CN110144457B - Method for preparing aluminum-silicon-iron alloy by carbon thermal reduction of aluminum ash pretreatment - Google Patents
Method for preparing aluminum-silicon-iron alloy by carbon thermal reduction of aluminum ash pretreatment Download PDFInfo
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- CN110144457B CN110144457B CN201910401876.XA CN201910401876A CN110144457B CN 110144457 B CN110144457 B CN 110144457B CN 201910401876 A CN201910401876 A CN 201910401876A CN 110144457 B CN110144457 B CN 110144457B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
- C22B1/2406—Binding; Briquetting ; Granulating pelletizing
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B4/00—Electrothermal treatment of ores or metallurgical products for obtaining metals or alloys
- C22B4/06—Alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B5/00—General methods of reducing to metals
- C22B5/02—Dry methods smelting of sulfides or formation of mattes
- C22B5/10—Dry methods smelting of sulfides or formation of mattes by solid carbonaceous reducing agents
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/02—Working-up flue dust
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C21/00—Alloys based on aluminium
- C22C21/02—Alloys based on aluminium with silicon as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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Abstract
The invention provides a method for preparing an aluminum-silicon-iron alloy by carbon thermal reduction of aluminum ash pretreatment, which comprises the steps of uniformly mixing secondary aluminum ash, waste cathode carbon blocks and dry paper pulp powder to prepare powder, pressing the mixture into pellets, and carrying out high-temperature vacuum distillation to volatilize fluoride and chloride in the aluminum ash and fluoride and metal sodium in the waste cathode carbon blocks so as to be separated from the aluminum ash and the waste cathode carbon blocks, and decomposing cyanide in the waste cathode carbon blocks; crushing the distillation slag, mixing the crushed distillation slag with fly ash, and reducing the materials mainly containing aluminum oxide and silicon oxide at high temperature in an electric arc furnace by using fixed carbon in the waste cathode carbon block as a reducing agent to prepare an aluminum-silicon-iron alloy with a certain component; meanwhile, the decomposition of aluminum nitride in aluminum ash and the complete decomposition of cyanide in the waste cathode carbon block are completed in the high-temperature reduction process, and the comprehensive utilization of various dangerous wastes and solid wastes is realized in the same process.
Description
Technical Field
The invention relates to the field of electric metallurgy, in particular to a method for preparing an aluminum-silicon-iron alloy by aluminum ash pretreatment and carbothermal reduction.
Background
The production method of ferro-silicon-aluminum is mainly divided into a metal melting and proportioning method and an electric heating reduction method. The metal melting method is to mix pure metal aluminum, silicon and iron according to a certain proportion in a melting state to form an alloy; the electrothermal reduction method is to prepare the alloy by taking oxides containing aluminum, silicon and iron as raw materials and carbonaceous materials as reducing agents and carrying out reduction smelting in an electric arc furnace. The metal melting and matching method has the problems of reheating of pure metal, secondary burning loss, high production cost and the like. The electrothermal reduction method also has the problems of pure mineral raw material shortage, poor economical efficiency of the production process and the like.
A large amount of aluminum ash is generated in the aluminum electrolysis, aluminum processing and scrap aluminum remelting recovery processes. The current methods for treating these aluminum ashes are mainly: after screening the aluminum ash, remelting the massive aluminum ash to obtain metal aluminum; or the aluminum ash is treated by an ash frying machine to recover the metal aluminum, and the aluminum ash left after screening or treatment by the ash frying machine is generally called secondary aluminum ash, and the secondary aluminum ash is mainly treated in a landfill or stockpiling mode at present. The aluminum ash generated in the aluminum smelting and processing process usually contains 50-80% of metallic aluminum, and after the conventional recovery treatment, the residual secondary aluminum ash mainly contains metallic aluminum, aluminum oxide and aluminum nitride, wherein the main components of the secondary aluminum ash contain 5-10% of metallic aluminum, more than 40% of aluminum oxide and 10-25% of aluminum nitride. According to different refining modes of manufacturers, the aluminum ash also contains 5-10% of fluoride and chloride. As a large amount of aluminum nitride contained in the aluminum ash can generate ammonia when meeting water, and chlorides and fluorides contained in the aluminum ash can also be dissolved in water, the aluminum ash is listed in the name of hazardous wastes by the ministry of environmental protection in 2016. At present, the method for treating the secondary aluminum ash not only does not utilize valuable resources in the secondary aluminum ash, but also has huge ecological risks.
