CN113292075A - Method for preparing high-purity silicon by using non-ferrous metal smelting waste residues - Google Patents
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Abstract
The invention discloses a method for preparing high-purity silicon by using non-ferrous metal smelting waste residues, which comprises the following steps: (1) carrying out chlorination roasting on non-ferrous metal smelting waste residues containing zinc and silicon, and collecting chloride flue gas generated in the chlorination roasting process in a partition mode to obtain zinc chloride smoke dust and liquid silicon tetrachloride; (2) reducing and roasting the zinc chloride smoke dust obtained in the step (1) to obtain metal zinc; (3) mixing the liquid silicon tetrachloride obtained in the step (1) with the metal zinc obtained in the step (2), and then carrying out heat treatment to obtain crude silicon; (4) and (4) distilling the crude silicon obtained in the step (3) to obtain high-purity silicon. The method for preparing high-purity silicon by using the non-ferrous metal smelting waste residue can obtain high-purity silicon and other valuable components in the slag from the non-ferrous metal smelting waste residue, and realizes resource utilization of the non-ferrous metal smelting waste residue.
Description
Technical Field
The invention belongs to the field of metallurgical slag resource utilization, and particularly relates to a method for preparing high-purity silicon by utilizing metallurgical slag.
Background
The non-ferrous metal is a basic material for social economic development and is a strategic material of national defense, military industry and new technological revolution. In 2020, the yield of ten nonferrous metals in China reaches 6168 ten thousand tons, and the nonferrous metals are the first to live in the world. As a large country of nonferrous metal production, China produces thousands of tons of nonferrous metal smelting waste slag every year. The slag is rich in elements such as silicon, iron, aluminum and the like, and is an important secondary mineral resource. At present, China lacks an efficient and environment-friendly waste residue utilization technology, and the waste residue is mainly treated by an open-air stacking method, so that the environment is seriously polluted. The non-ferrous metal smelting waste slag has stable structure and complex components, is difficult to dissociate by a conventional method, and has high difficulty in separating and enriching elements in the slag. Therefore, the development of a non-ferrous metal smelting waste residue resource utilization technology with harmless and high resource level can promote the development of circular economy.
The silicon material has excellent physical and chemical properties, is an element semiconductor with wide application, and plays a key role in the semiconductor industry, the microelectronic industry and the solar photovoltaic industry. And various non-ferrous metal smelting waste residues contain considerable silicon content, so that the high-efficiency recovery of silicon components from the non-ferrous metal smelting waste residues has important economic significance. For example, CN110540207A discloses a "method for preparing high-purity nano silicon material from industrial waste", the method comprises electrolyzing industrial solid waste sodium chloride to obtain chlorine gas and sodium hydroxide, melting and electrolyzing the obtained sodium hydroxide to prepare metallic sodium, then performing reduction reaction on the chlorine gas and a silicon material to prepare silicon tetrachloride, and finally performing high-temperature reduction reaction on the silicon tetrachloride and the metallic sodium to prepare the nano silicon material. The existing method for preparing high-purity silicon by using non-ferrous metal smelting waste residue has the problems of low waste residue utilization rate, single recovered product, complex process flow and the like. The non-ferrous metal smelting waste slag contains various valuable elements, and the high-purity silicon prepared by directly reducing the metal elements (such as zinc) in the waste slag can improve the resource utilization level of the waste slag.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects and shortcomings in the background art, and provide a method for preparing high-purity silicon by using non-ferrous metal smelting waste residues, wherein the method can obtain high-purity silicon and other valuable components in the residues from the non-ferrous metal smelting waste residues, and realize resource utilization of the non-ferrous metal smelting waste residues. In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a method for preparing high-purity silicon by using non-ferrous metal smelting waste residues comprises the following steps:
(1) carrying out chlorination roasting on non-ferrous metal smelting waste residues containing zinc and silicon, collecting chloride flue gas generated in the chlorination roasting process in a partitioning manner to obtain zinc chloride smoke dust and liquid silicon tetrachloride, and obtaining roasting residues after roasting is finished; the different chloride flue gases are collected in sections through different temperature zones in the furnace in the roasting process; chloride smoke dust collected in other temperature zones can be recycled as an additional product;
(2) reducing and roasting the zinc chloride smoke dust obtained in the step (1) to obtain metal zinc and gaseous hydrogen chloride (accessory products); the metal zinc can be ground into fine powder, so that the contact area between the metal zinc and liquid silicon tetrachloride is increased subsequently, and the reduction effect is improved;
(3) mixing the liquid silicon tetrachloride obtained in the step (1) with the metal zinc obtained in the step (2), and then carrying out heat treatment to obtain crude silicon; collecting the flue gas generated in the heat treatment process to obtain silicon tetrachloride, and finally obtaining crude silicon containing a silicon simple substance, a zinc simple substance (trace) and zinc chloride due to volatilization of the silicon tetrachloride after roasting;
(4) and (4) distilling the crude silicon obtained in the step (3) to obtain 5N high-purity silicon, and collecting and recycling the generated flue gas in the distillation process. The uncooled crude silicon in step (3) can be directly subjected to distillation treatment to save energy consumption.
