A silicon-magnesium treatment method based on black talc mineral

Abstract

The present invention provides a method for processing silicon and magnesium based on black talc mineral, comprising the steps of: S1, obtaining a pretreated powder; the pretreated powder comprising a powder mixture of black talc and a carbon material; S2, subjecting the pretreated powder to chlorination roasting to obtain a roasting gas, a product liquid phase, and residual solids; the atmosphere of the chlorination roasting comprising chlorine; S3, subjecting the roasting gas to a first condensation to obtain a crude silicon tetrachloride liquid; subjecting the crude silicon tetrachloride liquid to a rectification and a second condensation in sequence to obtain a refined silicon tetrachloride liquid; subjecting the refined silicon tetrachloride liquid to a gas-phase combustion treatment to obtain a silicon dioxide product; and subjecting the product liquid phase to molten salt electrolysis to obtain crude metallic magnesium; and refining the crude metallic magnesium to obtain refined metallic magnesium. The present invention can obtain high-purity nano-scale silicon dioxide products and refined metallic magnesium, and achieves high-value utilization of silicon and magnesium resources.

Description

Technical Field

[0001] The invention belongs to the field of mineral processing, and in particular relates to a silicon-magnesium processing method based on black talc mineral. Background Art

[0002] Black talc (4SiO2·3MgO·2H2O) has a layered talc structure, with carbon (C) between the layers being the primary cause of its black color. Its main components are approximately 77% talc and 23% quartz. The talc, which makes up the majority, has a silicon-oxygen tetrahedral structure that firmly encloses magnesium-oxygen octahedra. Therefore, most acids, except hydrofluoric acid, are unable to break down the silicon-oxygen tetrahedral structure, making acidic treatment of black talc difficult. While alkaline treatment of black talc can disrupt the silicon-oxygen tetrahedral structure and separate the silicon from solids such as magnesium hydroxide in the form of a silicate liquid, this method suffers from low-purity silica products and the production of large amounts of magnesium-rich slag. While some researchers have investigated the separation and economical utilization of silicon and magnesium from black talc, most have failed to produce high-purity nanoscale silica powder (SiO2 content ≥99.999%; 10-50nm) from black talc, nor have they converted the magnesium in black talc into refined metallic magnesium (Mg), effectively maximizing the value of these resources.

[0003] For example, the Chinese invention patent application with publication number CN115849385A discloses a method and application for the comprehensive utilization of silicon and magnesium in black talc, which comprises mixing black talc with an acid leaching solution to react and obtaining a leachate and a leach residue, wherein the acid leaching solution comprises at least hydrofluoric acid and hydrochloric acid; mixing the leachate with a precipitant to perform precipitation and crystallization to obtain a sodium fluorosilicate precipitate and a silicon precipitation filtrate; treating the silicon precipitation filtrate to obtain a magnesium-containing substance; and washing the sodium fluorosilicate precipitate with sodium salt to obtain silicon dioxide. Although the above patent application achieves the simultaneous comprehensive utilization of silicon and magnesium and has a high utilization rate of effective ingredients, it has several major defects. First, hydrofluoric acid is extremely corrosive to existing industrial equipment, and second, it is difficult to achieve water balance due to the huge water consumption. In addition, its process is complicated, and the purity of the obtained silicon dioxide product cannot reach an SiO2 content of ≥99.999%, making it difficult to achieve high-value utilization of silicon and magnesium resources.

[0004] In view of this, it is necessary to provide a silicon-magnesium treatment method based on black talc mineral to solve or at least alleviate the technical problems of hydrofluoric acid corrosion-resistant equipment, large water consumption, low purity of silica products, low high-value utilization of silicon-magnesium resources, and complex treatment process. Summary of the Invention

[0005] The main purpose of the present invention is to provide a silicon-magnesium treatment method based on black talc mineral, which aims to solve or at least alleviate the technical problems of hydrofluoric acid corrosion equipment, large water consumption, low purity of silica products, low high-value utilization of silicon-magnesium resources, and complex treatment process.

[0006] To achieve the above object, the present invention provides a method for treating silicon and magnesium based on black talc mineral, comprising the steps of:

[0007] S1, obtaining a pretreated powder; the pretreated powder comprises a mixture of black talc and a carbon material powder, wherein the carbon material comprises a single carbon substance;

[0008] S2, chlorination roasting the pretreated powder to obtain roasting gas, product liquid phase and residual solid; the atmosphere of the chlorination roasting includes chlorine;

[0009] S3, performing a first condensation on the roasting gas to obtain crude silicon tetrachloride liquid; and / or performing molten salt electrolysis on the product liquid phase to obtain crude metallic magnesium.

[0010] Furthermore, the step S3 further comprises: sequentially performing distillation and a second condensation on the crude silicon tetrachloride liquid to obtain refined silicon tetrachloride liquid; the distillation temperature is 70-130°C, and the second condensation temperature is -50°C to 30°C.

[0011] Furthermore, the step S3 further comprises: subjecting the refined silicon tetrachloride liquid to gas phase combustion treatment to obtain a silicon dioxide product;

[0012] The gas phase combustion treatment includes: heat treating the refined silicon tetrachloride liquid, hydrogen and oxygen at 950-2100° C., and quenching the gaseous product of the heat treatment to obtain the silicon dioxide product; the volume ratio of the refined silicon tetrachloride liquid, the hydrogen and the oxygen is 1:300-900:300-1300.