The aluminum electrolysis cell is the main equipment for producing the metal aluminum. After the aluminum electrolytic cell is damaged and overhauled, a large amount of overhauling slag of the aluminum electrolytic cell can be generated. The overhaul slag comprises a cathode carbon block, cathode paste, refractory bricks, insulating bricks, impermeable materials, an insulating plate and the like. The overhaul slag can be further divided into two main parts of waste cathode carbon blocks (cathode carbon blocks and cathode paste) and waste refractory material linings (anti-seepage materials, refractory bricks and insulating bricks) eroded by fluoride electrolyte, and the mass ratio of the waste cathode carbon blocks to the waste refractory materials respectively accounts for 50%. At present, 5-10kg of waste cathode carbon blocks and 5-10kg of waste refractory materials are produced per ton of metallic aluminum produced. The main component of the waste cathode carbon block is a carbonaceous material, and the most component except the carbonaceous material is an electrolyte. Electrolysis in waste cathode carbon blockThe main components of the composition are NaF and Na3AlF6、Na5Al3F14And CaF2And the like. The carbon content in the waste cathode carbon block for aluminum electrolysis is generally 60-70%, and the electrolyte component content is 15-25%. In addition, 4% -8% of alkali metal, mainly metallic sodium, is present in the aluminum electrolysis spent cathodes. When potassium salt is present in the electrolyte component, potassium metal is also present in the spent cathode carbon block. Besides the three main components, the waste cathode carbon block also contains a small amount of carbide, nitride, oxide and cyanide, wherein the content of cyanide accounts for 0.1-0.2% of the total mass of the waste cathode carbon. The NaCN, complex cyanides and fluorides in the spent cathode carbon block are major environmental hazards. Cyanide and most fluoride are dissolved in water, and the waste cathode carbon blocks accumulated for a long time pollute underground water and surface water and cause serious pollution to the environment. The treatment of the waste cathode carbon block of the aluminum electrolytic cell is divided into two types, one type is a treatment technology, namely, the waste cathode carbon block material is buried after being innoxious or is utilized by other industries, such as a high-temperature hydrolysis technology, a combustion power generation technology, a slag former for manufacturing a high-speed rail industry, a fuel and a mineral raw material used for a cement industry, an inert material which can be buried and the like; the other is a recycling technology, which mainly recycles fluoride and carbon in the waste cathode carbon block, such as wet leaching to recycle fluoride, serving as an additive of a cathode carbon block and an anode carbon block, separating fluoride electrolyte and the carbon block by a flotation method, and the like, but the existing treatment of the waste cathode carbon block has not reached the industrial level yet.
Each ton of coal burned will produce 0.15-0.3 ton of fly ash, and coal with high ash content will produce 0.4-0.5 ton of fly ash at most. At present, the quantity of the fly ash generated in China every year reaches more than 6 hundred million tons. A small amount of high-alumina fly ash can be used for extracting alumina, while a large amount of low-alumina fly ash is mainly used for producing various building materials, such as cement admixtures, concrete additives and building material deep-processing products, and refractory and heat-insulating materials by extracting floating beads from fly ash, but the utilization problem of the fly ash cannot be fundamentally solved by the methods. In addition, the added value of the produced building materials is low, and utilization enterprises of the building materials are required to be close to large cities with a large number of people, so that the utilization method is mainly adopted in east provinces of China. The fly ash distributed in Shanxi, inner Mongolia, Ningxia, Shaanxi, Gansu and Xinjiang is not effectively utilized, and most of the fly ash is still treated in a stacking and burying manner.
