MXPA95005142A - Method and apparatus for using scrub of foundation ovens in the production of esceme of ceme - Google Patents
Method and apparatus for using scrub of foundation ovens in the production of esceme of cemeInfo
- Publication number
- MXPA95005142A MXPA95005142A MXPA/A/1995/005142A MX9505142A MXPA95005142A MX PA95005142 A MXPA95005142 A MX PA95005142A MX 9505142 A MX9505142 A MX 9505142A MX PA95005142 A MXPA95005142 A MX PA95005142A
- Authority
- MX
- Mexico
- Prior art keywords
- slag
- furnace
- heat
- feed
- cement
- Prior art date
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 23
- 239000002893 slag Substances 0.000 claims abstract description 205
- 239000004568 cement Substances 0.000 claims abstract description 55
- 239000000463 material Substances 0.000 claims abstract description 55
- 238000003723 Smelting Methods 0.000 claims abstract description 42
- 239000002245 particle Substances 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 21
- 238000002844 melting Methods 0.000 claims description 62
- 239000000203 mixture Substances 0.000 claims description 16
- 235000019738 Limestone Nutrition 0.000 claims description 15
- 239000006028 limestone Substances 0.000 claims description 15
- 239000000126 substance Substances 0.000 claims description 13
- 238000000227 grinding Methods 0.000 claims description 11
- 229910001018 Cast iron Inorganic materials 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 6
- 235000012215 calcium aluminium silicate Nutrition 0.000 claims description 4
- 238000001914 filtration Methods 0.000 claims description 4
- 235000012241 calcium silicate Nutrition 0.000 claims description 3
- 239000002994 raw material Substances 0.000 description 25
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium monoxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 24
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 24
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 20
- 235000012255 calcium oxide Nutrition 0.000 description 13
- 235000012245 magnesium oxide Nutrition 0.000 description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 13
- 239000000395 magnesium oxide Substances 0.000 description 12
- 229910052742 iron Inorganic materials 0.000 description 10
- 150000001875 compounds Chemical class 0.000 description 9
- 238000010298 pulverizing process Methods 0.000 description 9
- 229910000831 Steel Inorganic materials 0.000 description 7
- 238000004458 analytical method Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 239000010959 steel Substances 0.000 description 7
- PNEYBMLMFCGWSK-UHFFFAOYSA-N AI2O3 Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 238000001354 calcination Methods 0.000 description 6
- 239000004576 sand Substances 0.000 description 6
- 239000000446 fuel Substances 0.000 description 5
- 229910000460 iron oxide Inorganic materials 0.000 description 5
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 230000035508 accumulation Effects 0.000 description 4
- 238000007792 addition Methods 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 4
- 239000000155 melt Substances 0.000 description 4
- 235000015927 pasta Nutrition 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000009825 accumulation Methods 0.000 description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 238000011109 contamination Methods 0.000 description 3
- 239000004615 ingredient Substances 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- 229910052570 clay Inorganic materials 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 235000010755 mineral Nutrition 0.000 description 2
- 230000000414 obstructive Effects 0.000 description 2
- 230000000644 propagated Effects 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 239000002912 waste gas Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- JHLNERQLKQQLRZ-UHFFFAOYSA-N Calcium silicate Chemical compound [Ca+2].[Ca+2].[O-][Si]([O-])([O-])[O-] JHLNERQLKQQLRZ-UHFFFAOYSA-N 0.000 description 1
- 241000867614 Mimus polyglottos Species 0.000 description 1
- 210000002105 Tongue Anatomy 0.000 description 1
- AGWMJKGGLUJAPB-UHFFFAOYSA-N aluminum;dicalcium;iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Al+3].[Ca+2].[Ca+2].[Fe+3] AGWMJKGGLUJAPB-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- 230000001413 cellular Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 230000002939 deleterious Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 239000008240 homogeneous mixture Substances 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical class [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006011 modification reaction Methods 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N silicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000004642 transportation engineering Methods 0.000 description 1
- -1 tricalcium silicate Chemical class 0.000 description 1
- 235000019976 tricalcium silicate Nutrition 0.000 description 1
Abstract
A process and apparatus by means of which smelting furnace slag can be added to the feed materials within the feed end of a rotary cement furnace to form cement slag. The smelting furnace slag is crushed and filtered to provide cast furnace slag particles with a predominant size of a maximum diameter of substantially 2"or less.
Description
"METHOD AND APPARATUS FOR USING SCRUBS OF FOUNDRY OVENS IN CEMENT PRODUCTION"
INVENTOR: ROM D. YOUNG.
NATIONALITY: NORTH AMERICAN CITIZEN.
