A silicon material de-titanium refining method based on carbon capture and silicon oxide slag synergistic effect

Abstract

This invention relates to a method for refining silicon materials by removing titanium based on the synergistic effect of carbon capture and silicon oxide slag, belonging to the field of metallurgical purification technology for silicon-based materials. Addressing the technical challenge of efficiently separating titanium impurities in silicon-based materials (such as industrial silicon, silicon waste, and silicon alloys), this invention introduces carbon-based materials as collectors under high-temperature conditions. Utilizing the strong affinity between carbon and titanium, stable titanium-carbides are preferentially generated. Combined with the synergistic capture effect of the multi-component oxide slag system, the titanium carbides and byproduct silicon carbides are migrated and fixed in the slag phase. Interfacial mass transfer enhancement methods such as electromagnetic stirring, mechanical stirring, or gas injection are used to accelerate the bonding of carbides and slag. Through slag-gold separation, silicon materials with low titanium content are obtained. The titanium content in the refined silicon melt is significantly reduced, and carbide residue is effectively controlled.

Description

Technical Field

[0001] This invention relates to a method for removing titanium from silicon materials based on the synergistic effect of carbon capture and silicon oxide slag, belonging to the field of metallurgical purification technology of silicon-based materials. Background Technology

[0002] Currently, in the industrial silicon production process, the control of Ti in industrial silicon products is mainly achieved through source reduction, thereby mitigating the adverse effects of FeTiSi2 on downstream products. However, with the depletion of high-quality raw material reserves, directly reducing the initial introduction of Ti through raw material selection becomes increasingly difficult. This necessitates targeted pretreatment measures for industrial silicon smelting raw materials, which is clearly challenging given the current technological capabilities of industrial silicon smelting enterprises.

[0003] Oxidation ladle refining is widely used for virgin industrial silicon melts. While this refining method effectively separates Ca and Al, it fails to separate Ti from virgin industrial silicon, leading to Ti deposition and enrichment in the industrial silicon product. Research indicates that slag refining does not remove Ti from the silicon melt; in fact, it tends to increase it. Therefore, achieving enhanced Ti separation in industrial silicon products is a pressing issue that industrial silicon companies need to address. Summary of the Invention

[0004] To address the technical challenge of efficiently separating titanium impurities from silicon-based materials (such as industrial silicon, silicon waste, and silicon alloys), this invention proposes a method for titanium removal refining of silicon materials based on the synergistic effect of carbon capture and silicon oxide slag. Under high-temperature conditions, carbon-based materials are introduced as collectors, utilizing the strong affinity between carbon and titanium to preferentially react and generate stable titanium-carbides. Combined with the synergistic capture effect of the multi-component oxide slag system, the titanium carbides and byproduct silicon carbides are migrated and fixed in the slag phase. Interfacial mass transfer enhancement methods such as electromagnetic stirring, mechanical stirring, or gas injection are used to accelerate the bonding of carbides and slag. Through slag-metal separation, silicon materials with low titanium content are obtained. The titanium content in the refined silicon melt is significantly reduced, and carbide residue is effectively controlled.

[0005] A method for removing titanium from silicon materials based on the synergistic effect of carbon capture and silicon oxide slag, the specific steps of which are as follows: (1) Heat Ti-containing silicon raw materials to a temperature of 1820~2173 K under a protective atmosphere and hold at that temperature to melt them to form a silicon melt; (2) Add the carbon-based collector to the silicon melt and disperse it evenly. Heat it to 1820~2173K under a protective atmosphere and melt it for 0.5~3h so that the carbon-based collector combines with the titanium in the silicon melt to form titanium carbide, and obtain the silicon melt system. (3) A silicon oxide slag catcher is added to the silicon melt system and refined at a temperature of 1820~2173 K for 0.5~3 h. The silicon oxide slag catcher catches titanium carbides and silicon carbides in the silicon melt system to form a slag phase that separates from the silicon melt. At the same time, the interface mass transfer enhancement method is used to promote the migration and catching of titanium carbides and silicon carbides from the silicon melt to the slag phase. The silicon oxide slag catcher is composed of SiO2 and basic oxides. (4) Separate the slag phase from the silicon melt, and cool the silicon melt to room temperature to obtain silicon material with low titanium content.