Generally, metal components such as Cu, Pb and the like in non-ferrous metal smelting waste residue can be used for reducing to prepare Si, and the method for finally obtaining high-purity silicon by utilizing the interaction of zinc chloride and silicon tetrachloride is based on the following considerations: zn metal with a low boiling point (907 ℃) is easy to distill off, while Cu and Pb with high boiling points are 2562 ℃ and 1740 ℃ respectively and are not easy to distill off. During the distillation treatment of the crude silicon in the step (4), Zn is more easily separated from the silicon, and the purity of the silicon is higher.
In the above method for preparing high purity silicon from non-ferrous metal smelting waste residue, preferably, the chloridizing roasting of non-ferrous metal smelting waste residue containing zinc and silicon comprises the following steps: mixing and grinding the non-ferrous metal smelting waste residue, a chlorinating agent and sulphide ore (grinding to 200 meshes), and drying to obtain a pretreated mineral aggregate; then the pretreated ore material is put into a roasting furnace (such as a tube furnace), oxygen-enriched air is introduced into the roasting furnace, and the temperature is raised for chlorination roasting.
In the above method for preparing high-purity silicon from non-ferrous metal smelting waste slag, preferably, the chlorinating agent comprises CaCl2NaCl and AlCl3The addition amount of the chlorinating agent is 10-30% of the mass of the non-ferrous metal smelting waste residue; the sulfide ore comprises pyrite (FeS) with the sulfur element mass content of not less than 30 percent2) Chalcopyrite (CuFeS)2) And zinc blende (ZnS) or galena (PbS), wherein the addition amount of the sulfide ore is 5-10% of the mass of the non-ferrous metal smelting waste residue.
Among the above chlorides, NaCl and AlCl are preferred3、FeCl3Compared with chlorinating agent, CaCl2Low cost and good chlorination effect. In addition, the roasting slag obtained by chloridizing roasting can be usually used as a building material, and CaCl is selected2The calcium content in the roasting slag can be increased by using the calcium chloride as a chlorinating agent, and the calcium content can be reducedConsumption of lime in the building material preparation process. Therefore, more preferably, the chlorinating agent is CaCl2Said CaCl2The addition amount of the non-ferrous metal smelting waste residue is 10-30% of the mass of the non-ferrous metal smelting waste residue. In the invention, the contact rate between the chlorine donor and the metal phase can be improved by properly increasing the content of the chlorinating agent, and the chlorination reaction can be promoted in a kinetic angle, but the chlorination effect of the waste residue cannot be improved by considering that the content of easily-chloridized elements in the non-ferrous metal smelting waste residue is limited and the chlorine source is too much. The invention selects CaCl2As chlorinating agent in the roasting process, CaCl in the high-temperature roasting process2Under the action of oxygen, the chlorine gas and silicon dioxide in sulfide ore and slag form stable silicate, chlorine gas and the like, and the chlorine gas reacts with easily chloridized phases in the non-ferrous metal smelting slag to generate low-boiling-point chlorides (such as ZnCl)2、SiCl4、PbCl2Etc.).
In the present invention, it is more preferable that the mass ratio of the chlorinating agent to the sulfide ore is 5: 1. in the invention, researches show that the addition of sulfide ore in the chloridizing roasting process can promote the decomposition of a chlorinating agent to generate chlorine. From the thermodynamic analysis, the S component in the sulfide ore can reduce Gibbs free energy of the chlorinating agent which is heated and decomposed into chlorine gas in the process of participating in the chlorination, volatilization and roasting of the non-ferrous metal smelting waste slag, and indirectly promotes the chlorination reaction process of the chlorine gas and the easily chloridized components in the slag. In the roasting process in which the sulfide ore participates, the S element in the sulfide ore is Ca2SO4The form of (A) is enriched and no other sulfur-containing waste gas is produced. The S content in the reaction system is too low, the promotion effect of the reaction process is not obvious, and the chlorination rate of waste residues is reduced due to the fact that sulfide has certain reducibility, and the chlorination reaction efficiency of chlorine to the phase of easily-chlorinated substances is reduced due to the excessive sulfide. Comprehensively considering, the adding amount of the sulfide ore is 5-10% of the mass of the non-ferrous metal smelting waste residue. More preferably, in view of the synergistic effect between the sulphide ore and the chlorinating agent, earlier studies showed that the chlorinating agent is CaCl (as CaCl)2For example) to sulphide ore in a mass ratio of 5: 1, the waste residue chloridizing, volatilizing and roasting effect is relatively better. More preferably, sphalerite is used as the main chlorination additive, so that the improvement can be realizedThe zinc content in the chloride smoke dust is beneficial to the subsequent process of reducing silicon by zinc.