[0013] Furthermore, the step S3 further comprises: refining the crude metallic magnesium to obtain refined metallic magnesium.

[0014] Furthermore, the method for obtaining the pretreated powder includes: ball-milling the black talc and the carbon material together to obtain the pretreated powder; the mass ratio of the black talc to the carbon material is 0.5-5:1; and the carbon material includes petroleum coke.

[0015] Furthermore, the ball milling speed is 100-600 rpm, and the ball milling time is 20-130 min.

[0016] Furthermore, the temperature of the chlorination roasting is not lower than 850° C.; and the duration of the chlorination roasting is not less than 8 minutes.

[0017] Furthermore, the atmosphere of the chlorination roasting further comprises an inert gas; and the volume ratio of the chlorine gas to the inert gas is 0.1-6:1.

[0018] Furthermore, the first condensation is step condensation; the final cooling temperature of the first condensation is -50°C to 30°C.

[0019] Furthermore, the chlorination roasting includes multiple roasting cycles, and the roasting time of each roasting cycle is not less than 8 minutes; after completing the previous roasting cycle, the next batch of the pretreated powder is roasted in the next roasting cycle; and the residual solid is repeatedly roasted with the next batch of the pretreated powder.

[0020] Compared with the prior art, the present invention has at least the following advantages:

[0021] The present invention can obtain high-purity nano-scale silica products and magnesium metal, with high value-added utilization of silicon and magnesium resources and a simple processing process. In addition, the present invention has a high chlorination conversion rate for black talc minerals, achieving the separation of silicon and magnesium resources in black talc minerals, and the purity of the crude silicon tetrachloride liquid obtained after chlorination roasting is basically not less than 99%. Specifically, black talc is a difficult-to-treat silicate. The present invention uses reduction chlorination-distillation-gas phase combustion to achieve the preparation of high-purity nano-scale silica powder with a particle size of 10-50nm and a SiO2 content of ≥99.999% from black talc. At the same time, the present invention successfully extracts magnesium components from black talc to produce refined magnesium metal through reduction chlorination-molten salt electrolysis-refining. Therefore, the present invention achieves the effective separation of black talc mineral components and high-value utilization of resources, and overcomes technical problems such as hydrofluoric acid corrosion equipment, high water consumption, low purity of silica products, low value-added utilization of silicon and magnesium resources, and complex processing procedures. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0023] Figure 1 This is the SEM-EDS mapping of the solid product after the roasting gas is hydrolyzed with ultrapure water in Example 1 of the present invention, and the hydrolysis temperature is room temperature. In the figure, (a) is the SEM image, (b) is the EDS image of the C element, (c) is the EDS image of the Si element, and (d) is the EDS image of the O element.

[0024] Figure 2This is the SEM-EDS mapping of the product after the liquid phase is condensed into a solid in Example 1 of the present invention. The condensation temperature is room temperature. In the figure, (a) is the SEM image, (b) is the EDS image of the Si element, (c) is the EDS image of the Mg element, and (d) is the EDS image of the Cl element.

[0025] Figure 3 This is the XPS valence band spectrum of Si 2p of the residual solid in Example 1 of the present invention; in the figure, chlorination time A refers to calcination for 10 minutes, and chlorination time B refers to calcination for 20 minutes;

[0026] Figure 4 This is the XPS valence band spectrum of Mg 1s of the residual solid in Example 1 of the present invention; in the figure, chlorination time A refers to calcination for 10 min, and chlorination time B refers to calcination for 20 min;

[0027] Figure 5 This is the XPS valence band spectrum of Cl 2p of the residual solid in Example 1 of the present invention; in the figure, chlorination time A refers to calcination for 10 minutes, and chlorination time B refers to calcination for 20 minutes;

[0028] Figure 6 This is a gas chromatography-mass spectrometry diagram of crude silicon tetrachloride liquid in Example 1 of the present invention.

[0029] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] Moreover, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0032] When numerical ranges are given in the examples, it should be understood that, unless otherwise specified herein, both endpoints of each numerical range and any value between them may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. The present invention may also be implemented using any prior art methods, equipment, and materials similar or equivalent to those described in the examples. In the present invention, the chlorination conversion rate is calculated as follows: chlorination conversion rate η = (1 - (mass of residual black talc / mass of black talc ore before chlorination)) × 100%. To eliminate the influence of excess petroleum coke on the calculation, the mass of the residual black talc after washing the residual solids and calcining them at 600°C in air for 2 hours is used as the mass of the residual black talc.

[0033] It should be noted that while existing research has methods for treating black talc and silicon magnesium, these methods suffer from at least one or more of the following deficiencies, preventing them from achieving high-value utilization of silicon magnesium resources: for example, long process steps, high energy consumption, low-purity silicon dioxide products, and large amounts of magnesium-rich slag generated when treating black talc minerals. The present invention addresses the issues of long process steps, high energy consumption, low-purity silicon dioxide products, and large amounts of magnesium-rich slag generated when treating black talc minerals using traditional metallurgical technologies. By innovatively utilizing a chlorination process to treat black talc minerals, the present invention achieves effective separation of the mineral components and high-value utilization of resources.

[0034] The present invention provides a method for treating silicon and magnesium based on black talc mineral, comprising the steps of:

[0035] S1, obtaining pretreated powder; the pretreated powder includes a powder mixture of black talc and carbon material.

