si + 2CO (1)
However, in reality, the reaction is complicated and is decomposed into the following elementary reactions, and these elementary reactions are considered to occur in parallel.
　ＳｉＯ２＋Ｃ→ＳｉＯ＋ＣＯ　　　（２）
　ＳｉＯ＋２Ｃ→ＳｉＣ＋ＣＯ　　　（３）
　ＳｉＯ２＋３Ｃ→ＳｉＣ＋２ＣＯ　　（４）
　ＳｉＯ＋ＳｉＣ→２Ｓｉ＋ＣＯ　　　（５）
　ＳｉＯ２＋２ＳｉＣ→３Ｓｉ＋２ＣＯ　（６）
　ＳｉＯ＋Ｃ→Ｓｉ＋ＣＯ　　　　（７）
　ＳｉＣ＋ＳｉＯ２→Ｓｉ＋ＳｉＯ＋ＣＯ　（８）
　Ｓｉ＋ＳｉＯ２→２ＳｉＯ　　　　（９）
　このように、アーク炉内温度範囲での凝縮相はＳｉＯ２、Ｃ、ＳｉＣ、Ｓｉであり、気相はＣＯ、ＳｉＯである。また、炉内電極先端付近の高温部から式（２）の反応によりＳｉＯガスが発生する。そして、原料層の上部では、層の隙間を生成したＳｉＯガスやＣＯガスが上昇し排出される際、その通路である隙間の壁面には次の反応で析出物が付着する。 SiO 2 + C → SiO + CO (2)
SiO + 2C → SiC + CO (3)
SiO 2 + 3C → SiC + 2CO (4)
SiO + SiC → 2Si + CO (5)
SiO 2 + 2SiC → 3Si + 2CO (6)
SiO + C → Si + CO (7)
SiC + SiO 2 → Si + SiO + CO (8)
Si + SiO 2 → 2SiO (9)
Thus, the condensed phase in the arc furnace temperature range is SiO 2 , C, SiC, Si, and the gas phase is CO, SiO. In addition, SiO gas is generated from the high temperature portion near the tip of the in-furnace electrode by the reaction of formula (2). In the upper part of the raw material layer, when the SiO gas or CO gas that generated the gap between the layers rises and is discharged, precipitates adhere to the wall surface of the gap that is the passage by the following reaction.
　３ＳｉＯ＋ＣＯ→ＳｉＯ２＋ＳｉＣ　　（１０）
　２ＳｉＯ→Ｓｉ＋ＳｉＯ２　　　　（１１）　
　一方、珪砂は珪石に比べて資源量が豊富であり、加えて採掘も容易であるので、金属シリコンの原料として珪石を代替できれは大きな利点となり得る。 3SiO + CO → SiO 2 + SiC (10)
2SiO → Si + SiO 2 (11)
On the other hand, quartz sand has abundant resources compared to quartz stone, and in addition, it is easy to mine, so it can be a great advantage to replace quartz stone as a raw material for metallic silicon.
　しかしながら、珪砂を原料にすると珪石に比べて空隙が少なくなり、前述の式（１０）、（１１）の反応により析出物が付着すると、上記珪石に比べて空隙の減少が著しく、アーク炉での反応において生成するＣＯやＳｉＯのガス抜けを困難にすることが危惧される。また、式（２）～（８）からわかるようにＣＯが滞留してしまうと反応の進行が阻害されることになる。それは、ＳｉＣが炉底に沈着固化して操業トラブルの原因にもなる。 However, when silica sand is used as a raw material, the number of voids is smaller than that of silica stone, and when deposits are deposited due to the reactions of the above-described formulas (10) and (11), the voids are significantly reduced compared with the above-mentioned silica stone. It is feared that it is difficult to escape the gas of CO and SiO generated in the reaction. Further, as can be seen from the formulas (2) to (8), if the CO stays, the progress of the reaction is hindered. That is, SiC is deposited on the bottom of the furnace and causes operational troubles.
　従って、アーク炉に供給する金属シリコンの原料としては、珪石と同等の大きさ、強度を有する性状に珪砂を造粒することが必要となる。 Therefore, it is necessary to granulate silica sand as a raw material for metallic silicon to be supplied to the arc furnace to have a size and strength equivalent to that of silica stone.
　これに対して、特許文献１には、珪砂を、石油コークスおよびピッチ含有結合剤のような非焼結炭素担体と混合して固め、生ペレットとし、これを硬化加熱処理してアーク炉への装填原料ペレットを形成することが記載されている。 On the other hand, in Patent Document 1, silica sand is mixed with a non-sintered carbon carrier such as petroleum coke and a pitch-containing binder and hardened to obtain green pellets, which are cured and heat-treated to give an arc furnace. It is described to form a charge pellet.
　しかしながら、上記硬化加熱処理による結合剤の不融化は、表面より進行するので、ペレットサイズが大きくなると内部まで不融化することが困難であり、これをアーク炉内へ装填原料として投入した場合、温度が上がるにつれてペレット内部の不融化されていないピッチが軟化して圧壊強度が低下し、ペレット崩壊の恐れがある。そして、ペレットの崩壊により、原料層内部の通気性が低下し、アーク炉での反応において生成するＣＯやＳｉＯのガス抜けを困難にする。 However, since the infusibilization of the binder by the curing heat treatment proceeds from the surface, it is difficult to infusibilize the inside as the pellet size increases. As the pitch rises, the infusibilized pitch inside the pellets softens, the crushing strength decreases, and the pellets may collapse. And the collapse | disintegration of a pellet reduces the air permeability inside a raw material layer, and makes it difficult for the gas escape of CO and SiO produced | generated in reaction in an arc furnace.
特公平０５－０００３３５号公報Japanese Patent Publication No. 05-000335
　従って、本発明は、金属シリコンを製造する際に原料として通常使用されている珪石を代替するために、珪石と同様の扱いができるようなサイズと強度を有した珪砂造粒体と、それを効率的に製造するための方法を提供することを目的とする。 Therefore, the present invention replaces the silica usually used as a raw material in the production of metal silicon, and has a silica sand granule having a size and strength that can be handled in the same manner as silica. It aims at providing the method for manufacturing efficiently.
　本発明者らは、上記目的に対して鋭意研究の結果、特定の平均粒径および圧壊強度を有する珪砂造粒体によればかかる目的が達成されること、
造粒体構造において珪砂粒子間にＳｉＯ２と反応性を有する無機質物質を介在させれば、比較的低温の加熱処理でも強度を高めることができ、また、高温での強度低下の問題も解決し得るとの知見を得、上記無機質物質としてアルカリ土類金属化合物、典型的には、カルシウム化合物またはマグネシウム化合物を選択することにより、かかる目的を達成し、しかも、アルカリ土類金属化合物の使用により、これを上記シリコン製造用原料として使用した場合、得られる金属シリコンの純度を著しく向上させることが出来ることを見出し、本発明を完成するに至った。 As a result of intensive studies on the above object, the present inventors have achieved this object according to the silica sand granule having a specific average particle diameter and crushing strength,
If an inorganic substance having reactivity with SiO 2 is interposed between silica sand particles in the granule structure, the strength can be increased even by heat treatment at a relatively low temperature, and the problem of strength reduction at a high temperature can be solved. By obtaining an alkaline earth metal compound, typically a calcium compound or a magnesium compound as the inorganic substance, the above object is achieved, and the use of the alkaline earth metal compound When this was used as the raw material for silicon production, it was found that the purity of the metal silicon obtained can be remarkably improved, and the present invention has been completed.
　即ち、本発明の珪砂造粒体は、珪砂から成形されており、平均粒径が５ｍｍ～２００ｍｍ、圧壊強度が２００Ｎ～１００，０００Ｎであることを特徴とする。 That is, the silica sand granule of the present invention is formed from silica sand and has an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N.
　上記珪砂造粒体において、アルカリ土類金属化合物を結合剤として用いて成形されていることが好ましい。このアルカリ土類金属化合物としては、カルシウム化合物、マグネシウム化合物またはそれらの混合物が好ましい。 The silica sand granule is preferably molded using an alkaline earth metal compound as a binder. As the alkaline earth metal compound, a calcium compound, a magnesium compound or a mixture thereof is preferable.
　アルカリ土類金属化合物を結合剤として用いた珪砂造粒体において、Ｓｉ原子に対するアルカリ土類金属原子の比（Ｍ２／Ｓｉ）は、０．００１～０．０４であることが珪砂造粒体の高い強度を維持しつつ、珪砂造粒体自体の純度を高めるために好ましい。例えば、カルシウム化合物を結合剤として用いた珪砂造粒体において、Ｓｉ原子に対するカルシウム原子の比（Ｃａ／Ｓｉ）は、０．００１～０．０４であることが珪砂造粒体の高い強度を維持しつつ、珪砂造粒体自体の純度を高めるために好ましい。 In the silica sand granule using an alkaline earth metal compound as a binder, the ratio of the alkaline earth metal atom to the Si atom (M 2 / Si) is 0.001 to 0.04. It is preferable in order to increase the purity of the silica sand granule itself while maintaining the high strength. For example, in a silica sand granule using a calcium compound as a binder, the ratio of calcium atoms to Si atoms (Ca / Si) is 0.001 to 0.04 to maintain the high strength of the silica sand granule. However, it is preferable for increasing the purity of the quartz sand granule itself.
　本発明において、上記珪砂造粒体を構成する珪砂のＳｉＯ２含有量は９７重量％以上であることが好ましい。 In the present invention, SiO 2 content of silica sand constituting the silica sand granule is preferably at least 97% by weight.
　また、上記珪砂は、粒径が１４００μｍ未満の範囲にあるものが好適に使用できる。
　中でも、粒径７５μｍ未満の範囲にある相対粒子量（重量）が２５％～７０％の珪砂を使用することは、前記結合材との作用により、低温度の加熱処理で高強度の造粒体を得ることができ、特に好ましい。更に、粒径１５０μｍ以上、１４００μｍ未満の範囲にある相対粒子量が１０％～５０％であるものは、原料珪砂として、未粉砕、或いは、軽度な粉砕による処理で、一部の珪砂を使用することが出来、経済的である。
　ただし、１４００μｍ未満の範囲にある相対粒子量は１００％である。 Moreover, the said silica sand can use a thing with a particle size in the range below 1400 micrometers suitably.
Among them, the use of silica sand having a relative particle amount (weight) of 25% to 70% within a particle size range of less than 75 μm is due to the action of the binder and a high-strength granule by heat treatment at a low temperature. Is particularly preferable. Furthermore, when the relative particle amount is in the range of 150 μm or more and less than 1400 μm and the relative particle amount is 10% to 50%, some silica sand is used as raw material silica sand by unpulverized or mild pulverization. Can be economical.
However, the relative particle amount in the range of less than 1400 μm is 100%.
　上記珪砂造粒体において、珪砂造粒体に含まれるＳｉ原子に対するアルカリ金属原子の比（Ｍ１／Ｓｉ）が０．０１未満であることが好ましい。 In the silica sand granule, the ratio of alkali metal atoms to Si atoms (M1 / Si) contained in the silica sand granule is preferably less than 0.01.
　上記珪砂造粒体は、珪砂を造粒して、平均粒径が５ｍｍ～２００ｍｍ、圧壊強度が２００Ｎ～１００，０００Ｎとすることにより製造することができる。 The silica sand granule can be produced by granulating silica sand to have an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N.
　上記珪砂造粒体は、好ましくは、珪砂の表面にカルシウム化合物などのアルカリ土類金属化合物を接触せしめて造粒することによって製造することができる。 The above-mentioned silica sand granule can be preferably produced by bringing an alkaline earth metal compound such as a calcium compound into contact with the surface of the silica sand for granulation.
　この場合、上記珪砂とカルシウム化合物などのアルカリ土類金属化合物との接触を水の存在下に行なって造粒した後、造粒体を１００℃～１６００℃の温度に加熱することが得られる珪砂造粒体の強度をより向上させるために好ましい。 In this case, the silica sand is obtained by granulating by contacting the silica sand with an alkaline earth metal compound such as a calcium compound in the presence of water, and then heating the granulated body to a temperature of 100 ° C. to 1600 ° C. This is preferable for further improving the strength of the granulated body.
　また、上記アルカリ土類金属化合物としては、水酸化カルシウム、炭酸カルシウム、酸化カルシウム、硫酸カルシウム等のカルシウム化合物、水酸化マグネシウム、炭酸マグネシウム、酸化マグネシウム、硫酸マグネシウム等のマグネシウム化合物またはそれらの混合物が好適に使用される。 Further, as the alkaline earth metal compound, calcium compounds such as calcium hydroxide, calcium carbonate, calcium oxide and calcium sulfate, magnesium compounds such as magnesium hydroxide, magnesium carbonate, magnesium oxide and magnesium sulfate, or a mixture thereof are suitable. Used for.