In the method for preparing high-purity silicon by using the non-ferrous metal smelting waste residue, preferably, during the chloridizing roasting, the flow rate of the oxygen-enriched air is controlled to be 2-10L/min, the roasting temperature is controlled to be 500-700 ℃, the roasting time is 10-20min, and the volume of oxygen in the oxygen-enriched air is not less than 30%. If the roasting temperature is too low, the metal chlorination effect in the slag cannot be ensured, and if the roasting temperature is too high, the slag can be sintered and even melted, so that the metal chlorination rate is reduced. If the roasting time is too short, the metal elements in the slag cannot be fully chlorinated, and if the roasting time is too long, the process cost is increased.
In the invention, the chloridizing roasting is carried out under the oxygen-enriched condition. According to the chloridizing roasting principle, the chloridizing reaction is carried out in two steps in the roasting process, firstly, the chloridizing agent reacts to decompose chlorine, and then, the chloridizing reaction is carried out on the easily chloridized components in the non-ferrous metal smelting waste residue under the action of the chlorine to form gas phase chloride. In aerobic environment, in non-ferrous metal smelting waste SiO2Under the action of the components, the chlorinating agent can be dissociated to generate chlorine, and further chlorination of waste residues is realized. The chlorination agent can not be fully dissociated due to too low oxygen-rich air flow, but the excessive oxygen-rich air flow can cause the hearth of the heating furnace to bear overlarge pressure stress, so that the pressure resistance requirement on the heating furnace is higher, and the energy consumption is increased. Comprehensively considering, the introduction amount of the oxygen-enriched air of the oxygen-enriched chlorination roasting system is optimal to be 2-10L/min.
In the above method for preparing high-purity silicon from non-ferrous metal smelting slag, preferably, the non-ferrous metal smelting slag containing zinc and silicon comprises one or more of copper smelting slag, zinc leaching slag and lead smelting slag, and the copper smelting slag, the zinc leaching slag and the lead smelting slag contain more than 3 wt.% of zinc and more than 12 wt.% of silicon.
In the method for preparing high-purity silicon by using the non-ferrous metal smelting waste residues, preferably, the step of collecting chloride flue gas generated in the chlorination roasting process in a subarea mode refers to the step of collecting the chloride flue gas in different subareas by using different condensation points of the chloride flue gas, the roasting furnace used in the chlorination roasting is a multi-temperature-zone heating furnace, the multi-temperature-zone heating furnace comprises a roasting section and three chloride collecting sections, the three chloride collecting sections comprise a first chloride solid collecting section, a second chloride solid collecting section and a third chloride liquid collecting section for collecting, and the chloride flue gas generated in the roasting section is collected by the first chloride solid collecting section, the second chloride solid collecting section and the third chloride liquid collecting section in sequence.
In the method for preparing high-purity silicon by using the non-ferrous metal smelting waste slag, preferably, the temperature of the first chloride solid-state collection section is controlled to be 300-400 ℃, the temperature of the second chloride solid-state collection section is controlled to be 50-250 ℃, and the temperature of the third chloride liquid-state collection section is controlled to be 0-50 ℃.
In the invention, the chlorination and volatilization process of the non-ferrous metal smelting waste slag mainly separates and enriches Si and Zn in the slag, and CuCl and PbCl are also generated in the chlorination roasting process because the waste slag possibly contains easy-to-chloridize elements such as Cu, Pb and the like2And the smoke is volatilized. In the invention, the heating furnace adopted in the chlorination roasting process is a multi-temperature-zone heating furnace and comprises a roasting section and three chloride collecting sections, and chloride flue gas generated in the roasting section sequentially passes through the first chloride solid collecting section, the second chloride solid collecting section and the third chloride liquid collecting section. More preferably, the temperature of the first chloride solid-state collection section is controlled to be 300-400 ℃, the temperature of the second chloride solid-state collection section is controlled to be 50-250 ℃, and the temperature of the third chloride liquid-state collection section is controlled to be 0-50 ℃. Further preferably, the temperature of the first chloride solid collecting section is controlled to be 300 ℃, the temperature of the second chloride solid collecting section is controlled to be 50 ℃, and the temperature of the third chloride liquid collecting section is controlled to be 25 ℃ (namely room temperature). The furnace chamber of the heating furnace is internally provided with a controllable multi-temperature section, the pressure in the furnace chamber can be kept unchanged in the temperature rising process, the roasting section is mainly responsible for high-temperature chlorination volatilization, the chloride solid/liquid collecting section is mainly used for collecting the chlorinated flue gas in a segmented mode, and the temperature is determined according to different melting points, different volatilization performances and different solidification characteristics of silicon tetrachloride, zinc chloride, lead chloride, cuprous chloride and the like, wherein the temperature of the first chloride solid collecting section is controlled to be aboutCondensing and recovering CuCl (melting point 426 ℃, boiling point 1490 ℃) and PbCl at 300 DEG C2(melting point 501 ℃ and boiling point 951 ℃), and the temperature of the second chloride solid-state collection section is controlled to be about 50 ℃, and ZnCl is condensed and recovered2(the melting point is 283 ℃, the boiling point is 732 ℃) flue gas and the temperature of the liquid collecting section of the third trichloride are controlled to be about 25 ℃, and SiCl is condensed and recovered4(melting point-70 ℃ C., boiling point 58 ℃ C.).
