CN114480855A

CN114480855A - Method for preparing ferro-silicon-aluminum alloy by using high-alumina fly ash and purifying ferro-silicon-aluminum alloy in grading mode

Info

Publication number: CN114480855A
Application number: CN202011267925.4A
Authority: CN
Inventors: 程妍; 魏存弟; 徐少南; 佐婧
Original assignee: Inner Mongolia Juncheng Technology Co ltd
Current assignee: Inner Mongolia Juncheng Technology Co ltd
Priority date: 2020-11-13
Filing date: 2020-11-13
Publication date: 2022-05-13
Anticipated expiration: 2040-11-13
Also published as: CN114480855B

Abstract

The invention discloses a method for preparing an aluminum-silicon-iron alloy by using high-alumina fly ash and purifying the aluminum-silicon-iron alloy in a grading way, which comprises the following steps: (1) crushing the high-alumina fly ash and the carbonaceous reducing agent, adding a binder and water, uniformly mixing, briquetting, drying to obtain dry briquettes, and carrying out reduction reaction to obtain an aluminum-silicon-iron alloy molten mass; (2) casting the molten mass in a mould, and controlling the cooling speed and time to obtain a first-grade ferro-silicon-aluminum alloy block; (3) loading the alloy blocks into a supergravity centrifugal device with a heating device, heating at low temperature, and cooling and solidifying a molten liquid after passing through a porous filter plate under the action of supergravity to obtain aluminum-silicon alloy, wherein the molten slag is a secondary aluminum-silicon-iron alloy block; (4) and (3) continuously heating the alloy block to high temperature, passing the molten liquid through a porous filter plate under the action of supergravity, cooling and solidifying to obtain the ferro-silicon-aluminum alloy, wherein the molten slag is industrial silicon or aluminum-silicon alloy. The invention takes the fly ash as the raw material, has wide source and low cost, does not have industrial waste, and obtains various products with high added value after grading purification.

Description

Method for preparing ferro-silicon-aluminum alloy by using high-alumina fly ash and purifying ferro-silicon-aluminum alloy in grading mode

Technical Field

The invention belongs to the technical field of metallurgy and environment, and particularly relates to a method for preparing an aluminum-silicon-iron alloy by using high-alumina fly ash and purifying the aluminum-silicon-iron alloy in a grading manner.

Background

The existing production methods of the ferro-silicon-aluminum alloy comprise two methods, namely a mixing method and an electrothermal reduction method. The mixing method is to melt and mix the electrolytic aluminum and the industrial silicon iron produced by the electric heating method. However, the method has the disadvantages of long production flow, complex process, high production cost, large energy consumption and great influence on the environment. The electric heating reduction method takes aluminosilicate minerals as raw materials and carbonaceous materials as reducing agents, and prepares the alloy through reduction smelting in an electric arc furnace. The method can shorten process flow and reduce production cost. However, the raw materials of the electrothermal reduction method are mainly bauxite, kaolinite and other aluminosilicates minerals, and the production of the aluminosilicates minerals is influenced by the distribution, the reserve, the ore characteristics and the like of the ore resources in China. At present, bauxite resources are in short supply in China, and the shortage of the bauxite resources not only can increase the production cost, but also directly influences the production. Therefore, actively exploiting the non-traditional aluminum minerals to produce the ferro-silicon-aluminum alloy has very important social and economic significance for promoting the sustainable development of the aluminum industry.

The fly ash is a solid waste discharged by coal-fired power plants, and the content of the fly ash accounts for 5-20% of the total weight of the coal. With the rapid development of the power industry, the discharge amount of the fly ash is increased day by day, the utilization rate of the fly ash is only about 40 percent at present, most of the fly ash still occupies a large amount of land for piling up, the environment is polluted, the resources are wasted, and the ecological balance is damaged. The high-alumina fly ash is a novel aluminum resource peculiar to China. The content of alumina in the fly ash can reach 40-50%, which is far higher than that in common fly ash, and is equivalent to that in medium grade bauxite, so that the fly ash is a precious regenerated aluminum-containing mineral resource. In the prior art, patent CN1676630A discloses a method for smelting ferro-silicon-aluminum alloy by using fly ash, and patent CN101469378A discloses a method for preparing ferro-silicon-aluminum alloy by using high-alumina fly ash and magnetic beads. Therefore, the high-alumina fly ash can replace natural minerals such as bauxite, kaolinite and the like to be used as raw materials for smelting the ferro-silicon-aluminum alloy, and can relieve the shortage situation of the domestic aluminum resources.

