WO2023204071A1 - Production method for grained iron, and grained iron - Google Patents

Production method for grained iron, and grained iron Download PDF

Info

Publication number
WO2023204071A1
WO2023204071A1 PCT/JP2023/014502 JP2023014502W WO2023204071A1 WO 2023204071 A1 WO2023204071 A1 WO 2023204071A1 JP 2023014502 W JP2023014502 W JP 2023014502W WO 2023204071 A1 WO2023204071 A1 WO 2023204071A1
Authority
WO
WIPO (PCT)
Prior art keywords
iron
molten iron
dephosphorization
concentration
temperature
Prior art date
Application number
PCT/JP2023/014502
Other languages
French (fr)
Japanese (ja)
Inventor
智裕 杉野
憲治 中瀬
太 小笠原
涼 川畑
Original Assignee
Ｊｆｅスチール株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ｊｆｅスチール株式会社 filed Critical Ｊｆｅスチール株式会社
Priority to JP2023547085A priority Critical patent/JPWO2023204071A1/ja
Publication of WO2023204071A1 publication Critical patent/WO2023204071A1/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B11/00—Making pig-iron other than in blast furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21B—MANUFACTURE OF IRON OR STEEL
    • C21B13/00—Making spongy iron or liquid steel, by direct processes
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising

Definitions

  • the present invention relates to granulated iron with reduced P concentration and a method for producing the same.
  • iron ore Fe 2 O 3
  • coke which is a reducing agent (carbon source)
  • hot metal with a C concentration of about 4.5-5%
  • This is a steelmaking process in which the hot metal is charged into a converter and impurity components such as C, Si, and P are oxidized and removed.
  • impurity components such as C, Si, and P are oxidized and removed.
  • the P concentration in the iron ore used in the current blast furnace method is 0.05 to 0.10 mass% (0.10 to 0.15 mass% when converted to P concentration as reduced iron), and it is expected that this will change in the future. It is expected that the P concentration will increase. This P concentration is 5 to 10 times higher than the P concentration of reduced iron produced using high-grade iron ore with a low P concentration, and in order to prevent quality deterioration due to phosphorus in steel products, reduced iron with a high P concentration must be used. It is necessary to remove phosphorus when melting to produce molten steel, or when producing reduced iron from iron ore with a high P concentration. Several techniques have been proposed regarding such phosphorus removal techniques.
  • Patent Document 1 describes a method for removing phosphorus from molten steel to a low concentration in a relatively short period of time using an electric arc furnace alone.
  • a flux for dephosphorization refining in an arc furnace has been proposed in which the mass % and the remainder consist of unavoidable impurities.
  • Patent Document 2 describes iron ore, titanium-containing iron ore, nickel-containing ore, chromium-containing ore, or iron ore containing CaO of 25% by mass or less and a CaO/(SiO 2 +Al 2 O 3 ) ratio of 5 or less, or these ores.
  • a method has been proposed for removing phosphorus by contacting a mixture mainly composed of ores with Ar, He, N 2, CO, H 2, one type of hydrocarbon, or a mixed gas of these at a temperature of 1600°C or higher. There is.
  • Patent Document 3 discloses that iron ore with a high P concentration is pulverized to 0.5 mm or less, water is added to this to make a pulp concentration of around 35% by mass, and H 2 SO 4 or HCl is added to a solvent to obtain a pH of 2.0.
  • H 2 SO 4 or HCl is added to a solvent to obtain a pH of 2.0.
  • a method has been proposed in which slaked lime or quicklime is added to neutralize P dissolved in the solution to a pH within the range of 5.0 to 10.0, and the P is separated and recovered as calcium phosphate.
  • Patent Document 1 assumes an iron source with a low P concentration such as scrap. Specifically, in order to reduce the P concentration in molten steel from 0.020% by mass to 0.005% by mass, 350g of flux is added to 7000g of molten steel. Assuming that the P concentration in reduced iron is 0.15% by mass, the amount of flux required to reduce the P concentration to 0.01% by mass, which is comparable to that of steel products, is 230 kg per ton of molten steel. Then, there is a problem that the volume ratio occupied by flux in the arc furnace increases, the amount of molten steel processed decreases, and manufacturing efficiency deteriorates.
  • the treatment temperature is 1,600°C or higher, and the specification states, ⁇ In order to perform more effective dephosphorization, the treatment temperature is preferably 1,800°C or higher. This is difficult to achieve with conventional heating methods, but can be achieved, for example, by using plasma arcs or high-frequency induced plasma.” Therefore, there is a problem that it requires a lot of energy and is not suitable for processing a large amount.
  • Patent Document 3 is a wet treatment using an acid, and there is a problem in that it requires time and cost to dry the recovered magnetic material to use it as a main raw material. Furthermore, this method also has the problem that it requires time and cost to crush the material to 0.5 mm or less in advance.
  • the present invention was made in view of the above circumstances, and even if the raw material is reduced iron obtained from low-grade iron ore with a high P concentration, it is possible to efficiently produce granulated iron with a low P concentration.
  • the purpose is to provide technology that enables
  • the method for producing granulated iron according to the present invention which advantageously solves the above problems, includes a first step of melting reduced iron to obtain primary molten iron, a second step of separating the primary molten iron and slag, and a second step of separating the primary molten iron from the slag.
  • the third step includes: Dephosphorizing the primary molten iron by supplying an oxygen source and a CaO source, and setting the temperature of the secondary molten iron at the end of the dephosphorization to be equal to or lower than the temperature of the primary molten iron at the start of the dephosphorizing process. It is characterized by
  • the method for producing granulated iron according to the present invention is as follows: (a) Raising the temperature Tf of the secondary molten iron at the end of the dephosphorization process by 20°C or more from the solidification temperature Tm of the secondary molten iron at the end of the dephosphorization process; (b) The slag composition at the end of the dephosphorization treatment has a basicity in the range of 1.0 to 4.0, which is the ratio of CaO concentration (%CaO) to SiO 2 concentration (%SiO 2 ) on a mass basis.
  • a granulating device that turns the secondary molten iron into droplets, a water flow control container provided at a position to receive the droplets and containing cooling water, and a water flow control container connected to the water flow control container are provided.
  • at least one cooling water pipe that supplies cooling water to the water flow control container, and the water flow control container has an inclined surface that is inclined so that the horizontal cross-sectional area of the water flow control container becomes narrower toward the bottom.
  • the granulated iron according to the present invention which advantageously solves the above problems, uses reduced iron with a P concentration of 0.050% by mass or more as a raw material, has a P concentration of 0.030% by mass or less, and has a particle size of 1 mm or more and 50 mm. It is characterized by the following:
  • the method for producing granulated iron according to the present invention it is possible to efficiently produce granulated iron with a low P concentration from reduced iron obtained from low-grade iron ore with a high P concentration. Further, the granulated iron according to the present invention satisfies the P concentration required for many steel products, that is, 0.030% by mass or less. Therefore, molten iron with a P concentration equivalent to that of a steel product can be obtained simply by remelting the granulated iron according to the present invention.
  • the iron is solidified into granules to form granular iron, so it becomes possible to produce iron in a form where the iron source manufacturing plant and the demand site are separated, rather than in a large-scale iron manufacturing plant.
  • a raw material-producing country goes as far as producing dephosphorized granulated iron, and a steel-producing country produces steel using this dephosphorized granulated iron as raw material.
  • the production of reduced iron and the production of granulated iron according to the present invention are carried out in an iron ore producing country, the gangue content contained in the raw material iron ore can be separated as slag. Therefore, by transporting only granulated iron, the transport amount per unit amount of Fe is reduced, and the transport cost and energy consumption to the demand site can be suppressed.
  • the particle size of iron granules is 1 to 50 mm, there is freedom in the equipment used for transportation, storage, and supply when considering transportation and storage of iron granules to demand sites, supply to equipment at demand sites, etc. The degree increases. Furthermore, it also has the effect of reducing the risk of hanging on shelves within the supply hopper.
  • Reduced iron produced from iron ore as a raw material depends on the brand of iron ore used, the type and basic unit of the raw material component adjusting agent to be mixed, the type and basic unit of the reducing agent, the reduction temperature, and the type of reduced iron manufacturing equipment. Properties such as conversion rate and composition are different. Table 1 shows examples of the components of reduced iron. In the example in Table 1, the P concentration is T. The P concentration in terms of molten iron divided by the Fe (total iron) concentration is 0.057 to 0.152% by mass. Therefore, even if these reduced irons are dissolved as they are, it is difficult to achieve a P concentration (0.030% by mass or less) at the level of steel products.
  • reduced iron is heated and melted in an electric furnace to obtain primary molten iron.
  • reduced iron manufactured at an adjacent reduced iron manufacturing plant may be used by keeping it at a high temperature.
  • the electric furnace may be an arc furnace, a submerged arc furnace, or an induction melting furnace.
  • the thermal energy supplied in the first step to melt reduced iron, which is a solid iron source, and heat up the iron source is not only electrical energy, but also gaseous fuels such as natural gas and propane gas, heavy oil, etc. as supplementary energy.
  • the heat of combustion of combustible solids such as liquid fuel, coal, metal Al, Si, etc. may be used. It is preferable that these energies be renewable energies from the viewpoint of reducing CO 2 emissions.
  • slag which is gangue of reduced iron, and primary molten iron are separated.
  • the molten metal is poured into a container for transportation and transported to equipment that performs dephosphorization treatment.
  • a CaO source is added to generate dephosphorization slag, so in order to secure the amount of slag and adjust the composition, slag containing a lot of SiO 2 generated as reduced iron is dissolved is used. At least a portion may be carried over.
  • the slag may be removed from the melting/heating container used in the first step using a slag dragger.
  • the molten metal is dephosphorized to obtain secondary molten iron.
  • [P] represents phosphorus in molten iron.
  • Pure oxygen gas is generally used as the oxygen source for dephosphorization. Since the dephosphorization reaction is an exothermic reaction, it is advantageous to perform the dephosphorization treatment at a low temperature, and considering that it will be solidified and turned into granulated iron in the next process, it is necessary to lower the temperature of the molten iron within a range that does not cause any problems in the process. It was concluded that this is advantageous.
  • the behavior of spitting differs depending on the freeboard (height from the surface of the molten iron to the top of the container) of the container where dephosphorization is performed and the shape of the nozzle of the top blowing lance. It is preferable to adjust the air supply speed and lance height. Also, in order to stir the molten iron, it is good to blow inert gas into it.
  • the inert gas may be injected through a porous plug installed at the bottom of the furnace or by dipping an injection lance into the molten iron.
  • the slag basicity which is the ratio of the CaO concentration (%CaO) to the SiO 2 concentration (%SiO 2 ) on a mass basis, is preferably in the range of 1.0 to 4.0. .
  • the amount of slag containing a large amount of SiO 2 carried over to the second step is adjusted, and the type and amount of the CaO source to be added are adjusted. If necessary, an SiO 2 source such as silica stone or ferrosilicon, or a CaO source such as quicklime may be added.
  • the slag basicity is low, the amount of phosphorus removed in the dephosphorization process will be small. If the slag basicity is high, some of the slag will solidify and adhere to the refractory when the molten iron temperature drops, making it difficult to remove the slag after dephosphorization, and causing abnormalities when charging molten iron for the next treatment. Problems may arise, such as reactions occurring and residual slag mixing with the produced slag, causing components to be removed.
  • a boiler or the like may be used to recover the exhaust heat.
  • the secondary molten iron after the dephosphorization treatment is solidified into granules to obtain granulated iron.
  • a method for producing granular iron for example, molten iron after dephosphorization is allowed to flow down and collide with a refractory surface plate, or water is allowed to collide with the molten iron that has flowed out, resulting in granular droplets that are then dropped into a water flow control container.
  • An example of this method is to obtain solidified iron granules.
  • the temperature of the molten iron decreases while the molten iron after the dephosphorization treatment is transported and supplied to the granular iron production equipment. If the temperature of the molten iron after the dephosphorization treatment is too low, a portion of the molten iron will solidify before all of the molten iron in the container is supplied to the granular iron manufacturing apparatus, resulting in a decrease in manufacturing yield. On the other hand, if the molten iron temperature after dephosphorization is high, the heat load during solidification in the granular iron production equipment will increase, the amount of cooling water used will increase, and the cooling rate will become a bottleneck, reducing productivity.
  • the waiting time before granulation may become longer due to a drop in the temperature of the molten iron.
  • the molten iron temperature T f after the dephosphorization treatment is set to be equal to or lower than the molten iron temperature T i at the time of starting the dephosphorization treatment.
  • the solidification temperature T m (°C) can be estimated by directly measuring the solidification temperature of the sample or based on past operational results (C concentration before dephosphorization, temperature, type of oxygen source, supply conditions, etc.) Any method may be used, such as setting the temperature to the temperature read from the liquidus temperature of the Fe--C phase diagram based on the C concentration of the molten iron after dephosphorization treatment.
  • the granulated iron manufacturing apparatus includes a granulating device that turns molten iron into droplets, and a water flow control container that is provided at a position to receive the droplets and that contains cooling water. At least one cooling water pipe for supplying cooling water is connected to the water flow control vessel through which the molten iron falls and solidifies. The cooling water is discharged from the cooling water pipe and a water flow is generated, thereby suppressing the formation of a stagnation area of the cooling water in the container. Therefore, the local temperature rise of the cooling water is suppressed, the granulated iron can be efficiently cooled, and the granulated iron is prevented from being sufficiently cooled and fused together.
  • the water flow control container has an inclined surface that is inclined so that the horizontal cross-sectional area of the container becomes narrower toward the bottom, and the lower part of the inclined surface is used as a discharge port.
  • the effect of diluting the P concentration can be obtained depending on the proportion used. This makes it possible to reduce the load in the dephosphorization process, and to ease restrictions on raw materials used in blast furnaces and converters.
  • the granulated iron obtained in this embodiment is used as an iron source in an electric furnace, a blast furnace, or a converter, there is a particle size range that is easy to use. Therefore, it is advisable to adjust the flow rate in the tundish to obtain the desired particle size. It is also good to classify as necessary. Generally, particles with a particle size in the range of 1 to 50 mm are easy to use. If granulated iron with a particle size smaller than 1 mm is included, there is a high possibility that clogging of conveyors for transportation or hanging on shelves in the hopper will occur, so it is better to classify and use particles with a particle size of 1 mm or more.
  • the particle size range of 1 to 50 mm can be defined as above the sieve of a sieve with an opening of 1 mm and below the sieve of a sieve with an opening of 50 mm.
  • Example 1 Reduced iron A shown in Table 1 was melted in a 250-ton electric furnace, the temperature was adjusted, and the melt was transferred to a pot-shaped container. At this time, about 10 kg/t of slag generated during electric furnace melting due to gangue contained in the reduced iron was transferred to a pot-shaped container, and the rest was transferred to another slag container. The pot-shaped container was moved to a dephosphorization treatment facility, and dephosphorization treatment was performed by changing the type and amount of oxygen source and lime source supplied.
  • the dephosphorization treatment equipment has a gas top-blowing lance, an auxiliary raw material cutting hopper, and a bottom-blowing porous plug.
  • a gas containing pure oxygen or air can be supplied from the gas top-blowing lance at a rate of about 1 Nm 3 /(min ⁇ t-molten iron).
  • Gas can be supplied from the bottom-blown porous plug, and in this example, pure Ar gas was supplied at a rate of about 0.1 Nm 3 /(min ⁇ t-molten iron).
  • the melting temperature in the electric furnace was adjusted so that the molten iron temperature before dephosphorization was approximately 1590°C. Temperature measurement and sampling were carried out using the sub-lance before and after the dephosphorization treatment, respectively, before and after the gas top-blowing lance was lowered and after the treatment. The sampled samples were cut and polished, and the C concentration [C] and P concentration [P] in the molten iron were evaluated using a calibration curve prepared in advance by emission spectrometry. Furthermore, it is possible to measure the solidification temperature of the molten metal at the timing of sublance temperature measurement and sampling, and the solidification temperature T m of the molten iron after dephosphorization treatment was actually measured.
  • the dephosphorization process was started when the gas top blowing lance started descending, and after the top blowing lance reached a predetermined height, the supply of the oxygen gas source and the addition of the auxiliary raw materials were started. After the supply of a predetermined amount of the oxygen gas source and the auxiliary raw material was completed, the dephosphorization process was defined as the time when the top blowing lance completed rising to the standby position. The time period was defined as the processing time t f (minutes).
  • the pot-shaped container was tilted and the slag on the molten iron was removed by a slag dragger. A portion of the removed slag was collected and chemically analyzed. After that, the pot is lifted and tilted by a crane, the molten iron is transferred to the tundish, and the molten iron flows down from the tundish and collides with the refractory surface plate, and the molten iron becomes droplets and falls into the water flow control container. Granulated iron was produced by solidification. The particle size of the obtained iron granules was 0.1 to 30 mm.
  • the particle size distribution was +0.1mm-1mm: 17.2% by mass, +1mm-10mm: 31.3% by mass, +10mm-20mm: 38.8% by mass, and +20mm-30mm: 12.7% by mass.
  • +NM means that it is above the sieve with a mesh size of N and below the sieve with a mesh size of M.
  • Table 2 shows the temperatures T i and T f (°C) of molten iron before and after dephosphorization treatment, C concentrations [C] i and [C] f (mass%), and P concentrations [P] i and [P] f ( mass %), the type and amount of the supplied oxygen source and CaO source, treatment time t f (minutes), basicity of the slag after treatment (mass-based CaO concentration (%CaO) relative to SiO 2 concentration (%SiO 2 ) The ratio (%CaO)/(%SiO 2 ), hereinafter referred to as C/S) was determined by the treatment No. Shown as 1 to 5.
  • the post-treatment molten iron temperature T f was lower than the pre-treatment molten iron temperature Ti , and the post-treatment P concentration [P] f was sufficiently reduced.
  • the post-dephosphorization temperature T f was higher than the pre-dephosphorization temperature T i , resulting in a high post-treatment P concentration [P] f , and a standby time occurred in the granulated iron manufacturing process, reducing productivity. did.
  • processing No. Compared with 1 to 3 processing No. In No.
  • the post-treatment molten iron temperature T f was lowered, so the P concentration [P] f was sufficiently lowered, but part of it solidified in the tundish during the production of granulated iron, resulting in a lower yield.
  • Processing No. 1 to 3 the molten iron temperature after treatment T f is lower than the molten iron temperature before treatment T i , the molten iron temperature after treatment T f is higher than the solidification temperature T m of molten iron by 20°C or more, and the P concentration after treatment [P] f is sufficient. At the same time, it was possible to produce the entire amount of granulated iron with good yield, and there was no decrease in productivity.
  • Example 2 Dephosphorization treatment and production of granulated iron were performed using the same method as in Example 1.
  • Table 3 shows the temperature T i and T f (°C) of molten iron before and after dephosphorization treatment, the C concentration [C] i and [C] f (mass%), and the P concentration [P] i and [P] f ( % by mass), the type and amount of the oxygen source and CaO source supplied, the treatment time t f (minutes), and the basicity C/S of the slag after treatment. Shown as 6 to 12. As shown in Table 3, treatment No. Processing No. 6 to 10. Sample No. 11 had a high P concentration after treatment because the basicity C/S of the slag was low. In addition, processing No. In No. 12, the basicity C/S of the slag was high and coagulation of the slag was confirmed.
  • Example 3 Reduced iron A shown in Table 1 was melted together with anthracite in a 250-ton electric furnace to obtain molten iron containing about 2.0% by mass of C, and after adjusting the temperature, it was transferred to a pot-shaped container. Thereafter, dephosphorization treatment and production of granulated iron were performed using the same methods as in Examples 1 and 2.
  • Table 4 shows the temperatures T i and T f (°C) of molten iron before and after dephosphorization treatment, C concentrations [C] i and [C] f (mass%), and P concentrations [P] i and [P] f ( % by mass), the type and amount of the oxygen source and CaO source supplied, the treatment time t f (minutes), and the basicity C/S of the slag after treatment. Shown as 13 to 19. As shown in Table 4, treatment No. For processing No. 13 to 17. Sample No. 18 had a high P concentration [P] f after treatment because the basicity C/S of the slag was low. In addition, processing No. In No. 19, the basicity C/S of the slag was high and coagulation of the slag was confirmed.
  • Processing No. The granulated iron produced in Examples 8 to 10, 12, 14 to 17, and 19 had a P concentration of 0.030% by mass or less. When these reduced irons were melted in an electric furnace, the P concentration of the resulting molten iron was 0.030% by mass or less. These achieved the P concentration required for steel products and did not require additional dephosphorization treatment. In addition, processing No. When the iron granules obtained in steps 8 to 10, 12, 14 to 17, and 19 were classified to 1 mm or more and used in an electric furnace, blast furnace, or converter, they could be used without problems.
  • the unit of mass "t” represents 10 3 kg.
  • [M] represents that element M is dissolved in molten iron or reduced iron.
  • the method for producing granulated iron and the granulated iron of the present invention even if the raw material is reduced iron obtained from low-grade iron ore with a high P concentration, it is possible to efficiently produce granulated iron with a low P concentration. This is industrially useful because it is possible to obtain molten iron with a P concentration equivalent to that of steel products simply by remelting the granulated iron according to the present invention.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Abstract

Provided is a technology that enables efficient production of grained iron having a low P concentration. The present invention comprises: a first step for melting reduced iron to obtain primary molten iron; a second step for separating the primary molten iron from slag; a third step for subjecting the primary molten iron separated from the slag to dephosphorization to obtain secondary molten iron; and a fourth step for solidifying the secondary molten iron into grains to obtain grained iron. In the third step, an oxygen source and a CaO source are supplied to the primary molten iron for dephosphorization, and the temperature of the secondary molten iron when the dephosphorization is finished is set to be equal to or lower than the temperature of the secondary molten iron when the dephosphorization is started.