In the method for preparing high-purity silicon by using the non-ferrous metal smelting waste residue, preferably, the reducing agent in the reduction roasting treatment process is hydrogen, and the reduction roasting treatment is heat preservation for 20-40min at the temperature of 800-1000 ℃; the heat treatment is heat preservation for 20-40min at the temperature of 100-200 ℃. Thermodynamic calculation shows that CO and CH4And other reactants are required to be added when the reducing agent cannot directly realize the reduction of the zinc chloride. The method utilizes hydrogen as a reducing agent, has better reduction effect, is cleaner, has no pollutant emission, reduces impurities brought in the reduction process of the zinc chloride, and is more beneficial to preparing and obtaining high-purity silicon. The heat treatment ensures the reaction of the silicon tetrachloride and the zinc on the one hand, and ensures the volatilization and removal of the redundant silicon tetrachloride on the other hand, and the volatilized silicon tetrachloride is used for returning to the heat treatment process again for recycling. Within the heat treatment temperature range, the silicon tetrachloride (the boiling point is 57.6 ℃) is in a gaseous state, and fully contacts with the metal zinc powder in the volatilization process to form a gas-solid reaction system, so that the kinetic condition of reduction reaction is improved, and the reaction is facilitated to obtain a silicon simple substance. Too high heat treatment temperature makes silicon tetrachloride preferentially volatilize, can't guarantee going on of reduction reaction, and too high incubation time will promote the technology cost, and too low heat treatment temperature can't satisfy the originated thermodynamic condition of reduction reaction, and too low incubation time can't guarantee that chemical reaction goes on completely and can't effectively get rid of remaining silicon tetrachloride.
In the method for preparing high-purity silicon by using the non-ferrous metal smelting waste slag, preferably, the crude silicon is subjected to secondary heat treatment before distillation treatment, and the secondary heat treatment is heat preservation at the temperature of 750-900 ℃ for 20-40 min. Because the crude silicon after heat treatment also contains a certain amount of zinc chloride and a trace amount of simple substance of zinc, if the crude silicon is directly distilled, the flue gas collected by distillation contains zinc and zinc chloride, and the flue gas is difficult to directly return to the step (3) to react with silicon tetrachloride. After the secondary heat treatment, the zinc chloride is removed and used for reduction roasting treatment in the step (2), so that the distillation treatment is facilitated to obtain a pure zinc simple substance. In addition, the secondary heat treatment is also equivalent to preheating the crude silicon, so that the energy consumption in the distillation process is reduced, and the energy consumption of the whole process flow is not increased substantially. Too high secondary heat treatment and heat preservation time can increase the process cost and possibly cause the volatilization of simple substance zinc, too low roasting temperature cannot reach the boiling point (732 ℃) of zinc chloride, and too short roasting time cannot effectively separate the zinc chloride.
In the method for preparing high-purity silicon by using the non-ferrous metal smelting waste residue, preferably, the distillation treatment is carried out in a microwave field enhanced distillation device by microwave heating, the microwave power is controlled to be 500-1500W, the temperature is increased to be 1000-1500 ℃, and the microwave radiation time is controlled to be 1-5 h. The crude silicon is subjected to zinc removal treatment by adopting a microwave distillation method, and zinc and silicon are separated by utilizing the difference of the boiling points of zinc and silicon (the boiling point of metal zinc is 907 ℃, and the boiling point of simple substance silicon is 2355 ℃). The material was heated to 1000 ℃ and 1500 ℃ by microwave radiation, which was above the melting point of elemental silicon (2355 ℃). Under this condition, silicon having a purity exceeding 5N can be obtained. The microwave distillation technology can realize the enhancement of the distillation and separation process and improve the separation efficiency. Researches show that microwave radiation has the characteristic of selective heating, substances with different dielectric constants have different microwave absorption capacities, so that the azeotropic point temperature and the composition of an azeotropic system under the microwave radiation are changed, taking a Zn-Si system as an example, when the composition of metal zinc is smaller than that of the azeotropic point, the relative volatility of the metal zinc and the elemental silicon can be increased by the microwave heating, and the zinc-silicon separation can be realized efficiently and energy-saving. After microwave distillation, high-purity silicon with the purity exceeding 5N is obtained. The effect of strengthening distillation cannot be achieved when the microwave power, the distillation temperature and the radiation time are too low, and the process energy consumption can be improved when the microwave power, the distillation temperature and the radiation time are too high.