The ferro-silicon-aluminum alloy prepared by carbon electro-thermal reduction of high-alumina fly ash has high iron content and often exists in the form of brittle iron-rich intermetallic compounds, so that the ferro-silicon-iron alloy can not be used as a casting ferro-silicon alloy with high value, and is mainly used as a steelmaking deoxidizer to be widely applied to steel plants. But the use amount of the steelmaking deoxidizer is limited and the price is lower, thereby restricting the application market of the ferro-silicon-aluminum alloy. If the ferroaluminum alloy can be subjected to iron reduction treatment, the obtained casting aluminum-silicon alloy meeting the industrial standard has great significance undoubtedly in the market capacity of products and also in the economic value.

In the prior art, patent CN107794390A discloses a method for removing iron from a regenerated Al-Si series aluminum alloy, wherein strontium added in the method is subjected to modification treatment, so that a needle-shaped beta-iron phase is broken and decomposed, primary crystal silicon is refined, and the tissue distribution is more uniform; manganese reacts with boron and iron to produce Fe₂B plays a positive correlation role, and meanwhile, manganese enables a beta-iron phase to be converted into an alpha-iron phase to play a role in precipitation; fe with high melting point and high density generated by the reaction of boron and impurity iron₂The B compound has high density difference with the melt, and the iron-rich phases sink to the bottom of the crucible under the action of gravity, so that impurity iron elements in the aluminum alloy are removed. Patent CN108165810A discloses a "device and process for removing iron and silicon phases in primary aluminum-silicon alloy by one-step method", in the method, under the action of an alternating electromagnetic field, manganese as a metal element is adopted as an iron removing agent, the iron removing agent is uniformly mixed with a primary aluminum-silicon alloy raw material, the mixture is heated and melted, after cooling, silicon and an iron-rich phase in the alloy are solidified and enriched at the bottom under the combined action of magnetic field force and temperature effect, the upper molten liquid is poured out, the aluminum-silicon alloy for casting meeting the industrial standard is obtained after cooling and solidification, and finally, the bottom alloy molten liquid is obtained after remelting a primary crystal silicon phase and an impurity iron phase at the bottom. The method for separating iron phase by gravity settling has low separation efficiency and low processThe defects of complexity, high production cost and the like are difficult to apply in practical production. Therefore, a need exists for a low cost, efficient separation method and technique.

The patent CN110904340A discloses a method for centrifugally removing harmful elements and impurities in an iron-containing mixture, wherein an aluminum silicon iron high-temperature molten mixture is placed into a centrifugal rotating device, the cooling speed of the molten mixture is controlled to be 0.1-160 ℃/min, the centrifugal temperature is controlled to be 700-2600 ℃, and silicon crystals are precipitated and grow; then, carrying out centrifugal separation on the high gravity field made from the molten mixture in the device to obtain silicon, wherein the high gravity coefficient is 10-4500 g, the temperature in the device is not lower than the centrifugal temperature when the high gravity field is applied, and gradually cooling to solidification; under the action of centrifugal gravity, the intermetallic compound of iron and other matters are deposited and enriched in the outer part of the supergravity field while the low-density matter of oxide and other matters float and are enriched in the inner layer of the supergravity field, so that the metal product is purified. The method introduces supergravity centrifugation into separation of different phases, and greatly improves the separation efficiency compared with the prior natural gravity separation. However, this process has a fatal problem: the centrifugal separation is carried out under the high-temperature liquid state, and the high-temperature molten aluminum alloy liquid has strong corrosivity on various metal materials, so that it is difficult to find a material which has high strength at high temperature and can resist the corrosion of high-temperature aluminum liquid at low cost. Therefore, the process cannot be effectively applied in a large-scale manner.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for preparing an aluminum-silicon-iron alloy by using high-alumina fly ash and purifying the aluminum-silicon-iron alloy in a grading manner. The invention can effectively reduce the iron content in the aluminum-silicon-iron alloy, not only can produce the aluminum-silicon alloy for casting meeting the industrial requirements, but also can obtain the aluminum-silicon-iron alloy for the deoxidizer and the industrial silicon for producing solar grade polysilicon after acid cleaning and impurity removal, has no new solid waste discharge, not only solves the environmental load problem of the high-alumina fly ash, realizes the comprehensive utilization of the high-alumina fly ash resource, but also can generate remarkable economic benefit, meets the national requirements of energy conservation and emission reduction, and has wide industrialized application prospect.

