Chlorination method of black talc mineral, deep chlorination process and application

Abstract

The present invention provides a chlorination method, deep chlorination process and application of black talc mineral. The chlorination method comprises the following steps: crushing black talc and carbonaceous substances in a mixed state to obtain pre-treated powder; carbonaceous substances contain carbon element; the pre-treated powder is roasted in an atmosphere of chlorine gas mixture to obtain chlorinated black talc; wherein the roasting temperature is 700-800 ° C, and the chlorine gas mixture includes chlorine and carbon monoxide. The above-mentioned chlorination method of black talc mineral, by crushing, allows part of the carbonaceous substances to enter the black talc structure to form intercalated carbon. Combined with the composition of the specific chlorine gas mixture and the selection of the roasting temperature, the magnesium component is chlorinated without chlorinating the silicon component. In this way, the chlorination efficiency of black talc is improved, the air permeability of the black talc chlorination method is enhanced, and the full conversion and utilization of magnesium resources in black talc is realized, and the magnesium conversion rate of the black talc mineral chlorination process can reach more than 77%, and some conditions can reach 90%.

Description

Technical Field

[0001] The invention relates to the field of black talc treatment, in particular to a chlorination method, deep chlorination process and application of black talc minerals. Background Art

[0002] Black talc (4SiO2·3MgO·2H2O) is a layered talc structure, and the carbon (C) between the layers is the main cause of the black color. The main components are about 77% talc and about 23% quartz. The silicon-oxygen tetrahedral structure of talc, which accounts for the majority, firmly wraps the magnesium-oxygen octahedron in the middle. Therefore, most acids except hydrofluoric acid find it difficult to break the silicon-oxygen tetrahedral structure, making it difficult to treat black talc by acid method. If the black talc is treated by alkali method, although the silicon-oxygen tetrahedral structure can be destroyed and silicon can be separated from solids such as magnesium hydroxide in the form of silicate liquid, this method has problems such as low purity of silica product and large amount of magnesium-rich slag produced. Although some researchers have conducted some research on the separation and economic utilization of silicon and magnesium in black talc, most of them have not achieved high-value utilization of silicon and magnesium resources.

[0003] Chlorination is an effective method for realizing high-value utilization of black talc. However, the conventional chlorination method has a low degree of chlorination of black talc, that is, the magnesium chloride conversion rate is low. In view of this, it is necessary to provide a chlorination method for black talc mineral to solve or at least alleviate the technical problem of low magnesium chloride conversion rate of black talc. Summary of the invention

[0004] The main purpose of the present invention is to provide a chlorination method for black talc mineral to solve the technical problem of low magnesium chloride conversion rate of black talc.

[0005] To achieve the above object, the present invention provides a method for chlorinating black talc mineral, comprising the following steps:

[0006] The black talc and the carbonaceous substance are first crushed in a mixed state to obtain a pre-treated powder; the carbonaceous substance contains a single carbon substance;

[0007] The pretreated powder is subjected to a first chlorination roasting in an atmosphere of a chlorine gas mixture and a first roasting temperature to obtain chlorinated black talc; wherein the first roasting temperature is 700-800°C, the chlorine gas mixture comprises chlorine and carbon monoxide, and the volume ratio of chlorine to carbon monoxide is 2.5-5:1.

[0008] According to an embodiment of the present application, the mass ratio of the black talc to the carbon element in the carbon-based substance is 1:3-1.

[0009] According to an embodiment of the present application, the carbon-based substance is petroleum coke.

[0010] According to an embodiment of the present application, the black talc and the carbonaceous material are first crushed by ball milling, the ball milling speed is 200-500 rpm, and the ball milling time is 30-120 min.

[0011] According to an embodiment of the present application, in the step of performing the first roasting of the pretreated powder, the first roasting time is not less than 90 minutes.

[0012] According to the implementation mode of the present application, after the pre-treated powder is heated to 700-800° C., the chlorine gas mixture is introduced to react.

[0013] According to an embodiment of the present application, in the step of first calcining the pretreated powder, the pretreated powder is first calcined under the condition of adding a chlorination catalyst, and the chlorination catalyst includes carbon tetrachloride or carbon disulfide.

[0014] The present application also provides an application of the above-mentioned chlorination method of black talc mineral in the preparation of nano silicon dioxide, comprising the following steps:

[0015] The chlorinated black talc obtained by the chlorination method is reacted with a hydrochloric acid solution, and the solid matter is collected to obtain nano silicon dioxide.

[0016] According to an embodiment of the present application, the concentration of the hydrochloric acid solution is 0.5-2 mol / L, and the liquid-to-solid ratio of the chlorinated black talc to the hydrochloric acid solution is 1:5-10.

[0017] According to an embodiment of the present application, the reaction time of the chlorinated black talc and the hydrochloric acid solution is 30 minutes.

[0018] The present application also provides a deep chlorination process of black talc mineral, comprising the following steps:

[0019] The chlorinated black talc obtained by the above chlorination method is soaked in water to wash away water-soluble substances, and dried to obtain washed black talc;

[0020] The washed black talc and the carbonaceous material are crushed for the second time in a mixed state to obtain a pre-chlorinated powder;

[0021] The pre-chlorinated powder is subjected to a second chlorination roasting in a chlorine atmosphere and at a second roasting temperature, and a gas phase is collected to obtain a silicon tetrachloride gas phase; the second roasting temperature is not less than 850°C.

[0022] According to an embodiment of the present application, the mass ratio of the chlorinated black talc to the carbon element in the carbon-based substance is 3-1:1.

[0023] According to an embodiment of the present application, in the step of performing the second chlorination roasting, the second roasting temperature is 850 - 1300 °C, and the heat preservation duration is 10 - 120 min.

[0024] According to an embodiment of the present application, in the step of performing the second chlorination roasting on the pre-chlorinated powder material under the conditions of a chlorine atmosphere and a second roasting temperature, chlorine and an inert gas are introduced in a volume ratio of (5 - 1):(5 - 1).

[0025] According to an embodiment of the present application, it further includes at least one of the following operations (1) - (2):

[0026] (1) Collect the water leaching solution in the step of soaking the chlorinated black talc to obtain a magnesium chloride solution;

[0027] (2) Collect the liquid phase substance in the second chlorination roasting to obtain a molten magnesium chloride.

[0028] According to an embodiment of the present application, it further includes:

[0029] Perform a first condensation on the silicon tetrachloride gas phase to obtain a crude silicon tetrachloride liquid.

[0030] According to an embodiment of the present application, the temperature of the first condensation is lower than 20 °C.

[0031] In the above-mentioned chlorination method of black talc minerals, during the crushing process, some carbonaceous substances enter the black talc structure to form intercalated carbon. Combined with the specific composition of the chlorine mixed gas and the selection of the roasting temperature, the magnesium component is chlorinated without chlorinating the silicon component. In this way, the chlorination efficiency of black talc is improved, the air permeability of the black talc chlorination method is enhanced, the full conversion and utilization of magnesium resources in black talc are realized, and the magnesium conversion rate in the black talc mineral chlorination process is high, which can reach more than 77%, and can reach 90% under some conditions. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0033] Figure 1(a) is an X-ray diffraction (XRD) pattern of Example 1 of the embodiment of the present invention.

[0034] Figure 1(b) is the SEM image of Example 1 of the embodiment of the present invention. Among them, "X5,000" in the figure means "magnification 5,000 times". "WD" is the abbreviation of "Working Distance", that is, "working distance". JEOL represents the instrument model.

[0035] Figure 1(c) is the EDS image of Example 1 of the embodiment of the present invention.

[0036] Figure 2 It is the X-ray diffraction (XRD) pattern of Example 2 of the embodiment of the present invention.

[0037] Figure 3 It is the X-ray diffraction (XRD) pattern of Example 3 of the embodiment of the present invention.

[0038] Figure 4 It is the X-ray diffraction (XRD) pattern of Example 8 of the embodiment of the present invention.