Description

粒鉄の製造方法および粒鉄Granulated iron manufacturing method and granulated iron
　本発明は、Ｐ濃度を低減した粒鉄およびその製造方法に関する。 The present invention relates to granulated iron with reduced P concentration and a method for producing the same.
　近年、製鉄業における冷鉄源（スクラップ）の使用拡大の需要が高まっている。循環型社会の構築のために、鉄源リサイクルは必要不可避である。そのうえ、地球温暖化防止の観点から、ＣＯ２排出量削減の需要からもスクラップ使用量増大は不可欠である。スクラップは酸化鉄（Ｆｅ２Ｏ３）である鉄鉱石と異なり、溶製プロセスに還元工程を要さないためＣＯ２排出量の低減が可能である。そこで、冷鉄源の使用量は増加の一途をたどっている。 In recent years, there has been an increasing demand for expanded use of cold iron sources (scrap) in the steel industry. In order to build a recycling-oriented society, recycling iron sources is essential. Furthermore, from the perspective of preventing global warming and the demand for reducing CO2 emissions, it is essential to increase the amount of scrap used. Unlike iron ore, which is iron oxide (Fe 2 O 3 ), scrap does not require a reduction step in the melting process, so it is possible to reduce CO 2 emissions. Therefore, the usage of cold iron sources continues to increase.
　高炉－転炉法は、原料である鉄鉱石（Ｆｅ２Ｏ３）を還元剤であるコークス（炭素源）とともに高炉へ装入してＣ濃度が４．５－５％程度の溶銑を溶製し、その溶銑を転炉に装入し不純物成分であるＣやＳｉ、Ｐを酸化除去する製鋼プロセスである。高炉での溶銑製造時には鉄鉱石の還元などのために溶銑１ｔあたり、５００ｋｇ程度の炭素源を必要とする。そして、約２ｔ程度のＣＯ２ガスが発生する。一方、鉄スクラップを原料として溶鋼を製造する場合には、鉄鉱石の還元に必要とされる炭素源が不要となる。そのため、鉄スクラップを溶解するのに必要なエネルギーを考慮しても、１トンの溶銑を１トンの鉄スクラップに置き換えることで、約１．５ｔのＣＯ２排出量の低減につながる。上記のことから、温室効果ガスの排出量の削減と生産活動の維持の両立のためにはスクラップの使用量を増やしていくことが必要である。 In the blast furnace-converter method, iron ore (Fe 2 O 3 ), which is a raw material, is charged into a blast furnace together with coke, which is a reducing agent (carbon source), and hot metal with a C concentration of about 4.5-5% is produced. This is a steelmaking process in which the hot metal is charged into a converter and impurity components such as C, Si, and P are oxidized and removed. When producing hot metal in a blast furnace, approximately 500 kg of carbon source is required per 1 ton of hot metal for reduction of iron ore. Then, approximately 2 tons of CO 2 gas is generated. On the other hand, when producing molten steel using iron scrap as a raw material, the carbon source required for reducing iron ore becomes unnecessary. Therefore, even considering the energy required to melt iron scrap, replacing 1 ton of hot metal with 1 ton of iron scrap leads to a reduction of approximately 1.5 tons of CO 2 emissions. From the above, it is necessary to increase the amount of scrap used in order to reduce greenhouse gas emissions and maintain production activities.
　しかし、鉄スクラップ、特に高級鋼製造に不可欠な高品位の鉄スクラップの需給が逼迫していることから、スクラップに換えて還元鉄のニーズが高まっている。還元鉄は鉄鉱石を還元して製造されるが、高炉－転炉法の様に生成した鉄中のＣ濃度を高位とする必要がなく、過剰な炭素源を使用しない分、鉄１トン当たり約０．２ｔのＣＯ２排出量の低減につながる。また、還元剤を炭素源でなく、水素または天然ガス等の炭化水素系ガスとすることで、更なるＣＯ２排出量の低減も可能である。 However, as the supply and demand for iron scrap, especially high-grade iron scrap essential for high-grade steel manufacturing, is tight, the need for reduced iron to replace scrap is increasing. Reduced iron is produced by reducing iron ore, but there is no need to increase the C concentration in the produced iron as in the blast furnace-converter process, and because there is no need to use an excessive carbon source, the reduction per ton of iron is reduced. This leads to a reduction in CO 2 emissions of approximately 0.2 tons. Further, by using hydrogen or a hydrocarbon gas such as natural gas as the reducing agent instead of a carbon source, it is possible to further reduce CO 2 emissions.
　還元鉄を使用する際の課題として、還元鉄に含有されるりんが挙げられる。鉄鋼製品中のりんは熱間脆性などの品質低下を及ぼすため、要求品質に応じたＰ濃度まで低減する必要があるが、電気炉法で還元鉄を溶解して溶鉄を製造する場合には、還元鉄中のりんの大部分が溶鉄中に入る（復りんともいう）。そのため、現状の還元鉄は鉄鉱石中のＰ濃度が低い高品位鉄鉱石（Ｐ濃度約０．０１質量％）により製造され、還元鉄としてのＰ濃度は約０．０２質量％程度である。 One of the issues when using reduced iron is the phosphorus contained in reduced iron. Phosphorus in steel products causes quality deterioration such as hot brittleness, so it is necessary to reduce the P concentration to a level that meets the required quality. However, when producing molten iron by melting reduced iron using the electric furnace method, Most of the phosphorus in the reduced iron goes into the molten iron (also called phosphorus). Therefore, the current reduced iron is produced from high-grade iron ore with a low P concentration (P concentration of about 0.01% by mass), and the P concentration as reduced iron is about 0.02% by mass.
　一方で、Ｐ濃度が低い高品位鉄鉱石の枯渇が予想されており、今後はＰ濃度の高い低品位鉄鉱石を使用した還元鉄を原料とした溶鋼製造が求められる。現行の高炉法で使用されている鉄鉱石中のＰ濃度は０．０５～０．１０質量％（還元鉄としてのＰ濃度に換算すると０．１０～０．１５質量％）であり、今後更なるＰ濃度増加が予想されている。このＰ濃度は前記Ｐ濃度が低い高品位鉄鉱石で製造した還元鉄のＰ濃度の５～１０倍以上であり、鉄鋼製品中のりんによる品質低下を防ぐためには、Ｐ濃度が高い還元鉄を溶解して溶鋼を製造する際にりん除去するか、Ｐ濃度の高い鉄鉱石から還元鉄を製造する際にりん除去する必要がある。この様なりん除去技術に関し、いくつかの技術が提案されている。 On the other hand, it is predicted that high-grade iron ore with a low P concentration will be depleted, and in the future there will be a need to manufacture molten steel using reduced iron as a raw material using low-grade iron ore with a high P concentration. The P concentration in the iron ore used in the current blast furnace method is 0.05 to 0.10 mass% (0.10 to 0.15 mass% when converted to P concentration as reduced iron), and it is expected that this will change in the future. It is expected that the P concentration will increase. This P concentration is 5 to 10 times higher than the P concentration of reduced iron produced using high-grade iron ore with a low P concentration, and in order to prevent quality deterioration due to phosphorus in steel products, reduced iron with a high P concentration must be used. It is necessary to remove phosphorus when melting to produce molten steel, or when producing reduced iron from iron ore with a high P concentration. Several techniques have been proposed regarding such phosphorus removal techniques.
　特許文献１には、アーク炉単独で比較的短時間に低濃度まで溶鋼中のりんを除去するための、酸化カルシウムを主成分とし、酸化アルミニウムが５ないし１５質量％、酸化鉄が２５ないし３５質量％および残部が不可避的不純物からなるアーク炉での脱りん精錬用フラックスが提案されている。 Patent Document 1 describes a method for removing phosphorus from molten steel to a low concentration in a relatively short period of time using an electric arc furnace alone. A flux for dephosphorization refining in an arc furnace has been proposed in which the mass % and the remainder consist of unavoidable impurities.
　また、特許文献２には、ＣａＯ含有量が２５質量％以下かつＣａＯ／（ＳｉＯ２＋Ａｌ２Ｏ３）比が５以下の鉄鉱石、含チタン鉄鉱石、含ニッケル鉱石、含クロム鉱石、あるいはこれらの鉱石を主成分とする混合物と、Ａｒ、Ｈｅ、Ｎ２、ＣＯ、Ｈ２、炭化水素の一種もしくはこれらの混合ガスを１６００℃以上で接触させることにより、りんを除去する方法が提案されている。 Furthermore, Patent Document 2 describes iron ore, titanium-containing iron ore, nickel-containing ore, chromium-containing ore, or iron ore containing CaO of 25% by mass or less and a CaO/(SiO 2 +Al 2 O 3 ) ratio of 5 or less, or these ores. A method has been proposed for removing phosphorus by contacting a mixture mainly composed of ores with Ar, He, N 2, CO, H 2, one type of hydrocarbon, or a mixed gas of these at a temperature of 1600°C or higher. There is.
　特許文献３には、Ｐ濃度の高い鉄鉱石を０．５ｍｍ以下に粉砕し、これに水を加えてパルプ濃度３５質量％前後とし、溶剤にＨ２ＳＯ４またはＨＣｌを添加してｐＨ２．０以下で反応させてりん鉱物を分解溶出し、ついで磁力選別により磁鉄鉱等の磁着物を採取することで、非磁着物であるＳｉＯ２やＡｌ２Ｏ３等をスライムとして沈降分離すると共に、このとき液中に溶出したＰを消石灰または生石灰を添加してｐＨ５．０～１０．０の範囲内で中和し、りん酸カルシウムとして分離回収する方法が提案されている。 Patent Document 3 discloses that iron ore with a high P concentration is pulverized to 0.5 mm or less, water is added to this to make a pulp concentration of around 35% by mass, and H 2 SO 4 or HCl is added to a solvent to obtain a pH of 2.0. By reacting below to decompose and elute phosphorus minerals, and then collecting magnetic substances such as magnetite by magnetic separation, non-magnetic substances such as SiO 2 and Al 2 O 3 are sedimented and separated as slime, and at this time A method has been proposed in which slaked lime or quicklime is added to neutralize P dissolved in the solution to a pH within the range of 5.0 to 10.0, and the P is separated and recovered as calcium phosphate.
特開平８－１２０３２２号公報Japanese Patent Application Publication No. 8-120322 特開昭５４－８３６０３号公報Japanese Patent Application Publication No. 54-83603 特開昭６０－２６１５０１号公報Japanese Unexamined Patent Publication No. 60-261501
　しかしながら、上記各従来技術には以下の様な解決しなければならない課題がある。
　すなわち、特許文献１に開示の技術では、スクラップ等のＰ濃度が低い鉄源を想定している。具体的には、溶鋼中のＰ濃度を０．０２０質量％から０．００５質量％まで低減するために、溶鋼量７０００ｇに対してフラックスを３５０ｇ添加している。還元鉄中のＰ濃度を０．１５質量％だと仮定すると、Ｐ濃度を鉄鋼製品程度の０．０１質量％まで低減するのに必要なフラックス量は溶鋼１ｔ当たり２３０ｋｇとなる。そうすると、アーク炉内でフラックスが占める体積割合が大きくなって溶鋼処理量が減少し、製造効率が悪化するという課題がある。 However, each of the above conventional techniques has the following problems that must be solved.
That is, the technique disclosed in Patent Document 1 assumes an iron source with a low P concentration such as scrap. Specifically, in order to reduce the P concentration in molten steel from 0.020% by mass to 0.005% by mass, 350g of flux is added to 7000g of molten steel. Assuming that the P concentration in reduced iron is 0.15% by mass, the amount of flux required to reduce the P concentration to 0.01% by mass, which is comparable to that of steel products, is 230 kg per ton of molten steel. Then, there is a problem that the volume ratio occupied by flux in the arc furnace increases, the amount of molten steel processed decreases, and manufacturing efficiency deteriorates.
　特許文献２に開示の方法は、処理温度が１６００℃以上であり、しかも明細書には、「より効果的な脱りんを行なうため１８００℃以上であることが好ましい。このような高い温度領域は通常の加熱方式で達成することは困難であるが、例えばプラズマアークや高周波誘導プラズマの利用により達成できる」と記載されている。このため、多くのエネルギーを要し、多量の処理には適しないという課題がある。 In the method disclosed in Patent Document 2, the treatment temperature is 1,600°C or higher, and the specification states, ``In order to perform more effective dephosphorization, the treatment temperature is preferably 1,800°C or higher. This is difficult to achieve with conventional heating methods, but can be achieved, for example, by using plasma arcs or high-frequency induced plasma." Therefore, there is a problem that it requires a lot of energy and is not suitable for processing a large amount.
　特許文献３に開示の方法は、酸を用いた湿式処理であり、回収した磁着物を主原料として利用するための乾燥に時間とコストを要するという課題がある。さらに、この方法は、事前に０．５ｍｍ以下に粉砕するのにも時間とコストを要するという課題もある。 The method disclosed in Patent Document 3 is a wet treatment using an acid, and there is a problem in that it requires time and cost to dry the recovered magnetic material to use it as a main raw material. Furthermore, this method also has the problem that it requires time and cost to crush the material to 0.5 mm or less in advance.
　本発明は、上記の事情を鑑みてなされたものであって、原料がＰ濃度の高い低品位鉄鉱石から得られた還元鉄であっても、Ｐ濃度の低い粒鉄を効率的に生産可能にする技術を提供することを目的とする。 The present invention was made in view of the above circumstances, and even if the raw material is reduced iron obtained from low-grade iron ore with a high P concentration, it is possible to efficiently produce granulated iron with a low P concentration. The purpose is to provide technology that enables
　上記課題を有利に解決する本発明にかかる粒鉄の製造方法は、還元鉄を溶解し１次溶鉄とする第一工程と、前記１次溶鉄とスラグとを分離する第二工程と、前記スラグと分離した前記１次溶鉄を脱りん処理し２次溶鉄とする第三工程と、前記２次溶鉄を粒状に凝固させて粒鉄化する第四工程と、を含み、前記第三工程では、前記１次溶鉄に酸素源とＣａＯ源を供給して脱りん処理を行ない、該脱りん処理終了時点の前記２次溶鉄の温度を、該脱りん処理開始時点の前記１次溶鉄の温度以下とすることを特徴とする。 The method for producing granulated iron according to the present invention, which advantageously solves the above problems, includes a first step of melting reduced iron to obtain primary molten iron, a second step of separating the primary molten iron and slag, and a second step of separating the primary molten iron from the slag. and a third step of dephosphorizing the separated primary molten iron to obtain secondary molten iron, and a fourth step of solidifying the secondary molten iron into granules to form granulated iron, and the third step includes: Dephosphorizing the primary molten iron by supplying an oxygen source and a CaO source, and setting the temperature of the secondary molten iron at the end of the dephosphorization to be equal to or lower than the temperature of the primary molten iron at the start of the dephosphorizing process. It is characterized by