　更に、上記製造方法においては、カルシウム化合物などのアルカリ土類金属化合物の使用割合が珪砂１００重量部に対して０．１重量部～５重量部であることが好ましい。 Furthermore, in the above production method, it is preferable that the use ratio of an alkaline earth metal compound such as a calcium compound is 0.1 to 5 parts by weight with respect to 100 parts by weight of silica sand.
　また、本発明において使用する珪砂は、粉砕により平均粒径１μｍ～２００μｍの範囲に調整されたものを使用することも可能である。 In addition, the silica sand used in the present invention can be adjusted to an average particle diameter of 1 μm to 200 μm by pulverization.
　本発明の珪砂造粒体は、金属シリコン、フェロシリコンまたは炭化珪素の製造におけるシリコン源として好適に使用される。 The silica sand granule of the present invention is suitably used as a silicon source in the production of metallic silicon, ferrosilicon or silicon carbide.
　特に、金属シリコンの製造方法としては、本発明の珪砂造粒体を、シリコン源の少なくとも一部としてアーク炉へ供給して還元反応を行なう方法が好適に採用される。また、金属シリコンの製造方法としては、珪砂を成形して平均粒径が５ｍｍ～２００ｍｍ、圧壊強度が２００Ｎ～１００，０００Ｎである珪砂造粒体を作製する工程、およびその珪砂造粒体を、シリコン源の少なくとも一部としてアーク炉へ供給して還元反応を行なう工程を含む方法が挙げられる。 In particular, as a method for producing metal silicon, a method in which the silica sand granule of the present invention is supplied to an arc furnace as at least a part of a silicon source and a reduction reaction is suitably employed. In addition, as a method for producing metal silicon, a step of forming silica sand to form a silica sand granule having an average particle size of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N, and the silica sand granule, Examples thereof include a method including a step of performing a reduction reaction by supplying at least part of a silicon source to an arc furnace.
　本発明の珪砂造粒体は、圧壊強度は２００Ｎ以上を達成し、かかる強度によりアーク炉内原料層に装填した場合に、珪石と同様に扱っても上部からの荷重により崩壊することがなく、上記層における空隙を確実に確保することができる。しかも、高温下においても、上記強度の大幅な低下が無く、反応を安定して行なうことが可能である。 The silica sand granule of the present invention achieves a crushing strength of 200 N or more, and when loaded into the raw material layer in the arc furnace with such strength, it does not collapse due to the load from the top even if handled in the same manner as silica stone, It is possible to ensure the voids in the layer. In addition, even at high temperatures, the strength is not significantly reduced, and the reaction can be performed stably.
　上記珪砂造粒体の高強度化は、典型的には、アルカリ土類金属化合物、例えばカルシウム化合物またはマグネシウム化合物を結合剤として用いて造粒されることにより、アルカリ土類金属が珪砂粒子表面でＳｉＯ２成分と反応し、その反応生成物である珪酸カルシウムが珪砂粒子間を強く結びつけることによるものと推定される。 Typically, the strength of the above-mentioned silica sand granule is increased by granulating using an alkaline earth metal compound such as a calcium compound or a magnesium compound as a binder, so that the alkaline earth metal is present on the surface of the silica sand particle. It is presumed that calcium silicate which is a reaction product reacts with the SiO 2 component and strongly binds the silica sand particles.
　また、本発明で得られた珪砂造粒体を金属シリコンの原料として使用した場合、アーク炉内で還元・溶融した金属シリコンが炉から排出されて凝固する際に分離され易く、しかも、高純度の金属シリコンを製造することができる。特に、アルカリ土類金属化合物、典型的には、カルシウム化合物またはマグネシウム化合物を結合剤に使用することにより、アーク炉内で還元・溶融した金属シリコンが炉から排出されて凝固する際により分離され易く、しかも、より高純度の金属シリコンを製造できる。 In addition, when the silica sand granule obtained in the present invention is used as a raw material for metallic silicon, the metallic silicon reduced and melted in the arc furnace is easily separated when discharged from the furnace and solidifies, and has high purity. Metallic silicon can be produced. In particular, by using an alkaline earth metal compound, typically a calcium compound or a magnesium compound, as a binder, metallic silicon reduced and melted in the arc furnace is more easily separated when discharged from the furnace and solidifies. Moreover, higher purity metal silicon can be produced.
　アルカリ土類金属化合物、典型的には、カルシウム化合物またはマグネシウム化合物を結合剤に使用した場合の高純度化の機構は、アルカリ土類金属化合物がアーク炉内で還元・溶融した金属シリコンが炉から排出されて凝固する際に分離され易いため、金属シリコンの純度低下が抑制されると共に、好都合なことに、カルシウム化合物は金属シリコンの中のリンやホウ素を捕獲除去するスカベンジャーとして作用し、金属シリコン中のリンやホウ素の不純物濃度を低減することができるものと推定される。 When an alkaline earth metal compound, typically a calcium compound or a magnesium compound, is used as a binder, the purification mechanism is such that metal silicon obtained by reducing and melting the alkaline earth metal compound in an arc furnace is removed from the furnace. Since it is easily separated when discharged and solidified, the purity of the metal silicon is suppressed, and advantageously, the calcium compound acts as a scavenger to capture and remove phosphorus and boron in the metal silicon. It is estimated that the impurity concentration of phosphorus and boron can be reduced.
　上記リンおよびホウ素などを除去する効果は、例えば、得られる金属シリコン（例えば、これをさらに精製して得られる多結晶シリコン）を、リン、ホウ素などの不純物が悪影響及ぼす半導体、太陽電池等への用途に使用する場合において有効である。 The effect of removing phosphorus, boron and the like is, for example, applied to semiconductors, solar cells, etc. in which impurities such as phosphorus and boron adversely affect the obtained metal silicon (for example, polycrystalline silicon obtained by further refining the silicon). It is effective when used for applications.
　また、本発明の珪砂造粒体の製造方法によれば、上記の優れた特徴を有する珪砂造粒体を、簡易な方法により、低いエネルギーで効率よく製造することができる。 Moreover, according to the method for producing a silica sand granule of the present invention, the silica sand granule having the above-mentioned excellent characteristics can be efficiently produced with low energy by a simple method.
　本発明の珪砂造粒体は、珪砂から成形されており、平均粒径が５ｍｍ～２００ｍｍ、圧壊強度が２００Ｎ～１００，０００Ｎであることを特徴とする。 The silica sand granule of the present invention is formed from silica sand and has an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N.
　本発明の珪砂造粒体は、珪砂を主体としながらも、圧壊強度２００Ｎ以上を有する。上記圧壊強度が２００Ｎより小さい場合、珪石の代替としての強度が不足し、例えば、金属シリコン製造におけるアーク炉の原料層において、原料の堆積による上部からの荷重で崩壊する虞があり、実用に供することができない。 The silica sand granule of the present invention has a crushing strength of 200 N or more while mainly containing silica sand. When the crushing strength is less than 200 N, the strength as a substitute for silica is insufficient, and, for example, in a raw material layer of an arc furnace in metal silicon production, there is a risk of collapsing due to a load from the top due to the deposition of the raw material. I can't.
　一方、１００，０００Ｎを超えるような圧壊強度の珪砂造粒体が得られても過剰品質となるばかりか、製造する際に多大なエネルギーを必要とするため、工業的ではない。 On the other hand, even if a silica sand granule having a crushing strength exceeding 100,000 N is obtained, it is not industrial because it requires excessive energy in production as well as excessive quality.
　本発明の珪砂造粒体において、圧壊強度の範囲は、好ましくは５００Ｎ～５０，０００Ｎ、さらに好ましくは１，０００Ｎ～５０，０００Ｎであり、また、好ましくは１，０００Ｎ～１０，０００Ｎであってもよい。 In the silica sand granule of the present invention, the range of the crushing strength is preferably 500 N to 50,000 N, more preferably 1,000 N to 50,000 N, and preferably 1,000 N to 10,000 N. Also good.
　本発明の珪砂造粒体の平均粒径は５ｍｍ～２００ｍｍであり、５ｍｍ未満では上記アーク炉内原料層をガスが通過するための十分な空隙を確保できないし、一方、２００ｍｍを超える平均粒径の造粒体を製造するのはコスト・生産性の点で不利になる。上記平均粒径は、好ましくは５ｍｍ～１５０ｍｍ、より好ましくは３０ｍｍ～１５０ｍｍ、更に好ましく５０ｍｍ～１５０ｍｍである。また、上記平均粒径は、好ましくは５ｍｍ～１００ｍｍ、より好ましくは１０ｍｍ～７０ｍｍ、更に好ましくは１５ｍｍ～５０ｍｍであってもよい。
　なお、本発明の造粒体の平均粒径は、無作為抽出した５０個の造粒体をサンプリングし、その粒径の算術平均により求めた数平均粒径である。 The average particle size of the silica sand granule of the present invention is 5 mm to 200 mm. If the average particle size is less than 5 mm, a sufficient space for the gas to pass through the raw material layer in the arc furnace cannot be secured. It is disadvantageous in terms of cost and productivity to produce a granulated product. The average particle diameter is preferably 5 mm to 150 mm, more preferably 30 mm to 150 mm, and still more preferably 50 mm to 150 mm. The average particle size may be preferably 5 mm to 100 mm, more preferably 10 mm to 70 mm, and still more preferably 15 mm to 50 mm.
The average particle size of the granulated material of the present invention is a number average particle size obtained by sampling 50 randomly extracted granulated materials and calculating the arithmetic average of the particle sizes.
　本発明の珪砂造粒体においてＳｉＯ２含有量は９０重量％～９９．９重量％であることが好ましい。即ち、ＳｉＯ２含有量が９０重量％未満の場合、後述するような必要に応じて使用される結合剤として作用するアルカリ土類金属成分、例えばカルシウム成分またはマグネシウム成分とそれ以外の不純物とが過剰に存在することを意味し、例えば金属シリコン製造用の原料として使用した場合、得られる金属シリコン純度の低下を招くことが懸念される。なお、後述の珪砂造粒体の製造方法において、熱処理温度が低い場合、具体的には、有機物の分解温度以下の場合は、バインダー成分等として添加した樹脂等の有機成分も不純物として残存する場合がある。このような有機成分の不純物も、例えば金属シリコン製造用の原料として使用した場合、問題となることが懸念されるため、上述の不純物とみなして考慮することが望ましい。
　なお、結合剤として、後述するようなアルカリ土類金属化合物、典型的にはカルシウム化合物またはマグネシウム化合物を使用した場合には、ＳｉＯ２含有量は、９０重量％以上９９．９重量％以下が好ましい。上記ＳｉＯ２含有量のさらに好ましい範囲は、９４重量％～９９．５重量％である。 In the silica sand granule of the present invention, the SiO 2 content is preferably 90% by weight to 99.9% by weight. That is, when the SiO 2 content is less than 90% by weight, an excess of an alkaline earth metal component, for example, a calcium component or a magnesium component, which acts as a binder used as necessary, as described later, and other impurities. For example, when used as a raw material for producing metal silicon, there is a concern that the purity of the obtained metal silicon may be reduced. In addition, in the method for producing a silica sand granule described later, when the heat treatment temperature is low, specifically, when the temperature is below the decomposition temperature of the organic matter, organic components such as a resin added as a binder component also remain as impurities. There is. Such an organic component impurity is also considered to be a problem when used as a raw material for producing metal silicon, for example, so it is desirable to consider it as the above-mentioned impurity.
When an alkaline earth metal compound as described later, typically a calcium compound or a magnesium compound, is used as the binder, the SiO 2 content is preferably 90% by weight or more and 99.9% by weight or less. . A more preferable range of the SiO 2 content is 94% by weight to 99.5% by weight.
　また、本発明の珪砂造粒体に、原料に含まれる不純物などに由来するアルカリ金属原子がある程度含まれていると、後述する加熱処理をする際に、クリストバライト化が進行し密度差に起因する膨張によって造粒体自体が自己破壊し易い傾向にある。そのため、珪砂造粒体に含まれるＳｉ原子に対するアルカリ金属原子の比（Ｍ１／Ｓｉ）が０．０１未満であることが好ましい。 In addition, when the silica sand granule of the present invention contains alkali metal atoms derived from impurities contained in the raw material to some extent, cristobaliteization progresses during the heat treatment described later, resulting from a density difference. The granulated body itself tends to self-destruct due to expansion. Therefore, the ratio of alkali metal atoms to Si atoms (M 1 / Si) contained in the silica sand granule is preferably less than 0.01.
　（造粒の原材料）
　本発明の珪砂造粒体の製造方法は、珪砂を成形して造粒することを特徴とする。 (Raw material for granulation)
The method for producing a silica sand granule according to the present invention is characterized in that silica sand is molded and granulated.