[0039] Figure 5 It is the X-ray diffraction (XRD) pattern of Comparative Example 1 of the embodiment of the present invention.

[0040] Figure 6 It is the X-ray diffraction (XRD) pattern of Comparative Example 2 of the embodiment of the present invention.

[0041] Figure 7 It is the gas chromatography-mass spectrometry (GC-MS) pattern of the silicon tetrachloride gas phase substance of Example 9 of the embodiment of the present invention.

[0042] Figure 8 It is the gas chromatography-mass spectrometry (GC-MS) pattern of the silicon tetrachloride gas phase substance of Example 10 of the embodiment of the present invention.

[0043] Figure 9 It is the gas chromatography-mass spectrometry (GC-MS) pattern of the silicon tetrachloride gas phase substance of Example 11 of the embodiment of the present invention.

[0044] Figure 10 It is the gas chromatography-mass spectrometry (GC-MS) pattern of the silicon tetrachloride gas phase substance of Example 12 of the embodiment of the present invention.

[0045] Figure 11 It is the gas chromatography-mass spectrometry (GC-MS) pattern of the silicon tetrachloride gas phase substance of Example 13 of the embodiment of the present invention.

[0046] The realization, functional features and advantages of the object of the present invention will be further described with reference to the accompanying drawings in combination with the embodiments. Detailed Embodiments

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0048] Furthermore, 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 they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0049] The present invention provides a chlorination method of black talc mineral, comprising the following steps:

[0050] S100: performing a first crushing on the black talc and the carbonaceous substance in a mixed state to obtain a pretreated powder; the carbonaceous substance contains a single carbon substance.

[0051] The main component of the black talc is 4SiO2·3MgO·2H2O, and the black talc contains interlayer carbon (C), and the content of interlayer carbon (C) is 0.51-0.67wt.%. Interlayer carbon (C) is a carbonaceous substance existing between talc layers or inside the structure, and the existence form may include adsorbed carbon, encapsulated carbon and graphitized carbon.

[0052] Since black talc and carbonaceous materials are crushed in a mixed state, such as grinding, ball milling and other crushing methods. During the crushing process, black talc and carbonaceous materials are broken up and refined, and black talc and carbonaceous materials also collide and mix with each other continuously. Specifically, black talc and carbonaceous materials are continuously crushed and refined, the particle size is reduced, and the specific surface area is increased. This makes the particles of the two substances have more contact points and a larger contact area, thereby achieving close contact between the particles of black talc and carbonaceous materials.

[0053] Therefore, in the pre-treated powder, a portion of the carbon in the carbon-based substances enters the interior of the black talc to form interlayer carbon. The other portion of the carbon remains on the surface of the black talc. Since the interlayer carbon content in the black talc of the pre-treated powder is increased, the intercalation carbonization of the black talc can be achieved, and a large amount of reducing agent carbon is introduced and enriched between the black talc TO layers, providing sufficient amorphous carbon source as a reducing agent for the black talc.

[0054] Intercalation carbonization is beneficial to the full contact of black talc, carbon and chlorine in the subsequent chlorination step, thereby promoting a more complete reaction.

[0055] In some embodiments, the black talc is pre-crushed and then added together with the carbonaceous material for crushing. The particle size of the pre-crushed black talc is less than 10 μm.

[0056] In some embodiments, the carbon content of the carbon material is as high as possible, such as greater than or equal to 90%. The carbon material includes petroleum coke, graphite powder, etc.

[0057] S200: subjecting the pretreated powder to a first chlorination roasting in an atmosphere of a chlorine gas mixture and a first roasting temperature to obtain chlorinated black talc; wherein the first roasting temperature is 700-800°C, the chlorine gas mixture comprises chlorine and carbon monoxide, and the volume ratio of chlorine to carbon monoxide is 2.5-5:1.

[0058] In this step, the pretreated powder is subjected to chlorination roasting under the condition of passing chlorine mixed gas. In this atmosphere, the interference of water in the reaction process can be reduced.

[0059] Under the above volume ratio of chlorine and carbon monoxide, it is ensured that chlorine and carbon monoxide as a gaseous carbon source are fully mixed; it can also be ensured that the relative stoichiometric ratio of chlorine and the gaseous carbon source is in excess.

[0060] For example, in some embodiments, before the step of first calcining the pretreated powder, the process further includes drying the calcining device and introducing an inert gas to remove air and moisture therein.

[0061] For example, the furnace chamber and the device pipeline are kept at 200°C for 1 hour for drying, and the pre-treated powder is fed into the furnace chamber; then the device pipeline and the furnace chamber are purged with 500 sccm of inert gas for 30 minutes. Before the reaction, a chlorine gas mixture is introduced to exhaust the inert gas therein.

[0062] In the present application, the carbonaceous material is ball-milled and mixed with black talc to form a ball, which can provide a carbon source inside the pretreated powder; at the same time, gaseous carbon monoxide provides a carbon source outside. In technical terms, the carbon source inside the sphere is internal carbon, and the carbon source outside the sphere is external carbon. The combination of internal carbon and external carbon will have a better effect.

[0063] The overall reaction equation is: 4SiO2·3MgO·2H2O(s) + 11Cl2(g) + 5.5C(s) = 3MgCl2(l) + 4SiCl4(g) + 5.5CO2(g) + H2O(g). Specifically, the chlorination temperature of the magnesium component in the black talc is 700 °C, and the chlorination temperature of the silicon component is 900 °C. That is, the hypothetical partial reaction occurs at 700 °C: MgO·xH2O(s) + Cl2(g) + 0.5C(s) = MgCl2(l) + 0.5CO2(g) + xH2O(g), and the hypothetical partial reaction occurs at 900 °C: SiO2·xH2O(s) + 2Cl2(g) + C(s) = SiCl4(g) + CO2(g) + xH2O(g). The silicon and magnesium components in the black talc belong to the T-O-T structure, and there is no separate SiO2·xH2O(s) and MgO·xH2O(s). The above hypothesis only illustrates the temperature difference. By controlling the chlorination temperature below 900 °C, only the chlorination of the magnesium component can be achieved without chlorinating the silicon component. It should be noted that carbon monoxide can also replace carbonaceous substances for the reaction, and since the gas-solid mass transfer effect is significantly better than the solid-solid mass transfer, adding carbon monoxide can promote the chlorination reaction. The reaction equation is: 4SiO2·3MgO·2H2O(s) + 11Cl2(g) + 11CO(g) = 3MgCl2(l) + 4SiCl4(g) + 11CO2(g) + 2H2O(g).

[0064] The magnesium element in the chlorinated black talc mainly exists in the form of magnesium chloride, and most of the silicon elements in the chlorinated black talc still exist in the form of silicate. The mass fraction of the magnesium element existing as magnesium chloride in all magnesium elements is the magnesium conversion rate. Referring to the subsequent examples, under different conditions, the magnesium conversion rate reaches more than 77%.

[0065] When performing the chlorination roasting of the present invention, by precisely controlling the temperature difference of the chlorination and gasification of the silicon and magnesium components, the effective separation of the mineral components of the black talc and the high-value utilization of resources are realized, so that porous nano-silica can be prepared from such difficult-to-treat silicates as black talc, and the magnesium resources in the black talc minerals can be fully recovered.

[0066] The above-mentioned chlorination method of the black talc mineral forms intercalated carbon when part of the carbonaceous substances enter the black talc structure during the crushing process. Combined with the specific composition of the chlorine mixed gas and the selection of the roasting temperature, the chlorination of the magnesium component without chlorinating the silicon component is achieved. In this way, the chlorination efficiency of the black talc is improved, the air permeability of the black talc chlorination method is enhanced, the full conversion and utilization of the magnesium resources in the black talc are realized, and the magnesium conversion rate in the black talc mineral chlorination process is high, exceeding 90%.