The technical scheme adopted by the invention for solving the technical problem is as follows:

a method for preparing Al-Si-Fe alloy by using high-alumina fly ash and purifying the Al-Si-Fe alloy by stages comprises the following steps:

(1) crushing the high-alumina fly ash and the carbonaceous reducing agent, adding a binder and water, fully and uniformly mixing, briquetting, drying to obtain a dry briquette, and then putting into an electric arc furnace for reduction reaction to obtain an aluminum-silicon-iron alloy molten mass;

(2) casting the molten mass in a mould, controlling the cooling speed and time to separate out and grow an alloy phase, and then naturally cooling to room temperature to obtain a first-grade ferro-silicon-aluminum alloy block;

(3) loading the primary aluminum-silicon-iron alloy block into a super-gravity centrifugal device with a heating device, heating to 580-650 ℃, and melting aluminum silicon to ensure that primary silicon and an iron phase are still kept in a solid state; starting a centrifugal machine, separating the melt through a porous filter plate under the action of supergravity, cooling and solidifying the melt to obtain aluminum-silicon alloy for casting meeting the industrial standard, wherein the slag is a secondary aluminum-silicon-iron alloy block;

(4) continuously heating the secondary ferro-silicon-aluminum alloy block to 850-1050 ℃ to melt the iron phase and keep the primary silicon in a solid state; and starting a centrifugal machine, separating the melt through a porous filter plate under the action of supergravity, cooling and solidifying the melt to obtain the ferro-silicon-aluminum alloy for the deoxidizer, and purifying the ferro-silicon-aluminum alloy in a grading way by using industrial silicon or aluminum-silicon alloy for casting meeting the industrial standard as slag.

In the method, Al in the high-alumina fly ash in the step (1)₂O₃30-60% of SiO₂30-60% of Fe by mass fraction₂O₃The mass fraction is less than or equal to 5 percent.

In the method, the particle sizes of the high-alumina fly ash and the carbonaceous reducing agent in the step (1) are both smaller than 100 meshes.

In the method, the carbonaceous reducing agent in the step (1) comprises one or a mixture of coal, petroleum coke, calcined anthracite, coke and metallurgical coke.

In the method, the carbon content of the carbonaceous reducing agent in the step (1) is 90-95% of the carbon content required by the complete reaction of the metal oxide and the carbon in the fly ash.

In the method, the adding mass of the binder in the step (1) is 5-10% of the mixed material amount, the briquetting pressure is 50-150 MPa, the briquette drying temperature is 150-200 ℃, and the moisture of the dried pellets is not more than 1%.

In the method, the reduction reaction temperature in the electric arc furnace in the step (1) is 2200-2500 ℃.

In the method, the melt in the step (2) is cooled to 1400 ℃, then casting is carried out, and then the temperature is cooled to 580-1050 ℃ at the speed of 1-20 ℃/min, and the temperature is kept for 30-120 min.

In the method, the first-stage sendust alloy block in the step (3) is heated to 580-650 ℃ and then is subjected to heat preservation for 60-300 min, the hypergravity coefficient is 200-500 g, and the separation time is 5-15 min.

In the method, the secondary ferro-silicon-aluminum alloy block in the step (4) is heated to 850-1050 ℃ and then is subjected to heat preservation for 60-300 min, the hypergravity coefficient is 200-500 g, and the separation time is 5-15 min.

In the method, the heating temperature in the step (4) is not higher than 900 ℃, and the slag is aluminum-silicon alloy for casting meeting the industrial standard; when the heating temperature is higher than 900 ℃, the slag is industrial silicon.

In the method, the porous filter plate in the steps (3) and (4) is an S310 high-temperature-resistant stainless steel filter.

In the above method, the supergravity separation in steps (3) and (4) is a continuous process or an intermittent batch process.

In the method, the steps (3) and (4) not only can produce the casting aluminum-silicon alloy meeting the industrial requirements, but also can obtain the aluminum-silicon-iron alloy for the deoxidizer and the industrial silicon for producing the solar grade polysilicon after acid washing and impurity removal.

The present invention is accomplished based on the following facts:

1. in the process of cooling and crystallizing the ferro-silicon-aluminum melt, the segregation purification principle of the ferro-silicon-aluminum melt is utilized to separate out and grow purer silicon crystals, the cooling curve is controlled to enable the silicon atom arrangement structure to form regular crystals on a solid-liquid interface, and the unique framework structure formed by the regular growth of the silicon atom arrangement structure is utilized; with the further reduction of the temperature, the needle-shaped or flake-shaped iron phase begins to crystallize out and forms a framework structure together with the crystalline silicon; and continuously cooling, and solidifying the molten aluminum-silicon alloy to form a solid block in a framework gap formed by a silicon phase and an iron phase.

2. When a primary sendust alloy block formed by cooling a sendust melt is heated and melted, a specific low-temperature melting temperature can be selected due to the difference of melting temperatures of an aluminum-silicon alloy, an iron phase and primary silicon, so that the aluminum-silicon is melted while the primary silicon and the iron phase are still kept in a solid state, and then the primary sendust alloy block and the secondary sendust alloy block can be separated into casting aluminum-silicon alloy and secondary sendust alloy blocks which meet industrial use standards under the action of a supergravity field; and the secondary aluminum-silicon-iron alloy block is further melted at high temperature, so that the iron phase is melted and the primary silicon still keeps solid state, and then under the action of supergravity, the aluminum-silicon-iron alloy for the deoxidizer and industrial silicon or aluminum-silicon alloy for casting meeting the industrial standard are obtained by separation, so that the graded purification of the aluminum-silicon-iron alloy is realized.