　本発明の上記製造方法で用いる珪砂は、珪砂が成形できる限り特に制限はないが、本発明により得られる珪砂造粒体が典型的には金属シリコンの原料として用いられ得ることを考慮すると、珪砂のＳｉＯ２含有量が９７重量％以上であることが好ましく、特に、９８％以上が好ましく、９９重量％以上がより好ましく、９９．５重量％以上がさらに好ましい。珪砂造粒体から金属シリコンを製造する場合、ＳｉＯ２成分以外の一部の不純物はアーク炉内で還元・溶融した金属シリコンが炉から排出されて凝固する際に分離されるものの、不純物含有量が増えると金属シリコン中に残存する量も増え、金属シリコンの品質低下を招く傾向にある。つまり、珪砂中の不純物が少ない、高い純度の珪砂を使用することで、得られるシリコン中に残存する不純物含量を効果的に低減できる。また、アーク炉内での加熱により、蒸発した不純物が炉の周壁や配管の壁に付着し、堆積し易くなるという問題をも防止することができ、アーク炉を長時間安定して使用することができる。 The silica sand used in the above production method of the present invention is not particularly limited as long as the silica sand can be molded. However, considering that the silica sand granule obtained by the present invention can typically be used as a raw material for metal silicon, the silica sand The SiO 2 content is preferably 97% by weight or more, particularly preferably 98% or more, more preferably 99% by weight or more, and further preferably 99.5% by weight or more. When metal silicon is produced from silica sand granules, some impurities other than SiO 2 components are separated when the metal silicon reduced and melted in the arc furnace is discharged from the furnace and solidifies, but the impurity content As the amount increases, the amount remaining in the metal silicon also increases, and the quality of the metal silicon tends to deteriorate. That is, the impurity content remaining in the obtained silicon can be effectively reduced by using high-purity silica sand with few impurities in the silica sand. In addition, it is possible to prevent the problem that the evaporated impurities adhere to the peripheral wall of the furnace and the wall of the piping due to heating in the arc furnace, and it is easy to deposit, and the arc furnace should be used stably for a long time. Can do.
　また、珪砂は必要に応じて粉砕して使用できる。造粒性を高める観点からは、珪砂の平均粒径は、好ましくは１０００μｍ以下、より好ましくは２００μｍ以下、さらに好ましくは１５０μｍ以下である。一方、粉砕にかかるエネルギー、粉砕機との接触による汚染の低減の観点からは、珪砂の平均粒径は、好ましくは５μｍ以上、より好ましくは２０μｍ以上、さらに好ましくは５０μｍ以上である。
　上記珪砂の平均粒径としては、特に、好ましくは１μｍ～２００μｍ、より好ましくは５μｍ～１５０μｍとなるように粉砕等により、粒度調整することが望ましい。珪砂粒子径を小さくすると粒子表面のシラノール基が増加し、その分造粒体構造内の粒子間結合力が高まる傾向にある。しかし、一方で平均粒径を小さくしようとすればする程、粉砕に多大なエネルギーが必要になる。 Silica sand can be crushed and used as necessary. From the viewpoint of improving the granulation property, the average particle size of the silica sand is preferably 1000 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less. On the other hand, from the viewpoint of reducing the energy required for pulverization and contamination due to contact with the pulverizer, the average particle size of the silica sand is preferably 5 μm or more, more preferably 20 μm or more, and even more preferably 50 μm or more.
The average particle size of the silica sand is particularly preferably adjusted by pulverization or the like so as to be preferably 1 μm to 200 μm, more preferably 5 μm to 150 μm. When the silica sand particle size is reduced, silanol groups on the particle surface increase, and the interparticle bonding force in the granulated body structure tends to increase accordingly. However, the smaller the average particle size, the more energy is required for grinding.
　また、上記珪砂は、造粒性を高める観点から粒径が１４００μｍ未満の範囲にあるものが好適に使用できる。
　中でも、粒径７５μｍ未満の範囲にある相対粒子量（重量）が２５％～７０％の珪砂を使用することは、前記結合材との作用により、低温度の加熱処理で高強度の造粒体を得ることができ、特に好ましい。
　上記粒径の小さい粒子（以下、微粉珪砂ともいう）と組み合わせる珪砂の粒径は特に制限されないが、原料珪砂として、未粉砕、或いは、軽度な粉砕による処理で得られる珪砂を使用できる観点より、粒径１５０μｍ以上、１４００μｍ未満の範囲にある相対粒子量が１０％～５０％であるものが好ましい。
　上記珪砂の中でも、前記微粉珪砂と粒径１５０μｍ以上、１４００μｍ未満の範囲にある珪砂との相対粒子量の合計が、６０％以上、特に７０％以上であることがより好ましい。
　また、前記微粉珪砂の相対粒子量が前記範囲を満たさない場合でも、粉砕により、平均粒径を２００μｍ以下、さらに好ましくは１５０μｍ以下に調整された珪砂は、同様に高い強度を発揮することもできる。
　なお、珪砂の平均粒径は、レーザー回折・散乱式粒度分析測定により求めた体積基準で求めたメジアン径である。また、上記珪砂の相対粒子量及び粒度分布の値は、実施例に示すように、篩により求めた。 Moreover, the said silica sand can use what has a particle size in the range below 1400 micrometers from a viewpoint of improving granulation property.
Among them, the use of silica sand having a relative particle amount (weight) of 25% to 70% within a particle size range of less than 75 μm is due to the action of the binder and a high-strength granule by heat treatment at a low temperature. Is particularly preferable.
The particle size of the silica sand combined with the above-mentioned small particle size particles (hereinafter also referred to as finely divided silica sand) is not particularly limited, but as a raw material silica sand, from the viewpoint of being able to use uncrushed or lightly crushed silica sand, A particle having a relative particle amount in the range of 150 μm or more and less than 1400 μm is preferably 10% to 50%.
Among the silica sands, the total relative particle amount of the fine silica sand and the silica sands having a particle size of 150 μm or more and less than 1400 μm is more preferably 60% or more, particularly 70% or more.
Further, even when the relative particle amount of the fine silica sand does not satisfy the above range, the silica sand whose average particle diameter is adjusted to 200 μm or less, more preferably 150 μm or less by pulverization can also exhibit high strength. .
In addition, the average particle diameter of silica sand is a median diameter determined on a volume basis determined by laser diffraction / scattering particle size analysis measurement. Moreover, the relative particle amount and the particle size distribution of the silica sand were determined with a sieve as shown in the examples.
　上記珪砂の粉砕は、公知の粉砕機を用いて実施することができる。この粉砕機としては、例えば、粉体工学便覧（粉体工学会編、昭和６１年２月２８日発行、日刊工業新聞社）５０３～５０５頁の表１・１０に記載されている、スクリューミル；スタンプミル等の粉体層打槌式粉砕機；ディスクミル、ピンミル、スクリーンミル、ハンマミル、遠心分級型ミル等の高速回転式衝撃粉砕機；ローラミル等のロール転動型粉砕機；ボールミル、振動ボールミル、遊星型粉砕機等のボール媒体ミル；塔式粉砕機、攪拌槽型粉砕機、流通管型粉砕機、アニュラ型粉砕機等の媒体攪拌式粉砕機；およびジェット粉砕機などが挙げられる。
　上記粉砕機の中でも、粉砕に要するエネルギーがより少なく、粉砕時に混入する不純物がより少ない粉砕機が好ましい。このような粉砕機としては、媒体撹拌式粉砕機、振動ボールミル、回転型ボールミル、遊星型粉砕機等のボール媒体ミルおよびローラミル等のロール転動型粉砕機などが挙げられる。上記ボール媒体ミルは、微粉砕可能で、且つ、大量処理に適しており、ロール転動型粉砕機は、汚染が少なく、且つ、処理能力が大きい。従って、目的とする粉砕物に合わせて、それぞれの粉砕機を使用すればよい。 The pulverization of the silica sand can be carried out using a known pulverizer. Examples of the pulverizer include a screw mill described in Tables 1 and 10 on pages 503 to 505 of the powder engineering manual (edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). Powder layer striking crushers such as stamp mills, high speed rotary impact crushers such as disc mills, pin mills, screen mills, hammer mills, centrifugal classification mills, roll rolling crushers such as roller mills, ball mills, vibrations Ball mills such as ball mills and planetary pulverizers; tower pulverizers, stirred tank pulverizers, flow-tube pulverizers, annular pulverizers and other medium agitation pulverizers, and jet pulverizers.
Among the above pulverizers, a pulverizer that requires less energy for pulverization and contains fewer impurities during pulverization is preferable. Examples of such a pulverizer include a medium agitating pulverizer, a ball ball mill such as a vibration ball mill, a rotary ball mill, and a planetary pulverizer, and a roll rolling pulverizer such as a roller mill. The ball medium mill can be finely pulverized and is suitable for mass processing, and the roll-rolling pulverizer has little contamination and a large processing capacity. Therefore, each pulverizer may be used in accordance with the intended pulverized product.
　上記珪砂造粒体を製造する際には、アルカリ土類金属化合物を結合剤として用いて珪砂が成形されていることが好ましい。このようなアルカリ土類金属化合物を結合剤として用いた珪砂造粒体は、珪砂の表面にアルカリ土類金属化合物、例えばカルシウム化合物またはマグネシウム化合物を接触せしめて造粒することにより製造できる。 When producing the silica sand granule, the silica sand is preferably molded using an alkaline earth metal compound as a binder. A silica sand granule using such an alkaline earth metal compound as a binder can be produced by bringing an alkaline earth metal compound such as a calcium compound or a magnesium compound into contact with the surface of the silica sand for granulation.
　アルカリ土類金属化合物、例えば、カルシウム化合物またはマグネシウム化合物を結合剤として用いて得られた珪砂造粒体は、珪砂を主体とし、その間を、アルカリ土類金属化合物を結合剤による反応生成物により結合したものである。かかる反応生成物は、アルカリ土類金属化合物が珪砂粒子表面でＳｉＯ２成分と反応して生成した珪酸アルカリ土類金属塩、例えば珪酸カルシウムであると推定されるが、かかる結合力により、圧壊強度が２００Ｎ以上という高い強度を発揮しやすくなる。 Silica sand granule obtained using an alkaline earth metal compound, for example, calcium compound or magnesium compound as a binder is mainly composed of silica sand, and the alkaline earth metal compound is bound by a reaction product of the binder between them. It is a thing. Such a reaction product is presumed to be an alkaline earth metal silicate, such as calcium silicate, produced by reacting an alkaline earth metal compound with the SiO 2 component on the surface of the silica sand particles. However, it is easy to exhibit a high strength of 200 N or more.
　なお、従来、骨材の製造方法として、二酸化珪素とカルシウム化合物との水熱反応により珪酸カルシウムを主体とする鉱物質の塊状物を製造することは報告されている。しかし、アルカリ土類金属化合物、例えばカルシウム化合物またはマグネシウム化合物を結合剤として使用した珪砂を主体とする造粒体は、本発明によって初めて提案されたものである。 Conventionally, as a method for producing an aggregate, it has been reported that a mass of a mineral substance mainly composed of calcium silicate is produced by a hydrothermal reaction between silicon dioxide and a calcium compound. However, a granulated body mainly composed of silica sand using an alkaline earth metal compound such as a calcium compound or a magnesium compound as a binder is proposed for the first time by the present invention.
　上記アルカリ土類金属化合物の中でも、工業的な応用を考慮すると他のアルカリ土類金属化合物と比較して入手がより容易であるという点で、カルシウム化合物、マグネシウム化合物およびそれらの混合物が好ましい。 Among the above alkaline earth metal compounds, calcium compounds, magnesium compounds, and mixtures thereof are preferable in that they are more easily available than other alkaline earth metal compounds in consideration of industrial applications.
　上記カルシウム化合物としては、例えば、水酸化カルシウム、炭酸カルシウム、酸化カルシウム、硫酸カルシウムおよびそれらの混合物が挙げられる。これらカルシウム化合物は、本発明により得られる造粒体を高強度化する上で好適である。
　中でも、水酸化カルシウム、炭酸カルシウムまたはそれらの混合物が好適に使用される。これらは、水との接触でアルカリ性を呈しＳｉＯ２との反応性が大きくなって、造粒体の高強度化により寄与する。 Examples of the calcium compound include calcium hydroxide, calcium carbonate, calcium oxide, calcium sulfate, and mixtures thereof. These calcium compounds are suitable for increasing the strength of the granulated product obtained by the present invention.
Among these, calcium hydroxide, calcium carbonate or a mixture thereof is preferably used. These exhibit alkalinity upon contact with water, increase the reactivity with SiO 2, and contribute to increasing the strength of the granulated body.
　上記マグネシウム化合物としては、例えば、水酸化マグネシウム、炭酸マグネシウム、酸化マグネシウム、硫酸マグネシウムおよびそれらの混合物が挙げられる。
　中でも、水酸化マグネシウム、炭酸マグネシウムまたはそれらの混合物が好適に使用される。これらは、水との接触でアルカリ性を呈しＳｉＯ２との反応性が大きくなって、本発明により得られる造粒体を高強度化する上で好適である。 Examples of the magnesium compound include magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium sulfate, and mixtures thereof.