[0067] In some embodiments, the mass ratio of the black talc to the elemental carbon in the carbonaceous material is 1:3 - 1. In this operation, by ball-milling the black talc and the petroleum coke together, intercalation carbonization of the black talc can be achieved, introducing and enriching a large amount of reducing agent carbon between the T-O layers of the black talc; by introducing the petroleum coke, an abundant amorphous carbon source can be provided for the black talc as a reducing agent.

[0068] In some embodiments, the carbonaceous material is petroleum coke. Petroleum coke is porous and irregular in shape with a disordered carbon structure. It has a relatively high content of elemental carbon and a low cost.

[0069] In some embodiments, the black talc and the carbonaceous material are first crushed by ball-milling at a ball-milling speed of 200 - 500 rpm for a ball-milling duration of 30 - 120 min.

[0070] The mechanical energy input during ball-milling can cause the chemical bonds on the surface of the material particles to break and recombine. This energy input not only helps with the mixing of the materials but also enables physical or chemical interactions between the particles of different substances, further strengthening their contact and combination, that is, achieving an activation effect. Under the above process parameters, the particle size of the pretreated powder is made appropriate by ball-milling, which results in more contact points and a larger contact area between the particles of the black talc and the carbonaceous material, thus achieving close contact without over-grinding and causing adverse effects such as particle agglomeration.

[0071] In some embodiments, in the step of first roasting the pretreated powder, the roasting duration is not less than 90 min.

[0072] In some more specific embodiments, after the pretreated powder is heated to 700 - 800 °C, the chlorine-containing gas mixture is then introduced for reaction.

[0073] Since chlorine will react with carbon to form phosgene (COCl2) at 200 - 500 °C, which is ten times more toxic than chlorine and poses a safety hazard to production, therefore, after the pretreated powder is heated to 700 - 800 °C, the chlorine-containing gas mixture is introduced for reaction to avoid the production of phosgene.

[0074] Exemplarily, before the chlorination roasting, the pretreated powder is first heated to 700 - 800 °C at a heating rate of 10 °C / min in an inert gas atmosphere; then the gas is switched to a mixed atmosphere of chlorine and inert gas. The magnesium conversion rate in the chlorination process of the talc mineral is high, exceeding 90%; the chlorination roasting in the present invention is bath smelting or fluidized chlorination; the inert gas in the present invention includes one or more of argon and nitrogen.

[0075] In some embodiments, in the step of first roasting the pretreated powder material, the pretreated powder material is first roasted under the condition of adding a chlorination catalyst, and the chlorination catalyst includes carbon tetrachloride or carbon disulfide. The reaction rate of roasting is accelerated by adding the chlorination catalyst. The addition amount of the chlorination catalyst is: pretreated powder material: carbon disulfide = 10 - 5:1, or pretreated powder material: carbon tetrachloride = 8:3 - 1.

[0076] In some embodiments, it further includes pelletizing the pretreated powder material to obtain pretreated pellets.

[0077] In some embodiments, before the step of first roasting the pretreated powder material, it further includes drying the pretreated powder material.

[0078] This operation removes the moisture in the talc raw material and reduces the influence of moisture on the chlorination reaction, because silicon tetrachloride reacts with water to generate silicon dioxide, which will prevent the chlorination reaction from proceeding further. In addition, moisture will consume chlorine to generate hydrogen chloride by-products. In this way, the above operation can greatly increase the amount of silicon tetrachloride obtained by the reaction. For example, after completing the ball milling, the product of the ball milling is dried at 90 - 120 °C for 30 - 90 min.

[0079] In some embodiments, before the step of first roasting the pretreated powder material, it further includes drying the roasting device and introducing an inert gas to remove the air and moisture therein.

[0080] This operation removes the moisture in the roasting device and reduces the influence of moisture on the chlorination reaction, and can also increase the amount of silicon tetrachloride obtained by the reaction.

[0081] Exemplarily, the furnace cavity and the device pipeline are dried by maintaining a temperature of 200 °C for 1 h, and the pretreated powder material and the chlorination catalyst are fed into the furnace cavity; then the device pipeline is purged with an inert gas at 500 sccm for 30 min.

[0082] In some embodiments, the chlorine gas mixture further includes an inert gas; the volume ratio of the chlorine gas to the inert gas is 5:1.

[0083] On the one hand, using an inert gas can reduce the amount of chlorine gas consumed per unit time; on the other hand, compared with using pure chlorine gas with a low flow rate alone, using an inert gas will reduce the activity of chlorine gas, making the reaction more controllable and the production safer.

[0084] In some embodiments, after the first roasting is completed, it further includes switching the chlorine gas mixture to an inert gas and closing the inert gas when the temperature in the furnace drops below 200 °C.

[0085] The switch to inert gas cooling is because chlorine gas will react with carbon to form phosgene (COCl2) at 200 - 500 °C. Therefore, after the chlorination reaction, cooling cannot be carried out when both chlorine gas and carbon are present, and it is necessary to replace the inert gas for cooling.

[0086] Closing the inert gas when the furnace temperature drops below 200 °C is to protect the generated product and prevent magnesium chloride from being oxidized to magnesium oxide by oxygen. If the inert gas is closed in advance, above 200 °C, air, especially oxygen in the air, will oxidize the generated magnesium chloride product to magnesium oxide.

[0087] This application also provides an application of the above-mentioned chlorination method of black talc minerals in the preparation of nano-silica, including the following steps:

[0088] React the chlorinated black talc obtained by the chlorination method with hydrochloric acid, and collect the solid to obtain nano-silica.

[0089] That is, the residual solid obtained by the chlorination method is stirred for a certain period of time with hydrochloric acid at a certain concentration and a certain solid-liquid ratio by volume, and then filtered by suction to obtain the solid.

[0090] In some embodiments, the concentration of the hydrochloric acid solution is 0.5 - 2 mol / L, for example, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L. In some specific embodiments, the concentration of the hydrochloric acid solution is 1 mol / L.

[0091] In some embodiments, the liquid-solid ratio of the chlorinated black talc to the hydrochloric acid solution is 1:5 - 10. For example, 1:5, 1:8, 1:10. In some specific embodiments, the liquid-solid ratio of the chlorinated black talc to the hydrochloric acid solution is 1:10.

[0092] In some embodiments, the reaction duration of the chlorinated black talc and the hydrochloric acid solution is 30 min. For example, during the reaction, magnetic stirring at 500 rpm is used for 30 min.

[0093] In the subsequent process, the leaching solution is collected for testing the concentration of magnesium by inductively coupled plasma optical emission spectrometer (ICP-OES), the filtered solid is collected and dried for testing whether the talc structure is damaged by X-ray diffraction (XRD), and its morphology and microstructure are tested by scanning electron microscope - energy dispersive spectrometer (SEM-EDS).

[0094] The inventors have also found that when chlorinating black talc at high temperature, the magnesium conversion rate and silicon conversion rate are low, and the two are related. The reason is that magnesium is more active than silicon, so magnesium chloride is generated first. Since the magnesium chloride generated on the surface of black talc will melt and wrap the black talc during roasting, further chlorination inside the black talc is prevented, resulting in low chlorination efficiency, so the overall chlorination conversion rates of magnesium and silicon are relatively low.

[0095] In addition, in the actual production process, the molten and solidified magnesium chloride will block the furnace cavity, affecting the air permeability in the furnace, and thus posing serious safety hazards to the chlorination process.

[0096] The technical solution of the present invention provides a deep chlorination process of black talc mineral, wherein the deep chlorination process is to continue chlorination on the basis of the chlorination method of black talc mineral, and it can be understood that the deep chlorination process includes all steps of the chlorination method of black talc mineral.

[0097] A deep chlorination process of black talc mineral comprises the following steps:

[0098] S10: soaking the chlorinated black talc in water to wash away water-soluble substances, and drying to obtain washed black talc.

