Method for preparing ferrochromium nitride from aluminum-chromium waste residues
阅读说明：本技术 一种利用铝铬废渣制备氮化铬铁的方法 (Method for preparing ferrochromium nitride from aluminum-chromium waste residues ) 是由 孔祥清 张婷婷 付莹 王学志 牛秀梅 周渊明 周宁宁 于 2020-04-29 设计创作，主要内容包括：本发明提出了一种利用铝铬废渣制备氮化铬铁的方法,属于工业固体废弃物资源化利用领域和有色金属的处理技术领域。其特征是以金属铬冶炼形成的工业废弃物铝铬渣作为原料,解决了固体废弃物的排放问题,所生产的产品符合优质氮化铬铁材料要求,原材料价格低廉,生产成本低,比常规方法低20％-30％；工艺相对简单,生产效率高,对环境影响小；产品质量稳定,含氮量较高,能达到5％-6％,年可节约铝矾土矿5万吨,铬矿1万吨,实现了铝铬渣的资源化循环利用,节约资源,对环境友好,为氮化铬铁的生产提供了一种较理想的方法。(The invention provides a method for preparing ferrochromium nitride from aluminum-chromium waste residues, belonging to the field of resource utilization of industrial solid wastes and the technical field of treatment of nonferrous metals. The method is characterized in that industrial waste aluminum chromium slag formed by smelting metal chromium is used as a raw material, the problem of solid waste discharge is solved, the produced product meets the requirements of high-quality chromium iron nitride materials, the raw material price is low, the production cost is low and is 20-30% lower than that of the conventional method; the process is relatively simple, the production efficiency is high, and the influence on the environment is small; the product quality is stable, the nitrogen content is high and can reach 5 to 6 percent, 5 ten thousand tons of bauxite ore and 1 ten thousand tons of chromium ore can be saved in one year, the resource recycling of the aluminum chromium slag is realized, the resource is saved, the method is environment-friendly, and a relatively ideal method is provided for the production of the chromium iron nitride.)
1. A method for preparing ferrochromium nitride from aluminum-chromium waste residue is characterized by comprising the following steps:
A. preparing raw materials: crushing the aluminum chromium slag to obtain aluminum chromium slag particles; mixing the aluminum chromium slag particles and the petroleum coke particles and then adding the mixture into an electric arc furnace; after the arc furnace was started, the temperature in the vicinity of the graphite electrode rapidly increased, and when the temperature reached 2039K, Cr was present7C3Melting, aggregating and sinking to finally obtain Cr7C3Block, crushing and ball milling into Cr7C3Powder of Fe in a certain amount3O4Powder and Cr7C3Uniformly mixing the powder;
B. putting the mixture into a furnace chamber of a vacuum induction heating furnace, and starting a vacuum system; when the vacuum degree reaches 10Pa, a heating system is opened, the heating rate is 50 ℃/min, and the constant temperature is started when the temperature reaches 1250 ℃; then heating to 1350 deg.C, keeping constant temperature, and observing vacuum degree value, at the same time, Cr7C3With Fe3O4Reacting at high temperature to generate ferrochrome and carbon monoxide, continuously discharging the generated carbon monoxide under vacuum or negative pressure until the vacuum degree is maintained within the range of 10-20Pa,continuously keeping constant temperature; after ensuring the reaction is sufficient, closing the vacuum system; then high-purity nitrogen is charged from an inflation valve, when the pressure of the nitrogen reaches 0.2Mpa, the inflation is stopped, the constant temperature is kept at 1350 ℃, and then the ferrochrome with 5-6% of nitrogen content is obtained after the ferrochrome is discharged from the furnace after being cooled to be lower than 100 ℃ along with the furnace.
2. The method for preparing ferrochromium nitride from aluminum-chromium waste residue according to claim 1, wherein the Cr in the step A7C3With Fe3O4The mass ratio of (A) to (B) is as follows: 1.5:1-3:1.
3. The method for preparing ferrochromium nitride from the aluminum-chromium waste residue according to claim 1, wherein the constant temperature of 1250 ℃ in the step B is 1 hour.
4. The method for preparing ferrochromium nitride from the aluminum-chromium waste residue according to claim 1, wherein the constant temperature time for maintaining the vacuum degree in the range of 10-20Pa in the step B is 5 hours.
5. The method for preparing ferrochromium nitride from aluminum-chromium slag according to claim 1, wherein the constant temperature time after stopping aeration in the step B is 2 hours.
6. The method for preparing ferrochromium nitride from the aluminum chromium slag according to claim 1, wherein the particle size of the crushed aluminum chromium slag in the step A is less than or equal to 10 mm.
7. A process for preparing ferrochromium nitride from waste Al-Cr dregs according to claim 1-6, where in step A, Cr is7C3The powder is 80-120 mesh.
Technical Field
The invention relates to the field of resource utilization of industrial solid wastes and the technical field of treatment of nonferrous metals, in particular to a method for preparing ferrochrome nitride from aluminum-chromium waste residues.