From the above analysis it can be seen that: hazardous wastes and solid wastes generated in the existing electrolytic aluminum and aluminum processing and power industry are respectively treated, most of the hazardous wastes are in a harmless treatment stage, and effective resource utilization is in a research stage, so that the problem of environmental pollution of the solid wastes is not fundamentally solved.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for preparing an aluminum-silicon-iron alloy by carbon thermal reduction of aluminum ash pretreatment, which comprises the steps of uniformly mixing secondary aluminum ash, waste cathode carbon blocks and dry paper pulp powder to prepare powder, pressing the mixture into pellets, and carrying out high-temperature vacuum distillation to volatilize fluoride and chloride in the aluminum ash and fluoride and metal sodium in the waste cathode carbon blocks so as to be separated from the aluminum ash and the waste cathode carbon blocks, and decomposing cyanide in the waste cathode carbon blocks; crushing the distillation slag, mixing the crushed distillation slag with fly ash, and reducing the materials mainly containing aluminum oxide and silicon oxide at high temperature in an electric arc furnace by using fixed carbon in the waste cathode carbon block as a reducing agent to prepare an aluminum-silicon-iron alloy with a certain component; meanwhile, the decomposition of aluminum nitride in aluminum ash and the complete decomposition of cyanide in the waste cathode carbon block are completed in the high-temperature reduction process, and the comprehensive utilization of various dangerous wastes and solid wastes is realized in the same process. In order to achieve the purpose, the invention adopts the following technical scheme:
a method for preparing an aluminum-silicon-iron alloy by aluminum ash pretreatment and carbothermic reduction comprises the following steps:
step 1, determining the use amounts of secondary aluminum ash, fly ash and waste cathode carbon blocks according to the components of the target Al-Si-Fe alloy, and reducing Al in the secondary aluminum ash by using fixed carbon contained in the waste cathode carbon blocks as a reducing agent according to a stoichiometric ratio2O3、SiO2The amount of metal aluminum and silicon generated by the oxide is calculated, and then the Al of the fly ash reduced by the waste cathode carbon block is calculated2O3、SiO2The amount of the metal aluminum and silicon obtained by the oxide,the amount of the metal aluminum and silicon obtained by reducing the secondary aluminum ash is adjusted by the amount of the aluminum and the silicon obtained by reducing the fly ash, so that the components of the aluminum and the silicon in the prepared aluminum-silicon-iron alloy and the use amounts of the secondary aluminum ash, the fly ash and the waste cathode carbon block are obtained; putting the secondary aluminum ash, the waste cathode carbon blocks and the dry paper pulp powder into a ball mill together for grinding and uniformly mixing, and then pressing the mixture into pellets by using a ball press;
step 2, putting the pellets into a vacuum container for high-temperature vacuum distillation, wherein the distillation temperature is 900-1100 ℃, the distillation time is 2-10h, and the vacuum degree is 0.1-100 Pa; the volatilized fluoride, chloride and metallic sodium enter a condensation system, and the distillation residue is left in a vacuum container;
step 3, taking the distillation residues out of the vacuum container and crushing the distillation residues by using a crusher; uniformly mixing the distilled slag powder with the fly ash;
step 4, starting the electric arc furnace and gradually increasing the temperature in the furnace, and when the temperature of the bottom arc zone is 1900-; and when the smelting process reaches 2-6 hours, the formed ferro-silicon-aluminum alloy is discharged from the bottom of the electric arc furnace.
The secondary aluminum ash comprises the following components in percentage by mass: al (Al)2O340～80％，AlN≤20％，Al≤10％，SiO2≤5％，Na2O≤5％，Fe2O3Less than or equal to 5 percent, less than or equal to 10 percent of chloride and less than or equal to 10 percent of fluoride.
The waste cathode carbon block comprises the following components in percentage by mass: 60-80% of C and Al2O3Less than or equal to 3 percent, Na 4-10 percent and fluoride electrolyte, wherein the fluoride electrolyte mainly comprises cryolite, sodium fluoride and calcium fluoride or contains lithium fluoride and potassium fluoride.
The dry pulp powder comprises the following components in percentage by mass: the calcium lignosulphonate is more than or equal to 90 percent, and the dry basis moisture is more than or equal to 8 percent.
The fly ash comprises the following components in percentage by mass: al (Al)2O315～50％，SiO230～50％，Fe2O3≤10％，CaO≤5％，MgO≤5％，Na2O≤3％，K2O≤3％，TiO2Less than or equal to 3%, itIt has a single metal oxide content of < 1%.