[0036] In the present invention, the carbon material contains carbon, which is primarily present in the form of a single carbon substance. Thus, the carbon material in the present invention comprises a single carbon substance. The carbon material is an amorphous carbon source. In the carbon material, carbon accounts for greater than 90% by mass, and further greater than 95% or 97% by mass. As an alternative embodiment, the carbon material comprises petroleum coke. Of course, other similar carbon materials may also be used.

[0037] In the present invention, the mass ratio of the black talc to the carbon material is 0.5-5:1, further 1-3:1, further 1-2:1. Taking petroleum coke as an example, the present invention can provide sufficient amorphous carbon source as a reducing agent for the black talc by introducing the carbon material.

[0038] In the present invention, the pretreated powder is obtained by ball-milling the black talc and the carbon material to obtain the pretreated powder. As a preferred embodiment, the ball-milling of the black talc and the carbon material facilitates further intercalation carbonization of the black talc, thereby introducing and enriching a large amount of reducing agent carbon between the black talc TO layers.

[0039] In the present invention, the main component of the black talc is 4SiO2·3MgO·2H2O, and the black talc contains interlayer carbon (C), the content of interlayer carbon is 0.5-0.65wt.%, and the interlayer carbon is a carbonaceous substance existing between talc layers or inside the structure; the black talc is crushed black talc mineral; before the ball milling, the particle size of the black talc is less than 10μm.

[0040] In the present invention, the ball milling speed is 100-600 rpm, further 200-500 rpm; the ball milling time is 20-130 min, further 30-120 min; as a preferred embodiment, after completing the ball milling, the ball milled product is dried, such as: drying at 90-150°C for 30-120 min to obtain the pretreated powder.

[0041] S2, performing chlorination roasting on the pretreated powder to obtain roasting gas, product liquid phase and residual solid.

[0042] In the present invention, the atmosphere during the chlorination roasting includes chlorine, and the temperature of the chlorination roasting is not less than 850°C; further, the temperature of the chlorination roasting is not less than 900°C or not less than 950°C; further, the temperature of the chlorination roasting is 850-1300°C; further, the temperature of the chlorination roasting is 900-1200°C; further, the temperature of the chlorination roasting is 950-1200°C; further, the temperature of the chlorination roasting is 1000-1200°C; further, the temperature of the chlorination roasting is 1000-1100°C or 1100-1200°C.

[0043] In the present invention, the duration of the chlorination roasting is not less than 8 minutes; the duration of the chlorination roasting is 8-150 minutes; or, the duration of the chlorination roasting is not less than 10 minutes; further, the duration of the chlorination roasting is 10-120 minutes; further, the duration of the chlorination roasting is 15-120 minutes; it can also be 15-30 minutes, 60-120 minutes, or 100-150 minutes.

[0044] In the present invention, the atmosphere used in the chlorination roasting further includes an inert gas, and the volume ratio of the chlorine gas to the inert gas is 0.1-6:1, further 0.2-5:1, further 2-6:1, and can also be 2-5:1, 4-5:1, or 4-6:1; the atmosphere during the chlorination roasting specifically consists of the chlorine gas and the inert gas.

[0045] The present invention achieves effective separation of black talc mineral components and high-value utilization of resources by precisely controlling the chlorination gasification temperature difference of silicon and magnesium components during the chlorination roasting, thereby enabling the preparation of high-purity nano-scale silicon dioxide powder (SiO2 content ≥99.999%) and refined metallic magnesium from difficult-to-treat silicates such as black talc.

[0046] The overall reaction equation is: 4SiO2·3MgO·2H2O(s)+11Cl2(g)+5.5C(s)=3MgCl2(l)+4SiCl4(g)+5.5CO2(g)+H2O(l). Specifically, the chlorination temperature of the magnesium component of black talc is around 700°C, and the chlorination temperature of the silicon component is around 900°C. This means that at around 700°C, the hypothetical sub-reaction occurs: MgO·xH2O(s)+Cl2(g)+0.5C(s)=MgCl2(l)+0.5CO2(g)+xH2O(l), and at around 900°C, the hypothetical sub-reaction occurs: SiO2·xH2O(s)+2Cl2(g)+C(s)=SiCl4(g)+CO2(g)+xH2O(l). The silicon and magnesium components in black talc belong to the TOT structure, and there is no separate SiO2·xH2O(s) and MgO·xH2O(s). The above assumption only explains the temperature difference.

[0047] In the present invention, the chlorination roasting may include multiple roasting cycles, and the roasting time of each roasting cycle is not less than 8 minutes, and further is 8-150 minutes; or, the roasting time of each roasting cycle is not less than 10 minutes, and further is 10-120 minutes, and further is 15-120 minutes, and can also be 15-30 minutes, 60-120 minutes, or 100-150 minutes; after completing the previous roasting cycle, in the next roasting cycle, the next batch of the pretreated powder is directly roasted; and the residual solid can also be repeatedly roasted with the next batch of the pretreated powder.

[0048] As a supplementary explanation, before carrying out the chlorination roasting, the present invention pre-heats the pretreated powder at a heating rate of 5-10°C / min in an inert gas atmosphere; then the gas is switched to a mixed atmosphere of chlorine and inert gas; after one cycle of heat preservation (after completing one roasting cycle), the present invention replenishes the pretreated powder and repeats the chlorination roasting (the next roasting cycle); in a specific form, the chlorination roasting in the present invention includes bath smelting or boiling chlorination; the inert gas in the present invention includes one or more of argon and nitrogen.