3. In the process of ultragravity centrifugation, a skeleton structure formed by the flaky crystalline silicon (and needle-shaped or flaky iron phase in low-temperature filtration) forms a good self-filtration device, thereby realizing effective separation and filtration in low-temperature and high-temperature stages.

The invention has the advantages that: the method has the advantages that the high-alumina fly ash is used as a raw material, the limitation of the existing iron removal technology is overcome, the method which is efficient, environment-friendly and capable of realizing continuous and large-scale production is provided, iron in the aluminum-silicon-iron alloy can be effectively separated, aluminum-silicon-iron alloy for casting meeting the industrial standard is obtained, aluminum-silicon-iron alloy for a deoxidizer is obtained, and industrial silicon for producing solar-grade polysilicon after acid cleaning and impurity removal is obtained, so that the environmental load problem of the high-alumina fly ash is solved, the comprehensive utilization of high-alumina fly ash resources is realized, remarkable economic benefits can be generated, the national energy-saving and emission-reduction requirements are met, and the method has great application value. The method is also suitable for the ferro-silicon-aluminum alloy produced by low-grade bauxite and other non-bauxite renewable resources so as to improve the production benefit.

Drawings

FIG. 1 is a phase diagram of the aluminum-silicon-iron ternary alloy of the present invention.

FIG. 2 is a process flow of the present invention.

Detailed Description

The following examples illustrate the invention in detail: the present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

Example 1

A method for preparing an Al-Si-Fe alloy by using high-alumina fly ash and purifying the Al-Si-Fe alloy by stages is shown in a process flow diagram of figure 2 and comprises the following steps:

crushing 1t of high-alumina fly ash and coal to the particle size of less than 100 meshes, and uniformly mixing to form a mixed material, wherein Al in fly ash components₂O₃47.62 percent of SiO₂45.32 percent of Fe₂O₃The mass fraction is 0.87%, the carbon content of coal is 90% of the carbon amount required by the complete reaction of metal oxide in the fly ash and carbon, then sulfurous acid paper pulp binder accounting for 6% of the mass of the mixed material and 10% of water are sequentially added for mixing, then the mixed material is made into pellets in a briquetting machine, the briquetting pressure is 100MPa, the prepared pellets are dried and dehydrated at 120 ℃ to obtain dry briquettes, the moisture content is required to be not more than 1%, then the dry briquettes are put into an electric arc furnace for reduction reaction, the smelting temperature is 2200-2500 ℃, the obtained molten aluminum-silicon-iron alloy is cast in a mold when the molten aluminum is cooled to 1400 ℃, then the temperature is reduced to 850 ℃ at 5 ℃/min, the temperature is kept for 60min at the temperature, and 497.53kg of first-grade aluminum-silicon-iron alloy blocks are obtained after the molten aluminum-silicon-iron alloy is cooled to room temperature. The mass fraction of Al in the first-grade ferro-silicon-aluminum alloy block is 51.09 percent, the mass fraction of Si is 42.86 percent, and the mass fraction of Fe is 3.70 percent. As shown in FIG. 1, the phase diagram of the alloy of the present invention shows that when the cooling temperature is reduced to 950-1000 ℃, silicon crystals precipitate and grow, the silicon content in the melt gradually decreases with the reduction of the cooling temperature, and when the temperature is reduced to 750-800 ℃, acicular or flaky iron phase is formedAnd (4) starting to crystallize, and continuously cooling to the temperature of 577 ℃, so that the molten aluminum-silicon alloy is solidified and exists in a framework gap formed by a silicon phase to form a solid block.

100kg of first-stage ferro-aluminum-silicon alloy blocks are put into a hypergravity centrifugal device with a heating device, the temperature is kept for 180min after the first-stage ferro-aluminum-silicon alloy blocks are heated to 650 ℃, so that the aluminum silicon is melted and primary silicon and iron phases are still kept solid, a centrifugal machine is started, the hypergravity coefficient is 212g, the separation time is 10min, under the action of hypergravity, the melt is separated through a porous filter plate, 53.18kg of casting aluminum-silicon alloy meeting the industrial standard is obtained after the melt is cooled and solidified, wherein the mass fraction of Fe is 0.65%, the mass fraction of Si is 13.35%, and the slag is 46.82kg of second-stage ferro-aluminum-silicon alloy blocks; and (2) continuously heating 46.82kg of secondary ferro-silicon-aluminum alloy blocks to 950 ℃, preserving the heat for 180min to enable an iron phase to be molten and primary silicon to be still kept in a solid state, starting a centrifugal machine, wherein the super-gravity coefficient is 212g, the separation time is 10min, the melt is separated through a porous filter plate under the action of super-gravity, and the melt is cooled and solidified to obtain 25.93kg of ferro-silicon-aluminum alloy for the deoxidizer, wherein the mass fraction of Fe is 12.69%, the mass fraction of Si is 57.74%, the slag is 20.89kg of industrial silicon, and the purity of the industrial silicon is 99.52%.