RESIDENCE: 411 TOWN CREEK DRIVE DALLAS, TEXAS 75232 E.U.A.
OWNER: TEXAS INDUSTRIES, INC.
NATIONALITY: NORTH AMERICAN SOCIETY.
RESIDENCE: 1341 W. MOCKINGBIRD LAÑE DALLAS, TEXAS 75247 E.U.A.
BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This invention relates in general to the manufacture of cement slag in long rotary kilns. In particular, the invention relates to the method and apparatus for the manufacture of cement slag in conventional long, wet or dry rotary kilns in which smelter slag is added at the inlet end of the kiln with a stream of material of feed containing limestone so that the stream of raw material and slag from the smelting furnace move towards the heat at the hot end of the furnace, the slag from the smelting furnace melts and propagates into the feed material to form cement slags. 2. STATE OF ART As stated in United States Patent No. 5, 156,676, the literature is replete with processes by which the calcining and slagging of cement ingredients can be achieved. The typical process which uses a rotary kiln, wet or dry, is well known. Raw cement materials such as limestone, clay and sand, or the like, are finely pulverized and intimately mixed to provide a substantially homogeneous mixture at the inlet or feed end of the furnace. The furnace tilts downwardly at an angle such that the heat end of the furnace is below the feed end. The furnace generally has four operating zones which include a precalcining zone, a calcining zone, a slagging zone, and a cooling zone. Conventional fuel is combined with preheated and injected air inside the furnace at the heat end. Fuels such as natural gas, oil or pulverized coal are conventionally used in cement manufacturing processes. As the finely divided cement raw materials pass within the rotary kiln at the feed end thereof, the materials are heated from near room temperature to about 538 ° C (1000 ° F) in the pre-calcination zone. In this zone, the heat of the combustion gases from the calcining zone is used to raise the temperature of the raw materials. Additionally, in the furnace, chain systems or the like can be fixed inside the furnace and are used to improve the efficiency in the heat exchange between the gases and the raw materials. The temperature of the raw materials increases from about 538 ° C to about 1093 ° C (1000 ° F to about 2000 ° F) as they pass through the calcination zone and in this zone the CaC03 decomposes with the evolution of C02. The material calcined at the temperature of about 1093 ° C (2000 ° F) then passes into the scorification or burn zone where the temperature rises to about 1500 ° C (2732 ° F). It is in this area that the main raw material is converted into the typical cement compounds such as tricalcium silicate, dicalcium silicate, tricalcium alutocyte and tetracalcium-aluminoferrite. The cement slag then leaves the slagging zone where the slag materials are cooled and subsequently further processed as for example by spraying. In addition, the use of pulverized smelter slag as a cementitious material dates back to 1774. In the production of iron, the smelting furnace is continuously loaded from its top with iron oxide sources, melting stone and fuel. Two products are obtained from the furnace: molten iron that settles to the bottom of the furnace and slag from the cast iron furnace that floats in the molten iron. Both are periodically bled from the furnace at a temperature of about 1500 ° C (2732 ° F). The slag consists mainly of silica and alumina combined with calcium and magnesium oxides from the melting stone. The cementitious activity of this slag for use in mortar or concrete is determined by its composition and the rate at which the molten material cools when it leaves the kiln. In addition, in steel production, a similar process occurs in which the liquid steel slag floats in the steel pool. Again, steel slag consists mainly of silica and alumina combined with oxides of magnesium oxide. Discarding both the steel slag and the slag from the smelting furnace represents a major disposal problem for the manufacturer because of the amount of materials involved. Both the steel slag and the smelting slag slag are composed of particles which are very hard. The melting furnace slag, when used, has always been in a finely pulverized or granulated form, which means that a large amount of energy must be used to grind and pulverize the slag into a finely pulverized form or granulate it. Such a process is disclosed in U.S. Pat. 2,600,515 in which the melting furnace slag, in a mixture with finely pulverized limestone, is fed into the rotary cement kilns and introduced directly into the furnace flame. The slag powder is blown in at the same time and through the same channels as the fuel, namely pulverized coal, heavy oil or gas. This process has several disadvantages. One of the most significant disadvantages is that large amounts of energy are required to spray and dry the material so that it can be blown into the oven. Many of the chemical compounds in steel slag and foundry furnace slag are common to chemical compounds and their heat of formation have been achieved in their respective processes. The American Concrete Institute defines the smelting furnace slag as follows: smelting furnace slag: the non-metallic product, consisting essentially of calcium silicates and aluminosilicates and other bases, which is out in a condition simultaneously with iron in a melting furnace. 1. air cooled smelting slag: is the material resulting from the solidification of molten smelter slag under atmospheric conditions: the subsequent cooling can be accelerated by the application of water on the solidified surface. 2. Expanded foundry furnace slag: is the light cellular material obtained by the controlled processing of foundry furnace slag that is melted with water, or with water and other agents, such as steam, compressed air, or both.