[0099] After the aforementioned chlorination method of black talc mineral, the magnesium element in the black talc is selectively chlorinated to form chlorinated black talc. The main component of the water-soluble substance of chlorinated black talc is magnesium chloride. By washing chlorinated black talc, magnesium chloride is dissolved in water, and then dried to obtain washed black talc. This step removes the encapsulation of the silicon component by molten magnesium chloride. Therefore, in the subsequent chlorination step, the silicon component can form a good contact with other components in the chlorination reaction, enhances the mass transfer effect, and thus can form a higher chlorination conversion rate for the silicon element. Moreover, by washing chlorinated black talc, the separation of most of the magnesium element and the silicon element is also achieved.

[0100] There is no specific limitation on the solid-to-liquid ratio of black talc chloride and water and the soaking time, as long as the water-soluble substances in the black talc chloride are basically dissolved in water.

[0101] S20: performing a second crushing on the washed black talc and the carbonaceous material in a mixed state to obtain a pre-chlorinated powder.

[0102] The chlorination method of the black talc mineral destroys the black talc structure. However, for the Si-O bond in black talc to become the Si-Cl bond in silicon tetrachloride, the participation of C in the reaction is still required to occur. Therefore, it is still necessary to incorporate carbonaceous substances into the reactants. The purpose of the carbonaceous substances in this step is also to form interlayer carbon in the washed black talc. The carbonaceous substances and the operation of the second crushing in this step can refer to the carbonaceous substances and the operation of the first crushing in step S100. The specific operation methods and related parameters of the second crushing and the first crushing can be the same or different. The carbonaceous substances in step S20 and the carbonaceous substances in step S100 can be the same or different.

[0103] S30: Perform second chlorination roasting on the pre-chlorinated powder under the conditions of a chlorine atmosphere and a second roasting temperature, collect the gas phase, and obtain silicon tetrachloride gas phase. The second roasting temperature is not lower than 850 °C.

[0104] In this step, the reaction of SiO2·xH2O(s)+2Cl2(g)+C(s)=SiCl4(g)+CO2(g)+xH2O(g) occurs, enabling the silicon element to form silicon tetrachloride gas. In addition, a small amount of liquid phase (mainly molten magnesium chloride) and unreacted residual solids will also be generated.

[0105] In the present invention, the first chlorination roasting and the second chlorination roasting in the present invention are bath smelting or fluidized chlorination. The second chlorination can include multiple roasting cycles, and the roasting duration of each roasting cycle is not less than 8 min, further 8 - 150 min; or, the roasting duration of each roasting cycle is not less than 10 min, further 10 - 120 min, further 15 - 120 min, and can also be 15 - 30 min or 60 - 120 min or 100 - 150 min; after completing the previous roasting cycle, in the next roasting cycle, directly roast the next batch of the pre-treated powder; the residual solids can also be repeatedly roasted together with the next batch of the pre-treated powder.

[0106] In the above-mentioned deep chlorination process of the black talc mineral, first, during the crushing process, part of the carbonaceous substances enter the black talc structure to form intercalated carbon. Then, combined with the specific composition of the chlorine mixed gas and the selection of the roasting temperature, the magnesium component is chlorinated while the silicon component is not chlorinated. Then, the generated magnesium chloride is removed by soaking, which greatly reduces the encapsulation of the silicon component by molten magnesium chloride in the subsequent chlorination process, enabling the silicon element to be better chlorinated, thereby improving the overall chlorination efficiency of the black talc and the comprehensive utilization rate of silicon and magnesium elements in the black talc.

[0107] In some embodiments, the mass ratio of carbon in the chlorinated black talc to the carbonaceous substances is 3 - 1:1. In some specific embodiments, the carbonaceous substances are petroleum coke.

[0108] The carbon in the chlorinated black talc and the carbonaceous material is crushed under the condition that the mass ratio of the carbon to the carbonaceous material is 3 to 1:1. Since the first chlorination roasting destroys the structure of the black talc, the difficulty of forming intercalated carbon by the carbon is reduced, so the dosage of the carbonaceous material is also relatively reduced.

[0109] In some embodiments, the second crushing is performed by ball milling, the ball milling speed is 100 - 600 rpm, and the ball milling duration is 20 - 130 min.

[0110] In some embodiments, in the step of performing the second chlorination roasting, the second roasting temperature is 850 - 1300 °C, and the heat preservation duration is 10 - 120 min. Further, the second roasting temperature is not lower than 900 °C or not lower than 950 °C; further, the second roasting temperature is 850 - 1300 °C; further, the second roasting temperature is 900 - 1200 °C; further, the second roasting temperature is 950 - 1200 °C; further, the second roasting temperature is 1000 - 1200 °C; further, the second roasting temperature is 1000 - 1100 °C or 1100 - 1200 °C.

[0111] In some embodiments, in the step of performing the second chlorination roasting on the pre-chlorinated powder under the conditions of a chlorine atmosphere and the second roasting temperature, the chlorine and the inert gas are introduced in a volume ratio of (5 - 1):(5 - 1).

[0112] Similarly, in the step of the second chlorination roasting, the introduction manner of the chlorine and the inert gas can refer to that in the first chlorination roasting, that is, when the temperature in the reaction furnace rises to the second roasting temperature and then introduced, before that, the pre-chlorinated powder is in an inert gas atmosphere.

[0113] In some embodiments, it further includes at least one of the following operations (1) - (2):

[0114] (1) Collect the water leaching solution in the step of soaking the chlorinated black talc to obtain a magnesium chloride solution.

[0115] (2) Collect the liquid phase in the second chlorination roasting to obtain a molten magnesium chloride.

[0116] In some specific embodiments, the liquid phase is subjected to molten salt electrolysis to obtain crude magnesium metal.

[0117] In some embodiments, it further includes:

[0118] The silicon tetrachloride gas phase is subjected to the first condensation to obtain a crude silicon tetrachloride liquid. In some specific embodiments, the temperature of the first condensation is lower than 20 °C.

[0119] The crude silicon tetrachloride liquid can be further refined by distillation to obtain the refined silicon tetrachloride liquid.

[0120] The following are specific examples of the present invention:

[0121] Example 1

[0122] A method for chlorinating a black talc mineral, comprising the steps of:

[0123] S1, co-milling the crushed black talc and petroleum coke, and drying the milled product to obtain a pretreated powder; pelletizing the pretreated powder to obtain a pretreated pellet.

[0124] In this embodiment, the main component of the black talc is 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.67 wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in the petroleum coke is greater than 97%.

[0125] In this embodiment, the mass ratio of the black talc to the petroleum coke is 1:1.85; the rotation speed of the ball milling is 500 rpm, and the ball milling time is 120 min; the drying temperature is 120 °C, and the drying time is 90 min.

[0126] S2, drying the furnace cavity and the device pipeline by maintaining the temperature at 200 °C for 1 h, feeding 100 g of the pretreated pellet and 10 g of carbon disulfide into the furnace cavity; then purging the device pipeline with an inert gas at 500 sccm for 30 min; subjecting 100 g of the pretreated pellet and 10 g of carbon disulfide to chlorination roasting; in this embodiment, the process of chlorination roasting is: in an inert gas atmosphere, heating up to 800 °C at a heating rate of 10 °C / min, then switching the gas to a mixed atmosphere of chlorine and carbon monoxide, maintaining the temperature for 120 min to obtain a residual solid; after the temperature maintenance is completed, switching the gas to an inert gas, and closing the inert gas when the furnace temperature drops below 200 °C.

[0127] In this embodiment, the chlorination roasting is fluidized chlorination; the inert gas is argon; in the mixed atmosphere, the volume ratio of chlorine to the inert gas is 5:1, and the volume ratio of chlorine to carbon monoxide is 5:1.

