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CN-121976063-A - Method and device for smelting chromium alloy from chromium slag

CN121976063ACN 121976063 ACN121976063 ACN 121976063ACN-121976063-A

Abstract

The invention relates to the technical field of chromium slag recycling, and particularly discloses a method and a device for smelting chromium alloy by using chromium slag, wherein S1, a fusion substance which can lead the interior of the fusion substance to form pores and generate reducing gas is introduced into the fusion substance, a protective coating for isolating gas is formed on the outer wall of the fusion substance, S2, heating and reducing the fusion substance to a hearth of a rotary hearth furnace, heating the fusion substance to 1250-1400 ℃ by adopting a radiation heating mode for carrying out reduction reaction, S3, separating or smelting, namely, sequentially carrying out reduction melting, cooling solidification and screening separation on a reduction mixture obtained in the step S2 into ferrochrome metal and slag in the rotary hearth furnace, or directly heating the reduction mixture obtained in the step S2 into a smelting furnace for smelting ferrochrome. The invention can improve the reduction degree of chromium in the process of recovering the ferrochrome from the chromium slag, thereby improving the chromium content in the ferrochrome.

Inventors

  • ZHANG GUOQING
  • ZHANG JIANJUN

Assignees

  • 成都邦隽化工科技有限公司

Dates

Publication Date
20260505
Application Date
20260210

Claims (20)