3. granulated foundry furnace slag: it is the vitreous granular material formed when the slag of the melting furnace is rapidly cooled, as by its immersion in water. In the present case, the term "smelting furnace slag" will be used hereafter to mean only "air-cooled smelting slag slag" and not expanded or granulated smelting slag unless otherwise specified. another way. These products, with the addition of Ca014, can be converted to 3CaO. Si02 (C3S), 2CaO. Si02 (C2S), 2CaO. Fe203 (CF), 4CaO. A1203. Fe203 (C4AF), 3CaO. A1203 (C3A) in the burn zone of the rotary kiln. Experience has shown that cast iron slag does not have a deleterious effect on the operation of a rotary cement kiln. The emission of volatile materials from the rotary kiln is improved as the slag has been pre-heat treated and most of the volatile materials have been removed, i.e. carbon dioxide, carbon, volatile organics, and the like. However, as stated in the prior art, fine pulverization or crushing or pulverization of the slag is required, therefore adding a step with a high cost in the cement manufacturing process. Also, granulated slag also has a very expensive training process.
SUMMARY OF THE INVENTION Since it has been recognized for a long time that many of the chemicals and chemical compounds in foundry furnace slag are common to the cements manufacturing materials and because the slag from the melting furnace is it is available in large quantities, it may be advantageous to make it possible to use the slag from the melting furnace in the cement manufacturing process if it can be used in a much thicker state than that pulverized or granulated state which is now required and if it can be added to the feed raw materials that are fed into the furnace at the feed end of the furnace instead of the heat end of the furnace. The present invention provides such a use of foundry furnace slag and provides a method and apparatus for the use of various foundry furnace slags which have been compressed and filtered to provide a coarse state with a predominant particle size having diameters of up to 2"and where the coarse melting furnace slag is fed into the inlet end of the furnace with the raw materials, thereby obtaining all the advantages of the use in the prior art of the melting furnace slag without the disadvantage of the requirements to provide the granulation of the slag or a grinding, pulverizing or fine grinding of the slag and introducing the fine-melting furnace slag into the heat end of the furnace As previously stated, the experience of the Applicant has shown that the slag of the melting furnace has no harmful effect on the operation of a rotary cement kiln. Volatile from the rotary kiln is improved because the slag from the melting furnace has been previously heat treated and most of the volatile materials have been removed, i.e. carbon dioxide, carbon, volatile organic and the like. Because of the previous history of the foundry furnace slag, the chemistry of the required foundry furnace slag has already been achieved during the steelmaking process, thus conserving the energy in the iron manufacturing process. Therefore there are a number of advantages in the use of this slag. First, as stated above, no grinding, pulverization or fine grinding of the slag is required. Large amounts of coarse slag (defined herein as smelting slag slag having predominant particle sizes that are up to 2"in diameter) may be incorporated within the cement slag composition only with minor chemical changes from the feed of the slag. Regular material to the rotary kiln Crushing and filtering is required only for slag particles larger than 2"in diameter. Secondly, no slag drying is required. The inherent humidity is usually between 1% and 6%. In the wet process rotary kiln system, the reduction and substantial moisture saving is carried out. In dry process rotary kilns, it is not required that the melting furnace slag should be dried. Third, there has been no obstruction of the furnace due to a sediment ring or slag accumulation. In both the rotary kiln systems for wet and dry processes, the slag from the thick melting furnace has a cleaning effect on the accumulation of materials as it moves through the furnace. Fourth, the coarse melting furnace slag can be used as part of the initial feed stock and is introduced into the furnace at the feed end thereof. The melting furnace slag and the wet or dry raw material can be injected into the feed end of the rotary kiln as separate materials and can be injected together at the feed end of the honing without prior mixing. Fifth, only slight chemical changes are required in the composition of the raw material so that the raw material includes the slag from the melting furnace. This usually means that the raw material must be rich in limestone content. Sixth, the chemical structure composed of the melting furnace slag is transformed into the desired slag structure during the heat treatment within the rotary kiln by diffusion. Seventh, the substantial energy savings are apparent when the smelting furnace slag is used because of the low temperature at which the smelting slag melts and because no grinding or pulverization of the smelter is required. smelting furnace slag. Eighth, the increase in the production of cement slag is practically proportional to the amount of smelting slag used. In ninth place, the environmental condition of the rotary kiln process improves because of the low volatile content of the melting furnace slag. # In tenth place, the recycling of the smelting furnace slag improves the environment because it provides an important use for the large quantities of smelting slag available and avoids any problem with the final disposal of the smelting slag slag. In eleventh place, the cost of cement production is substantially reduced because of energy savings, and the abundant supply of low cost smelting furnace slag. Therefore, it is an object of the present invention to provide an improved method and apparatus for operating a rotary kiln for the production of cement slag using coarse melting furnace slag, a by-product of the iron manufacturing processes. It is another object of the present invention to introduce the coarse melting furnace slag in a