[0006] Preferably, the Ti-containing silicon raw material in step (1) is one or more of industrial silicon, silicon waste, silicon alloy, or silicon-containing recycled materials.

[0007] Preferably, the carbon-based collector in step (2) is one or more of graphite, carbon powder, carbon fiber, biomass carbon, or carbon-based composite materials.

[0008] Preferably, the amount of carbon-based collector added in step (2) is 0.5 to 1.5% of the mass of the Ti-containing silicon raw material.

[0009] Preferably, the amount of silicon oxide slag catcher added in step (3) is 5 to 30% of the mass of the Ti-containing silicon raw material in step (1).

[0010] More preferably, the silicon oxide slag collector contains 10-60 wt% SiO2 and 40-90 wt% basic oxides; the basic oxides are a variety of Al2O3, CaO, MgO and BaO.

[0011] Preferably, the interface mass transfer enhancement method in step (3) is electromagnetic stirring, mechanical stirring or gas injection.

[0012] More preferably, the mechanical stirring rate is 100~500 rpm; when electromagnetic stirring is used, electromagnetic stirring is generated by the induction coil of the medium-frequency induction furnace during the heating process. Since the operating frequency is fixed, the temperature of the silicon melt is maintained at the set value by adjusting the current of the induction coil; based on 1 kg of silicon melt, the gas flow rate of the gas injection method is 1.0~5 L·min. -1 .

[0013] The beneficial effects of this invention are: At high temperatures, C has a stronger affinity for Ti than Si and Ti, and C preferentially reacts with Ti to form stable titanium-carbide, achieving effective capture of Ti by C. Combined with the synergistic capture effect of the multi-component oxide slag system, titanium carbide and by-product silicon carbide are migrated and fixed in the slag phase. The removal of Ti can reduce the adverse effects of this phase on the synthesis reaction of organosilicon monomers in industrial silicon. At the same time, C is difficult to be oxidized and separated during the oxidative ladle refining process. When a suitable amount of C is mixed in the primary industrial silicon, the method of this invention can achieve the synergistic separation of Ti and C. Detailed Implementation

[0014] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0015] Example 1: The silicon raw material containing Ti in this example is industrial silicon containing Ti, with a Ti content of 1100 ppm; A method for removing titanium from silicon materials based on the synergistic effect of carbon capture and silicon oxide slag, the specific steps of which are as follows: (1) Industrial silicon containing Ti is heated to 1820 K under a protective atmosphere (argon) and kept at that temperature to melt it, forming a silicon melt; (2) The carbon-based collector (carbon powder) is added to the silicon melt and dispersed evenly. The melt is heated to 1820 K under a protective atmosphere (argon) and held for 0.5 h to allow the carbon-based collector to combine with the titanium in the silicon melt to form titanium carbides, thus obtaining the silicon melt system. The amount of carbon-based collector (carbon powder) added is 0.5% of the mass of the Ti-containing silicon raw material. (3) A silicon oxide slag catcher (SiO2-Al2O3-CaO) is added to the silicon melt system and refined at 1820 K for 0.5 h. The silicon oxide slag catcher (SiO2-Al2O3-CaO) catches the titanium carbides and silicon carbides in the silicon melt system to form a slag phase that separates from the silicon melt. At the same time, the interface mass transfer enhancement method (mechanical stirring at a stirring rate of 100 rpm) is used to promote the migration and catching of titanium carbides and silicon carbides from the silicon melt to the slag phase. The amount of silicon oxide slag catcher (SiO2-Al2O3-CaO) added is 5% of the mass of the Ti-containing silicon raw material in step (1). The silicon oxide slag catcher (SiO2-Al2O3-CaO) contains 40 wt% SiO2, 15 wt% Al2O3, and 45 wt% CaO. (4) Separate the slag phase from the silicon melt, and cool the silicon melt to room temperature to obtain a silicon material with low titanium content; In this embodiment, the titanium content in the silicon material is 469.7 ppm, and the titanium removal rate reaches 57.3%.