The invention relates to a method for preparing high-purity silicon by using non-ferrous metal smelting waste residues, which belongs to the field of pyrometallurgy. Then, the collected zinc chloride is subjected to hydrogen reduction to prepare metal zinc and hydrogen chloride (additional products), the obtained metal zinc is used as a silicon reducing agent of silicon tetrachloride, and the metal zinc and the silicon tetrachloride are subjected to heat treatment to obtain crude silicon (a silicon-containing simple substance, the zinc chloride and a trace amount of unreacted zinc simple substance) and unreacted silicon tetrachloride (recycled and reacted with zinc). And performing secondary heat treatment on the crude silicon, volatilizing to remove zinc chloride (recycling and reacting with hydrogen), and distilling to remove trace zinc (recycling and reacting with silicon tetrachloride) by using a microwave enhanced distillation technology to realize the preparation of high-purity silicon. The whole process flow has no material waste, all the materials are effectively utilized after being basically separated in a pure way, the closed cycle of zinc and silicon is realized, the reduction of the intermediate product treatment process in the whole reaction system is facilitated, the cyclic utilization of resources is realized, and the method has the advantage of high resource utilization.
Under the condition of oxygen enrichment, sulfide ore is used as an auxiliary additive for chloridizing roasting, the chloridizing roasting of the non-ferrous metal smelting waste residue is carried out under the condition of oxygen enrichment, and the oxygen and the sulfide ore can synergistically promote the chloridizing reaction. In addition, the method can obviously reduce the partial pressure of gas-phase products under the oxygen-rich condition, reduce the Gibbs free energy change of chlorination reaction and is beneficial to the chlorination reaction. The oxygen-enriched condition reduces the roasting temperature of the chloridized volatile heavy metal elements and shortens the roasting time. Sulfide ore is used as a roasting additive, and sulfide has the functions of activating and reducing Gibbs free energy of chlorination reaction. The sulfide ore provided by the invention is used as a roasting additive to carry out chlorination volatilization roasting on the non-ferrous metal smelting waste residue, so that the chlorination volatilization of heavy metal elements in the non-ferrous metal smelting waste residue can be promoted, the roasting temperature of the chlorination volatilized heavy metal elements can be reduced, the roasting time can be shortened, the metal chlorination rate can be improved, and the process cost can be saved. In general, chlorination roasting is carried out under the condition of oxygen enrichment and sulfide ores, all factors are mutually matched and have synergistic effect, so that the roasting temperature can be greatly reduced, the roasting time is shortened, the recovery rate of metal elements is improved, all valuable metals in the non-ferrous metal smelting waste residue can be recovered in an energy-saving and efficient manner under a low-temperature environment, the non-ferrous metal smelting waste residue is fully utilized, and considerable economic benefit is created.
Compared with the prior art, the invention has the advantages that:
1. according to the method for preparing high-purity silicon by using the non-ferrous metal smelting slag, the non-ferrous metal smelting slag is subjected to chloridizing roasting, a zone condensation process is adopted in the flue gas collection process, silicon and heavy metal components in the slag are separated and recovered efficiently, the process flow of resource utilization of the waste slag is shortened, and the economic cost is reduced.
2. The method for preparing high-purity silicon by using the non-ferrous metal smelting waste residues has the advantages that the non-ferrous metal smelting waste residues are used as raw materials, the raw material cost is low, key components in the non-ferrous metal smelting waste residues can be fully utilized, high-purity silicon products can be prepared, additional metal products such as copper chloride and lead chloride can be obtained, the non-ferrous metal smelting waste residues can be efficiently recycled, the problem of recycling treatment of the non-ferrous metal smelting waste residues is solved, products with high additional values are obtained, the resource recycling rate is high, the environmental pollution caused by the non-ferrous metal smelting waste residues is avoided, and the method has wide application prospects.
3. The method for preparing high-purity silicon by using the non-ferrous metal smelting waste residue has low requirement on the waste residue raw material, only needs the waste residue raw material containing zinc and silicon, and has the advantage of good raw material applicability.