In the step 1, in the pellet pressing process, the particle sizes of the secondary aluminum ash and the waste cathode carbon block after ball milling are both smaller than 100 meshes, the pressing pressure of a ball press is 100-200MPa, and the diameter of the pellet is 30-50 mm.
And 2, crushing the distillation residues to obtain the granularity smaller than 100 meshes. The fluoride, chloride and metallic sodium separated by vacuum distillation are respectively recovered after cooling, wherein the fluoride electrolyte is returned to the electrolytic bath for use.
In the step 4, in the smelting process of the electric arc furnace, the hollow channel in the middle of the hollow electrode is connected with a compressed gas pipeline for conveying the powdery material, and the powdery material is conveyed to the electric arc reaction zone through the hollow channel by taking the compressed gas as a carrier to complete the rapid smelting reaction; the diameter of the hollow channel is 20mm-200 mm; the pressure of the compressed gas is controlled between 0.1 and 0.8 MPa.
The compressed gas is one of argon, air and carbon monoxide.
The prepared ferro-silicon-aluminum alloy can be used as a steel-making deoxidizer and a magnesium-smelting reducer; the soot and the slag generated in the smelting process of the electric arc furnace are returned to the batching process for continuous use.
Compared with the prior art, the invention has the beneficial effects that:
1. the existing aluminum ash, waste cathode carbon blocks and fly ash are treated separately, namely, a plurality of processes and a plurality of treatment systems are adopted. The method comprises the following steps of treating most of aluminum ash by a wet method, reacting aluminum nitride in the aluminum ash with water to generate ammonia gas through the wet method, using waste residues to produce refractory materials, producing a large amount of wastewater containing chlorine, fluorine and ammonia in the treatment process, and incompletely decomposing the aluminum nitride in the waste residues. The treatment process of the waste cathode carbon block also comprises a wet method and a fire method, wherein the wet method is mainly used, the method adopts strong acid or strong alkali for leaching so that fluoride is converted into soluble hydrogen fluoride or sodium fluoride to be separated from a carbonaceous material, and a large amount of acid-containing or alkali-containing wastewater is generated in the treatment process, so that secondary pollution is easily caused. The invention relates to an integrated treatment technology developed aiming at various dangerous wastes and solid wastes.A secondary aluminum ash and a waste cathode carbon block are subjected to vacuum distillation to separate out fluoride, chloride and metallic sodium, then are mixed with fly ash, and are subjected to an electrothermal carbon reduction process to prepare the aluminum-silicon-iron alloy. The high-temperature volatilization separation of fluoride, chloride and metallic sodium in the aluminum ash and the waste cathode carbon block and the high-temperature decomposition of cyanide are realized in the vacuum distillation process; the pyrolysis of the main toxic substance aluminum nitride is realized in the carbothermic reduction process, and the aluminum ash and the metal oxide in the waste cathode carbon block are reduced to enter the aluminum-silicon-iron alloy, so that the whole process has no generation of waste residues and waste water, and is a green and environment-friendly treatment process.
2. The treatment process realizes resource utilization of wastes while realizing harmlessness and reduction, namely, aluminum oxide, silicon oxide, iron oxide and the like in aluminum ash and fly ash are reduced in a metal form by taking fixed carbon in the waste cathode carbon blocks as a reducing agent, and fluoride, chloride and alkali metal are recycled, so that waste treatment by waste is realized, and the whole process is closed cycle.
3. The distilled slag is used as a raw material, the fly ash is used as an additive to adjust the aluminum content and the silicon content in the raw material, and the batching mode not only utilizes various wastes, but also is easy to prepare the aluminum-silicon-iron alloy with various components, so that the method is suitable for the smelting process of an electric arc furnace, the smelting process and the alloy components are easy to regulate and control, the production cost is favorably reduced, and the smelting difficulty of the aluminum-silicon-iron alloy is reduced.
4. The hollow electrode is adopted to convey the powdery material, so that the whole smelting process of the electric arc furnace can be strengthened, the reduction of oxides is promoted, particularly, the decomposition process of toxic substances, namely aluminum nitride and cyanide is accelerated, the production efficiency is improved, and the production cost is reduced.
Drawings
FIG. 1 is a process flow diagram of the method for preparing the sendust by carbothermic reduction of the pretreated aluminum ash.