Example 2

A method for preparing an Al-Si-Fe alloy by using high-alumina fly ash and purifying the Al-Si-Fe alloy by stages is shown in a process flow chart of figure 2 and comprises the following steps:

crushing 1t of high-alumina fly ash and coal to the particle size of less than 100 meshes, and uniformly mixing to form a mixed material, wherein Al in fly ash components₂O₃47.62 percent of SiO₂45.32 percent of Fe₂O₃The mass fraction is 0.87%, the carbon content of coal is 90% of the carbon amount required by the complete reaction of metal oxide in the fly ash and carbon, then sulfurous acid paper pulp binder accounting for 6% of the mass of the mixed material and 10% of water are sequentially added for mixing, then the mixed material is made into pellets in a briquetting machine, the briquetting pressure is 100MPa, the prepared pellets are dried and dehydrated at 120 ℃ to obtain dry briquettes, and the water content is required to be not more than 1%; then, putting the dry agglomerates into an electric arc furnace for reduction reaction, wherein the smelting temperature is 2200-2500 ℃, and obtaining the dry agglomeratesWhen the temperature of the molten mass is reduced to 1400 ℃, the molten mass is cast in a mould, then the temperature is reduced to 700 ℃ at the speed of 2 ℃/min, the temperature is kept for 60min at the temperature, and the temperature is continuously reduced to obtain 497.53kg of first-grade ferro-silicon-aluminum alloy blocks. The mass fraction of Al in the first-grade ferro-silicon-aluminum alloy block is 51.09 percent, the mass fraction of Si is 42.86 percent, and the mass fraction of Fe is 3.70 percent. As shown in figure 1, the phase diagram of the alloy shows that when the cooling temperature is reduced to 950-1000 ℃, silicon crystals are firstly separated out and grow, the silicon content in the melt is gradually reduced along with the reduction of the cooling temperature, when the temperature is reduced to 750-800 ℃, a needle-shaped or flaky iron phase begins to crystallize, the temperature is continuously reduced to be lower than 577 ℃, and molten aluminum-silicon alloy is solidified and exists in skeleton gaps formed by the silicon phase to form solid blocks.

100kg of first-stage ferro-aluminum-silicon alloy blocks are put into a supergravity centrifugal device with a heating device, the temperature is maintained for 180min after the first-stage ferro-aluminum-silicon alloy blocks are heated to 650 ℃, so that the aluminum-silicon is melted and primary silicon and iron phases are still kept in solid states, a centrifugal machine is started, the super-gravity coefficient is 212g, the separation time is 10min, under the action of supergravity, the melt is separated through a porous filter plate, and the melt is cooled and solidified to obtain 52.10kg of casting aluminum-silicon alloy meeting the industrial standard, wherein the mass fraction of Fe is 0.35%, the mass fraction of Si is 11.52%, and the slag is 47.90kg of second-stage ferro-aluminum-silicon alloy blocks; and (2) continuously heating 47.90kg of secondary Al-Si-Fe alloy blocks to 850 ℃, preserving heat for 180min to ensure that an iron phase is molten and primary silicon still keeps solid, starting a centrifugal machine, separating the melt through a porous filter plate under the action of supergravity, and cooling and solidifying the melt to obtain 21.97kg of Al-Si-Fe alloy for the deoxidizer, wherein the mass fraction of Fe is 15.24%, the mass fraction of Si is 64.85%, the slag is 25.93kg of casting Al-Si alloy which meets the industrial standard, the mass fraction of Fe is 0.65%, and the mass fraction of Si is 87.20%.