Among these, magnesium hydroxide, magnesium carbonate or a mixture thereof is preferably used. These are suitable for increasing the strength of the granulated product obtained by the present invention by exhibiting alkalinity upon contact with water and increasing the reactivity with SiO 2 .
　上記アルカリ土類金属化合物、例えば、カルシウム化合物またはマグネシウム化合物の粒径は、好ましくは０．００１μｍ～２０μｍ、より好ましくは０．００１μｍ～１０μｍである。
　上記アルカリ土類金属化合物、例えば、カルシウム化合物またはマグネシウム化合物の粒径は、特に、０．１μｍ～２０μｍが好ましく、１μｍ～１０μｍがより好ましい。また、アルカリ土類金属化合物粒子、典型的にはカルシウム化合物粒子またはマグネシウム化合物粒子が凝集していても、後述する混合過程で凝集体の一部または全部が解れるので、問題なく使用することができる。 The particle size of the alkaline earth metal compound such as calcium compound or magnesium compound is preferably 0.001 μm to 20 μm, more preferably 0.001 μm to 10 μm.
The particle size of the alkaline earth metal compound such as calcium compound or magnesium compound is particularly preferably 0.1 μm to 20 μm, and more preferably 1 μm to 10 μm. In addition, even if alkaline earth metal compound particles, typically calcium compound particles or magnesium compound particles are agglomerated, a part or all of the agglomerates can be released in the mixing process described later, so that they can be used without problems. it can.
　上記アルカリ土類金属化合物、典型的にはカルシウム化合物またはマグネシウム化合物の添加割合は、珪砂１００重量部に対して０．１～５重量部とすることが好ましく、０．５～３重量部とすることがより好ましい。アルカリ土類金属化合物、典型的にはカルシウム化合物またはマグネシウム化合物は、珪砂表面を覆うだけの量を添加すれば十分であり、それ以上の量の使用は、不純物量の増大を招く虞がある。また、アルカリ土類金属化合物の使用量が増加しても、１００，０００Ｎを超えるような圧壊強度の珪砂造粒体が得られても過剰品質となるばかりか、製造する際に多大なエネルギーを必要とするため、工業的ではない。 The addition ratio of the alkaline earth metal compound, typically a calcium compound or a magnesium compound, is preferably 0.1 to 5 parts by weight, and 0.5 to 3 parts by weight with respect to 100 parts by weight of silica sand. It is more preferable. Alkaline earth metal compounds, typically calcium compounds or magnesium compounds, need only be added in an amount sufficient to cover the surface of the silica sand, and the use of higher amounts may increase the amount of impurities. Moreover, even if the amount of the alkaline earth metal compound used is increased, even if a silica sand granule having a crushing strength exceeding 100,000 N is obtained, not only the quality is excessive, but a great deal of energy is required in the production. It is not industrial because it requires it.
　アルカリ土類金属を結合剤として用いて得られる珪砂造粒体の場合は、珪砂を主体とするものであるが、具体的には、Ｓｉ原子に対するアルカリ土類金属原子の比（Ｍ２／Ｓｉ）は、０．００１～０．０４であることが好ましく、０．００４～０．０３であることが好ましい。例えば、カルシウム化合物を結合剤として用いて得られる珪砂造粒体の場合は、珪砂を主体とするものであるが、具体的には、Ｓｉ原子に対するカルシウム原子の比（Ｃａ／Ｓｉ）は、０．００１～０．０４であることが好ましく、０．００４～０．０３であることが好ましい。Ｓｉ原子に対するアルカリ土類金属原子（例えばカルシウム原子）の比が上記範囲にあることにより、珪砂造粒体の高い強度を維持しつつ、珪砂造粒体自体の純度を高めることができる。 In the case of a silica sand granule obtained by using an alkaline earth metal as a binder, silica sand is mainly used. Specifically, the ratio of alkaline earth metal atoms to Si atoms (M 2 / Si ) Is preferably 0.001 to 0.04, more preferably 0.004 to 0.03. For example, in the case of a silica sand granule obtained by using a calcium compound as a binder, silica sand is mainly used. Specifically, the ratio of calcium atoms to Si atoms (Ca / Si) is 0. 0.001 to 0.04 is preferable, and 0.004 to 0.03 is preferable. When the ratio of the alkaline earth metal atom (for example, calcium atom) to the Si atom is within the above range, the purity of the silica sand granule itself can be increased while maintaining the high strength of the silica sand granule.
　（造粒方法）
　本発明の製造方法における珪砂の表面にアルカリ土類金属化合物、典型的にはカルシウム化合物またはマグネシウム化合物を接触せしめる手段は特に制限されないが、珪砂表面にアルカリ土類金属化合物をより均一に接触せしめて珪砂造粒体の強度を高めるためには、珪砂とアルカリ土類金属化合物と水とを混合することが好ましく、接触による反応を更に高めるためには、上記混合物を造粒して加熱することが好ましい。 (Granulation method)
The means for bringing an alkaline earth metal compound, typically a calcium compound or a magnesium compound, into contact with the surface of the silica sand in the production method of the present invention is not particularly limited, but the alkaline earth metal compound is brought into more uniform contact with the silica sand surface. In order to increase the strength of the silica sand granule, it is preferable to mix silica sand, an alkaline earth metal compound and water, and in order to further increase the reaction by contact, the mixture may be granulated and heated. preferable.
　上記混合、造粒は室温で実施することができ、後述の乾燥器や窯炉において、加熱処理を施すことができる。また、造粒機に加熱機能が付帯している場合には、造粒と加熱処理を同時に実施することもできる。 The above mixing and granulation can be performed at room temperature, and heat treatment can be performed in a dryer or a kiln described below. In addition, when the granulator is equipped with a heating function, granulation and heat treatment can be performed simultaneously.
　また、珪砂とアルカリ土類金属化合物、典型的にはカルシウム化合物またはマグネシウム化合物と水との混合物には、造粒性向上のためバインダーを添加することもできる。バインダーとしては水溶性の有機物が好ましい。水溶性の有機物としては、例えば、造粒便覧（日本粉体工業協会編、昭和５０年５月３０日発行、オーム社）の表１、３、４に記載される、カルボキシメチルセルロース（ＣＭＣ）、ポリビニルアルコール（ＰＶＡ）、砂糖、デキストローズ、コーンシロップなどが挙げられる。 In addition, a binder may be added to a mixture of silica sand and an alkaline earth metal compound, typically a calcium compound or magnesium compound, and water in order to improve granulation properties. The binder is preferably a water-soluble organic substance. Examples of water-soluble organic substances include, for example, carboxymethyl cellulose (CMC) described in Tables 1, 3, and 4 of the Granulation Handbook (edited by the Japan Powder Industry Association, published on May 30, 1975, Ohmsha). Polyvinyl alcohol (PVA), sugar, dextrose, corn syrup and the like can be mentioned.
　また、上記以外に使用可能な有機物からなるバインダーとしては、デキストリン、コーンスターチ、そくい等のその他のでん粉類；にかわ、カゼイン、大豆たん白等のたん白類；アラビアゴム等の天然ゴム類；ピッチ、加工タール、舗装タール等のタール類；ストレートアスファルト、ブローンアスファルト等のアスファルト類；アクリル系重合体、ポリアミド、ポリエチレン、その他セルロース等のその他の熱可塑性レジン；ユリア樹脂、メラミン樹脂、フェノール樹脂、フラン樹脂、エポキシ樹脂、熱硬化性ポリエステル、熱硬化性ポリウレタン等の熱硬化性レジン；ネオプレン、ニトリルゴム、スチレンブタジエンゴム、ブチルゴム、シリコーンゴム等のエラストマーなどが挙げられる。 In addition to the above, binders composed of organic substances that can be used include other starches such as dextrin, corn starch, and rice cake; proteins such as glue, casein and soybean protein; natural rubbers such as gum arabic; pitch, Tars such as processed tar and paving tar; asphalts such as straight asphalt and blown asphalt; other thermoplastic resins such as acrylic polymers, polyamide, polyethylene, and other cellulose; urea resin, melamine resin, phenol resin, furan resin And thermosetting resins such as epoxy resin, thermosetting polyester, and thermosetting polyurethane; and elastomers such as neoprene, nitrile rubber, styrene butadiene rubber, butyl rubber, and silicone rubber.
　さらに上記以外に使用可能な無機物からなるバインダーとしては、ポルトランドセメント、高炉セメント、シリカセメント、アルミナセメント、フライアッシュ、白色セメント、ジェットセメント等のセメント類；ケイ酸ソーダ１号、ケイ酸ソーダ２号、ケイ酸ソーダ３号、ケイ酸ソーダ４号、メタケイ酸等の水ガラス類；粘土、ベントナイト等の鉱物類などが挙げられる。 In addition to the above, usable inorganic binders include cements such as Portland cement, blast furnace cement, silica cement, alumina cement, fly ash, white cement, jet cement; sodium silicate 1 and sodium silicate 2 , Sodium silicate No. 3, sodium silicate No. 4, water glass such as metasilicic acid, and minerals such as clay and bentonite.
　珪砂とアルカリ土類金属化合物、典型的にはカルシウム化合物またはマグネシウム化合物と水との混合物の造粒は、これを公知の方法、例えば、造粒便覧（日本粉体工業協会編、昭和５０年５月３０日発行、オーム社）のＩ編、１・４節で分類されている方法の内、転動型、圧縮成形型、押出成形型の一般的な方法が好適に採用できる。各々の方法で造粒プロセスが異なるので、以下それぞれの方法における最良の形態を説明する。 Granulation of a mixture of silica sand and an alkaline earth metal compound, typically a calcium compound or a magnesium compound, and water is carried out by a known method, for example, granulation manual (edited by the Japan Powder Industry Association, 1975 5). Of the methods classified in Part 1, Sections 1 and 4 (issued on May 30, Ohm), the general methods of rolling molds, compression molds and extrusion molds can be suitably employed. Since each method has a different granulation process, the best mode of each method will be described below.
　（転動型造粒）
　転動型造粒において、珪砂、アルカリ土類金属化合物、典型的にはカルシウム化合物またはマグネシウム化合物、水、そして必要に応じて添加するバインダーの各成分は
　ａ．各成分を予め混合してから造粒機へ供給する手順
　ｂ．珪砂とアルカリ土類金属化合物とを混合し、その混合粉と水またはバインダー水溶液とを造粒機へ別々に供給する手順
　ｃ．珪砂、アルカリ土類金属化合物、そして必要に応じて添加するバインダーを予め混合し、その混合粉と水とを造粒機へ別々に供給する手順
のいずれかの手順を採用して造粒機へ供給されることができるが、連続造粒性を考慮すると、粉状成分と液状成分を別々に供給するｂまたはｃの手順を採用することが好ましい。 (Rolling granulation)
In rolling granulation, each component of the silica sand, alkaline earth metal compound, typically calcium compound or magnesium compound, water, and optionally added binder is a. Procedure for mixing each component in advance and then feeding to the granulator b. Procedure of mixing silica sand and alkaline earth metal compound, and separately supplying the mixed powder and water or aqueous binder solution to the granulator c. Pre-mixing silica sand, alkaline earth metal compound, and binder to be added as necessary, and using either procedure of supplying the mixed powder and water separately to the granulator to the granulator Although it can be supplied, in consideration of continuous granulation, it is preferable to adopt the procedure b or c in which the powdery component and the liquid component are separately supplied.
　珪砂、アルカリ土類金属化合物、そして必要に応じて添加するバインダーの各粉末の混合は、一般に公知の混合機を用いて行うことができる。例えば、粉体工学便覧（粉体工学会編、昭和６１年２月２８日発行、日刊工業新聞社）６１０頁の図９．１に示されている水平円筒型混合機（内設羽根付）、Ｖ型混合機（攪拌羽根付）、二重円錐型混合機などの容器回転型混合機；リボン混合機、円錐型スクリュー混合機、高速流動型混合機、回転円盤型混合機、気流攪拌型混合機、無攪拌型混合機などの容器固定型混合機；攪拌型混合機（加振機付）などの複合型混合機が挙げられる。また、水を添加して湿潤状態での混合となった場合には、混錬機、例えば粉体工学便覧（粉体工学会編、昭和６１年２月２８日発行、日刊工業新聞社）６４４頁の表１３．６に挙げられている各種混錬機も使用できる。 The mixing of each powder of silica sand, alkaline earth metal compound, and binder to be added as necessary can be generally performed using a known mixer. For example, powder engineering handbook (powder engineering society, issued on February 28, 1986, Nikkan Kogyo Shimbun) horizontal cylindrical mixer shown in Fig. 9.1 on page 610 (with internal blades) , V-type mixers (with stirring blades), double-cone mixers and other container rotating mixers; ribbon mixers, conical screw mixers, high-speed fluid mixers, rotating disk mixers, airflow mixers Examples thereof include a container-fixed mixer such as a mixer and a non-stirring mixer; and a composite mixer such as a stirring mixer (with a vibrator). Further, when water is added and mixing is performed in a wet state, a kneading machine such as a powder engineering manual (edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun) 644 Various kneaders listed in Table 13.6 on page can also be used.