4. When the invention finishes the production, taking the treatment of the copper smelting slag as an example, the production amount of the copper smelting slag per year in China is about 2000 ten thousand tons, and by adopting the method, 13.4 ten thousand tons of 5N high-purity silicon can be prepared per year, thereby creating great economic benefit. In addition, the heavy metal content of the non-ferrous metal smelting slag treated by the method is far lower than that of the national hazardous waste landfill pollution control standard (GB18598-2019), so that the non-ferrous metal smelting slag is treated in a clean manner.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a process flow diagram of the method for preparing high-purity silicon from non-ferrous metal smelting slag according to the present invention.
Detailed Description
In order to facilitate an understanding of the invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the invention is not limited to the specific embodiments below.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
The important chemical compositions of copper smelting slag, zinc leaching slag, lead smelting slag and sulfide ore (taking pyrite as an example) used in the following examples and comparative examples are shown in tables 1, 2, 3 and 4, respectively.
Table 1: chemical composition of copper smelting slag (%, omega)
| Name (R) | Pb | Zn | Cu | SiO2 |
| Mass fraction (%) | 0.39 | 3.12 | 0.47 | 12.91 |
Table 2: chemical composition of zinc leaching residue (%, omega)
| Name (R) | Pb | Zn | Cu | SiO2 |
| Mass fraction (%) | 4.72 | 5.82 | 0.12 | 17.42 |
Table 3: chemical composition of lead smelting slag (%, omega)
| Name (R) | Pb | Zn | SiO2 |
| Mass fraction (%) | 3.82 | 8.21 | 12.39 |
Table 4: chemical composition of pyrite (%, omega)
| Name (R) | Fe | S | SiO2 |
| Mass fraction (%) | 43.71 | 42.96 | 11.37 |
Example 1:
as shown in FIG. 1, a method for preparing high-purity silicon from non-ferrous metal smelting slag comprises the following steps:
(1) 100g of copper slag (composition shown in Table 1, the same applies below) and 20g of CaCl2And 4gFeS2(pyrite, the ingredients are shown in table 4, the same below) are mixed uniformly, ground to 200 meshes, put into a corundum boat, and dried for 60min to obtain a pretreated mineral aggregate;
(2) putting the pretreated mineral aggregate into a multi-temperature-zone heating furnace, introducing 6L/min of oxygen-enriched air (the volume of oxygen in the oxygen-enriched air is 40%, the same applies below) into the furnace, heating the material to 600 ℃ at the heating rate of 10 ℃/min, then carrying out chlorination volatilization roasting for 15min, collecting generated flue gas in a partition mode in the roasting treatment process, and finally recovering 36.43g of SiCl4、6.53gZnCl2And 1.25g of other metal chloride fumes.
(3) The collected 6.53gZnCl2Putting the mixture into a high-temperature heating furnace, introducing hydrogen (the purity is about 99.999%) into the furnace, heating the mixture to 900 ℃ at the heating rate of 10 ℃/min, and then carrying out hydrogen reduction roasting for 30 min. About 3.12g of metallic zinc was obtained and the zinc was ground into zinc powder.
(4) 36.43g of obtained liquid silicon tetrachloride is mixed with 3.12g of obtained metal zinc powder, the temperature in the furnace is controlled to be 150 ℃, heat treatment is carried out for 30min, and the redundant unreacted silicon tetrachloride is recycled to the working procedure; and then controlling the temperature in the furnace to 850 ℃, preserving the heat for 30min to obtain crude silicon (about 0.76g of zinc-silicon mixture), and recycling the volatilized zinc chloride (about 6.3g of zinc chloride) to the hydrogen reduction procedure.
(5) And putting the obtained crude silicon into microwave field enhanced distillation equipment, heating the material to 1500 ℃ with 600W microwave power, controlling the microwave radiation time to be 3h, and finally obtaining high-purity silicon and zinc flue gas, wherein the zinc flue gas can be recycled to the process of reducing silicon tetrachloride by zinc. It was determined that in this example, about 0.65g of silicon having a purity of 99.9993% could be prepared.
In this embodiment, the multi-temperature zone heating furnace includes a roasting section and three chloride collecting sections, and chloride flue gas generated in the roasting section sequentially passes through the first chloride solid collecting section, the second chloride solid collecting section, and the third chloride liquid collecting section. The temperature of the first chloride solid-state collection section is controlled to be 300 ℃,the temperature of the second chloride solid collection section was controlled to 50 deg.c and the temperature of the third chloride liquid collection section was controlled to 25 deg.c (i.e., room temperature). Wherein the first chloride solid-state collecting section condenses and recovers CuCl and/or PbCl2ZnCl recovery by flue gas and second chloride solid-state collection section condensation2Condensation recovery SiCl of flue gas and third trichloride liquid collecting section4. The structure and temperature control of the multi-temperature zone heating furnace in the following embodiments are the same as those in the present embodiment.