　なお、本発明にかかる粒鉄の製造方法は、
（ａ）前記脱りん処理終了時点の前記２次溶鉄の温度Ｔｆを、脱りん処理終了時点における２次溶鉄の凝固温度Ｔｍから２０℃以上高くすること、
（ｂ）前記脱りん処理終了時点のスラグ組成は、質量基準でＳｉＯ２濃度（％ＳｉＯ２）に対するＣａＯ濃度（％ＣａＯ）の比である塩基度を１．０～４．０の範囲とすること、
（ｃ）前記第四工程では、前記２次溶鉄を液滴とする粒化装置と、前記液滴を受ける位置に設けられ、冷却水を収容する水流制御容器と、前記水流制御容器に接続し、前記水流制御容器に冷却水を供給する少なくとも１つの冷却水管と、を有し、前記水流制御容器は、下方に向けて前記水流制御容器の水平断面積が狭くなるように傾斜した傾斜面を有し、前記傾斜面の下方には排出口が設けられる、粒鉄製造装置を用いること、
などが、より好ましい解決手段になり得るものと考えられる。 Note that the method for producing granulated iron according to the present invention is as follows:
(a) Raising the temperature Tf of the secondary molten iron at the end of the dephosphorization process by 20°C or more from the solidification temperature Tm of the secondary molten iron at the end of the dephosphorization process;
(b) The slag composition at the end of the dephosphorization treatment has a basicity in the range of 1.0 to 4.0, which is the ratio of CaO concentration (%CaO) to SiO 2 concentration (%SiO 2 ) on a mass basis. thing,
(c) In the fourth step, a granulating device that turns the secondary molten iron into droplets, a water flow control container provided at a position to receive the droplets and containing cooling water, and a water flow control container connected to the water flow control container are provided. , at least one cooling water pipe that supplies cooling water to the water flow control container, and the water flow control container has an inclined surface that is inclined so that the horizontal cross-sectional area of the water flow control container becomes narrower toward the bottom. using a granulated iron manufacturing apparatus, which has a discharge port provided below the inclined surface;
This is considered to be a more preferable solution.
　上記課題を有利に解決する本発明にかかる粒鉄は、Ｐ濃度が０．０５０質量％以上の還元鉄が原料であり、Ｐ濃度が０．０３０質量％以下であり、粒径が１ｍｍ以上５０ｍｍ以下であることを特徴とする。 The granulated iron according to the present invention, which advantageously solves the above problems, uses reduced iron with a P concentration of 0.050% by mass or more as a raw material, has a P concentration of 0.030% by mass or less, and has a particle size of 1 mm or more and 50 mm. It is characterized by the following:
　本発明にかかる粒鉄の製造方法によれば、Ｐ濃度の高い低品位鉄鉱石から得られた還元鉄からＰ濃度が低い粒鉄を効率的に生産することが可能となる。また、本発明にかかる粒鉄は、鉄鋼製品の多くで要求されるＰ濃度、つまり、０．０３０質量％以下を満足する。したがって、本発明にかかる粒鉄を再溶解するだけで鉄鋼製品相当のＰ濃度の溶鉄を得ることができる。 According to the method for producing granulated iron according to the present invention, it is possible to efficiently produce granulated iron with a low P concentration from reduced iron obtained from low-grade iron ore with a high P concentration. Further, the granulated iron according to the present invention satisfies the P concentration required for many steel products, that is, 0.030% by mass or less. Therefore, molten iron with a P concentration equivalent to that of a steel product can be obtained simply by remelting the granulated iron according to the present invention.
　さらに、脱りん処理後、一旦粒状に凝固させて粒鉄とするので、大規模な製鉄プラントではなく、鉄源の製造プラントと需要サイトを分離した形態での鉄鋼生産が可能になる。たとえば、原料産出国で脱りん粒鉄の生産までを行ない、鉄鋼生産国でこの脱りん粒鉄を原料とする鉄鋼生産を行なうといった形態が考えられる。 Furthermore, after the dephosphorization treatment, the iron is solidified into granules to form granular iron, so it becomes possible to produce iron in a form where the iron source manufacturing plant and the demand site are separated, rather than in a large-scale iron manufacturing plant. For example, it is conceivable that a raw material-producing country goes as far as producing dephosphorized granulated iron, and a steel-producing country produces steel using this dephosphorized granulated iron as raw material.
　加えて、鉄鉱石の産出国において、還元鉄の製造と本発明にかかる粒鉄の製造とを実施すると、原料である鉄鉱石に含まれる脈石分をスラグとして分離することができる。したがって、粒鉄のみを輸送することで単位Ｆｅ量当たりの輸送量が低減され、需要サイトへの輸送コストおよび消費エネルギーが抑制可能となる。また、粒鉄の粒径が１～５０ｍｍであれば、粒鉄の需要サイトへの輸送および保管、需要サイトでの設備への供給などを考える際、輸送・保管・供給に使用する設備の自由度が増す。さらに、供給ホッパー内での棚吊りなどのリスクを抑えられるという効果もある。 In addition, if the production of reduced iron and the production of granulated iron according to the present invention are carried out in an iron ore producing country, the gangue content contained in the raw material iron ore can be separated as slag. Therefore, by transporting only granulated iron, the transport amount per unit amount of Fe is reduced, and the transport cost and energy consumption to the demand site can be suppressed. In addition, if the particle size of iron granules is 1 to 50 mm, there is freedom in the equipment used for transportation, storage, and supply when considering transportation and storage of iron granules to demand sites, supply to equipment at demand sites, etc. The degree increases. Furthermore, it also has the effect of reducing the risk of hanging on shelves within the supply hopper.
　以下、本発明の実施の形態について具体的に説明する。なお、以下の実施形態は、本発明の技術的思想を具体化するための装置や方法を例示するものであり、構成を下記のものに特定するものでない。すなわち、本発明の技術的思想は、特許請求の範囲に記載された技術的範囲内において、種々の変更を加えることができる。 Hereinafter, embodiments of the present invention will be specifically described. Note that the following embodiments are intended to exemplify an apparatus and method for embodying the technical idea of the present invention, and the configuration is not limited to the following. That is, the technical idea of the present invention can be modified in various ways within the technical scope described in the claims.
　発明者らは、本発明にあたり以下のように考えた。
　鉄鉱石を原料として作製した還元鉄は、使用する鉄鉱石の銘柄、混合する原料成分調整剤の種類および原単位、還元剤の種類および原単位、還元温度、還元鉄製造設備の方式によって、金属化率や組成などの性状が異なる。表１に還元鉄の成分例を示す。表１の例では、Ｐ濃度をＴ．Ｆｅ（全鉄）濃度で除した、溶鉄換算Ｐ濃度は０．０５７～０．１５２質量％である。したがって、これらの還元鉄をそのまま溶解しても鉄鋼製品レベルのＰ濃度（０．０３０質量％以下）とすることは困難である。また、還元鉄を単純に溶解して脱りん処理をする場合、還元鉄に含まれるＳｉＯ２などの脈石が原因で生成スラグ量が膨大になり、処理設備の容積に対してスラグが占める割合が大きくなって生産性が低下する、溶鉄からのりん除去量を確保するために要するＣａＯ源の添加量が増え、処理コストが増大する、などの課題がある。 The inventors considered the following regarding the present invention.
Reduced iron produced from iron ore as a raw material depends on the brand of iron ore used, the type and basic unit of the raw material component adjusting agent to be mixed, the type and basic unit of the reducing agent, the reduction temperature, and the type of reduced iron manufacturing equipment. Properties such as conversion rate and composition are different. Table 1 shows examples of the components of reduced iron. In the example in Table 1, the P concentration is T. The P concentration in terms of molten iron divided by the Fe (total iron) concentration is 0.057 to 0.152% by mass. Therefore, even if these reduced irons are dissolved as they are, it is difficult to achieve a P concentration (0.030% by mass or less) at the level of steel products. In addition, when dephosphorizing reduced iron by simply melting it, a huge amount of slag is produced due to gangue such as SiO 2 contained in reduced iron, and the proportion of slag in the volume of the processing equipment increases. There are problems such as an increase in the amount of CaO, which lowers productivity, and an increase in the amount of CaO source added to ensure the amount of phosphorus removed from molten iron, which increases processing costs.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　そこで、還元鉄を一旦溶解して溶鉄を得るとともに脈石起因のスラグの少なくとも一部を除去し、得られた溶鉄に酸素源と石灰源を供給して脱りんを行い、その後、脱りん後溶鉄を粒状に凝固させる粒鉄を製造するプロセスを考案した。 Therefore, reduced iron is once melted to obtain molten iron, at least a part of the slag caused by gangue is removed, and an oxygen source and a lime source are supplied to the obtained molten iron to perform dephosphorization. We devised a process to produce granulated iron by solidifying molten iron into granules.
　以下、本発明の実施形態を具体的に説明する。
　第一工程として、電気炉にて還元鉄の昇熱および溶解を行い、１次溶鉄を得る。還元鉄は、たとえば、隣接する還元鉄製造プラントで製造されたものを高温のまま横持ちして使用しても良い。もちろん、一旦常温まで冷却されたものを用いてもよい。電気炉は、アーク炉、サブマージドアーク炉、または誘導溶解炉のいずれであってもよい。また、第一工程で固体鉄源である還元鉄の溶解および鉄源の昇熱のために供給する熱エネルギーは電気エネルギーだけではなく、補填的に天然ガスやプロパンガス等の気体燃料、重油等の液体燃料、石炭、金属Ａｌ、Ｓｉ等の可燃性固体の燃焼熱を使用してもよい。これらのエネルギーは、再生可能エネルギーであることがＣＯ２排出量削減の観点から好ましい。 Embodiments of the present invention will be specifically described below.
As a first step, reduced iron is heated and melted in an electric furnace to obtain primary molten iron. For example, reduced iron manufactured at an adjacent reduced iron manufacturing plant may be used by keeping it at a high temperature. Of course, one that has been cooled to room temperature may also be used. The electric furnace may be an arc furnace, a submerged arc furnace, or an induction melting furnace. In addition, the thermal energy supplied in the first step to melt reduced iron, which is a solid iron source, and heat up the iron source is not only electrical energy, but also gaseous fuels such as natural gas and propane gas, heavy oil, etc. as supplementary energy. The heat of combustion of combustible solids such as liquid fuel, coal, metal Al, Si, etc. may be used. It is preferable that these energies be renewable energies from the viewpoint of reducing CO 2 emissions.
　第二工程として、還元鉄の脈石分であるスラグと１次溶鉄を分離する。たとえば、溶湯を搬送用の容器に出湯し、脱りん処理を行う設備へと搬送する。この後の工程で脱りん処理を行う際、ＣａＯ源を加えて脱りん用スラグを生成するため、スラグ量確保および成分調整のため、還元鉄の溶解に伴い生成するＳｉＯ２を多く含むスラグの少なくとも一部を持ち越してもよい。第一工程で使用した溶解・昇熱用の容器からスラグドラッガーなどで除滓してもよい。 In the second step, slag, which is gangue of reduced iron, and primary molten iron are separated. For example, the molten metal is poured into a container for transportation and transported to equipment that performs dephosphorization treatment. When performing dephosphorization treatment in the subsequent process, a CaO source is added to generate dephosphorization slag, so in order to secure the amount of slag and adjust the composition, slag containing a lot of SiO 2 generated as reduced iron is dissolved is used. At least a portion may be carried over. The slag may be removed from the melting/heating container used in the first step using a slag dragger.
　第三工程として、溶湯の脱りん処理を行い２次溶鉄を得る。脱りん反応は下記（１）式で表されるように酸素源およびＣａＯ源が必要となる。
２［Ｐ］＋５／２・Ｏ２（ｇ）＋３ＣａＯ（ｓ）＝３ＣａＯ・Ｐ２Ｏ５（ｓ） ・・・（１）
　ここで、［Ｐ］は溶鉄中のりんを示す。 As a third step, the molten metal is dephosphorized to obtain secondary molten iron. The dephosphorization reaction requires an oxygen source and a CaO source as expressed by the following formula (1).
2 [P] + 5/2・O 2 (g) + 3CaO (s) = 3CaO・P 2 O 5 (s) ... (1)
Here, [P] represents phosphorus in molten iron.
　脱りん処理の酸素源には一般的に純酸素ガスが用いられる。脱りん反応は発熱反応であるため低温で脱りん処理を行うことが有利であること、また次工程で凝固させて粒鉄化することを考慮すると、処理に問題ない範囲で溶鉄温度を下げることが有利であるとの結論に至った。 Pure oxygen gas is generally used as the oxygen source for dephosphorization. Since the dephosphorization reaction is an exothermic reaction, it is advantageous to perform the dephosphorization treatment at a low temperature, and considering that it will be solidified and turned into granulated iron in the next process, it is necessary to lower the temperature of the molten iron within a range that does not cause any problems in the process. It was concluded that this is advantageous.