Detailed Description
The technical scheme of the invention is explained in detail by taking the following waste materials as examples.
Table 1 shows the phase composition of a treated secondary aluminum ash, and the phase composition and content of the aluminum ash produced by different enterprises are different due to different casting and refining processes.
TABLE 1 phase composition of treated Secondary aluminum Ash
Table 2 shows the main components of a waste cathode carbon block, and the components and contents of the waste cathode carbon block are different between different enterprises due to the difference in the electrolysis process and the composition of the electrolyte, and the difference in the service life of the electrolytic cell.
TABLE 2 Main Components of waste cathode carbon blocks
Table 3 shows the main components of a low-alumina fly ash.
TABLE 3 Main Components of Low-aluminum fly ash
Example 1
The method for preparing the ferro-silicon-aluminum alloy by the carbothermic reduction of the pretreated aluminum ash comprises the following steps:
step 1, according to the components of the target ferro-silicon-aluminum alloy: 29 percent of aluminum, 64 percent of silicon and the balance of iron, calcium, titanium and other trace metals; calculating the mass of secondary aluminum ash, fly ash and the waste cathode carbon block required for reducing metal oxide by taking fixed carbon contained in the waste cathode carbon block as a reducing agent according to a stoichiometric ratio, wherein the mass of metal aluminum in the secondary aluminum ash is calculated according to the condition that all the metal aluminum enters the aluminum-silicon-iron alloy, all the aluminum nitride is decomposed into metal aluminum and nitrogen, the obtained metal aluminum is calculated according to the condition that all the metal aluminum enters the aluminum-silicon-iron alloy, and the mass ratio of the obtained secondary aluminum ash, the fly ash and the waste cathode carbon block is 1:15: 8; putting the secondary aluminum ash, the waste cathode carbon blocks and the dry paper pulp powder together in a ball mill according to a certain proportion, grinding and uniformly mixing, wherein the addition amount of the dry paper pulp powder is 6 percent of the sum of the mass of the secondary aluminum ash and the mass of the fly ash; then pressing the mixture into pellets by a ball press; the pellet diameter is 50 mm.
Step 2, putting the pellets into a vacuum container for high-temperature vacuum distillation, wherein the distillation temperature is 1100 ℃, the distillation time is 10 hours, and the vacuum degree is 100 Pa; the volatilized fluoride, chloride and metallic sodium enter a condensation system, and the distillation residue is left in a vacuum container;
and 3, taking the distillation residues out of the vacuum container, crushing the distillation residues by using a crusher, and uniformly mixing the distillation residue powder and the fly ash, wherein the granularity of the crushed distillation residues is smaller than 100 meshes.
Step 4, starting the electric arc furnace, gradually increasing the temperature in the furnace, and when the temperature of the bottom arc zone is 2300 ℃, feeding the uniformly mixed materials into the electric arc furnace through the hollow electrode; the diameter of the hollow channel is 200 mm; the compressed gas is air, and the pressure is controlled to be 0.1 MPa. And when the smelting process reaches 6h, discharging the formed ferro-silicon-aluminum alloy from the bottom of the electric arc furnace.
Example 2
The method for preparing the ferro-silicon-aluminum alloy by the carbothermic reduction of the pretreated aluminum ash comprises the following steps:
step 1, according to the components of the target ferro-silicon-aluminum alloy: 38 percent of aluminum, 56 percent of silicon and the balance of iron, calcium, titanium and other trace metals; calculating the mass of secondary aluminum ash, fly ash and the waste cathode carbon block required for reducing metal oxide by taking fixed carbon contained in the waste cathode carbon block as a reducing agent according to a stoichiometric ratio, wherein the mass of metal aluminum in the secondary aluminum ash is calculated according to the condition that all the metal aluminum enters the aluminum-silicon-iron alloy, all the aluminum nitride is decomposed into metal aluminum and nitrogen, the obtained metal aluminum is calculated according to the condition that all the metal aluminum enters the aluminum-silicon-iron alloy, and the mass ratio of the obtained secondary aluminum ash, the fly ash and the waste cathode carbon block is 1:5: 3; putting the secondary aluminum ash, the waste cathode carbon blocks in the overhaul residues of the aluminum electrolytic cell and the dry pulp powder into a ball mill together for grinding and uniformly mixing, wherein the addition amount of the dry pulp powder is 8 percent of the sum of the mass of the secondary aluminum ash and the mass of the fly ash; then pressing the mixture into pellets by a ball press; the diameter of the pellet is 40 mm.