[0128] S3, Acid Leaching and Detection of Residual Solids: The residual solids were subjected to magnetic stirring at 500 rpm for 30 min with 1 mol / L hydrochloric acid at a solid-liquid ratio of 1:10, followed by suction filtration, and the process was repeated three times. The leachates from the first two and the third times were collected and the total volumes were recorded separately. The collected leachates were diluted by an appropriate multiple and fed into an inductively coupled plasma optical emission spectrometer (ICP-OES) to measure the concentration of magnesium. The suction-filtered solids were dried and subjected to X-ray diffraction (XRD) to test whether the talc structure was damaged, and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) was used to test their morphology and microstructure.

[0129] Experimental Results: Among the 100 g of pretreated pellets, there were 35.09 g of black talc, and among which magnesium accounted for 16% (i.e., 5.61 g). After acid leaching, the total mass of magnesium obtained by ICP-OES measurement was 5.31 g, and the calculated magnesium conversion rate during the chlorination process of black talc was 94.65%. Referring to Figure 1(a), the intensity of the talc peak in the XRD test was relatively low, indicating that the black talc structure was largely damaged. Referring to Figures 1(b) and 1(c), the SEM-EDS test showed that the suction-filtered solids were porous nano-silica.

[0130] Example 2

[0131] A chlorination method for black talc minerals, the steps of which are as follows:

[0132] S1, Co-grind the crushed black talc and petroleum coke, and dry the co-ground product to obtain pretreated powder.

[0133] In this embodiment, the main component of black talc is 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.64 wt.% of interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in the petroleum coke is greater than 97%.

[0134] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of co-grinding is 300 rpm, and the co-grinding time is 60 min; the drying temperature is 100 °C, and the drying time is 60 min.

[0135] S2, Keep the furnace cavity and the device pipeline at 200 °C for 1 h for drying, and feed 80 g of the pretreated powder and 30 g of carbon tetrachloride into the furnace cavity; then wash the device pipeline with an inert gas at 500 sccm for 30 min; carry out chlorination roasting on 80 g of the pretreated powder and 30 g of carbon tetrachloride. In this embodiment, the process of chlorination roasting is as follows: Under an inert gas atmosphere, heat up to 750 °C at a heating rate of 10 °C / min, then switch the gas to a mixed atmosphere of chlorine and carbon monoxide, keep it warm for 90 min to obtain residual solids; after the heat preservation ends, switch the gas to an inert gas, and close the inert gas when the furnace temperature drops below 200 °C.

[0136] In this embodiment, the chlorination roasting is fluidized chlorination; the inert gas is argon; in the mixed atmosphere, the volume ratio of chlorine gas to the inert gas is 5:1, and the volume ratio of chlorine gas to carbon monoxide is 5:1.

[0137] S3. Acid leaching and detection of the residual solid: The residual solid is magnetically stirred at 500 rpm for 30 min with 1 mol / L hydrochloric acid at a solid-liquid ratio of 1:10, and then filtered by suction, repeating three times. The leachates from the first two times and the third time are collected and the total volumes are recorded respectively. The collected leachates are diluted by an appropriate multiple and fed into an inductively coupled plasma optical emission spectrometer (ICP-OES) to test the concentration of magnesium; the suction-filtered solid is dried and subjected to X-ray diffraction (XRD) to test whether the talc structure is damaged, and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) is used to test its morphology and microstructure.

[0138] Experimental results: Among the 80 g of pretreated powder, there is 28.07 g of black talc, and magnesium accounts for 16%, which is 4.49 g. The total mass of magnesium obtained by ICP-OES test after acid leaching is 4.26 g, and the calculated value for the chlorination process of black talc is 94.88%; see Figure 2 , the intensity of the talc peak in the XRD test is relatively low, indicating that the black talc structure is largely damaged, indicating that most of the black talc participates in the chlorination reaction, so the chlorination conversion rate is high. The SEM-EDS test shows that the suction-filtered solid is porous nano-silica.

[0139] Example 3

[0140] A method for chlorinating a black talc mineral, the steps of which are:

[0141] S1. Co-ball mill the crushed black talc and petroleum coke, and dry the ball-milled product to obtain pretreated powder.

[0142] In this embodiment, the main component of black talc is 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.55 wt.% of interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in the petroleum coke is greater than 97%.

[0143] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; 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.

[0144] S2. Dry the furnace cavity and the device pipeline by keeping them at 200 °C for 1 h, and feed 80 g of pretreated powder and 50 g of carbon tetrachloride into the furnace cavity; then purge the device pipeline with inert gas at 500 sccm for 30 min; perform chlorination roasting on 80 g of pretreated powder and 50 g of carbon tetrachloride. In this embodiment, the process of chlorination roasting is as follows: Under an inert gas atmosphere, heat up at a heating rate of 10 °C / min to 750 °C, then switch the gas to a mixed atmosphere of chlorine and carbon monoxide, keep it warm for 90 min to obtain residual solid; after the heat preservation ends, switch the gas to inert gas, and close the inert gas when the temperature in the furnace drops below 200 °C.

[0145] In this embodiment, the chlorination roasting is fluidized chlorination; the inert gas is argon; in the mixed atmosphere, the volume ratio of chlorine to the inert gas is 5:1, and the volume ratio of chlorine to carbon monoxide is 3:1.

[0146] S3. Acid leaching and detection of the residual solid: Stir the residual solid with 1 mol / L hydrochloric acid at a solid-liquid ratio of 1:10 at 500 rpm magnetically for 30 min and then perform suction filtration, repeating three times. Collect the leaching solutions of the first two times and the third time and record the total volume respectively. Dilute the collected leaching solutions by an appropriate multiple and feed them into an inductively coupled plasma optical emission spectrometer (ICP-OES) to test the concentration of magnesium; dry the suction-filtered solid and perform X-ray diffraction (XRD) to test whether the talc structure is damaged, and perform scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) to test its morphology and microstructure.

[0147] Experimental results: Among the 80 g of pretreated powder, there is 28.07 g of black talc, and magnesium accounts for 16%, which is 4.49 g. The total mass of magnesium obtained by ICP-OES test after acid leaching is 4.32 g, and the calculated magnesium conversion rate in the chlorination process of black talc is 96.21%; see Figure 3 , the intensity of the talc peak in the XRD test is basically zero, indicating that the black talc structure is completely damaged, indicating that almost all of the black talc participates in the chlorination reaction, so the chlorination conversion rate is very high. The SEM-EDS test shows that the suction-filtered solid is porous nano-silica.

[0148] Example 4

[0149] A method for chlorinating black talc minerals, the steps of which are:

[0150] S1. Co-ball mill the crushed black talc and petroleum coke, and dry the ball-milled product to obtain pretreated powder; pelletize the pretreated powder to obtain pretreated pellets.

[0151] In this embodiment, the main component of the black talc is 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.67 wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in the petroleum coke is greater than 97%.

[0152] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of ball milling is 500 rpm, and the ball milling time is 120 min; the drying temperature is 120 °C, and the drying time is 90 min.

[0153] S2. The furnace cavity and the device pipeline are dried at 200 °C for 1 h, and 100 g of the pretreated pellets and 20 g of carbon disulfide are fed into the furnace cavity; then the device pipeline is purged with 500 sccm of inert gas for 30 min; 100 g of the pretreated pellets and 20 g of carbon disulfide are subjected to chlorination roasting; in this embodiment, the process of chlorination roasting is as follows: under an inert gas atmosphere, the temperature is raised to 800 °C at a heating rate of 10 °C / min, then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and held for 120 min to obtain the residual solid; after the holding ends, the gas is switched to an inert gas, and the inert gas is turned off when the temperature in the furnace drops below 200 °C.

[0154] In this embodiment, the chlorination roasting is fluidized chlorination; the inert gas is argon; in the mixed atmosphere, the volume ratio of chlorine to the inert gas is 5:1, and the volume ratio of chlorine to carbon monoxide is 2.5:1.