[0049] S3: Subjecting the roasted gas to a first condensation to obtain a crude silicon tetrachloride liquid; and / or subjecting the resulting liquid phase to molten salt electrolysis to obtain crude metallic magnesium. The first condensation is a step condensation, with the final cooling temperature of the first condensation being between -50°C and 30°C, and further between -40°C and 20°C.

[0050] Furthermore, the crude silicon tetrachloride liquid is sequentially subjected to distillation and a second condensation to purify and obtain refined silicon tetrachloride liquid; in the present invention, the distillation temperature is 70-130°C, further 80-120°C, and the second condensation temperature is -50°C to 30°C, further -40°C to 20°C.

[0051] Furthermore, the refined silicon tetrachloride liquid is subjected to gas phase combustion treatment to obtain a silicon dioxide product, which is a high-purity nano-scale silicon dioxide powder. In the present invention, the particle size of the silicon dioxide product is 10-50nm, and the SiO2 content is ≥99.999%.

[0052] In the present invention, the gas-phase combustion process comprises: heat-treating the refined silicon tetrachloride liquid, hydrogen, and oxygen at 950-2100°C (preferably 1000-2000°C), continuously collecting volatile gases during the heat treatment, and quenching (rapidly cooling in stages) the gaseous products of the heat treatment to obtain the silicon dioxide product. The volume ratio of the refined silicon tetrachloride liquid, hydrogen, and oxygen is 1:300-900:300-1300, preferably 1:390-780:390-1170. Specifically, silicon tetrachloride is combusted in the presence of oxygen and hydrogen to produce high-purity silicon dioxide particles. At the reactor inlet, the silicon tetrachloride is thoroughly mixed with hydrogen and oxygen in a specific ratio to form a uniform reaction gas flow that enters the combustion chamber, where it fully reacts at high temperature. After the reaction, the high-temperature product is rapidly cooled to form ultrafine silicon dioxide powder, which is collected through a filter or cyclone separator to obtain high-purity nano-scale silicon dioxide powder.

[0053] In the present invention, the melting temperature of the molten salt electrolysis is 680-770°C and the current density is 4-10 kA / m2 , the cell voltage is 3-6V, and the current efficiency is 85-93%.

[0054] In the present invention, the crude magnesium metal is refined to obtain refined magnesium metal. The refining process includes: melting the crude magnesium metal, adding a refining agent, and removing impurities and slag generated by the reaction to obtain refined magnesium metal.

[0055] During the refining process, the melting temperature is 650-750° C., the stirring and holding time is 15-40 min, the static time is 30-80 min, and the refining agent is added at a mass ratio of 2-5%. The refining agent includes one or more of MgCl2, NaCl, and KCl; specifically, the refining agent includes MgCl2 and NaCl, and the mass ratio of MgCl2 to NaCl is 0.8-1.2:0.8-1.2; the refining agent includes NaCl and KCl, and the mass ratio of NaCl to KCl is 0.8-1.2:0.8-1.2; the refining agent includes NaCl, KCl, and MgCl2, and the mass ratio of NaCl, KCl, and MgCl2 is 0.8-1.2:0.8-1.2:0.8-1.2.

[0056] The specific implementation process of the present invention can be understood as follows: crushed black talc and petroleum coke are ball-milled and mixed in a certain proportion to obtain a pretreated powder; a certain amount of pretreated powder is weighed for chlorination roasting; the temperature is increased under an inert gas atmosphere, and the gas is switched to a mixed atmosphere of chlorine and inert gas in a certain proportion, and the temperature is kept for a roasting cycle to obtain roasting gas, a product liquid phase and residual solids; after a roasting cycle, new pretreated powder is added and the chlorination roasting is repeated, thereby entering the next roasting cycle; the roasting gas is condensed to obtain a crude silicon tetrachloride liquid; the product liquid phase is transferred to a molten salt electrolysis furnace for molten salt electrolysis, and crude metallic magnesium is obtained at the cathode; the residual solid is repeatedly subjected to chlorination roasting with the newly added pretreated powder; the crude silicon tetrachloride liquid is distilled and condensed to obtain refined silicon tetrachloride liquid; the crude metallic magnesium is refined to obtain refined metallic magnesium; the refined silicon tetrachloride liquid is treated by gas phase combustion to obtain high-purity nano-scale silicon dioxide powder, SiO2 ≥ 99.999%. Therefore, the present invention can prepare high-purity nano-scale silicon dioxide powder and refined metallic magnesium based on black talc, thereby achieving effective separation of black talc mineral components and high-value utilization of resources.

[0057] The following are specific examples of the present invention:

[0058] Example 1

[0059] A method for treating silicon and magnesium based on black talc mineral, comprising the following steps:

[0060] S1, ball-milling the crushed black talc and petroleum coke, and drying the ball-milled product to obtain a pretreated powder.

[0061] In this embodiment, the main component of the black talc is 4SiO2·3MgO·2H2O, containing 0.62 wt.% of interlayer carbon; the particle size of the crushed black talc is less than 10 μm; and the carbon content of the petroleum coke is greater than 97%.

[0062] In this embodiment, the mass ratio of black talc to petroleum coke is 2:1; the rotation speed of the ball mill is 300 rpm, and the ball milling time is 60 min; the drying temperature is 100° C., and the drying time is 60 min.