Example 3

crushing 1t of high-alumina fly ash and coal to the particle size of less than 100 meshes, and uniformly mixing to form a mixed material, wherein the pulverized coal isAl in ash content₂O₃47.62 percent of SiO₂45.32 percent of Fe₂O₃The mass fraction is 0.87%, the carbon content of coal is 90% of the carbon amount required by the complete reaction of metal oxide in the fly ash and carbon, then sulfurous acid paper pulp binder accounting for 6% of the mass of the mixed material and 10% of water are sequentially added for mixing, then the mixed material is made into pellets in a briquetting machine, the briquetting pressure is 100MPa, the prepared pellets are dried and dehydrated at 120 ℃ to obtain dry briquettes, and the water content is required to be not more than 1%; and then, putting the dry agglomerates into an electric arc furnace for reduction reaction, wherein the smelting temperature is 2200-2500 ℃, obtaining an Al-Si-Fe alloy melt, casting the melt in a mould when the temperature of the melt is reduced to 1400 ℃, then reducing the temperature to 700 ℃ at the speed of 2 ℃/min, preserving the heat for 60min at the temperature, and continuously reducing the temperature to obtain 497.53kg of first-grade Al-Si-Fe alloy blocks. The mass fraction of Al in the first-grade ferro-silicon-aluminum alloy block is 51.09 percent, the mass fraction of Si is 42.86 percent, and the mass fraction of Fe is 3.70 percent. As shown in figure 1, the phase diagram of the alloy shows that when the cooling temperature is reduced to 950-1000 ℃, silicon crystals are firstly separated out and grow, the silicon content in the melt is gradually reduced along with the reduction of the cooling temperature, when the temperature is reduced to 750-800 ℃, a needle-shaped or flaky iron phase begins to crystallize, the temperature is continuously reduced to be lower than 577 ℃, and molten aluminum-silicon alloy is solidified and exists in skeleton gaps formed by the silicon phase to form solid blocks.

100kg of first-stage sendust alloy blocks are put into a supergravity centrifugal device with a heating device, the temperature is maintained for 300min after the first-stage sendust alloy blocks are heated to 650 ℃, aluminum silicon is melted, primary silicon and iron phases are still kept solid, a centrifugal machine is started, the supergravity coefficient is 212g, the separation time is 10min, under the action of supergravity, a melt is separated through a porous filter plate, 52.95kg of casting sendust alloy meeting the industrial standard is obtained after the melt is cooled and solidified, wherein the mass fraction of Fe is 0.42%, the mass fraction of Si is 11.79%, and the slag is 47.05kg of second-stage sendust alloy blocks; 47.05kg of secondary aluminum silicon iron alloy block is continuously heated to 850 ℃, the temperature is kept for 300min, so that the iron phase is melted and the primary silicon still keeps solid state, a centrifugal machine is started, the overweight force coefficient is 212g, the separation time is 10min, the melt is separated by a porous filter plate under the action of the overweight force, 22.42kg of aluminum silicon iron alloy for deoxidizer is obtained after the melt is cooled and solidified, wherein the mass fraction of Fe is 14.78%, the mass fraction of Si is 67.86%, the slag is 24.63kg of aluminum silicon alloy for casting meeting the industrial standard, the mass fraction of Fe is 0.67%, and the mass fraction of Si is 86.90%.

Example 4

crushing 1t of high-alumina fly ash and coal to the particle size of less than 100 meshes, and uniformly mixing to form a mixed material, wherein Al in fly ash components₂O₃48.90 percent of SiO₂39.20 percent of mass fraction and Fe₂O₃The mass fraction is 0.65%, the carbon content of coal is 90% of the carbon amount required by the complete reaction of metal oxide in the fly ash and carbon, then sulfurous acid paper pulp binder accounting for 6% of the mass of the mixed material and 10% of water are sequentially added for mixing, then the mixed material is made into pellets in a briquetting machine, the briquetting pressure is 100MPa, the prepared pellets are dried and dehydrated at 120 ℃ to obtain dry briquettes, and the moisture is required to be not more than 1%; and then, putting the dry agglomerates into an electric arc furnace for reduction reaction, wherein the smelting temperature is 2200-2500 ℃, obtaining an Al-Si-Fe alloy melt, casting the melt in a mould when the temperature of the melt is reduced to 1400 ℃, then reducing the temperature to 700 ℃ at a speed of 5 ℃/min, preserving the heat for 60min at the temperature, and continuously reducing the temperature to obtain 483.65kg of first-grade Al-Si-Fe alloy blocks. The mass fraction of Al in the first-grade ferro-silicon-aluminum alloy block is 54.96%, the mass fraction of Si is 38.84%, and the mass fraction of Fe is 2.90%. As shown in figure 1, the phase diagram of the alloy shows that when the cooling temperature is reduced to 900-950 ℃, silicon crystals are firstly separated out and grow, the silicon content in the melt is gradually reduced along with the reduction of the cooling temperature, when the temperature is reduced to 750-800 ℃, a needle-shaped or sheet-shaped iron phase begins to crystallize, the temperature is continuously reduced to be lower than 577 ℃, and molten aluminum-silicon alloy is solidified and exists in skeleton gaps formed by the silicon phase to form solid blocks.