Background
The ferrochromium nitride is used as an alloy additive and widely applied to the smelting production of stainless steel, heat-resistant steel, corrosion-resistant steel, alloy steel and other special steels. At present, the production mode of adding nitrogen into the produced austenitic stainless steel containing nickel to reduce the content of nickel has great economic benefit, and the nitrogen replaces the nickel to obviously improve the strength and the corrosion resistance of the steel, while the plasticity still keeps a good level. In recent years, many domestic iron and steel enterprises are developing and producing high-strength, heat-resistant and corrosion-resistant steel grades containing chromium and nitrogen. However, with the change of market demands, customers have a greater demand for the ferrochromium nitride product containing higher nitrogen and chromium.
At present, the traditional production method of the ferrochrome nitride is to inject nitrogen into a ferrochrome product under certain conditions to carry out chemical combination reaction with the ferrochrome to obtain the ferrochrome nitride, and the method specifically comprises two forms of liquid nitriding method and solid nitriding method. However, the traditional ferrochromium nitride has longer process flow and higher raw material cost.
The aluminum chromium slag is a byproduct derived from smelting metal chromium by aluminothermic reduction reaction. When smelting chromium metal, the reduction reaction of metallic aluminium and industrial chromium oxide is used to prepare chromium metal, and the metallic aluminium powder and Cr2O3In a molten state, a drastic chemical reaction occurs to produce Al2O3Quickly convert to corundum phase and simultaneously react with unreacted Cr2O3Solid solution is carried out to generate an aluminum chromium solid solution, namely aluminum chromium slag. Generally, every one ton of metal chromium produced discharges 15 tons of chromium slag, and the main component of the aluminum chromium slag is Al2O3And Cr2O3. The aluminum chromium slag has certain harmfulness to ecological environment and the like, but if the treatment is proper, the aluminum chromium slag is also an available resource.
Disclosure of Invention
The invention aims to provide a method for preparing ferrochromium nitride by using aluminum chromium waste residues, which aims to solve the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme:
a method for preparing ferrochromium nitride from aluminum-chromium waste residues comprises the following steps:
A. preparing raw materials: crushing the aluminum chromium slag to obtain aluminum chromium slag particles; mixing the aluminum chromium slag particles and the petroleum coke particles and then adding the mixture into an electric arc furnace; after the arc furnace was started, the temperature in the vicinity of the graphite electrode rapidly increased, and when the temperature reached 2039K, Cr was present7C3Melting, aggregating and sinking to finally obtain Cr7C3Block, crushing and ball milling into Cr7C3Powder of Fe in a certain amount3O4And Cr7C3Uniformly mixing the powder;
B. putting the mixture into a furnace chamber of a vacuum induction heating furnace, starting a vacuum system, starting the heating system when the vacuum degree reaches 10Pa, increasing the temperature at a rate of 50 ℃/min, starting to keep the temperature when the temperature reaches 1250 ℃, then heating to 1350 ℃, simultaneously observing the value of the vacuum degree, and at the moment, keeping the Cr in the constant temperature7C3With Fe3O4Reacting at high temperature to generate ferrochrome and carbon monoxide, continuously discharging the generated carbon monoxide under vacuum or negative pressure until the vacuum degree is maintained within the range of 10-20Pa, and continuously keeping constant temperature. After ensuring the reaction is sufficient, the vacuum system is shut down. Then high-purity nitrogen is charged from an inflation valve, when the pressure of the nitrogen reaches 0.2Mpa, the inflation is stopped, the constant temperature is kept at 1350 ℃, and then the ferrochrome with 5-6% of nitrogen content is obtained after the ferrochrome is discharged from the furnace after being cooled to be lower than 100 ℃ along with the furnace.
As a further technical scheme of the invention: cr in the step A7C3With Fe3O4The mass ratio of (A) to (B) is as follows: 1.5:1-3:1.
As a further technical scheme of the invention: the constant temperature time at 1250 ℃ in the step B is 1 hour.
As a further technical scheme of the invention: and in the step B, the constant temperature time for maintaining the vacuum degree within the range of 10-20Pa is 5 hours.
As a further technical scheme of the invention: and the constant temperature time after the air inflation is stopped in the step B is 2 hours.
As a further technical scheme of the invention: and C, the granularity of the crushed aluminum chromium slag in the step A is less than or equal to 10 mm.
As a further technical scheme of the invention: cr in the step A7C3The powder is 80-120 mesh.
Compared with the prior art, the invention has the beneficial effects that: the method has the characteristics of large consumption of the aluminum chromium slag, alleviation of the harm of the aluminum chromium slag to the environment, low price and environmental friendliness, and the prepared aluminum chromium slag with high nitrogen content as the main material.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A method for preparing chromium iron nitride by utilizing aluminum chromium waste residue, which solves the problems of environmental pollution and resource recycling of solid waste aluminum chromium residue.