  1. 1. A method for smelting chromium alloy from chromium slag, which is characterized by comprising the following steps: s1, preparing an aggregate: s11, mixing chromium slag, a carbonaceous reducing agent and a slag forming agent, and grinding to obtain powder; S12, uniformly mixing powder, a binder, a molten substance and water, and forming a plurality of uniform aggregates through a granulating device (18), wherein the molten substance at least comprises one of ferrous oxalate, corncob powder, saw dust, paper dust, polystyrene or foam plastic beads, and the mass ratio of the powder to the binder to the molten substance to the water is 10 (0.01-1.5) (0.01-2) (0.05-6); S13, forming a protective coating on the outer wall of the agglomerate, wherein the protective coating comprises the following components of (5-6): (1-2): (0.5-0.8): 10 by mass percent of kaolin, aluminum oxide, calcium fluoride and water; S2, heating and reducing, namely conveying the agglomerates prepared in the step S1 into a hearth of a rotary hearth furnace (19), heating to 1250-1400 ℃ by adopting a radiation heating mode, and carrying out reduction reaction to obtain a reduction mixture, wherein the heating rate is greater than or equal to 13.6 ℃ per second; s3, separating or smelting, namely sequentially carrying out reduction melting, cooling solidification and screening separation on the reduction mixture obtained in the step S2 into ferrochrome metal and slag in the rotary hearth furnace (19), or directly heating the reduction mixture obtained in the step S2 into a smelting furnace (28) to smelt ferrochrome.
  2. 2. The method for producing chromium alloy according to claim 1, wherein in step S11, the particle size of the powder is 80 μm or less.
  3. 3. The method for smelting chromium alloy from chromium slag according to claim 1, wherein the carbonaceous reducing agent is used in an amount of 10-20% by weight relative to the theoretical amount in the step S11, and the carbonaceous reducing agent comprises at least one of coal, waste plastics, waste tires, coke and charcoal.
  4. 4. The method for smelting chromium alloy from chromium slag according to claim 1, wherein in step S11, the slag former has a mass of 2-15% based on the mass of the chromium slag, and the slag former comprises at least one of silica and ferrosilicon.
  5. 5. The method according to claim 1, wherein in step S12, the molten material includes at least one of ferrous oxalate, corncob meal, saw dust and paper dust.
  6. 6. The method for smelting chromium alloy from chromium slag according to claim 1, wherein in the step S12, the molten substance is a mixture of ferrous oxalate and corncob powder in a mass ratio of (2-3): 10, or a mixture of ferrous oxalate and sawdust in a mass ratio of (2-3): 10, or a mixture of ferrous oxalate and paper dust in a mass ratio of (2-3): 10.
  7. 7. The method for producing chromium alloy according to claim 1, wherein in step S12, the binder comprises at least one of clay, bentonite and molasses.
  8. 8. The method for smelting chromium alloy from chromium slag according to claim 1, wherein in the step S13, the mass percentages of kaolin, aluminum oxide, calcium fluoride and water are 6:1:0.6:10.
  9. 9. The method for smelting chromium alloy from chromium slag according to claim 1, wherein in step S13, the process of forming the protective coating layer is: And mixing the protective coating in proportion to form slurry, and spraying the slurry on the surface of the dried aggregate.
  10. 10. A method of smelting chromium alloy from chromium slag according to any of claims 1-9 wherein the agglomerates comprise pellets, briquettes or extrudates.
  11. 11. The method of claim 10, wherein the agglomerates are extruded hollow bodies having a high aspect ratio, and wherein the extruded hollow bodies comprise tapered hollow members or hollow cylindrical members.
  12. 12. The method for smelting chromium alloy from chromium slag according to claim 1, wherein in step S2, the temperature rise rate is 13.8-14.5 ℃.
  13. 13. The method for smelting chromium alloy from chromium slag according to claim 1, wherein in step S2, the agglomerates are charged into a hearth of the rotary hearth furnace (19) together with a carbon-containing atmosphere regulator including at least one of coal, waste plastics, scrap tires, coke, charcoal or gas.
  14. 14. A method for smelting chromium alloy from chromium slag according to claim 1, characterised in that in step S3 the temperature of the reducing mixture entering the smelting furnace (28) is not lower than 500 ℃.
  15. 15. The method for smelting chromium alloy from chromium slag according to claim 1, wherein natural gas or coal gas is introduced into the rotary hearth furnace (19) as a reduction protecting gas and/or water sealing is carried out on the rotary hearth furnace (19) in the cooling and solidification process, and liquid adopted by the water sealing comprises paraffin, ethylene glycol, propylene glycol or heat conducting oil.
  16. 16. The method according to claim 1, characterized in that the molten ferrochrome is tapped from the tap hole (29) when the reducing mixture is transferred to the smelting furnace (28) for step S3, said smelting furnace (28) comprising an electric arc furnace or an induction furnace.
  17. 17. A method of smelting chromium alloy from chromium slag according to claim 16, characterised in that the smelting furnace (28) is provided with bottom blowing and side blowing, by means of which gas is blown into the smelting furnace (28), whereby the molten metal is crushed and dispersed into the slag.
  18. 18. A method of smelting chromium alloy from chromium slag according to claim 16, characterised in that the exhaust gases of the smelting furnace (28) are recycled as reducing gases to the rotary hearth furnace (19).
  19. 19. A chromium alloy installation for the chromium slag smelting according to the method of any one of claims 1 to 18, comprising: A first mixer (9) for mixing the chromium slag, the carbonaceous reducing agent and the slag forming agent uniformly; A ball mill (10) for grinding and pulverizing the raw materials mixed by the first mixer (9) to obtain the powder; a second mixer (17) for mixing the powder with the binder, the molten material and water to obtain a mixture; -granulation means (18) for leading the second mixer (17) out of the mix to form said agglomerates; And the rotary hearth furnace (19) is used for carrying out heating reduction on the agglomerates or carrying out heating reduction, reduction melting and cooling solidification on the agglomerates.
  20. 20. Chromium alloy plant according to claim 19, characterized in that the granulation device (18) comprises a granulator or an extrusion device.