　また、転動型造粒は、例えば造粒便覧（日本粉体工業協会編、昭和５０年５月３０日発行、オーム社）のＩＩ編、２・６節に記載されているドラム型造粒機や皿型造粒機造粒機を採用して実施することができる。 Rolling type granulation is, for example, drum type granulation described in Part II, Sections 2 and 6 of Granulation Handbook (edited by Japan Powder Industry Association, published on May 30, 1975, Ohmsha). It can be carried out by adopting a machine or a dish type granulator.
　これら造粒機の中でも、皿型造粒機は造粒工程の制御が容易であること等から好ましい。皿型造粒機の皿形状としては普通皿型（たらい型）、多段皿型、球面皿型、頭切円錐型等が挙げられるが、多段皿型、球面皿型、頭切円錐型の造粒機は回転軸に沿って回転半径が異なることから造粒体が遠心力の違いによって自動的に分級されるため、粒径の揃った粒成長した造粒体を回転する皿の外周側から選択的に取り出すのに適している。 Among these granulators, the dish-type granulator is preferable because the control of the granulation process is easy. The dish shape of the dish-type granulator includes ordinary dish type (basket type), multi-stage dish type, spherical dish type, truncated cone type, etc., but multi-stage dish type, spherical dish type, truncated cone type, etc. Since the granulator automatically classifies the granulated material according to the difference in centrifugal force because the radius of rotation differs along the rotation axis, the granulated material having a uniform particle size is grown from the outer peripheral side of the rotating dish. Suitable for selective removal.
　また、造粒機への混合粉末の供給は、例えば、粉体工学便覧（粉体工学会編、昭和６１年２月２８日発行、日刊工業新聞社）の５６７頁表５・１に分類されている供給機を使用して実施することができるが、供給量を制御し易い点で振動フィーダ、シェーキングフィーダー、スクリューフィーダ、ベルトコンベアーなどを用いることが好ましい。なお、上記混合粉末の供給は、連続的に行ってもよいし、断続的に行ってもよい。 The supply of the mixed powder to the granulator is classified, for example, in Table 5.1 on page 567 of Powder Engineering Handbook (Edited by Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). However, it is preferable to use a vibration feeder, a shaking feeder, a screw feeder, a belt conveyor or the like in terms of easy control of the supply amount. In addition, the supply of the mixed powder may be performed continuously or intermittently.
　ここで、水の量は粉体工学便覧（粉体工学会編、昭和６１年２月２８日発行、日刊工業新聞社）の５９９頁表８・３に分類されている固・液・気系の構造（以下、充てん域という）における策状域となるよう添加することが好ましい。充てん域が策状域にあると水が粒子間に介在し架橋液体として作用するからである。充てん域は珪砂に対する水の添加割合のみならず珪砂の粒度にも影響を受けるが、前述した平均粒径の範囲であれば珪砂１００重量部に対して水１０～３０重量部を添加することで架橋液体として機能させることができる。カルシウム化合物、マグネシウム化合物等のアルカリ土類金属化合物またはバインダーを添加する場合には、その添加量は珪砂１００重量部に対して５～２０重量部とすることが好適である。 Here, the amount of water is a solid / liquid / gas system classified in Table 8/3 on page 599 of the Powder Engineering Handbook (Edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). It is preferable to add so that it becomes a policy area in the structure (hereinafter referred to as a filling area). This is because when the filling area is in the policy area, water intervenes between the particles and acts as a crosslinking liquid. The filling area is affected not only by the ratio of water added to the silica sand but also by the particle size of the silica sand. If the average particle diameter is within the above range, 10 to 30 parts by weight of water can be added to 100 parts by weight of the silica sand. It can function as a crosslinking liquid. When an alkaline earth metal compound such as a calcium compound or a magnesium compound or a binder is added, the addition amount is preferably 5 to 20 parts by weight with respect to 100 parts by weight of silica sand.
　転動型造粒により珪砂造粒体を製造する場合には、上記転動造粒機を少なくとも２台準備し、これら転動造粒機により複数段に分けて造粒することが好ましい一態様である。
　その際、第一段の転動造粒機内に存在する粒径が２０ｍｍ以上の中間造粒体の割合が、好ましくは３０重量％以下、より好ましくは２０重量％以下、さらに好ましくは１５重量％以下となるように、粒成長させることが好ましい。 When producing a silica sand granule by rolling granulation, it is preferable that at least two rolling granulators are prepared and granulated in a plurality of stages by these rolling granulators. It is.
At that time, the proportion of the intermediate granule having a particle size of 20 mm or more present in the first-stage rolling granulator is preferably 30% by weight or less, more preferably 20% by weight or less, and further preferably 15% by weight. It is preferable to grow the grains so that
　第一段の転動造粒器内に存在する２０ｍｍ以上の中間造粒体の割合が、上記範囲となるように造粒を行うことにより、第１段の転動造粒器に供給される珪砂、バインダーよりなる混合物から、新たな核の生成、粒成長が起こり、造粒体の数を確実に増加させることができる。
　第一段の転動造粒機内に存在する粒径が２０ｍｍ以上の造粒体の割合を上記範囲内とするためには、その転動造粒機から粒成長した粒子を選択的かつ連続的に取り出せばよい。例えば、転動造粒機では、粒成長した造粒体は回転する皿の外周部に存在するため、この外周部に存在する所定の大きさの中間造粒体を取り出せばよい。 By performing granulation so that the ratio of the intermediate granule of 20 mm or more existing in the first-stage rolling granulator is in the above range, it is supplied to the first-stage rolling granulator. Generation of new nuclei and grain growth occur from the mixture composed of silica sand and binder, and the number of granules can be reliably increased.
In order to make the ratio of the granulated body having a particle size of 20 mm or more present in the first stage rolling granulator within the above range, the particles grown from the rolling granulator are selectively and continuously grown. You can take it out. For example, in a tumbling granulator, the granulated material that has undergone grain growth is present on the outer peripheral portion of a rotating dish, and therefore, an intermediate granule having a predetermined size existing on the outer peripheral portion may be taken out.
　上記第一段の転動造粒機からの中間造粒体の取り出しは、上述したように、該転動造粒機内に存在する粒径が２０ｍｍ以上の造粒体の割合がより低くなるように行うことが望ましい。一方で、第１段の造粒機内に存在する造粒体の粒径が、過度に小さい状態で取り出すと、次段の転動造粒機においてさらに粒成長させる際に、粒成長した造粒体により上記中間造粒体が破壊される場合があり、単位造粒機当たりの生産効率が低下する場合がある。そのため、上記第一段の転動造粒機からは、平均粒径が、好ましくは１０ｍｍ以上、より好ましくは１５ｍｍ以上、さらに好ましくは２０ｍｍ以上に粒成長した中間造粒体を取り出すことが望ましい。また、第一段の転動造粒機より取り出す中間造粒体の粒径が大きすぎる場合、該造粒機中の２０ｍｍ以上の造粒体の割合が上記範囲を超えやすくなるため、平均粒径が、好ましくは３０ｍｍ以下、より好ましくは２５ｍｍ以下の中間造粒体を取り出すことが望ましい。 As described above, the intermediate granule is taken out from the first-stage rolling granulator so that the proportion of the granulated body having a particle size of 20 mm or more present in the rolling granulator becomes lower. It is desirable to do this. On the other hand, when the particle size of the granulated body existing in the first stage granulator is taken out in an excessively small state, the granulated grains are grown when further grain growth is performed in the next stage rolling granulator. The intermediate granulated body may be destroyed by the body, and the production efficiency per unit granulator may be reduced. Therefore, it is desirable to take out an intermediate granule having an average particle diameter of 10 mm or more, more preferably 15 mm or more, and further preferably 20 mm or more from the first stage rolling granulator. In addition, when the particle size of the intermediate granule taken out from the first-stage rolling granulator is too large, the ratio of the granulated body of 20 mm or more in the granulator tends to exceed the above range. It is desirable to take out an intermediate granule having a diameter of preferably 30 mm or less, more preferably 25 mm or less.
　第一段の転動造粒機から上記特定の大きさの造粒体を取り出す条件は、２０ｍｍ以上の造粒体の割合が上記範囲内、好ましくは、中間造粒体の平均粒径が上記範囲となるように取り出し条件、例えば、転動造粒機のコーンの傾き、回転数等を、予め実験によって設定すればよい。 The condition for taking out the granulated body of the specific size from the first stage rolling granulator is that the ratio of the granulated body of 20 mm or more is within the above range, preferably the average particle size of the intermediate granulated body is the above What is necessary is just to set beforehand extraction conditions, for example, the inclination of a cone of a rolling granulator, a rotation speed, etc. so that it may become a range by experiment.
　このようにして第一段の転動造粒機より取り出された中間造粒体は、次段以降の転動造粒機に供給され、さらに、珪砂とバインダーとを添加して、粒成長を行わせることにより、所望の平均粒径、例えば、２０ｍｍ以上、好ましくは３０ｍｍ～２００ｍｍ、より好ましくは３０ｍｍ～１００ｍｍ、の平均粒径を有する珪砂造粒体を得ることができる。 Thus, the intermediate granule taken out from the first-stage rolling granulator is supplied to the subsequent-stage rolling granulator, and further, silica sand and a binder are added to promote grain growth. By carrying out, a quartz sand granule having a desired average particle diameter, for example, an average particle diameter of 20 mm or more, preferably 30 mm to 200 mm, more preferably 30 mm to 100 mm can be obtained.
　珪砂造粒体の平均粒径が２０ｍｍ以上の場合には、取扱性がより向上する傾向にあり、アーク炉内でこの珪砂造粒体からなる原料層をガスが通過するための十分な空隙を確保できる傾向にある。一方、珪砂造粒体の平均粒径が２００ｍｍ以下の場合には、造粒体を製造するのはコスト、生産性の点でより有利となる。 When the average particle size of the silica sand granule is 20 mm or more, the handling property tends to be further improved, and there is a sufficient gap for the gas to pass through the raw material layer made of this silica sand granule in the arc furnace. It tends to be secured. On the other hand, when the average particle size of the silica sand granule is 200 mm or less, it is more advantageous in terms of cost and productivity to produce the granule.
　（圧縮成形型造粒）
　圧縮成形型造粒でも、粉体の流動性が維持される範囲内で水を添加した方が強度増大の点で好ましい。その場合、水の量は粉体工学便覧（粉体工学会編、昭和６１年２月２８日発行、日刊工業新聞社）の５９９頁表８・３に分類されている充てん域における吸湿域となるよう添加することが好適である。前述した平均粒径の範囲であれば珪砂１００重量部に対して水１～２０重量部を添加することで成形後の強度が増すので好ましい。また、バインダーを添加する場合には、その添加量は珪砂１００重量部に対して５～２０重量部とすることが好適である。 (Compression mold granulation)
Even in compression molding granulation, it is preferable from the viewpoint of increasing strength that water is added within a range in which the fluidity of the powder is maintained. In that case, the amount of water is the moisture absorption area in the filling area classified in Table 8.3 on page 599 of the Powder Engineering Handbook (Edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). It is preferable to add so that it becomes. If the average particle size is within the above-mentioned range, it is preferable to add 1 to 20 parts by weight of water to 100 parts by weight of silica sand because the strength after molding is increased. In addition, when the binder is added, the addition amount is preferably 5 to 20 parts by weight with respect to 100 parts by weight of silica sand.
　珪砂、アルカリ土類金属化合物、典型的にはカルシウム化合物またはマグネシウム化合物、水、そして必要に応じて添加するバインダーの混合は、前述の転動型造粒の場合と同様に粉体工学便覧（粉体工学会編、昭和６１年２月２８日発行、日刊工業新聞社）６１０頁の図９．１に示されている混合機を使用して実施できる。 The mixing of silica sand, alkaline earth metal compound, typically calcium or magnesium compound, water, and optionally added binder is the same as in the case of the rolling granulation described above. (The Society of Physical Engineering, published on February 28, 1986, Nikkan Kogyo Shimbun)) It can be carried out using the mixer shown in FIG. 9.1 on page 610.