　検討の結果、酸素源として空気あるいは鉄鉱石やミルスケール等の酸化鉄源を供給することで、溶鉄を冷却しつつ十分に脱りんが可能であることを見出した。空気の利用については、空気に含まれる窒素ガスの顕熱として抜熱が進行することによって純酸素ガスを使用する場合に対する冷却効果が得られる。また、酸化鉄源の利用については、酸化鉄源が還元されて金属Ｆｅとなる吸熱反応、あるいは酸化鉄の形で溶融スラグを形成する際に吸熱することによって純酸素ガスを使用する場合に対する冷却効果が得られる。 As a result of our investigation, we found that by supplying air or an iron oxide source such as iron ore or mill scale as an oxygen source, it is possible to sufficiently dephosphorize the molten iron while cooling it. When using air, a cooling effect compared to when pure oxygen gas is used can be obtained by removing heat as sensible heat from the nitrogen gas contained in the air. In addition, regarding the use of iron oxide sources, the iron oxide source is reduced to metal Fe by an endothermic reaction, or by absorbing heat when forming molten slag in the form of iron oxide. Effects can be obtained.
　次に、石灰石に含まれる炭酸カルシウムはＣａＯとＣＯ２に分解する際に吸熱するため、ＣａＯ源として石灰石を使用することで、溶鉄を冷却することが可能となる。同様の冷却効果は、生ドロマイト等の炭酸塩を供給することによって得られるが、副原料中のＣａＯ割合が低くなると、添加する副原料の量が多くなり、スラグ生成量が増大したり、添加に要する時間が長くなるなどの操業上の課題が生じるため、求める冷却効果と安定した操業を考慮して添加する副原料の種類と量を調整することが好ましい。 Next, since calcium carbonate contained in limestone absorbs heat when decomposed into CaO and CO 2 , it becomes possible to cool molten iron by using limestone as a CaO source. A similar cooling effect can be obtained by supplying carbonate such as raw dolomite, but when the proportion of CaO in the auxiliary raw material becomes low, the amount of auxiliary raw material added increases, resulting in an increase in the amount of slag produced or However, it is preferable to adjust the type and amount of the auxiliary raw material to be added in consideration of the desired cooling effect and stable operation.
　脱りん処理を行う容器のフリーボード（溶鉄表面から容器上端までの高さ）や上吹きランスのノズルの形状によりスピッティングの発生挙動は異なるので、脱りん処理の操業状況に応じて純酸素ないしは空気の供給速度やランス高さを調整することが好ましい。また、溶鉄に攪拌を付与するため、不活性ガスを吹き込むと良い。不活性ガスは、炉底に設置したポーラスプラグを介して、またはインジェクションランスを溶鉄に浸漬して吹き込むと良い。脱りん処理終了時点のスラグ組成は、質量基準でＳｉＯ２濃度（％ＳｉＯ２）に対するＣａＯ濃度（％ＣａＯ）の比であるスラグ塩基度は１．０～４．０の範囲であることが好ましい。第二工程で持ち越すＳｉＯ２を多く含むスラグ量と、添加するＣａＯ源の種類と量で調整を行う。必要に応じて珪石やフェロシリコンなどのＳｉＯ２源や、生石灰などのＣａＯ源を添加してもよい。 The behavior of spitting differs depending on the freeboard (height from the surface of the molten iron to the top of the container) of the container where dephosphorization is performed and the shape of the nozzle of the top blowing lance. It is preferable to adjust the air supply speed and lance height. Also, in order to stir the molten iron, it is good to blow inert gas into it. The inert gas may be injected through a porous plug installed at the bottom of the furnace or by dipping an injection lance into the molten iron. Regarding the slag composition at the end of the dephosphorization treatment, the slag basicity, which is the ratio of the CaO concentration (%CaO) to the SiO 2 concentration (%SiO 2 ) on a mass basis, is preferably in the range of 1.0 to 4.0. . The amount of slag containing a large amount of SiO 2 carried over to the second step is adjusted, and the type and amount of the CaO source to be added are adjusted. If necessary, an SiO 2 source such as silica stone or ferrosilicon, or a CaO source such as quicklime may be added.
　なお、スラグ塩基度が低いと脱りん処理でのりん除去量が小さくなる。スラグ塩基度が高いと溶鉄温度が低下した際にスラグの一部が凝固し耐火物に付着するため、脱りん処理後スラグの除去が困難となり、次回の処理時に溶鉄を装入した際に異常反応が生じること、残留スラグが生成スラグに混入して成分外れの原因となることなどの問題が生じ得る。 Note that if the slag basicity is low, the amount of phosphorus removed in the dephosphorization process will be small. If the slag basicity is high, some of the slag will solidify and adhere to the refractory when the molten iron temperature drops, making it difficult to remove the slag after dephosphorization, and causing abnormalities when charging molten iron for the next treatment. Problems may arise, such as reactions occurring and residual slag mixing with the produced slag, causing components to be removed.
　また、このような空気を用いた脱りん処理では高温の排ガスが多量に発生するため、ボイラー等を用いて排熱回収してもよい。 Furthermore, since a large amount of high-temperature exhaust gas is generated in such a dephosphorization process using air, a boiler or the like may be used to recover the exhaust heat.
　第四工程として、脱りん処理後の２次溶鉄を粒状に凝固させて、粒鉄を得る。粒鉄の製造方法として、例えば脱りん処理後の溶鉄を流下し耐火物の定盤に衝突させる、もしくは流出された溶鉄に水を衝突させて粒滴となった溶鉄を、水流制御容器に落下させて凝固した粒鉄を得る方法が挙げられる。このとき溶鉄の流下速度に応じて粒鉄径が変化するため、脱りん処理後の溶鉄は流下速度を一定に保つことができるタンディッシュに移し替えることが好ましい。 As the fourth step, the secondary molten iron after the dephosphorization treatment is solidified into granules to obtain granulated iron. As a method for producing granular iron, for example, molten iron after dephosphorization is allowed to flow down and collide with a refractory surface plate, or water is allowed to collide with the molten iron that has flowed out, resulting in granular droplets that are then dropped into a water flow control container. An example of this method is to obtain solidified iron granules. At this time, since the grain iron diameter changes depending on the flow rate of the molten iron, it is preferable to transfer the molten iron after the dephosphorization treatment to a tundish that can maintain a constant flow rate.
　この際、脱りん処理後の溶鉄を運搬し、粒鉄製造装置に供給する間に溶鉄の温度降下が生じる。脱りん処理後の溶鉄温度が低すぎると、容器内の溶鉄を全て粒鉄製造装置に供給する前に溶鉄の一部が凝固してしまい、製造歩留まりが低下する。一方で、脱りん処理後の溶鉄温度が高いと、粒鉄製造装置で凝固させる際の熱負荷が大きくなり、使用する冷却水量が増大するなど、冷却速度がネックとなって生産性が低下する、または溶鉄の温度降下のために粒鉄化前の待機時間が長くなる、ことがある。このように、脱りん処理後の粒鉄化を想定すると、脱りん処理後の溶鉄温度には好適な範囲が存在する。具体的には、生産性の観点から、脱りん処理後の溶鉄温度Ｔｆを脱りん処理開始時点の溶鉄温度Ｔｉ以下とする。また、脱りん処理終了時点の温度Ｔｆを、脱りん処理終了時点における２次溶鉄の凝固温度Ｔｍから２０℃以上高くすると、高歩留まりで粒鉄製造装置に溶鉄を供給することが可能であるので好ましい。 At this time, the temperature of the molten iron decreases while the molten iron after the dephosphorization treatment is transported and supplied to the granular iron production equipment. If the temperature of the molten iron after the dephosphorization treatment is too low, a portion of the molten iron will solidify before all of the molten iron in the container is supplied to the granular iron manufacturing apparatus, resulting in a decrease in manufacturing yield. On the other hand, if the molten iron temperature after dephosphorization is high, the heat load during solidification in the granular iron production equipment will increase, the amount of cooling water used will increase, and the cooling rate will become a bottleneck, reducing productivity. , or the waiting time before granulation may become longer due to a drop in the temperature of the molten iron. As described above, assuming that granular iron is formed after dephosphorization, there is a suitable range for the temperature of molten iron after dephosphorization. Specifically, from the viewpoint of productivity, the molten iron temperature T f after the dephosphorization treatment is set to be equal to or lower than the molten iron temperature T i at the time of starting the dephosphorization treatment. Furthermore, by increasing the temperature T f at the end of the dephosphorization process by 20°C or more from the solidification temperature T m of the secondary molten iron at the end of the dephosphorization process, it is possible to supply molten iron to the granular iron production equipment at a high yield. It is preferable because there is.
　ここで、凝固温度Ｔｍ（℃）は、サンプルの凝固温度を直接測定すること、あるいは過去の操業実績（脱りん処理前のＣ濃度、温度、酸素源の種類および供給条件など）に基づき推定される脱りん処理後溶鉄のＣ濃度から、Ｆｅ－Ｃ状態図の液相線温度から読み取った温度とすることなど、いずれの方法でも構わない。 Here, the solidification temperature T m (°C) can be estimated by directly measuring the solidification temperature of the sample or based on past operational results (C concentration before dephosphorization, temperature, type of oxygen source, supply conditions, etc.) Any method may be used, such as setting the temperature to the temperature read from the liquidus temperature of the Fe--C phase diagram based on the C concentration of the molten iron after dephosphorization treatment.
　粒鉄製造装置には、溶鉄を液滴とする粒化装置と、その液滴を受ける位置に設けられ、冷却水を収容する水流制御容器とを備える。溶鉄を落下させて凝固させる水流制御容器には冷却水を供給する少なくとも１つの冷却水管が接続されている。この冷却水管から冷却水が吐出され水流が発生することで容器内の冷却水のよどみ領域の生成が抑制される。したがって冷却水の局所的な温度上昇が抑制されて粒鉄を効率的に冷却でき、粒鉄が十分に冷却されずに互いに融着することが抑制される。また、水流制御容器は下方に向けて容器の水平断面積が狭くなるように傾斜した傾斜面を有しており、傾斜面の下方を排出口としている。この傾斜面の傾斜角を水中での粒鉄の安息角以上とすることで粒鉄を傾斜面に滞留させることなく排出口に案内できる。 The granulated iron manufacturing apparatus includes a granulating device that turns molten iron into droplets, and a water flow control container that is provided at a position to receive the droplets and that contains cooling water. At least one cooling water pipe for supplying cooling water is connected to the water flow control vessel through which the molten iron falls and solidifies. The cooling water is discharged from the cooling water pipe and a water flow is generated, thereby suppressing the formation of a stagnation area of the cooling water in the container. Therefore, the local temperature rise of the cooling water is suppressed, the granulated iron can be efficiently cooled, and the granulated iron is prevented from being sufficiently cooled and fused together. Further, the water flow control container has an inclined surface that is inclined so that the horizontal cross-sectional area of the container becomes narrower toward the bottom, and the lower part of the inclined surface is used as a discharge port. By setting the angle of inclination of this inclined surface to be equal to or greater than the angle of repose of the granulated iron in water, the granulated iron can be guided to the discharge port without being retained on the slanted surface.
　上記のようにして得られた粒鉄を、高炉や転炉で鉄源の一部として使用すると、使用した割合に応じてＰ濃度の希釈効果が得られる。これにより脱りん処理における負荷を低減することが可能であり、高炉および転炉で使用する原料の制約を緩和することが可能になる。 When the granulated iron obtained as described above is used as part of the iron source in a blast furnace or converter, the effect of diluting the P concentration can be obtained depending on the proportion used. This makes it possible to reduce the load in the dephosphorization process, and to ease restrictions on raw materials used in blast furnaces and converters.
　なお、本実施形態で得られた粒鉄を電気炉や高炉、転炉で鉄源として利用する場合、使用しやすい粒径範囲がある。そのため、タンディッシュでの流下速度を調整して所望の粒径が得られるようにすると良い。また、必要に応じて分級すると良い。一般的には、粒径が１～５０ｍｍの範囲ものが使用しやすい。粒径が１ｍｍよりも小さい粒鉄が含まれる場合、運搬用のコンベアの目詰まりやホッパー内での棚吊りが生じる可能性が大きくなるので、分級して１ｍｍ以上のものを用いるとよい。また、粒径が５０ｍｍを超えると、落下による衝突などが生じたとき、運搬用のコンベアやホッパーなどの設備を損傷するリスクが高くなる。そのため、粒径が５０ｍｍ以下となるようタンディッシュでの流下速度を低下させると良い。また、必要に応じて分級し、５０ｍｍ超えのものを除いても良い。ここで、粒径が１～５０ｍｍの範囲とは、目開き１ｍｍの篩の篩上であって、目開き５０ｍｍの篩の篩下とすることができる。 Note that when the granulated iron obtained in this embodiment is used as an iron source in an electric furnace, a blast furnace, or a converter, there is a particle size range that is easy to use. Therefore, it is advisable to adjust the flow rate in the tundish to obtain the desired particle size. It is also good to classify as necessary. Generally, particles with a particle size in the range of 1 to 50 mm are easy to use. If granulated iron with a particle size smaller than 1 mm is included, there is a high possibility that clogging of conveyors for transportation or hanging on shelves in the hopper will occur, so it is better to classify and use particles with a particle size of 1 mm or more. Furthermore, if the particle size exceeds 50 mm, there is a high risk of damaging equipment such as a conveyor or hopper for transportation when a collision occurs due to a fall. Therefore, it is preferable to reduce the flow rate in the tundish so that the particle size becomes 50 mm or less. Further, if necessary, it may be classified to remove those exceeding 50 mm. Here, the particle size range of 1 to 50 mm can be defined as above the sieve of a sieve with an opening of 1 mm and below the sieve of a sieve with an opening of 50 mm.
（実施例１）