[0155] S3. Acid leaching and detection of the residual solid: The residual solid is magnetically stirred at 500 rpm for 30 min with 1 mol / L hydrochloric acid at a solid-liquid ratio of 1:10, and then filtered by suction, and the operation is repeated three times. The leachates of the first two times and the third time are collected and the total volumes are recorded respectively. The collected leachates are diluted by an appropriate multiple and fed into an inductively coupled plasma optical emission spectrometer (ICP-OES) to test the concentration of magnesium; the suction-filtered solid is dried and subjected to X-ray diffraction (XRD) to test whether the talc structure is damaged, and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) is used to test its morphology and microstructure.

[0156] Experimental results: Among the 100 g of the pretreated pellets, there is 35.09 g of black talc, and among which magnesium accounts for 16% which is 5.61 g. The total mass of magnesium obtained by ICP-OES test after acid leaching is 5.51 g, and the calculated magnesium conversion rate in the chlorination process of black talc is 98.22%; the XRD test shows that the peak intensity of talc is basically zero, indicating that the black talc structure is completely damaged, and the SEM-EDS test shows that the suction-filtered solid is porous nano-silica.

[0157] Example 5

[0158] A method for chlorinating a black talc mineral, the steps of which are as follows:

[0159] S1. Co - mill the crushed black talc and petroleum coke, and dry the milled product to obtain a pretreated powder material; pelletize the pretreated powder material to obtain a pretreated pellet.

[0160] In this embodiment, the main component of the black talc is 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.67 wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in the petroleum coke is greater than 97%.

[0161] In this embodiment, the mass ratio of the black talc to the petroleum coke is 1:3; the rotation speed of the ball milling is 500 rpm, and the ball milling time is 120 min; the drying temperature is 120 °C, and the drying time is 90 min.

[0162] S2. Dry the furnace cavity and the device pipeline by keeping them at 200 °C for 1 h, and feed 100 g of the pretreated pellet and 10 g of carbon disulfide into the furnace cavity; then wash the device pipeline with 500 sccm of inert gas continuously for 30 min; perform chlorination roasting on 100 g of the pretreated pellet and 10 g of carbon disulfide. In this embodiment, the process of chlorination roasting is as follows: Under an inert gas atmosphere, heat up to 800 °C at a heating rate of 10 °C / min, then switch the gas to a mixed atmosphere of chlorine and carbon monoxide, keep it warm for 120 min to obtain a residual solid; after the heat preservation ends, switch the gas to an inert gas, and close the inert gas when the temperature in the furnace drops below 200 °C.

[0163] In this embodiment, the chlorination roasting is fluidized chlorination; the inert gas is argon; in the mixed atmosphere, the volume ratio of chlorine to the inert gas is 5:1, and the volume ratio of chlorine to carbon monoxide is 4:1.

[0164] S3. Acid leaching and detection of the residual solid: Stir the residual solid with 1 mol / L hydrochloric acid at a solid - liquid ratio of 1:10 with magnetic stirring at 500 rpm for 30 min, and then perform suction filtration, repeating three times. Collect the leaching solutions of the first two times and the third time and record the total volume respectively. Dilute the collected leaching solutions by an appropriate multiple and feed them into an inductively coupled plasma optical emission spectrometer (ICP - OES) to test the concentration of magnesium; dry the suction - filtered solid and perform X - ray diffraction (XRD) to test whether the talc structure is damaged, and perform scanning electron microscopy - energy dispersive spectrometer (SEM - EDS) to test its morphology and microstructure.

[0165] Experimental results: In 100 g of the pretreated pellets, there are 25.00 g of black talc, among which magnesium accounts for 16%, that is, 4.00 g. After acid leaching, the total mass of magnesium obtained by ICP-OES test is 3.83 g. The calculated magnesium conversion rate in the chlorination process of black talc is 95.75%; The intensity of the talc peak in the XRD test is basically zero, indicating that the structure of black talc is completely destroyed. The SEM-EDS test shows that the filtered solid is porous nano-silica.

[0166] Example 6

[0167] In this example compared with Example 1, only the mass ratio of black talc to petroleum coke is adjusted to 1:1, and other conditions remain unchanged.

[0168] In this example, the magnesium conversion rate in the chlorination process is reduced to 80.34%.

[0169] Example 7

[0170] In this example compared with Example 2, only the amount of carbon tetrachloride added is adjusted to 10 g, and other conditions remain unchanged.

[0171] In this example, the magnesium conversion rate in the chlorination process is reduced to 82.13%.

[0172] Example 8

[0173] In this example compared with Example 2, only in the chlorination roasting process, the temperature is raised to 700 °C at a heating rate of 10 °C / min, and other conditions remain unchanged.

[0174] In this example, the magnesium conversion rate in the chlorination process is reduced to 77.06%. See Figure 4 , and the product of Example 8 is taken for XRD test. After being treated by the chlorination process, the structure of black talc is partially destroyed, indicating that part of the black talc participates in the chlorination reaction, so the chlorination conversion rate is relatively high.

[0175] Comparative Example 1

[0176] In this comparative example compared with Example 1, only the co-grinding of the crushed black talc and petroleum coke is adjusted to the separate grinding of black talc without adding petroleum coke, and other conditions remain unchanged.

[0177] In this comparative example, the magnesium conversion rate in the chlorination process is reduced to 72.50%. The product of Comparative Example 1 is taken for XRD test. See Figure 5 , and the intensity of the talc peak in the XRD test is relatively high, indicating that after being treated by the chlorination process, the structure of black talc is rarely destroyed, and only some black talc participates in the chlorination reaction, so the chlorination conversion rate is medium.

[0178] Comparative Example 2

[0179] In this comparative example, compared with Example 2, only the chlorination roasting process was heated to 600 °C at a heating rate of 10 °C / min, and other conditions remained unchanged.

[0180] In this comparative example, the magnesium conversion rate in the chlorination process decreased to 60.57%. The product of Comparative Example 2 was subjected to XRD testing. See Figure 6 , the intensity of the talc peak in the XRD test was relatively high, indicating that after treatment by the chlorination process, the structure of black talc was rarely damaged, and only some black talc participated in the chlorination reaction. Therefore, the chlorination conversion rate was medium.

[0181] Comparative Example 3

[0182] In this comparative example, compared with Example 3, only the chlorination roasting process was heated to 650 °C at a heating rate of 10 °C / min, and other conditions remained unchanged.

[0183] In this comparative example, the magnesium conversion rate in the chlorination process decreased to 69.46%.

[0184] From the results of Examples 1-8 and Comparative Examples 1-3, the chlorination method of the black talc mineral of the present application can improve the chlorination efficiency of black talc, and the magnesium conversion rate in the chlorination process of black talc mineral is high, reaching more than 77%, and some conditions can reach 90%, so as to realize the full conversion and utilization of magnesium resources in black talc.

[0185] In the following examples and comparative examples: The main components of black talc are 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.67 wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in petroleum coke is greater than 97%.

[0186] Example 9

[0187] A deep chlorination process for black talc minerals, the steps of which are:

[0188] S1, co-ball mill the crushed black talc and petroleum coke, and dry the ball-milled product to obtain a pretreated powder.

[0189] In this example, the main components of black talc are 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.67 wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in petroleum coke is greater than 97%.

[0190] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of ball milling is 300 rpm, and the ball milling time is 60 min; the drying temperature is 100 °C, and the drying time is 60 min.

[0191] S2. The furnace cavity and the device pipeline are dried at 200 °C for 1 h, and 80 g of pretreated powder and 30 g of carbon disulfide are fed into the furnace cavity; then the device pipeline is purged with 500 sccm of inert gas for 30 min; 80 g of pretreated powder and 30 g of carbon disulfide are subjected to the first chlorination roasting. In this embodiment, the process of the first chlorination roasting is as follows: under an inert gas atmosphere, the temperature is raised to 750 °C at a heating rate of 10 °C / min, then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and kept warm for 90 min to obtain chlorinated black talc; after the heat preservation ends, the gas is switched to inert gas, and the inert gas is turned off when the temperature in the furnace drops below 200 °C.