The aluminum chromium slag particles are slag generated by smelting metal chromium, and the chemical components of the aluminum chromium slag particles are Al2O375 to 85 wt% of Cr2O38-15 wt%, CaO is less than or equal to 3 wt%, Fe2O3Less than or equal to 2 weight percent, and less than or equal to 2 weight percent of MgO; the grain size of the aluminum chromium slag is less than or equal to 10 mm; al (Al)2O3Has a melting point of 2327K and a density of 3.9g/cm3，Cr2O3Has a melting point of 2539K and a density of 5.21g/cm3Melting point of C3823K and density of 2.26g/cm3，Cr7C3The melting point is 2039K, and the density is 6.89g/cm3. Mixing the aluminum chromium slag particles and the petroleum coke particles, adding the mixture into an electric arc furnace, starting the electric arc furnace, rapidly increasing the temperature near a graphite electrode, and according to the thermodynamic principle, when the temperature is 1400K, adding C and Cr2O3Reaction to produce Cr7C3The standard Gibbs free energy of (A) is less than zero, which shows that the carbon reduction reaction can automatically proceed, the reaction trend is stronger along with the increase of the temperature, and Cr is obtained when the temperature reaches 2039K7C3Starts to melt and aggregate, and sinks continuously due to the higher density of the alloy compared with other oxides to finally form Cr7C3And (3) a block body. Al when the temperature reaches 2327K2O3Melting begins, Al due to the greater density difference2O3And Cr7C3Layering is formed, and on one hand, Al with higher purity is obtained2O3The product, on the other hand, obtains cheap Cr7C3. Further, the ferrochromium nitride with higher added value is prepared by a vacuum reduction method, so that the comprehensive utilization of solid waste resources is realized to the maximum extent. Produced Cr7C3The main components of the alloy are 84.52% of chromium, 8.65% of carbon and 1.66% of iron. Using Cr7C3The reaction principle for preparing the ferrochrome nitride is as follows:
4Cr7C3+3Fe3O4＝9Fe+28Cr+12CO
Fe+Cr+N＝FeCrN
Cr7C3with Fe3O4The reaction is carried out at high temperature to generate ferrochrome and carbon monoxide, the generated carbon monoxide is continuously discharged under vacuum or negative pressure, whether the carbon monoxide is discharged or not can be judged through the display value of a vacuum gauge, after the reaction is sufficient and no carbon monoxide is discharged, a vacuum valve is closed, nitrogen is filled into a vacuum cavity, the ferrochrome reacts with the nitrogen at high temperature, and finally the chromium nitride is formed.
The preparation method comprises the following specific steps:
A. preparing raw materials: crushing the aluminum chromium slag until the granularity is less than or equal to 10mm to obtain aluminum chromium slag particles; mixing the aluminum chromium slag particles and the petroleum coke particles and then adding the mixture into an electric arc furnace; after the arc furnace was started, the temperature in the vicinity of the graphite electrode rapidly increased, and when the temperature reached 2039K, Cr was present7C3Melting, aggregating and sinking to finally obtain Cr7C3Block, crushing and ball milling into 80-120 mesh powder. Selecting a certain amount of Fe3O4And Cr7C3The powder is mixed evenly, the Cr is7C3With Fe3O4The mass ratio of (A) to (B) is as follows: 1.5:1-3:1.
B. Feeding raw materials into a furnace: putting the mixture into a furnace chamber of a vacuum induction heating furnace, starting a vacuum system, starting the heating system when the vacuum degree reaches 10Pa, increasing the temperature at a rate of 50 ℃/min, starting to keep the temperature when the temperature reaches 1250 ℃, keeping the temperature for 1 hour, then heating to 1350 ℃, and keeping the temperature, wherein Cr is at the moment7C3With Fe3O4Reacting at high temperature to generate ferrochrome and carbon monoxide, continuously discharging the generated carbon monoxide under vacuum or negative pressure until the vacuum degree is maintained within the range of 10-20Pa, keeping the constant temperature for 5 hours, ensuring that the reaction is sufficient, and then closing a vacuum system. Then high-purity nitrogen gas is filled from the charging valve, when the nitrogen gas pressure reaches 0.2Mpa, the charging is stopped, the constant temperature is kept at 1350 ℃, and the constant temperature time is 2 hours. And then, cooling the chromium iron with the furnace to be lower than 100 ℃, and discharging the chromium iron to obtain the chromium iron nitride with the nitrogen content of 5-6%.
By adopting the technical scheme, compared with the prior art, the invention has the following positive effects:
1. the method takes the byproduct aluminum-chromium slag formed by smelting the metal chromium as the raw material, solves the problem of discharging solid waste, realizes the resource recycling of the aluminum-chromium slag, saves resources, is environment-friendly, and can save 5 ten thousand tons of bauxite ore and 1 ten thousand tons of chromium ore per year according to the calculation of the conversion amount of 3.4 ten thousand tons of aluminum-chromium slag per year. The produced product meets the requirements of high-quality chromium iron nitride materials, and can be used for smelting nitrogen-containing steel by an electric furnace and an oxygen converter.
2. The raw material price is low, the production cost is low, and is 20 to 30 percent lower than that of the conventional method.
3. The process is relatively simple, the production efficiency is high, and the influence on the environment is small.
4. The product has stable quality and high nitrogen content which can reach 5 to 6 percent.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
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