Example 2:
as shown in FIG. 1, a method for preparing high-purity silicon from non-ferrous metal smelting slag comprises the following steps:
(1) 100g of copper slag (composition shown in Table 1, the same applies below) and 20g of CaCl2And 4gFeS2(pyrite, the ingredients are shown in table 4, the same below) are mixed uniformly, ground to 200 meshes, put into a corundum boat, and dried for 60min to obtain a pretreated mineral aggregate;
(2) putting the pretreated mineral aggregate into a multi-temperature-zone heating furnace, introducing 6L/min of oxygen-enriched air (the volume of oxygen in the oxygen-enriched air is 40%, the same applies below) into the furnace, heating the material to 600 ℃ at the heating rate of 10 ℃/min, then carrying out chlorination volatilization roasting for 15min, collecting generated flue gas in a partition mode in the roasting treatment process, and finally recovering 49.36g of SiCl4、12.18gZnCl2And 6.52g of other metal chloride fumes.
(3) Collecting 12.18g ZnCl2Putting the mixture into a high-temperature heating furnace, introducing hydrogen (the purity is about 99.999%) into the furnace, heating the mixture to 900 ℃ at the heating rate of 10 ℃/min, and then carrying out hydrogen reduction roasting for 30 min. About 5.82g of metallic zinc was obtained and the zinc was ground into zinc powder.
(4) 49.36g of obtained liquid silicon tetrachloride is mixed with 5.82g of obtained metal zinc powder, the temperature in the furnace is controlled to be 150 ℃, heat treatment is carried out for 30min, and the redundant unreacted silicon tetrachloride is recycled to the working procedure; then controlling the temperature in the furnace to 850 ℃, preserving the heat for 30min to obtain crude silicon (about 1.41g of zinc-silicon mixture), and recycling the volatilized zinc chloride to the hydrogen reduction process.
(5) And putting the obtained crude silicon into microwave field enhanced distillation equipment, heating the material to 1500 ℃ with 600W microwave power, controlling the microwave radiation time to be 1h, and finally obtaining high-purity silicon and zinc flue gas, wherein the zinc flue gas can be recycled to the process of reducing silicon tetrachloride by zinc. It was determined that in this example, about 1.21g of silicon having a purity of 99.9991% could be prepared.
Example 3:
as shown in FIG. 1, a method for preparing high-purity silicon from non-ferrous metal smelting slag comprises the following steps:
(1) 100g of copper slag (composition shown in Table 1, the same applies below) and 20g of CaCl2And 4gFeS2(pyrite, the ingredients are shown in table 4, the same below) are mixed uniformly, ground to 200 meshes, put into a corundum boat, and dried for 60min to obtain a pretreated mineral aggregate;
(2) placing the pretreated mineral aggregate into a multi-temperature-zone heating furnace, introducing 6L/min of oxygen-enriched air (the volume of oxygen in the oxygen-enriched air is 40%, the same applies below) into the furnace, heating the material to 600 ℃ at the heating rate of 10 ℃/min, then performing chlorination volatilization roasting, keeping the temperature for 15min, collecting the generated flue gas in a partition manner in the roasting treatment process, and finally recovering 35.1g of SiCl4、17.39gZnCl2And 5.13g other metal chloride fumes.
(3) Collecting 17.39g ZnCl2Putting the mixture into a high-temperature heating furnace, introducing hydrogen (the purity is about 99.999%) into the furnace, heating the mixture to 900 ℃ at the heating rate of 10 ℃/min, and then carrying out hydrogen reduction roasting for 30 min. About 8.31g of metallic zinc was obtained and the zinc was ground into zinc powder.
(4) Mixing 35.1g of obtained liquid silicon tetrachloride with 8.31g of obtained metal zinc powder, controlling the temperature in the furnace to be 150 ℃, preserving the heat for 30min for heat treatment, and recycling the redundant unreacted silicon tetrachloride to the working procedure; then controlling the temperature in the furnace to 850 ℃, preserving the heat for 30min to obtain crude silicon (about 1.91g of zinc-silicon mixture), and recycling the volatilized zinc chloride to the hydrogen reduction process.
(5) And putting the obtained crude silicon into microwave field enhanced distillation equipment, heating the material to 1500 ℃ with 600W microwave power, controlling the microwave radiation time to be 5h, and finally obtaining high-purity silicon and zinc flue gas, wherein the zinc flue gas can be recycled to the process of reducing silicon tetrachloride by zinc. It was determined that in this example, about 1.76g of silicon having a purity of 99.9996% was produced.