[0192] In this embodiment, the chlorination roasting is fluidized chlorination; the inert gas is argon; in the mixed atmosphere, the volume ratio of chlorine to inert gas is 5:1, and the volume ratio of chlorine to carbon monoxide is 5:1.

[0193] S3. The chlorinated black talc is soaked in water to wash away water-soluble substances, taken out and dried to obtain water-washed black talc. The water immersion liquid is a magnesium chloride solution.

[0194] S4. The water-washed black talc and petroleum coke are ball milled together, and the ball milled product is dried to obtain pre-chlorinated powder.

[0195] In this step, the mass ratio of water-washed black talc to petroleum coke is 2:1; the rotation speed of ball milling is 300 rpm, and the ball milling time is 60 min; the drying temperature is 100 °C, and the drying time is 60 min.

[0196] S5. The furnace cavity and the device pipeline are dried at 200 °C for 1 h, and 100 g of pre-chlorinated powder is fed into the furnace cavity; then the device pipeline is purged with 500 sccm of inert gas for 30 min; the pre-chlorinated powder is subjected to the second chlorination roasting to generate gas-phase substances, liquid-phase substances and unreacted residual solids.

[0197] In this step, the process of the second chlorination roasting is as follows: under an inert gas atmosphere, the temperature is raised to 1000 °C at a heating rate of 10 °C / min, then the gas is switched to a mixed atmosphere of chlorine and inert gas, and kept warm for 20 min to obtain chlorinated black talc; after the heat preservation ends, the gas is switched to inert gas, and the inert gas is turned off when the temperature in the furnace drops below 200 °C.

[0198] In this step, the chlorination roasting is fluidized chlorination; the inert gas is argon; the volume ratio of chlorine to inert gas is 1:1.

[0199] S6. Condense and recover the gaseous phase at -20 °C to obtain the silicon tetrachloride gaseous phase. Collect the liquid phase to obtain molten magnesium chloride.

[0200] Experimental results: Refer to Figure 7 , the detection result of gas chromatography - mass spectrometry shows that the purity of silicon tetrachloride in the silicon tetrachloride gaseous phase is 99.93%. The calculated chlorination conversion rate of black talc is 96.32%.

[0201] The calculation method of the chlorination conversion rate of black talc is: chlorination conversion rate η = (1 - (mass of unreacted residual solid after the second chlorination roasting / mass of the original black talc ore before chlorination)) × 100%; where, to exclude the influence of excessive petroleum coke on the calculation, after washing the unreacted residual solid after the second chlorination roasting, the mass after calcination at 600 °C for 2 h in an air atmosphere is counted as the mass of the unreacted residual solid after the second chlorination roasting.

[0202] Because the silicon and magnesium in black talc (4SiO2·3MgO·2H2O) undergo chlorination reactions in a fixed stoichiometric ratio of 4SiO2:3MgO, the chlorination conversion rate of silicon and the chlorination conversion rate of magnesium in black talc are numerically equal to the chlorination conversion rate of black talc.

[0203] Example 10

[0204] A deep chlorination process for a black talc mineral, the steps of which are:

[0205] S1. Co - ball - mill the crushed black talc and petroleum coke, and dry the ball - milled product to obtain a pretreated powder; pelletize the pretreated powder to obtain a pretreated pellet.

[0206] In this example, the main component of black talc is 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.67 wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in petroleum coke is greater than 97%.

[0207] In this example, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of ball - milling is 500 rpm, and the ball - milling time is 120 min; the drying temperature is 100 °C, and the drying time is 90 min.

[0208] S2, dry the furnace cavity and the device pipeline by maintaining at 200 °C for 1 h, and feed 100 g of pretreated pellets and 20 g of carbon disulfide into the furnace cavity; then purge the device pipeline with 500 sccm of inert gas for 30 min; perform the first chlorination roasting on 100 g of pretreated pellets and 20 g of carbon disulfide. In this embodiment, the process of the first chlorination roasting is as follows: under an inert gas atmosphere, heat up at a heating rate of 10 °C / min to 800 °C, then switch the gas to a mixed atmosphere of chlorine and carbon monoxide, maintain the temperature for 120 min to obtain chlorinated black talc; after the temperature maintenance ends, switch the gas to an inert gas, and close the inert gas when the furnace temperature drops below 200 °C.

[0209] In this embodiment, the chlorination roasting is fluidized chlorination; the inert gas is argon; in the mixed atmosphere, the volume ratio of chlorine to the inert gas is 5:1, and the volume ratio of chlorine to carbon monoxide is 2.5:1.

[0210] S3, soak the chlorinated black talc in water to wash away water-soluble substances, take it out and dry it to obtain water-washed black talc. The water leaching solution is a magnesium chloride solution.

[0211] S4, co-grind the water-washed black talc and petroleum coke, and dry the ground product to obtain pre-chlorinated powder; pelletize the pre-chlorinated powder to obtain pre-chlorinated pellets.

[0212] In this step, the mass ratio of the water-washed black talc to petroleum coke is 1:1; the rotation speed of the grinding is 500 rpm, and the grinding time is 120 min; the drying temperature is 150 °C, and the drying time is 120 min.

[0213] S5, dry the furnace cavity and the device pipeline by maintaining at 200 °C for 1 h, and feed 100 g of pre-chlorinated pellets into the furnace cavity; then purge the device pipeline with 500 sccm of inert gas for 30 min; perform the second chlorination roasting on 100 g of pre-chlorinated pellets to generate gas-phase substances, liquid-phase substances and unreacted residual solids.

[0214] In this step, the process of the second chlorination roasting is as follows: under an inert gas atmosphere, heat up at a heating rate of 10 °C / min to 1200 °C, then switch the gas to a mixed atmosphere of chlorine and the inert gas, maintain the temperature for 120 min to obtain chlorinated black talc; after the temperature maintenance ends, switch the gas to an inert gas, and close the inert gas when the furnace temperature drops below 200 °C.

[0215] In this step, the chlorination roasting is fluidized chlorination; the inert gas is argon; the volume ratio of chlorine to the inert gas is 5:1.

[0216] S6, condense and recover the gas-phase substances at -40 °C to obtain silicon tetrachloride gas-phase substances. Collect the liquid-phase substances to obtain molten magnesium chloride.

[0217] Experimental results: Refer to Figure 8 , the gas chromatography-mass spectrometry detection results show that the purity of silicon tetrachloride in the silicon tetrachloride gas phase is 99.99%. The calculated conversion rate of chlorination of black talc is 99.78%.

[0218] Example 11

[0219] A deep chlorination process for black talc minerals, the steps of which are as follows:

[0220] S1, co-mill the crushed black talc and petroleum coke, and dry the milled product to obtain a pretreated powder.

[0221] In this embodiment, the main component of black talc is 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.67 wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in petroleum coke is greater than 97%.

[0222] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of ball milling is 300 rpm, and the ball milling time is 60 min; the drying temperature is 100 °C, and the drying time is 60 min.

[0223] S2, dry the furnace cavity and device pipeline by maintaining the temperature at 200 °C for 1 h, and feed 80 g of the pretreated powder and 50 g of carbon tetrachloride into the furnace cavity; then wash the device pipeline with an inert gas at 500 sccm for 30 min; conduct the first chlorination roasting on 80 g of the pretreated powder and 30 g of carbon disulfide; in this embodiment, the process of the first chlorination roasting is as follows: in an inert gas atmosphere, heat up to 750 °C at a heating rate of 10 °C / min, then switch the gas to a mixed atmosphere of chlorine and carbon monoxide, keep it warm for 90 min to obtain chlorinated black talc; after the heat preservation ends, switch the gas to an inert gas, and close the inert gas when the temperature in the furnace drops below 200 °C.

[0224] In this embodiment, the chlorination roasting is fluidized chlorination; the inert gas is argon; in the mixed atmosphere, the volume ratio of chlorine to the inert gas is 5:1, and the volume ratio of chlorine to carbon monoxide is 3:1.