[0016] Example 2: The silicon raw material containing Ti in this example is industrial silicon containing Ti, with a Ti content of 1100 ppm; A method for removing titanium from silicon materials based on the synergistic effect of carbon capture and silicon oxide slag, the specific steps of which are as follows: (1) Industrial silicon containing Ti is heated to 1923 K under a protective atmosphere (argon) and kept at that temperature to melt it, forming a silicon melt; (2) A carbon-based collector (biomass carbon) is added to the silicon melt and dispersed evenly. The melt is heated to 1923 K under a protective atmosphere (argon) and held for 1.5 h to allow the carbon-based collector to combine with titanium in the silicon melt to form titanium carbides, thus obtaining a silicon melt system. The amount of carbon-based collector (biomass carbon) added is 0.7% of the mass of the Ti-containing silicon raw material. (3) Add silicon oxide slag catcher (SiO2-Al2O3-CaO) to the silicon melt system and refine it at 1923 K for 1.5 h. The silicon oxide slag catcher (SiO2-Al2O3-CaO) catches titanium carbides and silicon carbides in the silicon melt system to form a slag phase that separates from the silicon melt. At the same time, the interface mass transfer enhancement method (electromagnetic stirring, since the working frequency of the medium frequency induction furnace is kept at a fixed value, the temperature of the silicon melt is stabilized at 1923 K by adjusting the current of the induction coil) is used to promote the migration and collection of titanium carbides and silicon carbides from the silicon melt to the slag phase. The amount of silicon oxide slag catcher (SiO2-Al2O3-CaO) added is 15% of the mass of the silicon raw material containing Ti in step (1). In the silicon oxide slag catcher (SiO2-Al2O3-CaO), SiO2 accounts for 40wt%, Al2O3 accounts for 20wt%, and CaO accounts for 40wt%. (4) Separate the slag phase from the silicon melt, and cool the silicon melt to room temperature to obtain a silicon material with low titanium content; In this embodiment, the titanium content in the silicon material is 390.5 ppm, and the titanium removal rate reaches 64.5%.

[0017] Example 3: The silicon raw material containing Ti in this example is industrial silicon containing Ti, with a Ti content of 1100 ppm; A method for removing titanium from silicon materials based on the synergistic effect of carbon capture and silicon oxide slag, the specific steps of which are as follows: (1) Industrial silicon containing Ti is heated to 2173 K under a protective atmosphere (argon) and kept at that temperature to melt it, forming a silicon melt; (2) A carbon-based collector (graphite) is added to the silicon melt and dispersed evenly. The melt is heated to 2173 K under a protective atmosphere (argon) and held for 3 h to allow the carbon-based collector to combine with titanium in the silicon melt to form titanium carbides, thus obtaining a silicon melt system. The amount of carbon-based collector (graphite) added is 1.5% of the mass of the Ti-containing silicon raw material. (3) Add silicon oxide slag catcher (SiO2-Al2O3-MgO) to the silicon melt system and refine it at 2173 K for 3 h. The silicon oxide slag catcher (SiO2-Al2O3-MgO) catches titanium carbides and silicon carbides in the silicon melt system to form a slag phase that separates from the silicon melt. At the same time, the interface mass transfer enhancement method (electromagnetic stirring, since the working frequency of the medium frequency induction furnace is kept at a fixed value, the temperature of the silicon melt is stabilized at 2173 K by adjusting the current of the induction coil) is used to promote the migration and collection of titanium carbides and silicon carbides from the silicon melt to the slag phase. The amount of silicon oxide slag catcher (SiO2-Al2O3-MgO) added is 30% of the mass of the silicon raw material containing Ti in step (1). In the silicon oxide slag catcher (SiO2-Al2O3-MgO), SiO2 accounts for 10wt%, Al2O3 accounts for 50wt%, and MgO accounts for 40wt%. (4) Separate the slag phase from the silicon melt, and cool the silicon melt to room temperature to obtain a silicon material with low titanium content; In this embodiment, the titanium content in the silicon material is 500.5 ppm, and the titanium removal rate reaches 54.5%.