[0063] S2, chlorination roasting the pretreated powder; in this embodiment, the chlorination roasting process is: in an inert gas atmosphere, the temperature is raised to 1000°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and inert gas, and the temperature is kept for 20 minutes to obtain a roasting gas, a product liquid phase and a residual solid.

[0064] In this embodiment, the chlorination roasting is molten pool smelting; the inert gas is nitrogen; and in the mixed atmosphere, the volume ratio of chlorine to inert gas is 1:1.

[0065] S3, treatment of roasting gas, product liquid phase and residual solids:

[0066] S31, the roasting gas is sequentially subjected to step condensation at 600°C, 300°C, and 100°C, with the final cooling temperature being -20°C, to obtain crude silicon tetrachloride liquid; the crude silicon tetrachloride liquid is sequentially distilled at 100°C and condensed at -20°C to purify it to obtain refined silicon tetrachloride liquid; the refined silicon tetrachloride liquid is subjected to gas phase combustion treatment to obtain high-purity nano-scale silicon dioxide powder.

[0067] The process of gas phase combustion treatment is as follows: at the inlet of the reactor, the refined silicon tetrachloride liquid is fully mixed with hydrogen and oxygen in a volume ratio of 1L:390L:780L to form a uniform reaction gas flow that enters the combustion chamber; it is fully reacted at 1000°C, and the high-temperature product after the reaction is rapidly cooled in stages at 800°C, 400°C, and less than 100°C, and finally cooled to room temperature to form ultrafine silicon dioxide powder. The ultrafine silicon dioxide powder is collected by a cyclone separator to obtain high-purity nano-scale silicon dioxide powder.

[0068] S32, transferring the liquid phase of the product to a molten salt electrolysis furnace for molten salt electrolysis to obtain crude metallic magnesium at the cathode; and refining the crude metallic magnesium to obtain refined metallic magnesium.

[0069] The melting temperature of molten salt electrolysis is 720℃ and the current density is 6kA / m 2, the cell voltage is 5V and the current efficiency is 90%.

[0070] The refining process involves melting crude magnesium metal and adding refining agents (MgCl2, NaCl). The impurities and slag generated by the reaction are removed to obtain refined magnesium metal. The refining process is carried out at a melting temperature of 700°C, with stirring and holding times of 20 minutes and a rest time of 50 minutes. The refining agent is added at a mass ratio of 3%, with a mass ratio of MgCl2 to NaCl of 1:1.

[0071] Experimental results:

[0072] The crude silicon tetrachloride liquid produced in this example contained 99.06% SiCl₄. The chlorination conversion rate of the black talc mineral reached 90.3%. The reaction of 1 kg of black talc, 500 g of petroleum coke, and chlorine gas yielded 680 g of product liquid and 1619 g of crude silicon tetrachloride liquid.

[0073] In the high-purity nano-scale silicon dioxide powder of this embodiment, the particle size of SiO2 particles is 10-50nm, and the SiO2 content is ≥99.999%; in the refined metallic magnesium of this embodiment, the content of metallic magnesium is 98.60%.

[0074] The gas obtained by chlorination roasting in the same embodiment is hydrolyzed with ultrapure water; Figure 1 As shown, after the gas obtained by chlorination roasting is hydrolyzed with ultrapure water, the solid product obtained is SiO2.

[0075] See also Figure 2 As shown, in this embodiment, the product obtained by chlorination roasting is a liquid phase, and the solid after condensation is MgCl2.

[0076] While keeping other conditions of this example unchanged, the residual solids obtained after chlorination roasting for 10 min and 20 min were tested respectively.

[0077] See also Figure 3 As shown, chlorination roasting transforms the Si-O bonds in black talc into Si-Cl bonds, indicating that the stable silicon-oxygen tetrahedron (SiO4) structure of black talc is destroyed and silicon tetrachloride is generated.

[0078] See also Figure 4 As shown, chlorination roasting transforms the Mg-O bond in black talc into Mg-Cl bond, indicating that the stable magnesium oxide octahedron (MgO6) structure of black talc is destroyed and magnesium chloride is generated instead.

[0079] See also Figure 5 As shown, chlorination roasting causes Mg-Cl bonds and Si-Cl bonds to appear in the black talc after reaction, and the generated silicon tetrachloride enters the gas phase and magnesium chloride enters the liquid phase.

[0080] See also Figure 6 As shown in FIG. 1 , the gas chromatography-mass spectrometry chart confirms that the roasting gas in this embodiment is silicon tetrachloride after condensation.

[0081] Example 2

[0082] A method for treating silicon and magnesium based on black talc mineral, comprising the following steps:

[0083] S1, ball-milling the crushed black talc and petroleum coke, and drying the ball-milled product to obtain a pretreated powder.

[0084] In this embodiment, the main component of the black talc is 4SiO2·3MgO·2H2O, containing 0.51 wt.% of interlayer carbon; the particle size of the crushed black talc is less than 10 μm; and the carbon content of the petroleum coke is greater than 97%.

[0085] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1; the rotation speed of the ball mill is 500 rpm, and the ball milling time is 120 min; the drying temperature is 150° C., and the drying time is 120 min.