rotary kiln into a rotary kiln for the manufacture of cement at the feed end thereof. It is still another object of the present invention to use coarse melting furnace slag having predominant particle sizes that are substantially 2"in diameter or less.Therefore, the present invention relates to a method of making cement slag. which uses an elongated rotary cement furnace having a feed end and a heat end, the heat end is inclined downward with respect to the feed end, the method comprising the steps of directing heat from a heat source within the heat end of the furnace, introducing a stream of feed material containing limestone into the feed end of the furnace such that the feed stream of raw material moves towards the heat at the heat end of the furnace, and add a predetermined quantity of ground and filtered smelting slag from the raw material feed stream at the feed end of the furnace such that as the feed stream of the raw material and the slag of the smelting furnace move towards the heat end of the furnace, the slag from the melting furnace melts because of the heat and is propagated inside the raw material to form cement slag. The invention also relates to an apparatus for forming cement slag comprising a rotary cement kiln having a feed end and a heat end, the heat end is inclined downwardly with respect to the feed end, a source of heat. heat at the hot end to heat the interior of the rotary kiln, and transportation means for introducing a feed stream of raw material containing limestone and slag from the melting furnace into the feed end of the rotary kiln according to the feed stream of the rotary kiln. Raw material and slag furnace slag move towards the heat end of the furnace, slag melting furnace is propagated by heat inside the raw material to form cement slag. BRIEF DESCRIPTION OF THE ILLUSTRATIONS These and other more detailed objects of the present invention will be disclosed in more detail in the DETAILED DESCRIPTION OF THE ILLUSTRATIONS below, in which: FIG. 1 is a basic diagrammatic representation of a rotary kiln system of the present invention for forming cement slag in which the raw material and slag from the melting furnace are fed together into the inlet end of the rotary kilns; FIG. 2 is a diagrammatic representation of the feed material and cast iron slag being fed separately into the inlet end of the rotary kiln. FIG. 3 is a flowchart representation of the process in which the raw material and slag from the melting furnace are fed into the inlet end of the furnace in a combined mixture; and FIG. 4 is a flow diagram representation of an alternative process in which the feedstock and slag furnace slag are fed separately pqr into the input or feed end of the rotary kiln. DETAILED DESCRIPTION OF THE ILLUSTRATIONS The present invention allows crushed and filtered slag to be added to the furnace feed as a separate component at the feed end of the rotary kiln of cement in various particle sizes where the predominant particle size is up to a maximum of 2"in diameter The term" raw smelting furnace slag "as used herein is used to refer to smelting slag that has not been processed in any way except for The crushing and filtering of foundry furnace slag that is in a solid state.Most of the foundry furnace slag has particles below 2"in diameter. However, some particles are more than 2"in diameter and therefore a crushing and filtering process is required to achieve only the predominant particle size that is substantially 2" in diameter or smaller. No grinding, pulverization or grinding of the melting furnace slag by the present invention is required. The invention provides a method of using several slag furnace slags in a much thicker state than previously recognized in the rotary cement kiln processes which allow the elements in the chemical compounds of the smelting furnace slag, ie, silicates, calcium aluminosilicates and the like, to become an integral part of the cement slag. As understood by those skilled in the art, the chemistry of the slag must be understood and controlled as part of the ingredients as a whole of the cement and therefore the amount of slag from the smelting furnace is added to the feed material should be balanced with the raw material of food and chemical compounds. In a burn test in a laboratory furnace with 100% of the melting furnace slag, the melting point of the melting furnace slag was determined and is the key for use in a cement kiln. As can be seen in Table I, it was determined that the melting point was 2552 ° F / 1400 ° C for the melting furnace slag which allows the melting furnace slag to be added to the feed end of the furnace at Large particle sizes, the size of predominant particles is up to 2"in diameter TABLE I BURNED IN LABORATORY OVEN
EFFECTS ON THE SCORING Temp. Interval None Slightly Melts Sticky Start 800C 15 Min. X 1000C 15 Min. X 1100C 15 Min. X 1200C '15 Min. X 1300C 15 Min, X 1385C 15 Min, X 1395C 15 Min. X 1400C 15 Min, X Table I illustrates the effects on the melting furnace slag when heated at various temperatures. The tests established in Table 1 were carried out for 15 minutes at each temperature with the size of the slag particles approaching 3/8. "As a result of the tests, it has been determined that the slag will not cause the pulp It will swell in the chain section of the rotary kiln, cause sediment rings or increase the loss of dust due to particle size, and will reduce the moisture content by as much as 2.2% or more depending on the amount of kiln slag The melting furnace slag begins to melt and combine with other raw materials at some point between the calcination zone and the burning zone in the rotary kiln, because of the low melting point, it is not necessary to grind , pulverizing or grinding this material as in the prior art which requires that 80% of the material pass through a 200-mesh screen for a chemical combination with other ingredients. n silicate and calcium aluminosilicates and other bases which are similar to cement slag compounds, if not the same, have been previously achieved in the smelting furnace slag during the steelmaking process. These compounds, with the addition of CaO, can be converted to 2CaO. Si02 (C2S), 3CaO. Si02 (C3S), 2CaO. Fe203 (C2F), 3CaO.