[0018] Example 4: The silicon raw material containing Ti in this example is industrial silicon containing Ti, with a Ti content of 1100 ppm; A method for removing titanium from silicon materials based on the synergistic effect of carbon capture and silicon oxide slag, the specific steps of which are as follows: (1) Industrial silicon containing Ti is heated to 1873 K under a protective atmosphere (argon) and kept at that temperature to melt it, forming a silicon melt; (2) The carbon-based collector (carbon fiber) is added to the silicon melt and dispersed evenly. The melt is heated to 1873 K under a protective atmosphere (argon) and held for 1 h to allow the carbon-based collector to combine with the titanium in the silicon melt to form titanium carbides, thus obtaining a silicon melt system. The amount of carbon-based collector (carbon fiber) added is 0.9% of the mass of the Ti-containing silicon raw material. (3) A silicon oxide slag trap (SiO2-Al2O3-BaO) was added to the silicon melt system and refined at 1873 K for 1 h. The silicon oxide slag trap (SiO2-Al2O3-BaO) traps the titanium carbides and silicon carbides in the silicon melt system to form a slag phase that separates from the silicon melt. At the same time, an interfacial mass transfer enhancement method (gas injection method, with a gas flow rate of 1.0 L·min for 1 kg of silicon melt) was adopted. -1This promotes the migration and collection of titanium carbides and silicon carbides from the silicon melt to the slag phase; the amount of silicon oxide slag collector (SiO2-Al2O3-BaO) added is 10% of the mass of the Ti-containing silicon raw material in step (1); the silicon oxide slag collector (SiO2-Al2O3-BaO) contains 40wt% SiO2, 20wt% Al2O3, and 40wt% BaO. (4) Separate the slag phase from the silicon melt, and cool the silicon melt to room temperature to obtain a silicon material with low titanium content; In this embodiment, the titanium content in the silicon material is 393.8 ppm, and the titanium removal rate reaches 64.2%.

[0019] Example 5: The silicon raw material containing Ti in this example is a silicon alloy containing Ti (Si content 95 wt%, Al content 5 wt%), and the Ti content is 900 ppm; A method for removing titanium from silicon materials based on the synergistic effect of carbon capture and silicon oxide slag, the specific steps of which are as follows: (1) A silicon alloy containing Ti (Si content 95 wt%, Al content 5 wt%) is heated to 2100 K under a protective atmosphere (argon) and held at that temperature to melt it, forming a silicon melt; (2) The carbon-based collector (carbon powder) is added to the silicon melt and dispersed evenly. The melt is heated to 2173 K under a protective atmosphere (argon) and held for 2 h to allow the carbon-based collector to combine with the titanium in the silicon melt to form titanium carbides, thus obtaining the silicon melt system. The amount of carbon-based collector (carbon powder) added is 1% of the mass of the Ti-containing silicon raw material. (3) A silicon oxide slag trap (SiO2-Al2O3-CaO-BaO) was added to the silicon melt system and refined at 1993 K for 2 h. The silicon oxide slag trap (SiO2-Al2O3-CaO-BaO) traps the titanium carbides and silicon carbides in the silicon melt system to form a slag phase that separates from the silicon melt. At the same time, an interface mass transfer enhancement method (gas injection method, with a gas flow rate of 5 L·min for 1 kg of silicon melt) was adopted. -1 This promotes the migration and collection of titanium carbides and silicon carbides from the silicon melt to the slag phase; the amount of silicon oxide slag collector (SiO2-Al2O3-CaO-BaO) added is 20% of the mass of the Ti-containing silicon raw material in step (1); the silicon oxide slag collector (SiO2-Al2O3-CaO-BaO) contains 60 wt% SiO2, 15 wt% Al2O3, 15 wt% CaO, and 10 wt% BaO. (4) Separate the slag phase from the silicon melt, and cool the silicon melt to room temperature to obtain a silicon material with low titanium content; In this embodiment, the titanium content in the silicon material is 331.2 ppm, and the titanium removal rate reaches 63.2%.