[0086] S2, chlorination roasting the pretreated powder; in this embodiment, the chlorination roasting process is: in an inert gas atmosphere, the temperature is raised to 1200°C at a heating rate of 8°C / min, and then the gas is switched to a mixed atmosphere of chlorine and inert gas, and the temperature is kept for 120 minutes to obtain roasting gas, product liquid phase and residual solid.

[0087] In this embodiment, the chlorination roasting is boiling chlorination; the inert gas is nitrogen; and in the mixed atmosphere, the volume ratio of chlorine to inert gas is 5:1.

[0088] S3, treatment of roasting gas, product liquid phase and residual solids:

[0089] S31, the roasting gas is sequentially subjected to step condensation at 600°C, 300°C, and 100°C, with the final cooling temperature being -40°C, to obtain crude silicon tetrachloride liquid; the crude silicon tetrachloride liquid is sequentially distilled at 80°C and condensed at -40°C to purify it to obtain refined silicon tetrachloride liquid; the refined silicon tetrachloride liquid is subjected to gas phase combustion treatment to obtain high-purity nano-scale silicon dioxide powder.

[0090] The process of gas phase combustion treatment is as follows: at the inlet of the reactor, the refined silicon tetrachloride liquid is fully mixed with hydrogen and oxygen in a volume ratio of 1L:780L:1170L to form a uniform reaction gas flow that enters the combustion chamber; it is fully reacted at 2000°C, and the high-temperature product after the reaction is rapidly cooled in stages at 800°C, 400°C, and less than 100°C, and finally cooled to room temperature to form ultrafine silicon dioxide powder. The ultrafine silicon dioxide powder is collected through a filter to obtain high-purity nano-scale silicon dioxide powder.

[0091] S32, transferring the liquid phase of the product to a molten salt electrolysis furnace for molten salt electrolysis to obtain crude metallic magnesium at the cathode; and refining the crude metallic magnesium to obtain refined metallic magnesium.

[0092] The melting temperature of molten salt electrolysis is 750℃ and the current density is 10kA / m 2 , the cell voltage is 5V and the current efficiency is 92%.

[0093] The refining process involves melting crude magnesium metal and adding refining agents (NaCl, KCl, and MgCl2). The resulting impurities and scum are then removed to produce refined magnesium metal. The refining process is carried out at a melting temperature of 720°C, with stirring and holding times of 30 minutes and a rest time of 60 minutes. The refining agents are added at a mass ratio of 3%, with a mass ratio of NaCl, KCl, and MgCl2 of 1:1:1.

[0094] Experimental results:

[0095] The crude silicon tetrachloride liquid in this example had a SiCl4 content of 99.25%. The chlorination conversion rate of the black talc mineral reached 96.10%. 1 kg of black talc, 1 kg of petroleum coke, and chlorine gas produced 724 g of liquid phase and 1723 g of crude silicon tetrachloride liquid.

[0096] In the high-purity nano-scale silicon dioxide powder of this embodiment, the SiO2 particle size is 10-50nm, and the SiO2 content is ≥99.999%; in the refined metallic magnesium of this embodiment, the metallic magnesium content is 99.50%.

[0097] Example 3

[0098] A method for treating silicon and magnesium based on black talc mineral, comprising the following steps:

[0099] S1, ball-milling the crushed black talc and petroleum coke, and drying the ball-milled product to obtain a pretreated powder.

[0100] In this embodiment, the main component of the black talc is 4SiO2·3MgO·2H2O, containing 0.58 wt.% of interlayer carbon; the particle size of the crushed black talc is less than 10 μm; and the carbon content of the petroleum coke is greater than 97%.

[0101] In this embodiment, the mass ratio of black talc to petroleum coke is 2:1; the rotation speed of the ball mill is 400 rpm, and the ball milling time is 90 min; the drying temperature is 120° C., and the drying time is 90 min.

[0102] S2, chlorination roasting the pretreated powder; in this embodiment, the chlorination roasting process is: in an inert gas atmosphere, the temperature is raised to 1100°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and inert gas, and the temperature is kept for 60 minutes to obtain roasting gas, product liquid phase and residual solid.

[0103] In this embodiment, the chlorination roasting is molten pool smelting; the inert gas is argon; and in the mixed atmosphere, the volume ratio of chlorine to inert gas is 2:1.

[0104] S3, treatment of roasting gas, product liquid phase and residual solids:

[0105] S31, the roasting gas is sequentially subjected to step condensation at 600°C, 300°C, and 100°C, with the final cooling temperature being -40°C, to obtain crude silicon tetrachloride liquid; the crude silicon tetrachloride liquid is sequentially distilled at 80°C and condensed at -40°C to purify it to obtain refined silicon tetrachloride liquid; the refined silicon tetrachloride liquid is subjected to gas phase combustion treatment to obtain high-purity nano-scale silicon dioxide powder.

[0106] The process of gas phase combustion treatment is as follows: at the inlet of the reactor, the refined silicon tetrachloride liquid is fully mixed with hydrogen and oxygen in a volume ratio of 1L:780L:1170L to form a uniform reaction gas flow that enters the combustion chamber; it is fully reacted at 2000℃, and the high-temperature product after the reaction is rapidly cooled in stages at 800℃, 400℃, and less than 100℃, and finally cooled to room temperature to form ultrafine silicon dioxide powder. The ultrafine silicon dioxide powder is collected through a filter to obtain high-purity nano-scale silicon dioxide powder.