Alj-OsíQjA) and 4CaO. A1203. Fe203 (C4AF) with very little additional heat. These are the main chemical compounds of cement slag. The apparatus of the present invention is illustrated in Fig. 1. The apparatus 10 includes the rotary kiln 12 supported in a well-known manner by tongues 14 rotating together with the furnace. The furnace has a feed end and a heat end or burn zone 18. The heat end 18 is inclined downwardly with respect to the feed end 16 as is well known in the art. A fuel source creates a flame 22 at the heat end 18 of the rotary kiln 12 to provide a temperature of approximately 1500 ° C (2732 ° F). The raw cement materials or feedstock such as limestone, clay, sand and the like are carried by means of a variable speed conveyor belt 24 to the rotary kiln 12. If a slurry is used, the conveyor belt of variable speed will drive the raw material to a shredder 26 and from the shredder 26 to the feed end 16 of the rotary kiln 12. The feedstock moves in a stream 28 through the rotary kiln 12 to the flame 22. The processes Well-known chemicals take place inside the furnace 12 and the cement slag 30 leaves the heat end 18 of the furnace 12 for further processing. Contamination control devices 32 and 34, well known in the art, are located at the heat end and at the feed end, respectively, of the furnace 12. At the heat end 18, outside the device for control of contamination, the waste gases 38 are expelled into the atmosphere and the reclaimed waste products 40 are recovered. At the feed end 16, the contamination control equipment 34 removes the waste gases 36 which are ejected and reclaims the waste products at 42. In the present invention, the melting furnace slag 44 is carried by a device conveyor 46, such as a variable speed conveyor belt, to the feed stock 48 being fed through a hopper 56 (FIG 2) at the feed end 16 of the rotary kiln 12. A controller 25 controls the speed of the conveyor belts 24 and 46 so that the appropriate proportion of slag from the melting furnace 44 is set in relation to the feedstock depending on the chemical compositions of the latter. Such control is well known in the art and will not be discussed in detail. FIG. 2 is a diagrammatic representation of the apparatus for providing a separate feed of the foundry furnace slag and the feed material within the feed end of the rotary furnace 12. In FIG. 2, it can be seen that the smelting slag 50 is thrown into a hopper 52 and transported upwards by a conveyor system 54 where it is deposited at 55 so as to pass through the hopper 56 to the inlet end 16 of the rotary kiln 12. The feeding of the material to the inlet end of the kiln can be done in any well known manner. In a similar manner, the feed material 58 is dropped into a hopper 60 where it is transported upward by conveyor means 62 and thrown into 64 within the hopper 56 to feed it into the inlet end 16 of the rotary kiln 12. Any of the apparatuses of FIG. 1 or of FIG. 2 produce the desired results. Table II describes the results of the chemical analysis of a smelting furnace slag sample taken from a random smelting furnace slag feed stock. Of course, the chemical analysis of the melting furnace slag can vary with respect to the values in Table II depending on the slag.
TABLE II
OVEN CASTING OF ELEMENTS ELEMENTS OF OVEN OF SOMETHING OF FOUNDRY Si02 35.76 A1203 9.42 Fe203 0.63 CaO 40.01 MgO 8.55 S03 2.70 P205 0.00 T102 0.00 Na20 0.32 K20 0.57
It can be seen that the composition of the melting furnace slag is suitable for the manufacture of cement. Table III illustrates the typical calculations of the mixtures for a feed material having 0% smelting slag slag, 89.67% limestone, 4.42% shale.