　２５０ｔ規模電気炉において表１に示す還元鉄Ａを溶解し、温度調整をした上で鍋型の容器に移し替えた。この時、還元鉄に含まれる脈石起因で電気炉溶解時に生成したスラグの内、約１０ｋｇ／ｔ－溶鉄を一緒に鍋型容器に移し替え、残りは別のスラグ容器に移し替えた。鍋型の容器を脱りん処理設備へと移動し、供給する酸素源と石灰源の種類と量を変更して脱りん処理を行った。脱りん処理設備はガス上吹きランス、副原料切り出しホッパー、底吹きポーラスプラグを有する。ガス上吹きランスからは、約１Ｎｍ３／（分・ｔ－溶鉄）の速度で純酸素ないしは空気を含むガスを供給可能である。副原料切り出しホッパーは３基あり、それぞれ鉄鉱石、生石灰（ＣａＯ）、炭酸カルシウム（ＣａＣＯ３）が充填されており、それぞれ約１０ｋｇ／分の速度で供給が可能である。底吹きポーラスプラグからはガスを供給することが可能であり、本実施例では約０．１Ｎｍ３／（分・ｔ－溶鉄）の速度で純Ａｒガスを供給した。 (Example 1)
Reduced iron A shown in Table 1 was melted in a 250-ton electric furnace, the temperature was adjusted, and the melt was transferred to a pot-shaped container. At this time, about 10 kg/t of slag generated during electric furnace melting due to gangue contained in the reduced iron was transferred to a pot-shaped container, and the rest was transferred to another slag container. The pot-shaped container was moved to a dephosphorization treatment facility, and dephosphorization treatment was performed by changing the type and amount of oxygen source and lime source supplied. The dephosphorization treatment equipment has a gas top-blowing lance, an auxiliary raw material cutting hopper, and a bottom-blowing porous plug. A gas containing pure oxygen or air can be supplied from the gas top-blowing lance at a rate of about 1 Nm 3 /(min·t-molten iron). There are three auxiliary raw material cutting hoppers, each filled with iron ore, quicklime (CaO), and calcium carbonate (CaCO 3 ), each of which can be supplied at a rate of about 10 kg/min. Gas can be supplied from the bottom-blown porous plug, and in this example, pure Ar gas was supplied at a rate of about 0.1 Nm 3 /(min·t-molten iron).
　脱りん処理前の溶鉄温度が１５９０℃程度となる様に電気炉での溶解温度を調整した。ガス上吹きランスを下降する前および処理後にガス上吹きランスの上昇が完了したタイミングをそれぞれ脱りん処理前後とし、それぞれサブランスを用いて測温・サンプリングを実施した。サンプリングしたサンプルは切断・研磨を行い、発光分光分析法により、予め作成した検量線から溶鉄中のＣ濃度［Ｃ］およびＰ濃度［Ｐ］を評価した。また、サブランス測温・サンプリングを行ったタイミングにおける溶湯の凝固温度を測定することが可能であり、脱りん処理後の溶鉄の凝固温度Ｔｍを実測した。 The melting temperature in the electric furnace was adjusted so that the molten iron temperature before dephosphorization was approximately 1590°C. Temperature measurement and sampling were carried out using the sub-lance before and after the dephosphorization treatment, respectively, before and after the gas top-blowing lance was lowered and after the treatment. The sampled samples were cut and polished, and the C concentration [C] and P concentration [P] in the molten iron were evaluated using a calibration curve prepared in advance by emission spectrometry. Furthermore, it is possible to measure the solidification temperature of the molten metal at the timing of sublance temperature measurement and sampling, and the solidification temperature T m of the molten iron after dephosphorization treatment was actually measured.
　ガス上吹きランスの下降開始を脱りん処理開始とし、上吹きランスが所定高さに到達後、酸素ガス源の供給および副原料の添加を開始した。所定量の酸素ガス源および副原料の供給が完了した後、上吹きランスが待機位置まで上昇完了した時点を脱りん処理終了とした。その間を処理時間ｔｆ（分）とした。 The dephosphorization process was started when the gas top blowing lance started descending, and after the top blowing lance reached a predetermined height, the supply of the oxygen gas source and the addition of the auxiliary raw materials were started. After the supply of a predetermined amount of the oxygen gas source and the auxiliary raw material was completed, the dephosphorization process was defined as the time when the top blowing lance completed rising to the standby position. The time period was defined as the processing time t f (minutes).
　脱りん処理後、鍋型容器を傾動し、スラグドラッガーにより溶鉄上のスラグを除去した。除去したスラグの一部を採取し、化学分析を行った。その後、鍋をクレーンで吊り上げて傾動し、タンディッシュに溶鉄を移し替え、タンディッシュから溶鉄を流下し耐火物の定盤に衝突させて粒滴となった溶鉄を、水流制御容器に落下させて凝固させることで粒鉄を製造した。得られた粒鉄の粒径は０．１～３０ｍｍであった。粒度分布は、＋０．１ｍｍ－１ｍｍ：１７．２質量％、＋１ｍｍ－１０ｍｍ：３１．３質量％、＋１０ｍｍ－２０ｍｍ：３８．８質量％、＋２０ｍｍ－３０ｍｍ：１２．７質量％であった。ここで、＋Ｎ－Ｍとは、目開きＮの篩上であって、目開きＭの篩下であることを意味する。 After the dephosphorization treatment, the pot-shaped container was tilted and the slag on the molten iron was removed by a slag dragger. A portion of the removed slag was collected and chemically analyzed. After that, the pot is lifted and tilted by a crane, the molten iron is transferred to the tundish, and the molten iron flows down from the tundish and collides with the refractory surface plate, and the molten iron becomes droplets and falls into the water flow control container. Granulated iron was produced by solidification. The particle size of the obtained iron granules was 0.1 to 30 mm. The particle size distribution was +0.1mm-1mm: 17.2% by mass, +1mm-10mm: 31.3% by mass, +10mm-20mm: 38.8% by mass, and +20mm-30mm: 12.7% by mass. Here, +NM means that it is above the sieve with a mesh size of N and below the sieve with a mesh size of M.
　表２に、それぞれ脱りん処理前後の溶鉄の温度ＴｉおよびＴｆ（℃）、Ｃ濃度［Ｃ］ｉおよび［Ｃ］ｆ（質量％）、Ｐ濃度［Ｐ］ｉおよび［Ｐ］ｆ（質量％）ならびに供給した酸素源とＣａＯ源の種類と量、処理時間ｔｆ（分）、処理後スラグの塩基度（質量基準のＣａＯ濃度（％ＣａＯ）のＳｉＯ２濃度（％ＳｉＯ２）に対する比（％ＣａＯ）／（％ＳｉＯ２）、以下Ｃ／Ｓと記載する。）を処理Ｎｏ．１～５で示す。 Table 2 shows the temperatures T i and T f (°C) of molten iron before and after dephosphorization treatment, C concentrations [C] i and [C] f (mass%), and P concentrations [P] i and [P] f ( mass %), the type and amount of the supplied oxygen source and CaO source, treatment time t f (minutes), basicity of the slag after treatment (mass-based CaO concentration (%CaO) relative to SiO 2 concentration (%SiO 2 ) The ratio (%CaO)/(%SiO 2 ), hereinafter referred to as C/S) was determined by the treatment No. Shown as 1 to 5.
　表２に示す通り、発明例のいずれにおいても、処理後溶鉄温度Ｔｆが処理前溶鉄温度Ｔｉより低く、処理後Ｐ濃度［Ｐ］ｆは十分に低下した。比較例は脱りん処理後温度Ｔｆが脱りん処理前温度Ｔｉよりも上昇した結果、処理後Ｐ濃度［Ｐ］ｆが高く、また粒鉄製造工程で待機時間が発生し生産性が低下した。また、処理Ｎｏ．１～３と比較して、処理Ｎｏ．４は処理後溶鉄温度Ｔｆが低下したため、Ｐ濃度［Ｐ］ｆは十分に低下したが、粒鉄製造時に一部がタンディッシュ内で凝固し歩留が低下した。処理Ｎｏ．１～３は、処理後溶鉄温度Ｔｆが処理前溶鉄温度Ｔｉより低く、処理後溶鉄温度Ｔｆが溶鉄の凝固温度Ｔｍから２０℃以上高く、処理後Ｐ濃度［Ｐ］ｆは十分に低下するとともに、歩留まりよく全量粒鉄に製造でき、生産性の低下もなかった。 As shown in Table 2, in all of the invention examples, the post-treatment molten iron temperature T f was lower than the pre-treatment molten iron temperature Ti , and the post-treatment P concentration [P] f was sufficiently reduced. In the comparative example, the post-dephosphorization temperature T f was higher than the pre-dephosphorization temperature T i , resulting in a high post-treatment P concentration [P] f , and a standby time occurred in the granulated iron manufacturing process, reducing productivity. did. In addition, processing No. Compared with 1 to 3, processing No. In No. 4, the post-treatment molten iron temperature T f was lowered, so the P concentration [P] f was sufficiently lowered, but part of it solidified in the tundish during the production of granulated iron, resulting in a lower yield. Processing No. 1 to 3, the molten iron temperature after treatment T f is lower than the molten iron temperature before treatment T i , the molten iron temperature after treatment T f is higher than the solidification temperature T m of molten iron by 20°C or more, and the P concentration after treatment [P] f is sufficient. At the same time, it was possible to produce the entire amount of granulated iron with good yield, and there was no decrease in productivity.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
（実施例２）
 実施例１と同様の方法を用いて、脱りん処理および粒鉄製造を行った。表３に、それぞれ脱りん処理前後の溶鉄の温度ＴｉおよびＴｆ（℃）、Ｃ濃度［Ｃ］ｉおよび［Ｃ］ｆ（質量％）、Ｐ濃度［Ｐ］ｉおよび［Ｐ］ｆ（質量％）ならびに供給した酸素源とＣａＯ源の種類と量、処理時間ｔｆ（分）、処理後スラグの塩基度Ｃ／Ｓを処理Ｎｏ．６～１２で示す。表３に示す通り、処理Ｎｏ．６～１０に対し処理Ｎｏ．１１はスラグの塩基度Ｃ／Ｓが低いため処理後Ｐ濃度が高位であった。また、処理Ｎｏ．１２ではスラグの塩基度Ｃ／Ｓが高くスラグの凝固が確認された。 (Example 2)
Dephosphorization treatment and production of granulated iron were performed using the same method as in Example 1. Table 3 shows the temperature T i and T f (°C) of molten iron before and after dephosphorization treatment, the C concentration [C] i and [C] f (mass%), and the P concentration [P] i and [P] f ( % by mass), the type and amount of the oxygen source and CaO source supplied, the treatment time t f (minutes), and the basicity C/S of the slag after treatment. Shown as 6 to 12. As shown in Table 3, treatment No. Processing No. 6 to 10. Sample No. 11 had a high P concentration after treatment because the basicity C/S of the slag was low. In addition, processing No. In No. 12, the basicity C/S of the slag was high and coagulation of the slag was confirmed.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
（実施例３）
　２５０ｔ規模電気炉において表１に示す還元鉄Ａを無煙炭と共に溶解し、Ｃ濃度が２．０質量％程度含まれる溶鉄とした後、温度調整をした上で鍋型の容器に移し替えた。その後、実施例１、２と同様の方法を用いて脱りん処理および粒鉄製造を行った。表４に、それぞれ脱りん処理前後の溶鉄の温度ＴｉおよびＴｆ（℃）、Ｃ濃度［Ｃ］ｉおよび［Ｃ］ｆ（質量％）、Ｐ濃度［Ｐ］ｉおよび［Ｐ］ｆ（質量％）ならびに供給した酸素源とＣａＯ源の種類と量、処理時間ｔｆ（分）、処理後スラグの塩基度Ｃ／Ｓを処理Ｎｏ．１３～１９で示す。表４に示す通り、処理Ｎｏ．１３～１７に対し処理Ｎｏ．１８はスラグの塩基度Ｃ／Ｓが低いため処理後Ｐ濃度［Ｐ］ｆが高位であった。また、処理Ｎｏ．１９ではスラグの塩基度Ｃ／Ｓが高くスラグの凝固が確認された。 (Example 3)
Reduced iron A shown in Table 1 was melted together with anthracite in a 250-ton electric furnace to obtain molten iron containing about 2.0% by mass of C, and after adjusting the temperature, it was transferred to a pot-shaped container. Thereafter, dephosphorization treatment and production of granulated iron were performed using the same methods as in Examples 1 and 2. Table 4 shows the temperatures T i and T f (°C) of molten iron before and after dephosphorization treatment, C concentrations [C] i and [C] f (mass%), and P concentrations [P] i and [P] f ( % by mass), the type and amount of the oxygen source and CaO source supplied, the treatment time t f (minutes), and the basicity C/S of the slag after treatment. Shown as 13 to 19. As shown in Table 4, treatment No. For processing No. 13 to 17. Sample No. 18 had a high P concentration [P] f after treatment because the basicity C/S of the slag was low. In addition, processing No. In No. 19, the basicity C/S of the slag was high and coagulation of the slag was confirmed.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　処理Ｎｏ．８～１０、１２、１４～１７および１９で作製された粒鉄は、Ｐ濃度が０．０３０質量％以下であった。これらの還元鉄を電気炉で溶解すると、得られる溶鉄のＰ濃度は０．０３０質量％以下となった。これらは、鉄鋼製品として要求されるＰ濃度が達成されており、追加の脱りん処理を必要としなかった。また、処理Ｎｏ．８～１０、１２、１４～１７および１９で得られた粒鉄を１ｍｍ以上で分級したのちに電気炉や高炉、転炉で使用したところ、問題なく使用できた。 Processing No. The granulated iron produced in Examples 8 to 10, 12, 14 to 17, and 19 had a P concentration of 0.030% by mass or less. When these reduced irons were melted in an electric furnace, the P concentration of the resulting molten iron was 0.030% by mass or less. These achieved the P concentration required for steel products and did not require additional dephosphorization treatment. In addition, processing No. When the iron granules obtained in steps 8 to 10, 12, 14 to 17, and 19 were classified to 1 mm or more and used in an electric furnace, blast furnace, or converter, they could be used without problems.
　本明細書中で、質量の単位「ｔ」は、１０３ｋｇを表す。また、体積の単位「Ｎｍ３」に付すＮは気体の標準状態を示し、本明細書では気体の標準状態を１ａｔｍ（＝１０１３２５Ｐａ）、０℃とする。化学式の表記で［Ｍ］は元素Ｍが溶融鉄や還元鉄中に溶解していることを表す。 In this specification, the unit of mass "t" represents 10 3 kg. Further, the N appended to the unit of volume "Nm 3 " indicates the standard state of gas, and in this specification, the standard state of gas is 1 atm (=101325 Pa) and 0°C. In the chemical formula, [M] represents that element M is dissolved in molten iron or reduced iron.
　本発明の粒鉄の製造方法および粒鉄によれば、原料がＰ濃度の高い低品位鉄鉱石から得られた還元鉄であっても、Ｐ濃度の低い粒鉄を効率的に生産可能であり、本発明にかかる粒鉄を再溶解するだけで鉄鋼製品相当のＰ濃度の溶鉄を得ることができるので産業上有用である。 According to the method for producing granulated iron and the granulated iron of the present invention, even if the raw material is reduced iron obtained from low-grade iron ore with a high P concentration, it is possible to efficiently produce granulated iron with a low P concentration. This is industrially useful because it is possible to obtain molten iron with a P concentration equivalent to that of steel products simply by remelting the granulated iron according to the present invention.