　工業的に広く用いられている圧縮成形型造粒の方法として、シリンダーの中に粉体を充てんし、ピストンで圧縮するタブレッティングと、二つの回転するロール間で粉体を圧縮するブリケッティングがある。本発明の製造方法ではそれらのいずれの方法を用いても、造粒体を製造することができる。造粒機を例示すると、造粒便覧（日本粉体工業協会編、昭和５０年５月３０日発行、オーム社）のＩＩ編、４・５節に記載されている単発打錠機；１点圧縮型機、多点圧縮型機、多段圧縮型機、傾斜ロール型機などのロータリー打錠機が、また同４・６節に記載されているブリケットマシンが挙げられる。また、混合粉末の供給は前述の転動型造粒の場合と同様に振動フィーダ、シェーキングフィーダー、またはスクリューフィーダなどを用いて実施できる。 As a compression molding granulation method widely used industrially, a cylinder is filled with powder, tableting compressed by a piston, and briquetting compressing powder between two rotating rolls. There is. In the production method of the present invention, a granulated body can be produced using any of these methods. As an example of a granulator, a single tableting machine described in Part II, 4/5 of Granulation Handbook (Edited by Japan Powder Industry Association, published on May 30, 1975, Ohmsha); 1 point Examples of the rotary tableting machine include a compression type machine, a multipoint compression type machine, a multistage compression type machine, and an inclined roll type machine, and the briquette machine described in Sections 4 and 6 above. Further, the mixed powder can be supplied using a vibration feeder, a shaking feeder, a screw feeder, or the like as in the case of the rolling granulation.
　（押出成形型造粒）
　押出成形型造粒では押出し圧が加わるため、水の量は粉体工学便覧（粉体工学会編、昭和６１年２月２８日発行、日刊工業新聞社）の５９９頁表８・３に分類されている充てん域における懸吊域となるよう添加することが好適である。前述した平均粒径の範囲であれば珪砂１００重量部に対して水５～２５重量部を添加することで成形後の強度が増すので好ましい。また、バインダーを添加する場合には、その添加量は珪砂１００重量部に対して３～１５重量部とすることが好適である。 (Extrusion mold granulation)
Since extrusion pressure is applied in extrusion mold granulation, the amount of water is classified in Table 8.3 on page 599 of Powder Engineering Handbook (Edited by the Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun). It is preferable to add so as to be a suspended region in the filled region. If the average particle size is within the above-mentioned range, it is preferable to add 5 to 25 parts by weight of water to 100 parts by weight of silica sand since the strength after molding increases. In addition, when the binder is added, the addition amount is preferably 3 to 15 parts by weight with respect to 100 parts by weight of silica sand.
　珪砂、カルシウム化合物、水、そして必要に応じて添加するバインダーの混合は、前述の転動型造粒の場合と同様に粉体工学便覧（粉体工学会編、昭和６１年２月２８日発行、日刊工業新聞社）６１０頁の図９．１に示されている混合機を使用して実施できる。 The mixing of silica sand, calcium compound, water, and binder added as necessary is similar to the case of the rolling granulation described above. Powder Engineering Handbook (Edited by the Powder Engineering Society, February 28, 1986) The Nikkan Kogyo Shimbun, Inc.) can be carried out using the mixer shown in FIG. 9.1 on page 610.
　押出成形型造粒は、例えば造粒便覧（日本粉体工業協会編、昭和５０年５月３０日発行、オーム社）のＩＩ編、表２・３・１に分類されている押出し造粒機を採用して実施することができる。具体的には、前押出し式、真空押出し式などのスクリュー型押出し造粒機；円筒型ダイス水平式造粒機、円筒型ダイス垂直式造粒機、円板型ダイス水平式造粒機などのロール型押出し造粒機；オシレーティング式造粒機などのブレード型押出し造粒機；ギヤー式造粒機などの自己成形型押出し造粒機；ラム型押出し造粒機等が挙げられる。また、混合粉末の供給は前述の転動型造粒の場合と同様に振動フィーダ、シェーキングフィーダー、またはスクリューフィーダなどを用いて実施できる。 Extrusion mold granulation is an extruding granulator classified into, for example, Part II of the Granulation Handbook (edited by the Japan Powder Industry Association, published on May 30, 1975, Ohmsha), Tables 2.3.1. Can be implemented. Specifically, screw type extrusion granulators such as pre-extrusion type and vacuum extrusion type; cylindrical die horizontal granulator, cylindrical die vertical granulator, disc type die horizontal granulator, etc. Examples thereof include a roll-type extrusion granulator; a blade-type extrusion granulator such as an oscillating granulator; a self-molding extrusion granulator such as a gear-type granulator; a ram-type extrusion granulator. Further, the mixed powder can be supplied using a vibration feeder, a shaking feeder, a screw feeder, or the like as in the case of the rolling granulation.
　（造粒体の加熱処理）
　上記造粒方法により得られた造粒体は、より強度を高めるために加熱処理が施されることが好ましい。上記加熱処理温度は、珪砂造粒体が、所期の強度を呈する温度以上で、且つ、珪砂が溶融しない温度が好適である。上記加熱処理温度は、例えば７００℃以上、好ましくは１０００℃以上である。また、上記加熱処理温度は、好ましくは１６００℃以下、より好ましくは１３００℃以下であれば十分であり、それ以上の温度では経済的にも不利となる。
　なお、アルカリ土類金属化合物を併用する場合は、かかる加熱処理温度をより低下させることができる。アルカリ土類金属化合物を併用する場合の加熱処理温度は、例えば、５０℃以上であればよい。しかしながら、造粒体の製造においてさらに水を併用する場合は、水の除去を効率的に実施する観点から、好ましくは１００℃以上、より好ましくは２００℃以上である。
　したがって、加熱処理温度は、５０～１６００℃の範囲において、前記造粒方法によって得られる造粒体の組成等に応じて適宜決定すればよい。 (Heat treatment of granulated body)
The granulated body obtained by the above granulation method is preferably subjected to a heat treatment in order to further increase the strength. The heat treatment temperature is preferably a temperature at which the silica sand granule is not less than the temperature at which the desired strength is exhibited and the silica sand does not melt. The said heat processing temperature is 700 degreeC or more, for example, Preferably it is 1000 degreeC or more. Further, the heat treatment temperature is preferably 1600 ° C. or lower, more preferably 1300 ° C. or lower, and a temperature higher than that is economically disadvantageous.
In addition, when using an alkaline-earth metal compound together, this heat processing temperature can be lowered more. The heat treatment temperature when the alkaline earth metal compound is used in combination may be, for example, 50 ° C. or higher. However, when water is further used in the production of the granulated body, the temperature is preferably 100 ° C. or higher, more preferably 200 ° C. or higher, from the viewpoint of efficiently removing water.
Therefore, the heat treatment temperature may be appropriately determined in the range of 50 to 1600 ° C. according to the composition of the granulated body obtained by the granulation method.
　上記加熱処理に用いる装置としては、例えば窯業操作（窯業読本変種委員会著、昭和４８年９月２０日発行、窯業協会）の５・１節に記載されている窯炉などが挙げられる。このような窯炉としては、具体的には、倒炎式角窯、倒炎式丸窯、シャトルキルン、ベルキルンの不連続窯；輪窯、連続室窯、トンネル窯の連続窯；回転窯；抵抗炉などの電気炉が挙げられる。また乾燥に用いる好適な装置としては、例えば粉体工学便覧（粉体工学会編、昭和６１年２月２８日発行、日刊工業新聞社）５９１頁に分類されている、箱型乾燥器、回転乾燥器などが挙げられる。加熱処理および乾燥の雰囲気は、窒素などの不活性ガスであってもよいが、大気であってもよい。
　また、加熱処理温度が低い場合は、公知の乾燥装置などを加熱処理装置として使用することも出来る。また、この場合、乾燥と加熱処理とを同時に行うことも可能である。 Examples of the apparatus used for the heat treatment include a kiln described in Section 5.1 of the ceramics operation (Ceramics Reading Variety Committee, issued September 20, 1973, Ceramics Association). Specifically, as such a kiln, a flame flame corner kiln, a flame flame type round kiln, a shuttle kiln, a bell kiln discontinuous kiln; a ring kiln, a continuous chamber kiln, a continuous kiln of a tunnel kiln; a rotary kiln; An electric furnace such as a resistance furnace may be mentioned. Further, as a suitable apparatus used for drying, for example, a box-type dryer, a rotating machine, which is classified in 591 page of Powder Engineering Handbook (Edited by Powder Engineering Society, published on February 28, 1986, Nikkan Kogyo Shimbun) Examples include dryers. The atmosphere for the heat treatment and drying may be an inert gas such as nitrogen, but may be air.
In addition, when the heat treatment temperature is low, a known drying device or the like can be used as the heat treatment device. In this case, drying and heat treatment can be performed simultaneously.
　（金属シリコン等の製造方法）
　本発明の製造方法で得られた珪砂造粒体は、金属シリコン、フェロシリコン、および炭化珪素の製造に使用することができ、特にアーク炉による金属シリコンの製造に好適に用いられる。 (Manufacturing method of metal silicon etc.)
The silica sand granule obtained by the production method of the present invention can be used for production of metal silicon, ferrosilicon, and silicon carbide, and is particularly suitably used for production of metal silicon by an arc furnace.
　金属シリコンの製造には、例えばシリコン源である珪砂造粒体を単独あるいは珪石と併用して使用し、これに還元材として木炭、コークス、石炭、ウッドチップなどを混合して、アーク炉内で還元・溶融する方法が挙げられる。アーク炉内へは偏析のないよう十分に混合されて、必要量投入される。炉内では電極先端部がアーク放電により最も高温となり、その到達温度が１９００℃～２０００℃となるように通電することによってシリコン源が還元され、金属シリコン融液が炉の底部に溜る。アーク炉底部に溜まった金属シリコン融液は、流し口を酸素ガスなどで開孔し、取鍋に抽出される。そして金属シリコン融液が凝固する過程でカルシウム化合物などの不純物が比重差によってスラグとして分離される。スラグの全部または一部を取り除くことで、金属シリコン塊が得られる。アーク炉は、例えばシリコン原料調査研究成果報告書（昭和５８年３月、（社）日本電子工業振興協会）の４７～５５頁に記載されているような公知の構造、材質を有するものが特に制限なく使用される。 In the production of metallic silicon, for example, a silica sand granule, which is a silicon source, is used alone or in combination with silica stone, and charcoal, coke, coal, wood chips, etc. are mixed as a reducing material in an arc furnace. A method of reducing and melting is mentioned. The arc furnace is thoroughly mixed so as not to segregate, and the required amount is charged. In the furnace, the tip of the electrode reaches the highest temperature due to arc discharge, and the silicon source is reduced by energization so that the ultimate temperature is 1900 ° C. to 2000 ° C., and the metal silicon melt accumulates at the bottom of the furnace. The metal silicon melt collected at the bottom of the arc furnace is extracted into a ladle by opening the spout with oxygen gas or the like. In the process of solidifying the metal silicon melt, impurities such as calcium compounds are separated as slag by the difference in specific gravity. By removing all or part of the slag, a metallic silicon mass is obtained. For example, an arc furnace having a known structure and material as described in, for example, pages 47 to 55 of the silicon raw material research report (March 1983, Japan Electronics Industry Promotion Association) Used without limitation.
　なお、上記金属シリコンの製造方法としては、珪砂を成形して平均粒径が５ｍｍ～２００ｍｍ、圧壊強度が２００Ｎ～１００，０００Ｎである珪砂造粒体を作製する工程、およびその珪砂造粒体を、シリコン源の少なくとも一部としてアーク炉へ供給して還元反応を行なう工程を一体として行う態様も好ましい。 The method for producing the metal silicon includes a step of forming silica sand to produce a silica sand granule having an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N, and the silica sand granule. Also preferred is an aspect in which the step of supplying the arc furnace as at least a part of the silicon source to perform the reduction reaction is integrated.
　フェロシリコンや炭化珪素の製造の場合には、前者では鉄源を所望の組成となるように別に所定量加える必要があり、また後者では前出の式（４）からわかるとおり還元材を炭素のモル当量がシリカの３倍以上となるよう多量に添加することになる。そして、当然ながら加熱温度についても、目的物に応じて調整が必要となる。 In the case of manufacturing ferrosilicon or silicon carbide, the former requires adding a predetermined amount of iron source so as to have a desired composition. In the latter, as shown in the above formula (4), the reducing material is made of carbon. A large amount is added so that the molar equivalent is 3 times or more that of silica. Of course, the heating temperature also needs to be adjusted according to the object.
　以下、実施例および比較例により本発明をさらに詳細に説明するが、本発明はこれら実施例に制限されるものではない。 Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
　尚、実施例および比較例における数値は次に示す方法により測定した。 In addition, the numerical value in an Example and a comparative example was measured by the method shown next.
　（１）圧壊強度
　最大加圧重１００ｋＮの電動式万能圧縮試験機（ＭＡＲＵＩ製ＭＩＳ－２２５－１－１６型）にて圧壊強度（Ｎ）を測定した。円柱状造粒体を立てて圧縮機に配置し、鉛直方向に載荷した。荷重を１分間に圧縮ひずみが１％生じる速度とした。 (1) Crushing strength The crushing strength (N) was measured with an electric universal compression tester (MIS-225-1-16, manufactured by MARUI) having a maximum pressurization weight of 100 kN. A columnar granule was erected and placed in a compressor, and loaded in the vertical direction. The load was set to a speed at which 1% of compressive strain was generated per minute.