Description

Method and device for smelting chromium alloy from chromium slag Technical Field The invention relates to the technical field of chromium slag recycling, in particular to a method and a device for smelting chromium alloy by using chromium slag. Background The chromium salt is one of important serial products in inorganic salt industry, and is mainly used in electroplating, tanning, printing and dyeing, medicine, catalyst, metal corrosion inhibition, etc. and the chromium salt production adopts the main waste slag-chromium slag discharged from calcium-free technological process. The main components of the chromium slag comprise ：Cr2O39.79%、Cr6+0.02%、H2O 15.3%、Fe2O341.16%、Al2O314.8%、CaO 0.56%、V2O50.06%、MgO 12.67%、SiO25.64%. The chromium slag contains chromium and iron with recovery values, so that the chromium slag has economic values for recycling, and the chromium slag contains about 0.02% of water-soluble hexavalent chromium ions, so that the chromium slag has high toxicity and needs to be treated. At present, the recycling of chromium slag is mainly to reduce the chromium slag into ferrochrome for recycling, and two processes mainly exist, namely 1) the chromium slag and a carbonaceous reducing agent are sintered and cooled, and then the ferrochrome is smelted by a blast furnace, the method has high energy consumption and cannot realize industrialization, and 2) the energy consumption is reduced by a ball-forming pre-reduction mode, and the main process principle is that the carbonaceous reducing agent is added into the chromium slag, crushed and granulated into green balls, and then the green balls are subjected to reduction roasting at high temperature in a rotary kiln. The basic principle of the rotary kiln is that the raw materials roll over, so that a large amount of dust is generated, and scale rings are easily formed in the kiln. In addition, rotary kilns require longer kiln bodies due to variations in raw material residence time, thereby occupying greater equipment installation area and surface area. Thus, the rotary kiln can dissipate a lot of heat, resulting in higher fuel consumption than expected. In addition, the use of additional coke in combination with the additional coke can also have adverse effects, resulting in significant oxidation losses of the additional coke within the rotary kiln. Secondly, the lack of sealing problem of the rotary kiln can cause incomplete chromium reduction, because hexavalent chromium is contained in chromium slag, and the chromium slag mainly exists in the form of sodium chromate, and the following reaction can be generated during the reduction reaction: 2Na2CrO4+C+CO=Cr2O3+2CO2+2Na2O (1) 4Na2CrO4+2C+4CO2=2Cr2(CO3)3+4Na2O+ O2 （2） 4Na2CrO4+2S=2Cr2(SO4)3+4Na2SO4 (3) Cr 2(CO3)3 and Cr 2(SO4)3 are extremely unstable when exposed to oxygen, and undergo oxidation reaction to generate hexavalent chromium, i.e. yellowing. 2 Cr2(CO3)3+8Na2O+O2=4 Na2CrO4+ 6CO2 （4） 2Cr2(SO4)3+10Na2O+3O2=4 Na2CrO4+ 6Na2SO4 （5） Therefore, it still does not have a good chromium reduction to solve the problem of energy consumption. In addition, the reduction degree of chromium is lower in both processes, so that the problem of lower chromium recovery rate is caused. The reduction performance of the chromium oxide is inferior to that of iron oxide, the temperature of pellets in a kiln is gradually increased, coke added in the kiln is preferentially used for reducing the iron oxide contained in chromium ore, as the chromium oxide is harder to reduce than the iron oxide, the temperature of the reduced chromium is higher than that of the reduced iron, the temperature of a mixture in the pellets reaches 1114 ℃, chromium starts to be reduced, the reduction process is lagged, when chromium is reduced, the carbonaceous reducing agent in the mixture is less, the contact opportunity of the carbonaceous reducing agent and the chromium oxide is reduced, and the reduction degree of the chromium is lower. In order to solve the problem of lower chromium reduction levels caused by chromium reduction compared to iron lag during the recovery of chromium containing materials, CN 1329537C-process for reducing chromium containing materials begins by rapidly increasing the temperature of the mixture in a moving hearth furnace, so that the reduction of chromium oxide begins before the carbonaceous material added to the mixture is consumed in the reduction of iron oxide. Thus, the chromium oxide reduction reaction proceeds while maintaining the opportunity for contact between the ferrochrome and the internally charged carbonaceous material. Further, the reduction degree of chromium is increased, which defines an average temperature rise rate of preferably 13.6 ℃ per second or more. The reduction object in CN1329537C is chromium ore, the main component of the chromium ore is Cr 2O3, and the content of iron is less than that of Cr 2O3, so that CN1329537C can greatly improve the reduction degree of chromium by a rapid