Claims (5)

  1. 還元鉄を溶解し１次溶鉄とする第一工程と、
    前記１次溶鉄とスラグとを分離する第二工程と、
    前記スラグと分離した前記１次溶鉄を脱りん処理し２次溶鉄とする第三工程と、
    前記２次溶鉄を粒状に凝固させて粒鉄化する第四工程と、を含み、
    前記第三工程では、前記１次溶鉄に酸素源とＣａＯ源を供給して脱りん処理を行ない、該脱りん処理終了時点の前記２次溶鉄の温度を、該脱りん処理開始時点の前記１次溶鉄の温度以下とする、粒鉄の製造方法。     A first step of melting reduced iron to obtain primary molten iron,
    a second step of separating the primary molten iron and slag;
    a third step of dephosphorizing the primary molten iron separated from the slag to obtain secondary molten iron;
    A fourth step of solidifying the secondary molten iron into granules to form granular iron,
    In the third step, dephosphorization is performed by supplying an oxygen source and a CaO source to the primary molten iron, and the temperature of the secondary molten iron at the end of the dephosphorization is set to the same temperature as the first molten iron at the start of the dephosphorization. A method for producing granulated iron at a temperature below that of molten iron.
  2. 前記脱りん処理終了時点の前記２次溶鉄の温度Ｔfを、脱りん処理終了時点における２次溶鉄の凝固温度Ｔｍから２０℃以上高くする、請求項１に記載の粒鉄の製造方法。 The method for producing granulated iron according to claim 1, wherein the temperature T f of the secondary molten iron at the end of the dephosphorization treatment is set higher than the solidification temperature T m of the secondary molten iron at the end of the dephosphorization treatment by 20° C. or more.
  3. 前記脱りん処理終了時点のスラグ組成は、質量基準でＳｉＯ２濃度（％ＳｉＯ２）に対するＣａＯ濃度（％ＣａＯ）の比である塩基度を１．０～４．０の範囲とする、請求項１または２に記載の粒鉄の製造方法。 The slag composition at the end of the dephosphorization treatment has a basicity in the range of 1.0 to 4.0, which is the ratio of CaO concentration (%CaO) to SiO 2 concentration (%SiO 2 ) on a mass basis. The method for producing granulated iron according to 1 or 2.
  4. 前記第四工程では、前記２次溶鉄を液滴とする粒化装置と、前記液滴を受ける位置に設けられ、冷却水を収容する水流制御容器と、前記水流制御容器に接続し、前記水流制御容器に冷却水を供給する少なくとも１つの冷却水管と、を有し、前記水流制御容器は、下方に向けて前記水流制御容器の水平断面積が狭くなるように傾斜した傾斜面を有し、前記傾斜面の下方には排出口が設けられる、粒鉄製造装置を用いる、請求項１に記載に粒鉄の製造方法。 In the fourth step, a granulating device that converts the secondary molten iron into droplets, a water flow control container installed at a position to receive the droplets and containing cooling water, and a water flow control container connected to the water flow control container and configured to control the water flow. at least one cooling water pipe for supplying cooling water to a control container, the water flow control container having an inclined surface that is inclined so that the horizontal cross-sectional area of the water flow control container becomes narrower toward the bottom; 2. The method for producing granulated iron according to claim 1, comprising using a granulated iron manufacturing apparatus in which a discharge port is provided below the inclined surface.
  5. Ｐ濃度が０．０５０質量％以上の還元鉄が原料であり、Ｐ濃度が０．０３０質量％以下であり、粒径が１ｍｍ以上５０ｍｍ以下である、粒鉄。 Granulated iron whose raw material is reduced iron with a P concentration of 0.050% by mass or more, a P concentration of 0.030% by mass or less, and a particle size of 1 mm or more and 50 mm or less.
PCT/JP2023/014502 2022-04-22 2023-04-10 Production method for grained iron, and grained iron WO2023204071A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2023547085A JPWO2023204071A1 (en) 2022-04-22 2023-04-10