　（２）造粒体の平均粒径
　円柱状造粒体の高さｈ（ｃｍ）と直径２ｒ（ｃｍ）をノギスで計測し、次式により造粒体の平均粒径Ｌ（ｃｍ）を決定した。
       Ｌ＝２・（（３／４）・ｒ２・ｈ）１／３
　（３）造粒体のＳｉＯ２含有量
　円柱状造粒体を測定治具に装着し、蛍光Ｘ線にて元素分析し、ＳｉＯ２含有量を算出した。 (2) Average particle diameter of granulated body The height h (cm) and diameter 2r (cm) of a cylindrical granulated body are measured with a caliper, and the average particle diameter L (cm) of the granulated body is determined by the following equation. did.
L = 2 · ((3/4) · r 2 · h) 1/3
(3) SiO 2 content of granulated body The columnar granulated body was mounted on a measuring jig and subjected to elemental analysis with fluorescent X-rays to calculate the SiO 2 content.
　（４）造粒体の見掛け密度
　ノギスにて計測した円柱状造粒体の高さｈと直径２ｒ、および電子天秤にて秤量した円柱状造粒体の重量ｍから、次式にて見掛け密度ρを計算した。
       ρ＝ｍ／（π・ｒ２・ｈ）
　（５）珪砂の平均粒径
　コールター社製光散乱回折タイプ粒度分布測定装置ＬＳ２３０により０．０４～０．４μｍの範囲で粒度分布（体積基準分布）を測定し、珪砂の平均粒径を算出した。 (4) Apparent density of the granulated body From the height h and diameter 2r of the cylindrical granulated body measured with calipers, and the weight m of the cylindrical granulated body weighed with an electronic balance, the apparent density is expressed by the following equation: ρ was calculated.
ρ = m / (π · r 2 · h)
(5) Average particle size of silica sand The particle size distribution (volume-based distribution) was measured in the range of 0.04 to 0.4 μm using a light scattering diffraction type particle size distribution measuring device LS230 manufactured by Coulter, and the average particle size of silica sand was calculated. .
　（６）珪砂のＳｉＯ２含有量及びＮａ２Ｏ含有量
　珪砂を一面に垂らした両面テープを測定治具に貼り付け、蛍光Ｘ線にて元素分析し、ＳｉＯ２及びＮａ２Ｏ含有量を算出した。
　（７）相対粒子量
　ＩＳＯ３３０１－１に準拠した、目開き７５μｍの篩、目開き１５０μｍ、及び目開き１４００μｍの篩を用い、４０ｇの珪砂の相対粒子量を求めた。相対粒子量は、１４００μｍの篩を全通過することを確認した後、目開き７５μｍの篩を通過した粒子の重量と、目開き１５０μｍの篩を通り目開き７５μｍの篩を通過しない粒子の重量、目開き１５０μｍの篩を通過しない粒子の重量を測定し、全体を１００重量％としたときの割合（重量％）として計測した。 (6) SiO 2 content and Na 2 O content of silica sand A double-sided tape with silica sand suspended on one side is attached to a measurement jig, and elemental analysis is performed with fluorescent X-rays to calculate SiO 2 and Na 2 O content. did.
(7) Relative Particle Amount Based on ISO3301-1, a sieve having an aperture of 75 μm, an aperture of 150 μm, and an aperture of 1400 μm was used to determine the relative particle amount of 40 g of silica sand. After confirming that the relative particle amount completely passes through the 1400 μm sieve, the weight of the particles passed through the 75 μm sieve and the weight of the particles passing through the 150 μm sieve and not passing through the 75 μm sieve, The weight of the particles that do not pass through a sieve having an opening of 150 μm was measured, and the weight was measured as a ratio (% by weight) when the whole was 100% by weight.
　実施例１
　珪砂（平均粒径２４５μｍ、ＳｉＯ２含有量９９．４重量％、Ｎａ２Ｏ含有量０．０重量％）を遊星型ボールミルにて平均粒径１３０μｍまで粉砕した。この珪砂１００重量部に水酸化カルシウム（和光純薬試薬特級）１．０重量部と水１６．７重量部を加え乳鉢にて良く混合した。この混合物を内径２０ｍｍの金型へ移し、圧力約６ＭＰａにて加圧造粒した。金型から取り出した円柱状造粒体を送風乾燥器中１５０℃で乾燥した。得られた円柱状造粒体の重量を秤量し、また直径および高さを計測した。そして、これらの値から造粒体の平均粒径と見掛け密度を計算した。さらに、元素分析によってＳｉＯ２含有量を測定した後、圧壊強度を評価した。結果を表１にまとめた。 Example 1
Silica sand (average particle size: 245 μm, SiO 2 content: 99.4 wt%, Na 2 O content: 0.0 wt%) was pulverized to an average particle size of 130 μm with a planetary ball mill. To 100 parts by weight of this silica sand, 1.0 part by weight of calcium hydroxide (special grade of Wako Pure Chemicals) and 16.7 parts by weight of water were added and mixed well in a mortar. This mixture was transferred to a mold having an inner diameter of 20 mm and granulated under pressure at a pressure of about 6 MPa. The columnar granule taken out from the mold was dried at 150 ° C. in a blower dryer. The weight of the obtained cylindrical granule was weighed, and the diameter and height were measured. And the average particle diameter and apparent density of the granulated body were calculated from these values. Furthermore, after measuring the SiO 2 content by elemental analysis, the crushing strength was evaluated. The results are summarized in Table 1.
　実施例２～５
　実施例１の１５０℃加熱処理に加えて、空気中、電気炉により加熱処理を表１に示した温度で実施した以外は実施例１と全く同様にして造粒体を得た。得られた造粒体を実施例１と同じ測定に供した。各種測定の結果を表１にまとめた。 Examples 2-5
In addition to the 150 ° C. heat treatment of Example 1, a granulated body was obtained in exactly the same manner as in Example 1 except that the heat treatment was carried out in air in an electric furnace at the temperature shown in Table 1. The obtained granule was subjected to the same measurement as in Example 1. The results of various measurements are summarized in Table 1.
　実施例６、７
　水酸化カルシウムの添加割合を表１に示したように変更した以外は実施例３と全く同様にして造粒体を得た。各種測定の結果を表１にまとめた。 Examples 6 and 7
A granulated material was obtained in exactly the same manner as in Example 3 except that the addition ratio of calcium hydroxide was changed as shown in Table 1. The results of various measurements are summarized in Table 1.
比較例１～３
　カルシウム化合物を添加しなかった以外は実施例１～３と全く同様にして造粒体を得た。各種測定の結果を表１にまとめた。 Comparative Examples 1 to 3
Granules were obtained in exactly the same manner as in Examples 1 to 3, except that no calcium compound was added. The results of various measurements are summarized in Table 1.
　実施例８
　遊星型ボールミルにて平均粒径７μｍまで粉砕した珪砂を用いて実施例１と同様に加圧造粒した。この円柱状造粒体を送風乾燥器中１５０℃のみの加熱処理にて、実施例１と同様の各種測定に供した。結果を表１にまとめた。 Example 8
Pressure granulation was performed in the same manner as in Example 1 using silica sand ground to an average particle size of 7 μm with a planetary ball mill. This cylindrical granule was subjected to various measurements similar to those in Example 1 by heat treatment only at 150 ° C. in a blower dryer. The results are summarized in Table 1.
　実施例９～１２
　実施例８の１５０℃加熱処理に加えて、空気中、電気炉により加熱処理を表１に示した温度で実施した以外は実施例８と全く同様にして造粒体を得た。各種測定の結果を表１にまとめた。 Examples 9-12
In addition to the heat treatment at 150 ° C. in Example 8, a granulated product was obtained in exactly the same manner as in Example 8, except that the heat treatment was performed in air in an electric furnace at the temperature shown in Table 1. The results of various measurements are summarized in Table 1.
　実施例１３
　水酸化カルシウムの添加割合を表１に示したように０．１重量部へ変更した以外は実施例９と全く同様にして造粒体を得た。各種測定の結果を表１にまとめた。 Example 13
A granulated product was obtained in exactly the same manner as in Example 9, except that the addition ratio of calcium hydroxide was changed to 0.1 parts by weight as shown in Table 1. The results of various measurements are summarized in Table 1.
　比較例４
　カルシウム化合物を添加しなかった以外は実施例９と全く同様にして造粒体を得た。各種測定の結果を表１にまとめた。 Comparative Example 4
A granulated body was obtained in the same manner as in Example 9 except that the calcium compound was not added. The results of various measurements are summarized in Table 1.
　実施例１４
　遊星型ボールミルによる粉砕しなかった、即ち珪砂（平均粒径２４５μｍ、ＳｉＯ２含有量９９．４重量％）そのものを用いた以外は実施例５と全く同様に１５００℃で加熱処理して造粒体を得た。各種測定の結果を表１にまとめた。 Example 14
Granules that were not pulverized by a planetary ball mill, that is, heat treated at 1500 ° C. in exactly the same manner as in Example 5 except that silica sand (average particle size 245 μm, SiO 2 content 99.4 wt%) was used. Got. The results of various measurements are summarized in Table 1.
　実施例１５
　水酸化カルシウムの添加割合を表１に示したように５．０重量部へ変更した以外は実施例１４と全く同様にして造粒体を得た。各種測定の結果を表１にまとめた。 Example 15
A granulated product was obtained in exactly the same manner as in Example 14, except that the addition ratio of calcium hydroxide was changed to 5.0 parts by weight as shown in Table 1. The results of various measurements are summarized in Table 1.
　比較例５
　カルシウム化合物を添加しなかった以外は実施例１４と全く同様にして造粒体を得た。各種測定の結果を表１にまとめた。 Comparative Example 5
A granulated body was obtained in the same manner as in Example 14 except that the calcium compound was not added. The results of various measurements are summarized in Table 1.
　実施例１６
　珪砂（平均粒径２４５μｍ、ＳｉＯ２含有量９９．４重量％、Ｎａ２Ｏ含有量０．０重量％）を遊星型ボールミルにて平均粒径１３８μｍまで粉砕した。この珪砂１００重量部に炭酸カルシウム（和光純薬試薬特級）１．４重量部と水２０．８重量部を加え乳鉢にて良く混合した。この混合物を内径２０ｍｍの金型へ移し、圧力約６ＭＰａにて加圧造粒した。金型から取り出した円柱状造粒体を送風乾燥器中１５０℃で乾燥した後、引き続き電気炉にて空気中１１００℃で加熱処理した。得られた造粒体を実施例１と同じ測定に供した。なお、炭酸カルシウムの添加割合を１．４重量部としたのは実施例１～５で添加した水酸化カルシウムのモル数と合わせるためである。各種測定の結果を表１にまとめた。 Example 16
Silica sand (average particle size 245 μm, SiO 2 content 99.4 wt%, Na 2 O content 0.0 wt%) was pulverized to an average particle size of 138 μm with a planetary ball mill. To 100 parts by weight of this silica sand, 1.4 parts by weight of calcium carbonate (special grade of Wako Pure Chemicals) and 20.8 parts by weight of water were added and mixed well in a mortar. This mixture was transferred to a mold having an inner diameter of 20 mm and granulated under pressure at a pressure of about 6 MPa. The columnar granule taken out from the mold was dried at 150 ° C. in a blower dryer, and subsequently heat-treated at 1100 ° C. in air in an electric furnace. The obtained granule was subjected to the same measurement as in Example 1. The reason why the addition ratio of calcium carbonate was 1.4 parts by weight was to match the number of moles of calcium hydroxide added in Examples 1 to 5. The results of various measurements are summarized in Table 1.
　実施例１７
　加熱処理温度を表１に示したように１３００℃へ変更した以外は実施例１７と全く同様にして造粒体を得た。各種測定の結果を表１にまとめた。 Example 17
Granules were obtained in exactly the same manner as in Example 17 except that the heat treatment temperature was changed to 1300 ° C. as shown in Table 1. The results of various measurements are summarized in Table 1.
　比較例６
　炭酸カルシウムの代わりに水酸化ナトリウム（和光純薬試薬特級）を添加し、その添加割合を０．５６重量部、そして水の添加割合を１６．７重量部とした以外は実施例１６と全く同様にして造粒体を得た。なお、水酸化ナトリウムの添加割合を０．５６重量部としたのは実施例１６で添加した炭酸カルシウムのモル数と合わせるためである。各種測定の結果を表１にまとめた。 Comparative Example 6
Except for calcium carbonate, sodium hydroxide (special grade of Wako Pure Chemicals) was added, the addition ratio was 0.56 parts by weight, and the addition ratio of water was 16.7 parts by weight. Thus, a granulated body was obtained. The addition ratio of sodium hydroxide was 0.56 parts by weight in order to match the number of moles of calcium carbonate added in Example 16. The results of various measurements are summarized in Table 1.
　実施例１８
　結合剤を１．８重量部の硫酸カルシウムとした以外は実施例３と同様に評価を行った。結果を表２にまとめた。 Example 18
Evaluation was performed in the same manner as in Example 3 except that the binder was 1.8 parts by weight of calcium sulfate. The results are summarized in Table 2.