Step 2, putting the pellets into a vacuum container for high-temperature vacuum distillation, wherein the distillation temperature is 1000 ℃, the distillation time is 6 hours, and the vacuum degree is 10 Pa; the volatilized fluoride, chloride and metallic sodium enter a condensation system, and the distillation residue is left in a vacuum container;
and 3, taking the distillation residues out of the vacuum container, crushing the distillation residues by using a crusher, and uniformly mixing the distillation residue powder and the fly ash, wherein the granularity of the crushed distillation residues is smaller than 100 meshes.
Step 4, starting the electric arc furnace, gradually increasing the temperature in the furnace, and feeding the uniformly mixed materials into the electric arc furnace through the hollow electrode when the temperature of a bottom arc zone is 2100 ℃; the diameter of the hollow channel is 100 mm; the compressed gas adopts argon, and the pressure is controlled to be 0.4 MPa. And when the smelting process reaches 4 hours, discharging the formed ferro-silicon-aluminum alloy from the bottom of the electric arc furnace.
Example 3
The method for preparing the ferro-silicon-aluminum alloy by the carbothermic reduction of the pretreated aluminum ash comprises the following steps:
step 1, according to the components of the target ferro-silicon-aluminum alloy: 51 percent of aluminum, 44 percent of silicon and the balance of iron, calcium, titanium and other trace metals; calculating the mass of secondary aluminum ash, fly ash and the waste cathode carbon block required for reducing metal oxide by taking fixed carbon contained in the waste cathode carbon block as a reducing agent according to a stoichiometric ratio, wherein the mass of metal aluminum in the secondary aluminum ash is calculated according to the condition that all the metal aluminum enters the aluminum-silicon-iron alloy, all the aluminum nitride is decomposed into metal aluminum and nitrogen, the obtained metal aluminum is calculated according to the condition that all the metal aluminum enters the aluminum-silicon-iron alloy, and the mass ratio of the obtained secondary aluminum ash, the fly ash and the waste cathode carbon block is 2:4: 3; putting the secondary aluminum ash, the waste cathode carbon blocks in the overhaul residues of the aluminum electrolytic cell and the dry pulp powder into a ball mill together for grinding and uniformly mixing, wherein the addition amount of the dry pulp powder is 10 percent of the sum of the mass of the secondary aluminum ash and the mass of the fly ash; then pressing the mixture into pellets by a ball press; the pellet diameter is 30 mm.
Step 2, putting the pellets into a vacuum container for high-temperature vacuum distillation, wherein the distillation temperature is 900 ℃, the distillation time is 2 hours, and the vacuum degree is 0.1 Pa; the volatilized fluoride, chloride and metallic sodium enter a condensation system, and the distillation residue is left in a vacuum container;
and 3, taking the distillation residues out of the vacuum container, crushing the distillation residues by using a crusher, and uniformly mixing the distillation residue powder and the fly ash, wherein the granularity of the crushed distillation residues is smaller than 100 meshes.
Step 4, starting the electric arc furnace, gradually increasing the temperature in the furnace, and feeding the uniformly mixed materials into the electric arc furnace through the hollow electrode when the temperature of a bottom arc zone is 1900 ℃; the diameter of the hollow channel is 20 mm; the compressed gas adopts carbon monoxide, and the pressure is controlled to be between 0.8 MPa. And when the smelting process reaches 2 hours, discharging the formed ferro-silicon-aluminum alloy from the bottom of the electric arc furnace.