100kg of first-stage ferro-aluminum-silicon alloy blocks are filled into a supergravity centrifugal device with a heating device, the temperature is maintained for 180min after the first-stage ferro-aluminum-silicon alloy blocks are heated to 650 ℃, so that the aluminum-silicon is melted and primary silicon and iron phases still keep solid, a centrifugal machine is started, the super-gravity coefficient is 212g, the separation time is 10min, under the action of supergravity, the melt is separated through a porous filter plate, and the melt is cooled and solidified to obtain 51.86kg of casting aluminum-silicon alloy meeting the industrial standard, wherein the mass fraction of Fe is 0.39%, the mass fraction of Si is 11.10%, and the slag is 48.14kg of second-stage ferro-aluminum-silicon alloy blocks; and (2) continuously heating 48.14kg of secondary ferro-silicon-aluminum alloy blocks to 1000 ℃, preserving the heat for 180min at the temperature to melt an iron phase and keep primary silicon in a solid state, starting a centrifugal machine, wherein the super-gravity coefficient is 212g, the separation time is 10min, the melt is separated by a porous filter plate under the action of super-gravity, and the melt is cooled and solidified to obtain 32.00kg of ferro-silicon-aluminum alloy for the deoxidizer, wherein the mass fraction of Fe is 8.28%, the mass fraction of Si is 53.18%, the slag is 16.14kg of industrial silicon, and the purity of the industrial silicon is 99.55%.

Example 5

crushing 1t of high-alumina fly ash and coal to the particle size of less than 100 meshes, and uniformly mixing to form a mixed material, wherein Al in fly ash is selected₂O₃48.90 percent of SiO₂39.20 percent of mass fraction and Fe₂O₃The mass fraction is 0.65%, the carbon content of coal is 90% of the carbon amount required by the complete reaction of metal oxide in the fly ash and carbon, then sulfurous acid paper pulp binder accounting for 6% of the mass of the mixed material and 10% of water are sequentially added for mixing, then the mixed material is made into pellets in a briquetting machine, the briquetting pressure is 100MPa, the prepared pellets are dried and dehydrated at 120 ℃ to obtain dry briquettes, and the moisture is required to be not more than 1%; and then, putting the dry agglomerates into an electric arc furnace for reduction reaction, wherein the smelting temperature is 2200-2500 ℃, obtaining an Al-Si-Fe alloy melt, casting the Al-Si-Fe alloy melt in a mould when the temperature of the melt is reduced to 1400 ℃, then reducing the temperature to 850 ℃ at 5 ℃/min, preserving the temperature for 60min at the temperature, and continuously reducing the temperature to obtain 482.89kg of first-grade Al-Si-Fe alloy blocks. The mass fraction of Al in the first-grade ferro-aluminium alloy block is 54.96 percent,The mass fraction of Si was 38.84% and the mass fraction of Fe was 2.90%. As shown in figure 1, the phase diagram of the alloy shows that when the cooling temperature is reduced to 900-950 ℃, silicon crystals are firstly separated out and grow, the silicon content in the melt is gradually reduced along with the reduction of the cooling temperature, when the temperature is reduced to 750-800 ℃, a needle-shaped or sheet-shaped iron phase begins to crystallize, the temperature is continuously reduced to be lower than 577 ℃, and molten aluminum-silicon alloy is solidified and exists in skeleton gaps formed by the silicon phase to form solid blocks.

100kg of first-stage ferro-aluminum-silicon alloy blocks are filled into a supergravity centrifugal device with a heating device, the temperature is maintained for 180min after the first-stage ferro-aluminum-silicon alloy blocks are heated to 600 ℃, so that the aluminum silicon is melted and primary silicon and iron phases are still kept in a solid state, a centrifugal machine is started, the super-gravity coefficient is 212g, the separation time is 10min, under the action of supergravity, the melt is separated through a porous filter plate, and the melt is cooled and solidified to obtain 52.89kg of casting aluminum-silicon alloy meeting the industrial standard, wherein the mass fraction of Fe is 0.67%, the mass fraction of Si is 12.24%, and the slag is 47.11kg of second-stage ferro-aluminum-silicon alloy blocks; and (2) continuously heating 47.11kg of secondary aluminum-silicon-iron alloy blocks to 850 ℃, preserving the temperature for 180min to enable an iron phase to be molten and primary silicon to be kept in a solid state, starting a centrifugal machine, wherein the overweight coefficient is 212g, the separation time is 10min, the melt is separated through a porous filter plate under the action of the overweight force, 21.11kg of aluminum-silicon-iron alloy for the deoxidizer is obtained after the melt is cooled and solidified, the mass fraction of Fe is 11.21%, the mass fraction of Si is 44.25%, the slag is 26.00kg of aluminum-silicon alloy for casting meeting the industrial standard, the mass fraction of Fe is 0.69%, and the mass fraction of Si is 88.56%.