　実施例１９
　結合剤を１．８重量部の硫酸カルシウムとした以外は実施例４と同様に評価を行った。結果を表２にまとめた。 Example 19
Evaluation was performed in the same manner as in Example 4 except that the binder was changed to 1.8 parts by weight of calcium sulfate. The results are summarized in Table 2.
　実施例２０
　結合剤を０．８重量部の水酸化マグネシウムとした以外は実施例３と同様に評価を行った。結果を表２にまとめた。 Example 20
Evaluation was performed in the same manner as in Example 3 except that the binder was changed to 0.8 parts by weight of magnesium hydroxide. The results are summarized in Table 2.
　実施例２１
　結合剤を０．８重量部の水酸化マグネシウムとした以外は実施例４と同様に評価を行った。結果を表２にまとめた。 Example 21
Evaluation was performed in the same manner as in Example 4 except that 0.8 parts by weight of magnesium hydroxide was used as the binder. The results are summarized in Table 2.
　実施例２２
　用いた珪砂を、珪砂（平均粒径２４１μｍ、ＳｉＯ２含有量９９．４重量％、Ｎａ２Ｏ含有量０．５重量％）とした以外は実施例３と同様に評価を行った。結果を表３にまとめた。 Example 22
Evaluation was performed in the same manner as in Example 3 except that the silica sand used was silica sand (average particle size 241 μm, SiO 2 content 99.4 wt%, Na 2 O content 0.5 wt%). The results are summarized in Table 3.
　実施例２３
　用いた珪砂を、珪砂（平均粒径２４９μｍ、ＳｉＯ２含有量９８．８重量％、Ｎａ２Ｏ含有量１．０重量％）とした以外は実施例３と同様に評価を行った。結果を表３にまとめた。 Example 23
Evaluation was performed in the same manner as in Example 3 except that the silica sand used was silica sand (average particle size 249 μm, SiO 2 content 98.8 wt%, Na 2 O content 1.0 wt%). The results are summarized in Table 3.
　実施例２４
　用いた珪砂を、珪砂（平均粒径２５２μｍ、ＳｉＯ２含有量９８．２重量％、Ｎａ２Ｏ含有量１．５重量％）とした以外は実施例３と同様に評価を行った。結果を表３にまとめた。 Example 24
Evaluation was performed in the same manner as in Example 3 except that the silica sand used was silica sand (average particle size 252 μm, SiO 2 content 98.2 wt%, Na 2 O content 1.5 wt%). The results are summarized in Table 3.
　実施例２５～３３
　珪砂（平均粒径２４５μｍ、ＳｉＯ２含有量９９．４重量％、Ｎａ２Ｏ含有量０．０重量％）を遊星型ボールミルにて平均粒径１８μｍまで粉砕した。未粉砕珪砂と所定の割合で混合し、評価を行った。結果を表４に示す。 Examples 25-33
Silica sand (average particle size 245 μm, SiO 2 content 99.4 wt%, Na 2 O content 0.0 wt%) was pulverized to an average particle size of 18 μm with a planetary ball mill. It was mixed with unground crushed silica sand at a predetermined ratio and evaluated. The results are shown in Table 4.
　実施例３４
　実施例４で作製した珪砂造粒体と平均粒径５ｍｍの仮焼コークスとを重量比２：１で混合し、合計３０ｋｇの原料を用い、エルー式アーク炉（アンドー工業所社製）にて加熱処理を行った。運転時の内部温度は、放射温度計にて測定し、２０００℃で６時間の運転を行った。加熱終了後、１６時間の冷却を行い、試料を取出した。試料下部に高純度の金属シリコンの塊５ｋｇを得た。 Example 34
The silica sand granulate produced in Example 4 and calcined coke having an average particle diameter of 5 mm were mixed at a weight ratio of 2: 1, and a total of 30 kg of raw materials were used in an ER type arc furnace (manufactured by Ando Kogyosho). Heat treatment was performed. The internal temperature during operation was measured with a radiation thermometer and operated at 2000 ° C. for 6 hours. After completion of heating, cooling was performed for 16 hours, and a sample was taken out. 5 kg of high-purity metallic silicon lump was obtained at the bottom of the sample.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　本発明の珪砂造粒体は、珪石の代替として、金属シリコンの製造や、フェロシリコンなどのシリコン合金や炭化珪素の製造に有効に利用できる。 The silica sand granule of the present invention can be effectively used for the production of metallic silicon, silicon alloys such as ferrosilicon, and silicon carbide as an alternative to silica stone.

Claims (18)

  1. 　珪砂から成形されており、平均粒径が５ｍｍ～２００ｍｍ、圧壊強度が２００Ｎ～１００，０００Ｎであることを特徴とする珪砂造粒体。 A silica sand granule formed from silica sand, having an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N.
  2. 　アルカリ土類金属化合物を結合剤として用いて珪砂が成形されている請求項１記載の珪砂造粒体。 The silica sand granule according to claim 1, wherein the silica sand is molded using an alkaline earth metal compound as a binder.
  3. 　結合剤であるアルカリ土類金属化合物が、カルシウム化合物、マグネシウム化合物またはそれらの混合物である請求項２記載の珪砂造粒体。 The quartz sand granule according to claim 2, wherein the alkaline earth metal compound as a binder is a calcium compound, a magnesium compound or a mixture thereof.
  4. 　Ｓｉ原子に対するアルカリ土類金属原子の比（Ｍ２／Ｓｉ）が０．００１～０．０４である請求項２記載の珪砂造粒体。 The quartz sand granule according to claim 2 , wherein the ratio of alkaline earth metal atoms to Si atoms (M 2 / Si) is 0.001 to 0.04.
  5. 　珪砂のＳｉＯ２含有量が９７重量％以上であることを特徴とする請求項１記載の珪砂造粒体。 Silica sand granulation of claim 1, wherein the SiO 2 content of silica sand, characterized in that at least 97% by weight.
  6. 　粒径が１４００μｍ未満の範囲にあり、粒径７５μｍ未満の範囲にある相対粒子量（重量）が２５％～７０％、粒径１５０μｍ以上、１４００μｍ未満の範囲にある相対粒子量が１０％～５０％である珪砂（ただし、１４００μｍ未満の範囲にある相対粒子量は１００％である。）から得られる請求項１記載の珪砂造粒体。 The particle size is in the range of less than 1400 μm, the relative particle amount (weight) in the range of less than 75 μm is 25% to 70%, the relative particle amount in the range of 150 to 1400 μm is 10% to 50% The silica sand granule according to claim 1, wherein the silica sand granule is obtained from the silica sand of 100% (however, the relative particle amount in the range of less than 1400 μm is 100%).
  7. 　珪砂造粒体に含まれるＳｉ原子に対するアルカリ金属原子の比（Ｍ１／Ｓｉ）が０．０１未満であることを特徴とする請求項１に記載の珪砂造粒体。 2. The silica sand granule according to claim 1, wherein the ratio of alkali metal atoms to Si atoms (M 1 / Si) contained in the silica sand granule is less than 0.01.
  8. 　珪砂を造粒することを特徴とする、平均粒径が５ｍｍ～２００ｍｍ、圧壊強度が２００Ｎ～１００，０００Ｎである珪砂造粒体の製造方法。 A method for producing a silica sand granule having an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N, characterized by granulating silica sand.
  9. 　珪砂の表面に結合剤であるアルカリ土類金属化合物を接触せしめて造粒することを特徴とする請求項８記載の珪砂造粒体の製造方法。 The method for producing a quartz sand granule according to claim 8, wherein granulation is carried out by bringing an alkaline earth metal compound as a binder into contact with the surface of the silica sand.
  10. 　アルカリ土類金属化合物の珪砂表面への接触を水の存在下に行なった後、さらに１００℃～１６００℃の温度に加熱することを特徴とする請求項９記載の珪砂造粒体の製造方法。 The method for producing a silica sand granule according to claim 9, wherein the contact with the surface of the silica earth of the alkaline earth metal compound is carried out in the presence of water, and further heated to a temperature of 100 ° C to 1600 ° C.
  11. 　アルカリ土類金属化合物が水酸化カルシウム、炭酸カルシウム、酸化カルシウム、硫酸カルシウムまたはそれらの混合物であることを特徴とする請求項９記載の珪砂造粒体の製造方法。 The method for producing a quartz sand granule according to claim 9, wherein the alkaline earth metal compound is calcium hydroxide, calcium carbonate, calcium oxide, calcium sulfate or a mixture thereof.
  12. 　アルカリ土類金属化合物の使用割合が珪砂１００重量部に対して０．１～５重量部であることを特徴とする請求項９記載の珪砂造粒体の製造方法。 10. The method for producing a quartz sand granule according to claim 9, wherein the use ratio of the alkaline earth metal compound is 0.1 to 5 parts by weight with respect to 100 parts by weight of the silica sand.
  13. 　珪砂のＳｉＯ２含有量が９７重量％以上であることを特徴とする請求項８記載の珪砂造粒体の製造方法。 The method for producing a quartz sand granule according to claim 8, wherein the SiO 2 content of the silica sand is 97% by weight or more.
  14. 　粒径が１４００μｍ未満の範囲にあり、粒径７５μｍ未満の範囲にある相対粒子量（重量）が２５％～７０％、粒径１５０μｍ以上、１４００μｍ未満の範囲にある相対粒子量が１０％～５０％である珪砂（ただし、１４００μｍ未満の範囲にある相対粒子量は１００％である。）を使用することを特徴とする請求項８記載の珪砂造粒体の製造方法。 The particle size is in the range of less than 1400 μm, the relative particle amount (weight) in the range of less than 75 μm is 25% to 70%, the relative particle amount in the range of 150 to 1400 μm is 10% to 50% % Silica sand (however, the relative particle amount in the range of less than 1400 μm is 100%).
  15. 　粉砕により平均粒径１μｍ～２００μｍの範囲に調整された珪砂を使用することを特徴とする請求項８記載の珪砂造粒体の製造方法。 9. The method for producing a quartz sand granule according to claim 8, wherein the silica sand is adjusted to a mean particle size of 1 μm to 200 μm by pulverization.
  16. 　請求項１に記載の珪砂造粒体をシリコン源の少なくとも一部として使用する、金属シリコン、フェロシリコンまたは炭化珪素を製造する方法。 A method for producing metal silicon, ferrosilicon or silicon carbide, wherein the silica sand granule according to claim 1 is used as at least part of a silicon source.
  17. 　請求項１記載の珪砂造粒体を、シリコン源の少なくとも一部としてアーク炉へ供給して還元反応を行なうことを特徴とする金属シリコンの製造方法。 A method for producing metallic silicon, wherein the silica sand granule according to claim 1 is supplied to an arc furnace as at least a part of a silicon source to perform a reduction reaction.
  18. 　珪砂を成形して平均粒径が５ｍｍ～２００ｍｍ、圧壊強度が２００Ｎ～１００，０００Ｎである珪砂造粒体を作製する工程、および
    　その珪砂造粒体を、シリコン源の少なくとも一部としてアーク炉へ供給して還元反応を行なう工程を含む金属シリコンの製造方法。     Forming a silica sand granule having an average particle diameter of 5 mm to 200 mm and a crushing strength of 200 N to 100,000 N by molding the silica sand, and using the silica sand granule as at least a part of a silicon source to an arc furnace A method for producing metal silicon, comprising a step of supplying and performing a reduction reaction.
PCT/JP2011/074898 2010-11-02 2011-10-28 Granulated body of silica sand and production method therefor WO2012060285A1 (en)

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JP2015098429A (en) * 2013-10-16 2015-05-28 株式会社トクヤマ Method for producing silica sand-granulated body
WO2018145953A1 (en) * 2017-02-13 2018-08-16 Sibelco Nederland N.V. Grains comprising silica and methods of forming grains comprising silica
WO2021228370A1 (en) * 2020-05-12 2021-11-18 Wacker Chemie Ag Method for producing technical silicon
WO2021228371A1 (en) * 2020-05-12 2021-11-18 Wacker Chemie Ag Method for producing silicon dioxide-containing agglomerates

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CN111268685B (en) * 2020-03-09 2022-10-28 邓咏兰 Synthesis process of fumed silica
CN113231192B (en) * 2021-06-16 2022-05-27 江西省矿产资源保障服务中心 Beneficiation method for silicon dioxide in silicon-planted ore

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JP2015098429A (en) * 2013-10-16 2015-05-28 株式会社トクヤマ Method for producing silica sand-granulated body
WO2018145953A1 (en) * 2017-02-13 2018-08-16 Sibelco Nederland N.V. Grains comprising silica and methods of forming grains comprising silica
WO2021228370A1 (en) * 2020-05-12 2021-11-18 Wacker Chemie Ag Method for producing technical silicon
WO2021228371A1 (en) * 2020-05-12 2021-11-18 Wacker Chemie Ag Method for producing silicon dioxide-containing agglomerates

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CN103201220B (en) 2015-11-25

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