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2022-070747 2022-04-22
JP2022070747 2022-04-22

Publications (1)

Publication Number Publication Date
WO2023204071A1 true WO2023204071A1 (en) 2023-10-26

Family

ID=88420043

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2023/014502 WO2023204071A1 (en) 2022-04-22 2023-04-10 Production method for grained iron, and grained iron

Country Status (3)

Country Link
JP (1) JPWO2023204071A1 (en)
TW (1) TW202344694A (en)
WO (1) WO2023204071A1 (en)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS491996B1 (en) * 1970-02-04 1974-01-17
JPS5439357A (en) * 1977-09-02 1979-03-26 Hitachi Ltd Continuous production method of steel pellet
JPS5785905A (en) * 1980-11-14 1982-05-28 Sumitomo Metal Ind Ltd Spray medium for production of metallic powder
JPH01252753A (en) * 1988-03-31 1989-10-09 Kawasaki Steel Corp Method for refining of stainless steel mother molten metal, arrangement of tuyere at bottom of reactor for refining and bottom tuyere
JP2011144431A (en) * 2010-01-15 2011-07-28 Kobe Steel Ltd Dephosphorizing method for preparing extra-low phosphorus steel by melting
JP2021161465A (en) * 2020-03-31 2021-10-11 Ｊｆｅスチール株式会社 Granular iron manufacturing apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS491996B1 (en) * 1970-02-04 1974-01-17
JPS5439357A (en) * 1977-09-02 1979-03-26 Hitachi Ltd Continuous production method of steel pellet
JPS5785905A (en) * 1980-11-14 1982-05-28 Sumitomo Metal Ind Ltd Spray medium for production of metallic powder
JPH01252753A (en) * 1988-03-31 1989-10-09 Kawasaki Steel Corp Method for refining of stainless steel mother molten metal, arrangement of tuyere at bottom of reactor for refining and bottom tuyere
JP2011144431A (en) * 2010-01-15 2011-07-28 Kobe Steel Ltd Dephosphorizing method for preparing extra-low phosphorus steel by melting
JP2021161465A (en) * 2020-03-31 2021-10-11 Ｊｆｅスチール株式会社 Granular iron manufacturing apparatus

Also Published As

Publication number Publication date
JPWO2023204071A1 (en) 2023-10-26
TW202344694A (en) 2023-11-16

Similar Documents

Publication Publication Date Title
CA2422253C (en) Refining agent and refining method
KR101648652B1 (en) Method for preliminary treatment of molten iron
RU2146716C1 (en) Method of producing pozzolans, synthetic blast-furnace slags, belite and alite clinkers and cast iron alloys from oxide slags and device for method embodiment
RU2349647C2 (en) Method and plant for receiving alloyed metal melt
JP2001506315A (en) Direct reduction of metal oxide nodules
KR20130045955A (en) Method for removing copper in steel scraps
CA1244656A (en) Processes and appparatus for the smelting reduction of smeltable materials
JP6164151B2 (en) Method for refining molten iron using a converter-type refining furnace
US4756748A (en) Processes for the smelting reduction of smeltable materials
JP5408379B2 (en) Hot metal pretreatment method
JP2011246760A (en) Method of manufacturing ferromolybdenum, and ferromolybdenum
US4576638A (en) Process for the production of ferromanganese
KR101189182B1 (en) Method for separating vanadium from vanadium-containing melt
WO2023204071A1 (en) Production method for grained iron, and grained iron
WO2023204069A1 (en) Method for melting direct-reduced iron, solid iron and method for producing solid iron, and civil engineering and construction material and method for producing civil engineering and construction material
WO2023204063A1 (en) Method for melting direct reduction iron, solid iron and method for manufacturing solid iron, material for civil engineering and construction, method for producing material for civil engineering and construction, and system for melting direct reduction iron
EP0382900B1 (en) Method for manufacturing molten pig iron
JP2006328519A (en) Method for producing steel
TWI843517B (en) Direct-reduction iron melting method, solid iron and method for producing solid iron, civil engineering and construction material and method for producing civil engineering and construction material, and direct-reduction iron melting system
JPS6250544B2 (en)
CN111334703B (en) Production method of low-titanium-phosphorus iron alloy
TW202409300A (en) Methods for melting direct reduced iron, solid iron and methods for manufacturing solid iron, and materials for civil engineering and construction and methods for manufacturing materials for civil engineering and construction
JP4311098B2 (en) Manufacturing method of molten steel
JP2004010935A (en) Method for manufacturing molten steel
JP4466145B2 (en) Hot metal desiliconization method

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 2023547085

Country of ref document: JP

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23791720

Country of ref document: EP

Kind code of ref document: A1