While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A method for preparing an aluminum-silicon-iron alloy by using high-alumina fly ash and purifying the aluminum-silicon-iron alloy in a grading manner is characterized by comprising the following steps: (1) crushing the high-alumina fly ash and the carbonaceous reducing agent, adding a binder and water, fully and uniformly mixing, briquetting, drying to obtain a dry briquette, and then putting into an electric arc furnace for reduction reaction to obtain an aluminum-silicon-iron alloy molten mass; (2) casting the molten mass in a mould, controlling the cooling speed and time to separate out and grow an alloy phase, and then naturally cooling to room temperature to obtain a first-grade ferro-silicon-aluminum alloy block; (3) loading the primary aluminum-silicon-iron alloy block into a super-gravity centrifugal device with a heating device, heating to 580-650 ℃, and melting aluminum silicon to ensure that primary silicon and an iron phase are still kept in a solid state; starting a centrifugal machine, separating the melt through a porous filter plate under the action of supergravity, cooling and solidifying the melt to obtain aluminum-silicon alloy for casting meeting the industrial standard, wherein the slag is a secondary aluminum-silicon-iron alloy block; (4) continuously heating the secondary ferro-silicon-aluminum alloy block to 850-1050 ℃ to melt the iron phase and keep the primary silicon in a solid state; and starting a centrifugal machine, separating the melt through a porous filter plate under the action of supergravity, cooling and solidifying the melt to obtain the ferro-silicon-aluminum alloy for the deoxidizer, and purifying the ferro-silicon-aluminum alloy in a grading way by using industrial silicon or aluminum-silicon alloy for casting meeting the industrial standard as slag.

2. The method for preparing Al-Si-Fe alloy and purifying by stages by using high-alumina fly ash as claimed in claim 1, wherein in step (1), Al in the high-alumina fly ash is₂O₃30-60% of SiO₂30-60% of Fe by mass fraction₂O₃The mass fraction is less than or equal to 5 percent.

3. The method for preparing the sendust alloy and purifying the sendust alloy by using the high-alumina fly ash according to claim 1, wherein in the step (1), the high-alumina fly ash and the carbonaceous reducing agent have a particle size of less than 100 meshes.

4. The method for preparing sendust from high-alumina fly ash and purifying by stages as claimed in claim 1, wherein in step (1), the carbonaceous reducing agent comprises one or more selected from coal, petroleum coke, calcined anthracite, coke and metallurgical coke.

5. The method for preparing the sendust alloy and purifying the sendust alloy in a grading manner by using the high-alumina fly ash as claimed in claim 1, wherein in the step (1), the carbon content of the carbonaceous reducing agent is 90-95% of the carbon content required for the complete reaction of the metal oxide and the carbon in the fly ash.

6. The method for preparing the ferro-silicon-aluminum alloy and purifying the ferro-silicon-aluminum alloy in a grading manner by using the high-alumina fly ash as claimed in claim 1, wherein in the step (1), the adding mass of the binder is 5-10% of the mass of the mixed materials, the briquetting pressure is 50-150 MPa, the briquette drying temperature is 150-200 ℃, and the moisture of the pellets after drying is not more than 1%.

7. The method for preparing the sendust alloy by using the high-alumina fly ash and carrying out the classification purification according to claim 1, wherein in the step (1), the reduction reaction temperature in the electric arc furnace is 2200 to 2500 ℃.

8. The method for preparing the sendust alloy and purifying the sendust alloy in a grading manner by using the high-alumina fly ash as claimed in claim 1, wherein in the step (2), the melt is cooled to 1400 ℃, cast, cooled to 580-1050 ℃ at a speed of 1-20 ℃/min, and then kept warm for 30-120 min.

9. The method for preparing the sendust alloy and purifying the sendust alloy in a grading manner by using the high-alumina fly ash as claimed in claim 1, wherein in the step (3), the primary sendust alloy block is heated to 580-650 ℃ and then is subjected to heat preservation for 60-300 min, the hypergravity coefficient is 200-500 g, and the separation time is 5-15 min.

10. The method for preparing the sendust alloy and purifying the sendust alloy in a grading manner by using the high-alumina fly ash as claimed in claim 1, wherein in the step (4), the secondary sendust alloy block is heated to 850-1050 ℃, and then is subjected to heat preservation for 60-300 min, the hypergravity coefficient is 200-500 g, and the separation time is 5-15 min.

11. The method for preparing the sendust alloy and purifying the sendust alloy in grades by using the high-alumina fly ash according to claim 10, wherein in the step (4), the heating temperature is not higher than 900 ℃, and the molten slag is the casting aluminum-silicon alloy meeting the industrial standard; when the heating temperature is higher than 900 ℃, the slag is industrial silicon.

12. The method for preparing sendust from high-alumina fly ash and purifying by stages as claimed in claim 1, wherein the porous filter plates in steps (3) and (4) are S310 high temperature stainless steel filters.

13. The method for preparing sendust from high-alumina fly ash and purifying by classification as claimed in claim 1, wherein the supergravity separation is a continuous process or an intermittent batch process in steps (3) and (4).