TABLE III MIXING CALCULATIONS TYPE I - 0% SCORING I LS LUTITA ARENA MINERAL
Si02 8.25 49.25 90.00 0.81
A1203 2.31 18.60 3.24 0.28
Fe203 '1.30 5.79 1.90 96.17
CaO 47.60 3.30 0.51 0.51
MgO 0.46 1.25 0.07 0.70
S03 0.90 3.37 0.13 0.11
P205 0.00 0.00 0.00 0.00 T102 0.00 0.00 0.00 0.00 Na20 0.10 0.73 0.03 0.03 K20 0.50 3.10 0.31 0.04
ANALYSIS OF THE SCENE
PASTA AGUADA ESCORIA
Si02 14.01 21.78
A1203 3.06 4.75
Fe203 2.46 3.83
CaO 42.86 66.62
MgO 0.48 0.74
S03 0.96 0.75
P205 0.00 0.21
T102 0.00 0.21
Na20 0.12 0.19
K20 0.60 0.50
TOTAL 99.59
* S / R 2.42 A / F 1.35
C3S - 63.33 C2S 14.66 C3A 7.22 C4AF 11.65 Table IV illustrates the calculation for a test mix that has 5% smelting slag slag, 86.11 limestone, 4.14% shale, 3.76% sand, and 0.97% of iron oxide flakes.
TABLE IV TYPE I WITH 5% OF AGUARDED FOUNDRY OVEN SCRUB
ELEMENTS MIDL. LS LUTITA ARENA ESCALAS ESCORIA PHILIPS OF OXIDO DE OOR
OF IRON OF FOUNDRY
YES02 8.25 49.25 90.00 0.81 35.76
Al203 2.31 18.60 3.24 0.28 9.42
Fe203 1.30 5.79 1.90 96.17 0.63
CaO 47.60 3.30 0.51 0.51 40.01
MgO 0.46 1.25 0.07 0.70 8.55
S03 0.90 3.37 0.13 0.11 2.70
P2.05 0.00 0.00 0.00 0.00 0.00
T102 0.00 0.00 0.00 0.00 0.00
Na20 0.10 0.73 0.03 0.03 0.32
K20 0.50 3.10 0.31 0.04 0.57
ANALYSIS OF THE SCULPTURE PASTA AGUADA ESCORIA YES02 13.19 '21.38 A1203 3.04 4.98 Fe203 2.51 3.76 CaO 43.36 66.33 MgO 0.48 1.14 S03 0.97 0.70 P205 0.00 0.22 T102 0.00 0.22 Na20 0.12 0.12 K20 0.60 0.50 TOTAL 99.47
S / R 2.33 A / F 1.44
C3S 63.76 C2S 13.20 C3A 8.00 CáAF 11.44
Table V illustrates the calculation for a test mix that has 10% smelting slag slag,
82. 66% limestone, 2.94% shale, 3.32% sand, and 1.08% iron oxide scale.
TABLE V TYPE I WITH 10% OF ESCORIA DE OVEN OF FUNDICIÓN AGREGADA
ELEMENTS MIDL. LS LUTITA ARENA ESCALAS ESCORIA PHILIPS OF OXIDE OF IRON OVEN
FOUNDRY
Si02 8.25 49.25 90.00 0.81 35.76
A1203 2.31 18.60 3.24 0.28 9.42
Fe203 1.30 5.79 1.90 96.17 0.63
CaO 47.60 3.30 0.51 0.51 40.01
MgO 0.46 1.25 0.07 0.70 8.55
S03 0.90 3.37 0.13 0.11 2.70
P205 0.00 0.00 0.00 0.00 0.00
T102 0.00 0.00 0.00 0.00 0.00
Na20 0.10 0.73 0.03 0.03 0.32
K20 0.50 3.10 0.31 0.04 0.57
ANALYSIS OF THE SCENE
PASTA AGUADA ESCORIA
YES02 12.52 21.30 Al203 2.85 4.98 Fe203 2.61 3.76 CaO 43.85 66.09 MgO 0.47 1.53 S03 0.94 0.70 P205 0.00 0., 22 T102 0.00 0., 22 Na20 0.12 0., 24 K20 0.57 0.50 0.99 TOTAL 99. 54
S / R 2, .32 A / F 1, .44
C3S 63 .39 C2S 13 .25 C3A 8 .00 C4AF 11 .44
Table VI illustrates the calculation for a test mix having 15% smelting slag slag, 74.22% limestone, 1.68 shale, 2.93% sand, and 1-16 iron oxide flakes.