Claims (8)
1. The method for preparing the ferro-silicon-aluminum alloy by the carbothermic reduction of the pretreated aluminum ash is characterized by comprising the following steps of:
step 1, determining the use amounts of secondary aluminum ash, fly ash and waste cathode carbon blocks according to the components of the target Al-Si-Fe alloy, and reducing Al in the secondary aluminum ash by using fixed carbon contained in the waste cathode carbon blocks as a reducing agent according to a stoichiometric ratio2O3、SiO2The amount of metal aluminum and silicon generated by the oxide is calculated, and then the Al of the fly ash reduced by the waste cathode carbon block is calculated2O3、SiO2The amount of the metal aluminum and the silicon obtained by the oxide, the amount of the metal aluminum and the silicon obtained by reducing the secondary aluminum ash are adjusted by the amount of the metal aluminum and the silicon obtained by reducing the fly ash, so that the components of the aluminum and the silicon in the prepared aluminum-silicon-iron alloy and the amounts of the secondary aluminum ash, the fly ash and the waste cathode carbon block are obtained; the secondary aluminum ash comprises the following components in percentage by mass: al (Al)2O340～80％，AlN≤20％，Al≤10％，SiO2≤5％，Na2O≤5％，Fe2O3Less than or equal to 5 percent, less than or equal to 10 percent of chloride and less than or equal to 10 percent of fluoride; the fly ash comprises the following components in percentage by mass: al (Al)2O315～50％，SiO230～50％，Fe2O3≤10％，CaO≤5％，MgO≤5％，Na2O≤3％，K2O≤3％，TiO2Less than or equal to 3 percent, and the content of other single metal oxides is less than 1 percent; putting the secondary aluminum ash, the waste cathode carbon blocks and the dry pulp powder into a ball mill together for grinding and uniformly mixing, and then utilizing a ball press to mixPressing the mixture into pellets;
step 2, putting the pellets into a vacuum container for high-temperature vacuum distillation, wherein the distillation temperature is 900-1100 ℃, the distillation time is 2-10h, and the vacuum degree is 0.1-100 Pa; the volatilized fluoride, chloride and metallic sodium enter a condensation system, and the distillation residue is left in a vacuum container;
step 3, taking the distillation residues out of the vacuum container, crushing the distillation residues by using a crusher, and uniformly mixing the distillation residue powder with the fly ash;
step 4, starting the electric arc furnace and gradually increasing the temperature in the furnace, and when the temperature of the bottom arc zone is 1900-; and when the smelting process reaches 2-6h, discharging the formed ferro-silicon-aluminum alloy from the bottom of the electric arc furnace.
2. The method for preparing the sendust according to claim 1, wherein the waste cathode carbon block comprises the following components by mass: 60-80% of C and Al2O3Less than or equal to 3 percent, Na 4-10 percent and fluoride electrolyte 10-20 percent.
3. The method for preparing the sendust by the carbothermic reduction of the pretreated aluminum ash according to claim 1, wherein the dry powder of the paper pulp comprises the following components by mass: the calcium lignosulphonate is more than or equal to 90 percent, and the dry basis moisture is more than or equal to 8 percent.
4. The method for preparing Al-Si-Fe alloy through aluminum ash pretreatment and carbothermal reduction according to claim 1, wherein the addition amount of the pulp dry powder is 6-10% of the sum of the mass of the secondary aluminum ash and the mass of the fly ash.
5. The method for preparing the alundum alloy by the carbothermic reduction of the pretreated aluminum ash according to claim 1, wherein in the step 1, in the pellet pressing process, the particle sizes of the powder of the secondary aluminum ash and the waste cathode carbon block after ball milling are both smaller than 100 meshes, the pressing pressure of a ball press is 100-200MPa, and the diameter of the pellet is 30-50 mm.
6. The method for preparing the sendust according to claim 1, wherein in step 2, the distilled slag is crushed to have a particle size of less than 100 meshes.
7. The method for preparing AlSiFe alloy through carbon thermal reduction by pretreating aluminum ash according to claim 1, wherein in step 4, in the smelting process of an electric arc furnace, the hollow channel in the middle of the hollow electrode is connected with a compressed gas pipeline for conveying powdery materials, and the powdery materials are conveyed to an electric arc reaction zone through the hollow channel by using compressed gas as a carrier, so that the rapid smelting reaction is completed; the diameter of the hollow channel is 20mm-200 mm; the pressure of the compressed gas is controlled between 0.1 and 0.8 MPa.
8. The method of claim 7, wherein the compressed gas is one of argon, air and carbon monoxide.
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