[0107] S32, transferring the liquid phase of the product to a molten salt electrolysis furnace for molten salt electrolysis to obtain crude metallic magnesium at the cathode; and refining the crude metallic magnesium to obtain refined metallic magnesium.

[0108] The melting temperature of molten salt electrolysis is 730℃ and the current density is 8kA / m 2 , the cell voltage is 5V and the current efficiency is 91%.

[0109] The refining process involves melting crude magnesium metal and adding refining agents (NaCl, KCl, and MgCl2). The resulting impurities and scum are then removed to produce refined magnesium metal. The refining process is carried out at a melting temperature of 720°C, with stirring and holding times of 30 minutes and a rest time of 60 minutes. The refining agents are added at a mass ratio of 3%, with a mass ratio of NaCl, KCl, and MgCl2 of 1:1:1.

[0110] Experimental results:

[0111] The crude silicon tetrachloride liquid in this example had a SiCl4 content of 99.10%. The chlorination conversion rate of the black talc mineral reached 95.4%. The reaction of 1 kg of black talc, 500 g of petroleum coke, and chlorine gas yielded 718 g of liquid phase and 1710 g of crude silicon tetrachloride liquid.

[0112] In the high-purity nano-scale silicon dioxide powder of this embodiment, the particle size of SiO2 particles is 10-50nm, and the SiO2 content is ≥99.999%; in the refined metallic magnesium of this embodiment, the content of metallic magnesium is 99.4%.

[0113] Example 4

[0114] A method for treating silicon and magnesium based on black talc mineral, comprising the following steps:

[0115] S1, ball-milling the crushed black talc and petroleum coke, and drying the ball-milled product to obtain a pretreated powder.

[0116] In this embodiment, the main component of the black talc is 4SiO2·3MgO·2H2O, containing 0.53 wt.% of interlayer carbon; the particle size of the crushed black talc is less than 10 μm; and the carbon content of the petroleum coke is greater than 97%.

[0117] In this embodiment, the mass ratio of black talc to petroleum coke is 3:1; the rotation speed of the ball mill is 200 rpm, and the ball milling time is 30 min; the drying temperature is 90° C., and the drying time is 30 min.

[0118] S2, chlorination roasting the pretreated powder; in this embodiment, the chlorination roasting process is as follows: in an inert gas atmosphere, the temperature is raised to 900°C (roasting temperature) at a heating rate of 5°C / min, and then the gas is switched to a mixed atmosphere of chlorine and inert gas, and the temperature is kept for 10 minutes to obtain a roasting gas, a product liquid phase and a residual solid.

[0119] In this embodiment, the chlorination roasting is boiling chlorination; the inert gas is argon; and in the mixed atmosphere, the volume ratio of chlorine to inert gas is 0.2:1.

[0120] S3, treatment of roasting gas, product liquid phase and residual solids:

[0121] S31, the roasting gas is sequentially subjected to step condensation at 600°C, 300°C, and 100°C, with the final cooling temperature being 20°C, to obtain crude silicon tetrachloride liquid; the crude silicon tetrachloride liquid is sequentially distilled at 120°C and condensed at 20°C to purify it to obtain refined silicon tetrachloride liquid; the refined silicon tetrachloride liquid is subjected to gas phase combustion treatment to obtain high-purity nano-scale silicon dioxide powder.

[0122] The process of gas phase combustion treatment is as follows: at the inlet of the reactor, the refined silicon tetrachloride liquid is fully mixed with hydrogen and oxygen in a volume ratio of 1L:390L:780L to form a uniform reaction gas flow that enters the combustion chamber; it is fully reacted at 1000°C, and the high-temperature product after the reaction is rapidly cooled in stages at 800°C, 400°C, and less than 100°C, and finally cooled to room temperature to form ultrafine silicon dioxide powder. The ultrafine silicon dioxide powder is collected by a cyclone separator to obtain high-purity nano-scale silicon dioxide powder.

[0123] S32, transferring the liquid phase of the product to a molten salt electrolysis furnace for molten salt electrolysis to obtain crude metallic magnesium at the cathode; and refining the crude metallic magnesium to obtain refined metallic magnesium.

[0124] The melting temperature of molten salt electrolysis is 700℃ and the current density is 4kA / m 2 , the cell voltage is 4V and the current efficiency is 85%.

[0125] The refining process involves melting crude magnesium metal and adding refining agents (NaCl and KCl). The resulting impurities and slag are removed to produce refined magnesium metal. The melting temperature is 680°C. During the refining process, stirring and holding time are 20 minutes, and the rest time is 50 minutes. The refining agent is added at a mass ratio of 3%, with a mass ratio of NaCl to KCl of 1:1.

[0126] Experimental results:

[0127] The crude silicon tetrachloride liquid in this example had a SiCl4 content of 99.02%. The chlorination conversion rate of the black talc mineral reached 80.20%. 1 kg of black talc, 333 g of petroleum coke, and chlorine gas produced 604 g of liquid phase and 1438 g of crude silicon tetrachloride liquid.

[0128] In the high-purity nano-scale silicon dioxide powder of this embodiment, the particle size of SiO2 particles is 10-50nm, and the SiO2 content is ≥99.999%; in the refined metallic magnesium of this embodiment, the content of metallic magnesium is 98.30%.

[0129] Example 5

[0130] Compared with Example 4, in this example, only the calcination temperature is adjusted to 1100° C., and other conditions remain unchanged.