TABLE VI
TYPE I WITH 15% OF ESCORIA DE OVEN DE FUNDICIÓN AGREGADA ELEMENTOS MIDL. LS LUTITA ARENA ESCOSES ESCORIA PHILIPS OF IRON OVEN OF IRON OF FOUNDRY YES 02 8.25 49.25 90.00 0.81 35.76
Al203 2.31 18.60 3.24 0.28 9.42
Fe203 1.30 5.79 1.90 96.17 0.63
CaO 47.60 3.30 0.51 0.51 40.01
MgO 0.46 1.25 0.07 0.70 8.55
S03 0.90 3.37 0.13 0.11 2.70
P205 0.00 0.00 0.00 0.00 0.00
T102 0.00 0.00 0.00 0.00 0.00
Na20 0.10 0.73 0.03 0.03 0.32
K20 0.50 3.10 0.31 0.04 0.57
ANALYSIS OF THE SCENE
STA AGUADA ESCORIA
YES02 11.78 21.21 Al203 2.64 4.96 Fe203 2.71 3.74 CaO 44.45 65.81 MgO 0.47 1.91 S03 0.91 0.70 P205 0.00 0.22 T102 0.00 0.22 Na20 0.11 0.24 K20 0.54 0.50 TOTAL 99.51 S / R 2..32 A / F 1. .44
C3S 63., 09 C2S 13, .21 C3A 7, .98 C4AF 11, .38
Table VII illustrates the calculation for a test mix that has 30% smelting slag slag, 1.81% iron oxide scale, 0.33% sand, and 67.86% limestone.
TABLE VII TYPE I WITH 30% OF AGUARDED FOUNDRY OVEN SCRUB
LS MINERAL ARENA ESCORIA H.F.
Sip2 8.25 0.81 90.00 35.76
A1203 2.31 0.28 3.24 9.42
Fe203 1.30 96.17 1.90 0.63
CaO 47.60 '0.51 0.51 40.01
MgO 0.46 0.70 0.07 8.55
S03 0.90 0.11 0.13 2.70
P205 0.00 0.00 0.00 0.00
T102 0.00 0.00 0.00 0.00 Na20 0..10 0, .03 0..03 0.32
K20 0., 50 0, .04 0. .31 0.57
ANALYSIS OF THE SCENE
PASTA AGUADA ESCORIA
Si02 8. 44 20.31
A1203 2. 26 5.39
Fe203 3. 76 4.46
CaO 4É ¡.16 64.43
MgO 0. 46 3.09
S03 0. 88 0.70
P205 0. 00 0.22
T102 0., 00 0.22
Na20 0., 10 0.24
K20 0., 49 0.50
TOTAL 62.55 99.57
S R 2.06
A / F 1.21
C3S 60.37 C2S 12.75 C3A 7.92 C4AF 13.57 Clearly, Tables III, IV, V and VII confirm that the addition of foundry furnace slag (air cooled) is suitable as the raw material for the manufacture of cement slag. FIG. 3 illustrates the process of the present invention in which the feed material and slag from the melting furnace are combined as illustrated in FIG. 1 before entering the furnace at the feeding end thereof, in step 76, the feed material is provided and is combined in step 78 with the slag from the melting furnace which has been crushed and filtered to obtain particles of which the predominant particle sizes have a maximum diameter of substantially 2 inches or less in step 80. The combined material is then fed into the feed end of the rotary kiln in step 82. In FIG. 4, the process feeds the furnace slag d, casting and feedstock into the feed end of the rotary furnace separately as illustrated in FIG. 2. In such case, in step 66 the feed material is supplied and transported by a conveyor means in step 68 to the input or feed end of the rotary kiln. The melting furnace slag is crushed and filtered to obtain particle sizes having a predominant particle size with a maximum diameter of substantially two inches or less in step 72 and the resulting final product is transported in step 74 to the entrance or feed end of the rotary kiln. In step 70, the feed material and the slag from the melting furnace are heated in the rotary kiln until the cement slag is formed. Therefore, a method and apparatus for forming cement slag with the addition of coarse melting furnace slag which is fed together with the feed material into the feed end of the rotary kiln have been disclosed. The coarse melting furnace slag is defined herein as smelting slag slag which has been crushed and filtered into particles having a predominant particle size up to a maximum diameter of 2". Many advantages are obtained by means of The present invention No grinding, pulverization or crushing of the slag is required Large amounts of coarse slag with a predominant particle size of up to 2"can be incorporated into the cement slag composition only with minor changes required in the material Regular fed in the rotary kiln. Drying of the slag is not required. The inherent humidity is generally between one and six percent. In the wet process rotary kiln system, a substantial reduction of humidity and savings are carried out. In the dry process furnace system, the melting furnace slag may dry but is not necessary. With the present invention, melting furnace slag can be used in the production of cement slag as part of the initial feed material by means of a rotary kiln. The melting furnace slag and the wet (or dry) feed material are injected into the feed end of the rotary kiln as separate materials. They can also be injected together into the oven feeding inlet mixing in advance. No obstruction of the furnace has been experienced due to sediment rings or slag accumulations. Both in the rotary kilns of wet and dry process, the slag of the melting furnace has a cleaning effect on the accumulation of material as it moves through the furnace. Only slight chemical changes are required in the normal feed material to incorporate the cast iron slag. This usually means that the feed material must be richer in limestone content. The chemical structure composed of the coarse melting furnace slag is transformed into the desired cement slag structure during the heat treatment within the rotary kiln by diffusion. Since grinding, pulverizing or crushing the foundry