In the above embodiment, the intermediate products of zinc chloride, elemental zinc, silicon tetrachloride and the like can be recycled to corresponding processes, so that continuous production is realized, and no material is wasted in the whole process.
Claims (10)
1. A method for preparing high-purity silicon by using non-ferrous metal smelting waste residues is characterized by comprising the following steps:
(1) carrying out chlorination roasting on non-ferrous metal smelting waste residues containing zinc and silicon, and collecting chloride flue gas generated in the chlorination roasting process in a partition mode to obtain zinc chloride smoke dust and liquid silicon tetrachloride;
(2) reducing and roasting the zinc chloride smoke dust obtained in the step (1) to obtain metal zinc;
(3) mixing the liquid silicon tetrachloride obtained in the step (1) with the metal zinc obtained in the step (2), and then carrying out heat treatment to obtain crude silicon;
(4) and (4) distilling the crude silicon obtained in the step (3) to obtain high-purity silicon.
2. The method for producing high-purity silicon using non-ferrous metallurgical slag according to claim 1, wherein the chloridizing roasting of the non-ferrous metallurgical slag containing zinc and silicon comprises the steps of: mixing and grinding non-ferrous metal smelting waste residues, a chlorinating agent and sulphide ores, and drying to obtain a pretreated mineral aggregate; and then placing the pretreated mineral aggregate into a roasting furnace, introducing oxygen-enriched air into the roasting furnace, and heating for chlorination roasting.
3. The method for producing high-purity silicon from non-ferrous metal smelting slag according to claim 2, wherein the chlorinating agent comprises CaCl2NaCl and AlCl3The addition amount of the chlorinating agent is 10-30% of the mass of the non-ferrous metal smelting waste residue; the sulphide ore comprises at least one of pyrite, chalcopyrite, sphalerite or galena with the sulfur element mass content of not less than 30 percent, andthe addition amount of the sulfide ore is 5-10% of the mass of the non-ferrous metal smelting waste residue.
4. The method for preparing high-purity silicon by using non-ferrous metal smelting waste residue as claimed in claim 2, wherein during the chloridizing roasting, the flow rate of the oxygen-enriched air is controlled to be 2-10L/min, the roasting temperature is controlled to be 500-700 ℃, the roasting time is 10-20min, and the volume ratio of oxygen in the oxygen-enriched air is not less than 30%.
5. The method for producing high-purity silicon from non-ferrous smelting slag according to any one of claims 1 to 4, wherein the non-ferrous smelting slag containing zinc and silicon comprises one or more of copper smelting slag, zinc leaching slag and lead smelting slag, and the content of zinc in the copper smelting slag, the zinc leaching slag and the lead smelting slag is more than 3 wt.%, and the content of silicon is more than 12 wt.%.
6. The method for preparing high-purity silicon using non-ferrous metal smelting waste slag according to any one of claims 1 to 4, wherein the partitioned collection of chloride fume generated during the chloridizing roasting is that chloride fume is collected in partitions with different condensation points of the chloride fume, the roasting furnace used for the chloridizing roasting is a multi-temperature-zone heating furnace, the multi-temperature-zone heating furnace comprises a roasting section and three chloride collecting sections, the three chloride collecting sections comprise a first chloride solid collecting section, a second chloride solid collecting section and a third chloride liquid collecting section, and the chloride fume generated by the roasting section is collected by the first chloride solid collecting section, the second chloride solid collecting section and the third chloride liquid collecting section in sequence.
7. The method for preparing high-purity silicon using non-ferrous metal smelting waste slag as claimed in claim 6, wherein the temperature of the first chloride solid state collecting section is controlled to be 300-400 ℃, the temperature of the second chloride solid state collecting section is controlled to be 50-250 ℃, and the temperature of the third chloride liquid state collecting section is controlled to be 0-50 ℃.
8. The method for preparing high-purity silicon by using non-ferrous metal smelting waste residue as claimed in any one of claims 1 to 4, wherein the reducing agent in the reducing roasting treatment is hydrogen, and the reducing roasting treatment is heat preservation at 800-1000 ℃ for 20-40 min; the heat treatment is heat preservation for 20-40min at the temperature of 100-200 ℃.
9. The method for preparing high-purity silicon from non-ferrous metal smelting waste slag according to any one of claims 1 to 4, characterized in that the crude silicon is further subjected to a secondary heat treatment before the distillation treatment, wherein the secondary heat treatment is performed by heat preservation at 750-900 ℃ for 20-40 min.
10. The method for preparing high-purity silicon from non-ferrous metal smelting waste residue as claimed in any one of claims 1 to 4, wherein the distillation treatment is carried out by heating with microwave in a microwave field enhanced distillation device, controlling the microwave power at 500-.
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