[0020] Example 6: The silicon raw material containing Ti in this example is silicon waste containing Ti, with a Ti content of 1500 ppm; A method for removing titanium from silicon materials based on the synergistic effect of carbon capture and silicon oxide slag, the specific steps of which are as follows: (1) Heat Ti-containing silicon waste to 2073 K under a protective atmosphere (argon) and keep it at that temperature to melt it and form a silicon melt; (2) The carbon-based collector (carbon powder) is added to the silicon melt and dispersed evenly. The melt is heated to 2073 K under a protective atmosphere (argon) and held for 2.5 h to allow the carbon-based collector to combine with the titanium in the silicon melt to form titanium carbides, thus obtaining the silicon melt system. The amount of carbon-based collector (carbon powder) added is 1.3% of the mass of the Ti-containing silicon raw material. (3) A silicon oxide slag catcher (SiO2-Al2O3-CaO-MgO) is added to the silicon melt system and refined at 2073 K for 2.5 h. The silicon oxide slag catcher (SiO2-Al2O3-CaO-MgO) catches the titanium carbides and silicon carbides in the silicon melt system to form a slag phase that separates from the silicon melt. At the same time, the interface mass transfer enhancement method (mechanical stirring at a stirring rate of 500 rpm) is used to promote the migration and catching of titanium carbides and silicon carbides from the silicon melt to the slag phase. The amount of silicon oxide slag catcher (SiO2-Al2O3-CaO-MgO) added is 25% of the mass of the Ti-containing silicon raw material in step (1). In the silicon oxide slag catcher (SiO2-Al2O3-CaO-MgO), SiO2 accounts for 30 wt%, Al2O3 accounts for 20 wt%, CaO accounts for 35 wt%, and MgO accounts for 15 wt%. (4) Separate the slag phase from the silicon melt, and cool the silicon melt to room temperature to obtain a silicon material with low titanium content; In this embodiment, the titanium content in the silicon material is 538.5 ppm, and the titanium removal rate reaches 64.1%.

[0021] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for titanium removal refining of silicon materials based on the synergistic effect of carbon capture and silicon oxide slag, characterized in that, The specific steps are as follows: (1) Heat Ti-containing silicon raw materials to a temperature of 1820~2173 K under a protective atmosphere and hold at that temperature to melt them to form a silicon melt; (2) Add the carbon-based collector to the silicon melt and disperse it evenly. Heat it to 1820~2173 K under a protective atmosphere and melt it for 0.5~3h so that the carbon-based collector combines with the titanium in the silicon melt to form titanium carbide, and obtain the silicon melt system. (3) A silicon oxide slag catcher is added to the silicon melt system and refined at a temperature of 1820~2173 K for 0.5~3 h. The silicon oxide slag catcher catches titanium carbides and silicon carbides in the silicon melt system to form a slag phase that separates from the silicon melt. At the same time, the interface mass transfer enhancement method is used to promote the migration and catching of titanium carbides and silicon carbides from the silicon melt to the slag phase. The silicon oxide slag catcher is composed of SiO2 and basic oxides. (4) Separate the slag phase from the silicon melt, and cool the silicon melt to room temperature to obtain silicon material with low titanium content.

2. The silicon material detitanium refining method based on the synergistic effect of carbon capture and silicon oxide slag according to claim 1, characterized in that: Step (1) The silicon raw material containing Ti is one or more of industrial silicon, silicon waste, silicon alloy or silicon-containing recycled materials.

3. The silicon material detitanium refining method based on the synergistic effect of carbon capture and silicon oxide slag according to claim 1, characterized in that: Step (2) The carbon-based collector is one or more of graphite, carbon powder, carbon fiber, biomass carbon or carbon-based composite materials.

4. The silicon material detitanium refining method based on the synergistic effect of carbon capture and silicon oxide slag according to claim 1, characterized in that: In step (2), the amount of carbon-based collector added is 0.5 to 1.5% of the mass of the Ti-containing silicon raw material.

5. The method for titanium removal refining of silicon materials based on the synergistic effect of carbon capture and silicon oxide slag according to claim 1, characterized in that: In step (3), the silicon oxide slag collector contains 10-60 wt% SiO2 and 40-90 wt% alkaline oxides.

6. The silicon material detitanium refining method based on the synergistic effect of carbon capture and silicon oxide slag according to claim 5, characterized in that: The basic oxides are a variety of Al2O3, CaO, MgO and BaO.

7. The silicon material detitanium refining method based on the synergistic effect of carbon capture and silicon oxide slag according to claim 1, characterized in that: Step (3) The interface mass transfer enhancement method is electromagnetic stirring, mechanical stirring or gas injection.