[0131] Experimental results:

[0132] The crude silicon tetrachloride liquid in this example had a SiCl4 content of 99.07%. The chlorination conversion rate of the black talc mineral reached 93.1%. 1 kg of black talc, 333 g of petroleum coke, and chlorine gas produced 701 g of liquid phase and 1669 g of crude silicon tetrachloride liquid.

[0133] In the high-purity nano-scale silicon dioxide powder of this embodiment, the SiO2 particle size is 10-50nm, and the SiO2 content is ≥99.999%; in the refined metallic magnesium of this embodiment, the metallic magnesium content is 98.94%.

[0134] Comparative Example 1

[0135] Compared with Example 4, this comparative example only omitted petroleum coke (black talc was directly ball-milled and dried as pretreated powder), and other conditions remained unchanged.

[0136] In this comparative example, the chlorination reaction could not occur and the black talc powder did not react. The experimental phenomenon was: the weight of the black talc powder did not change substantially before and after the reaction, and the XRD test showed that the characteristic peak of black talc was strong and substantially unchanged.

[0137] Comparative Example 2

[0138] Compared with Example 4, this comparative example only omitted the chlorine gas in the chlorination roasting process, and directly used inert gas as the roasting atmosphere, while other conditions remained unchanged.

[0139] In this comparative example, the chlorination reaction could not occur and the black talc powder was basically unreacted. The experimental phenomenon was: after removing the petroleum coke, the weight of the black talc powder was basically unchanged before and after the reaction. The XRD test showed that the characteristic peak of black talc was strong and basically unchanged.

[0140] Comparative Example 3

[0141] Compared with Example 1, this comparative example only changes the chlorine gas to hydrogen chloride gas, and other conditions remain unchanged.

[0142] The SiCl₄ content in the crude silicon tetrachloride liquid of this comparative example was 75.12%, and the chlorination conversion rate of the black talc mineral in this comparative example was 60.20%. The actual yield from the reaction of 1 kg of black talc, 500 g of petroleum coke, and hydrogen chloride gas was 453 g of liquid phase and 946 g of crude silicon tetrachloride liquid.

[0143] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for treating silicon and magnesium based on black talc mineral, characterized in that: Including steps: S1, obtaining a pretreated powder; the pretreated powder comprises a mixture of black talc and a carbon material powder, wherein the carbon material comprises a single carbon substance; S2, chlorination roasting the pretreated powder to obtain roasting gas, product liquid phase and residual solid; the atmosphere of the chlorination roasting includes chlorine and inert gas; before the chlorination roasting, the pretreated powder is heated in an inert gas atmosphere; the temperature of the chlorination roasting is 850-1300°C; S3, performing a first condensation on the roasting gas to obtain crude silicon tetrachloride liquid.

2. The method for treating silicon and magnesium based on black talc mineral according to claim 1, characterized in that: The liquid phase of the product is subjected to molten salt electrolysis to obtain crude metallic magnesium.

3. The method for treating silicon and magnesium based on black talc mineral according to claim 1, characterized in that: The step S3 further comprises: sequentially performing rectification and second condensation on the crude silicon tetrachloride liquid to obtain refined silicon tetrachloride liquid; the rectification temperature is 70-130° C., and the second condensation temperature is -50° C. to 30° C.

4. The method for treating silicon and magnesium based on black talc mineral according to claim 3, characterized in that: The step S3 further comprises: subjecting the refined silicon tetrachloride liquid to gas phase combustion treatment to obtain a silicon dioxide product; The gas phase combustion treatment includes: heat treating the refined silicon tetrachloride liquid, hydrogen and oxygen at 950-2100° C., and quenching the gaseous product of the heat treatment to obtain the silicon dioxide product; the volume ratio of the refined silicon tetrachloride liquid, the hydrogen and the oxygen is 1:300-900:300-1300.

5. The method for treating silicon and magnesium based on black talc mineral according to claim 2, characterized in that: The step S3 further includes: refining the crude metallic magnesium to obtain refined metallic magnesium.

6. The method for treating silicon and magnesium based on black talc mineral according to claim 1, characterized in that: The method for obtaining the pretreated powder includes: ball-milling the black talc and the carbon material together to obtain the pretreated powder; the mass ratio of the black talc to the carbon material is 0.5-5:1; and the carbon material includes petroleum coke.

7. The method for treating silicon and magnesium based on black talc mineral according to claim 6, characterized in that: The ball milling speed is 100-600 rpm, and the ball milling time is 20-130 min.

8. The method for treating silicon and magnesium based on black talc mineral according to claim 1, characterized in that: The duration of the chlorination roasting is not less than 8 minutes.

9. The method for treating silicon and magnesium based on black talc mineral according to claim 1, characterized in that: In the atmosphere of the chlorination roasting, the volume ratio of chlorine gas to inert gas is 0.1-6:

1.

10. The method for treating silicon and magnesium based on black talc mineral according to claim 1, characterized in that: The first condensation is step condensation; the final cooling temperature of the first condensation is -50°C to 30°C.

11. The method for treating silicon and magnesium based on black talc mineral according to any one of claims 1 to 10, characterized in that: The chlorination roasting includes multiple roasting cycles, and the roasting time of each roasting cycle is not less than 8 minutes; after completing the previous roasting cycle, the next batch of the pretreated powder is roasted in the next roasting cycle; the residual solid is repeatedly roasted with the next batch of the pretreated powder.

Images