furnace slag is not required, substantial energy savings are realized by using this invention to produce cement slag. The increase in production is almost proportional to the amount of slag used. In addition, the environmental condition of the rotary kiln process improves because of the low volatile content of the melting furnace slag. In addition, the recycling of foundry furnace slag improves the environment and provides a useful outlet for foundry furnace slag rather than the smelting furnace slag occupying vast areas of land used in its storage. The recycling of foundry furnace slag improves the environment and substantially reduces the cost of cement production. While the invention has been described in connection with a preferred embodiment, it is not intended to limit the scope of the invention to the particular form described, but on the contrary, it is intended to cover such alternatives, modifications and equivalences that may be included within the spirit and scope of the invention as defined in the attached clauses.
Claims (9)
- NOVELTY OF THE INVENTION Having described the invention, it is considered as a novelty, and therefore the provisions of the following are claimed: CLAUSES 1. A method for the manufacture of cement slag using an elongated rotary cement furnace which has a feed end and a heat end, the heat end is inclined downward with respect to the feed end, the method comprising the steps of: directing heat from a heat source within said heat end of the furnace; introducing a stream of feed material containing limestone within said feed end of the furnace such that the stream of feed material moves towards said heat at the heat end of the furnace; grinding and filtering air-cooled smelting slag to obtain particles with a predominant size up to a maximum diameter of 2"substantially, and adding a quantity of said smelting slag cooled by air crushed and filtered from said stream. of feed material air at said feed end of the furnace, such that as the feed material stream and the slag from the melting furnace move towards said heat end, the slag from the melting furnace it is melted by said heat and propagates into the feed material to form cement slag 2. A method as described in clause 1 in which the smelting furnace slag is added to the feed end of the furnace as a material separated from the feedstock 3. A method as described in clause 1 in which the melting furnace slag and the feedstock They are mixed before being introduced into the feed end of the oven. 4. A method as described in clause 1 which further includes the step of using a wet process rotary kiln to receive the stream of feed material and slag from the melting furnace. 5. A method as described in clause 1 which further includes the step of using a dry process rotary kiln to receive the stream of feed material and slag from the melting furnace. 6. A method as described in clause 1 in which said cast iron slag has a chemical composition of calcium silicates and aluminosilicates. 7. An apparatus for forming cement slag that comprises: a rotary cement kiln having a feed end and a heat end, the heat end is inclined downward with respect to the feed end. a source of heat at the heat end to heat the interior of the rotary kiln; and conveying means for introducing a feed material stream containing shredded and filtered chilled cast iron slag limestone and slag having a predominant particle size with a maximum diameter of up to 2"substantially within the end of the feed. feeding said rotary kiln in such a manner that as said stream of feedstock and slag from the melting furnace are moved towards said furnace heat end, said melting furnace slag propagates by said heat within said feedstock for forming cement slag 8. An apparatus as described in clause 7 wherein the conveying means further comprises: a first conveyor means for introducing the stream of feed material into the feed end of said rotary kiln; medium conveyor to introduce the cast iron furnace into the former feed of the rotary kiln separately from the feed material. 9. An apparatus as described in clause 7 further comprising: a controller coupled to the first and second conveyor means for controlling the proportion of slag from melting furnace to feed material introduced into the rotary furnace to achieve a cement slag which has a predetermined chemical composition. IN WITNESS WHEREOVER, I have signed the above description and claims of novelty of the invention, as attorney of TEXAS INDUSTRIES, INC., In Mexico City, Republic of Mexico on December 8, 1995.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08404902 | 1995-03-15 | ||
US08404902 US5494515C1 (en) | 1995-03-15 | 1995-03-15 | Method and apparatus for using blast-furnace slag in cement clinker production |
Publications (2)
Publication Number | Publication Date |
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MX9505142A MX9505142A (en) | 1998-07-31 |
MXPA95005142A true MXPA95005142A (en) | 1998-11-09 |
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