[0225] S3, soak the chlorinated black talc in water to wash away water-soluble substances, take it out and dry it to obtain water-washed black talc. The water immersion liquid is a magnesium chloride solution.

[0226] S4, co-mill the water-washed black talc and petroleum coke, and dry the milled product to obtain a pre-chlorinated powder.

[0227] In this step, the mass ratio of washed black talc to petroleum coke is 2:1; the rotation speed of ball milling is 400 rpm, and the ball milling time is 90 min; the drying temperature is 120 °C, and the drying time is 90 min.

[0228] S5. Dry the furnace chamber and the device pipeline at 200 °C for 1 h, and feed 100 g of pre-chlorinated powder into the furnace chamber; then wash the device pipeline with an inert gas at 500 sccm for 30 min; perform second chlorination roasting on the pre-chlorinated powder to generate gas-phase substances, liquid-phase substances, and unreacted residual solids.

[0229] In this step, the process of second chlorination roasting is as follows: Under an inert gas atmosphere, heat up at a heating rate of 10 °C / min to 1100 °C, then switch the gas to a mixed atmosphere of chlorine and inert gas, keep it warm for 60 min to obtain chlorinated black talc; after the heat preservation ends, switch the gas to an inert gas, and close the inert gas when the furnace temperature drops below 200 °C.

[0230] In this step, the chlorination roasting is fluidized chlorination; the inert gas is argon; the volume ratio of chlorine to the inert gas is 2:1.

[0231] S6. Condense and recover the gas-phase substances at -40 °C to obtain silicon tetrachloride gas-phase substances. Collect the liquid-phase substances to obtain molten magnesium chloride.

[0232] Experimental results: Refer to Figure 9 , the detection result of gas chromatography-mass spectrometry shows that the purity of silicon tetrachloride in the silicon tetrachloride gas-phase substances is 99.97%. The calculated chlorination conversion rate of black talc by characterization is 96.40%.

[0233] Example 12

[0234] A deep chlorination process for black talc minerals, the steps of which are as follows:

[0235] S1. Ball mill the crushed black talc and petroleum coke together, and dry the ball milled product to obtain pre-treated powder; pelletize the pre-treated powder to obtain pre-treated pellets.

[0236] In this embodiment, the main component of black talc is 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.67 wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in petroleum coke is greater than 97%.

[0237] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of ball milling is 500 rpm, and the ball milling time is 120 min; the drying temperature is 100 °C, and the drying time is 90 min.

[0238] S2. Dry the furnace cavity and the device pipeline by maintaining at 200 °C for 1 h, and feed 100 g of pretreated pellets and 10 g of carbon disulfide into the furnace cavity; then purge the device pipeline with 500 sccm of inert gas for 30 min; conduct the first chlorination roasting on 100 g of pretreated pellets and 10 g of carbon disulfide. In this embodiment, the process of the first chlorination roasting is as follows: Under an inert gas atmosphere, heat up at a heating rate of 10 °C / min to 800 °C, then switch the gas to a mixed atmosphere of chlorine and carbon monoxide, maintain the temperature for 120 min to obtain chlorinated black talc; after the temperature maintenance ends, switch the gas to an inert gas, and close the inert gas when the furnace temperature drops below 200 °C.

[0239] In this embodiment, the chlorination roasting is fluidized chlorination; the inert gas is argon; in the mixed atmosphere, the volume ratio of chlorine to the inert gas is 5:1, and the volume ratio of chlorine to carbon monoxide is 3:1.

[0240] S3. Immerse the chlorinated black talc in water to wash away water-soluble substances, take it out and dry it to obtain water-washed black talc. The water immersion liquid is a magnesium chloride solution.

[0241] S4. Co-ball mill the water-washed black talc and petroleum coke, and dry the ball-milled product to obtain pre-chlorinated powder; pelletize the pre-chlorinated powder to obtain pre-chlorinated pellets.

[0242] In this step, the mass ratio of the water-washed black talc to petroleum coke is 1:1; the rotation speed of the ball milling is 200 rpm, and the ball milling time is 30 min; the drying temperature is 150 °C, and the drying time is 120 min.

[0243] S5. Dry the furnace cavity and the device pipeline by maintaining at 200 °C for 1 h, and feed 100 g of pre-chlorinated pellets into the furnace cavity; then purge the device pipeline with 500 sccm of inert gas for 30 min; conduct the second chlorination roasting on 100 g of pre-chlorinated pellets to generate gas-phase substances, liquid-phase substances and unreacted residual solids.

[0244] In this step, the process of the second chlorination roasting is as follows: Under an inert gas atmosphere, heat up at a heating rate of 10 °C / min to 900 °C, then switch the gas to a mixed atmosphere of chlorine and the inert gas, maintain the temperature for 10 min to obtain chlorinated black talc; after the temperature maintenance ends, switch the gas to an inert gas, and close the inert gas when the furnace temperature drops below 200 °C.

[0245] In this step, the chlorination roasting is fluidized chlorination; the inert gas is argon; the volume ratio of chlorine to the inert gas is 1:5.

[0246] S6. Condense and recover the gas-phase substances at 20 °C to obtain silicon tetrachloride gas-phase substances. Collect the liquid-phase substances to obtain molten magnesium chloride.

[0247] Experimental results: Refer to Figure 10 , the gas chromatography - mass spectrometry detection results show that the purity of silicon tetrachloride in the silicon tetrachloride gas phase is 99.91%. The calculated conversion rate of chlorination of black talc is 95.52%.

[0248] Example 13

[0249] A deep chlorination process for black talc minerals, the steps of which are:

[0250] S1, co - ball - mill the crushed black talc and petroleum coke, and dry the ball - milled product to obtain pretreated powder; pelletize the pretreated powder to obtain pretreated pellets.

[0251] In this embodiment, the main component of black talc is 4SiO2·3MgO·2H2O (content greater than 90%), containing 0.67 wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10 μm; the carbon content in the petroleum coke is greater than 97%.

[0252] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of ball - milling is 500 rpm, and the ball - milling time is 120 min; the drying temperature is 100 °C, and the drying time is 90 min.

[0253] S2, dry the furnace cavity and the device pipeline by keeping them at 200 °C for 1 h, feed 100 g of pretreated pellets and 10 g of carbon disulfide into the furnace cavity; then wash the device pipeline with an inert gas at 500 sccm for 30 min; conduct the first chlorination roasting on 100 g of pretreated pellets and 10 g of carbon disulfide. In this embodiment, the process of the first chlorination roasting is: in an inert gas atmosphere, heat up at a heating rate of 10 °C / min to 800 °C, then switch the gas to a mixed atmosphere of chlorine and carbon monoxide, keep it warm for 120 min to obtain chlorinated black talc; after the insulation ends, switch the gas to an inert gas, and close the inert gas when the temperature in the furnace drops below 200 °C.

[0254] In this embodiment, the chlorination roasting is fluidized chlorination; the inert gas is argon; in the mixed atmosphere, the volume ratio of chlorine to the inert gas is 5:1, and the volume ratio of chlorine to carbon monoxide is 3:1.

[0255] S3, soak the chlorinated black talc in water to wash away water - soluble substances, take it out and dry it to obtain water - washed black talc. The water - immersion liquid is a magnesium chloride solution.

[0256] S4, co - ball - mill the water - washed black talc and petroleum coke, and dry the ball - milled product to obtain pre - chlorinated powder; pelletize the pre - chlorinated powder to obtain pre - chlorinated pellets.

[0257] In this step, the mass ratio of water-washed black talc to petroleum coke is 1:1; the rotation speed of ball milling is 200 rpm, and the ball milling time is 30 min; the drying temperature is 150 °C, and the drying time is 120 min.

[0258] S5, dry the furnace cavity and the device pipeline by keeping them at 200 °C for 1 h, and feed 100 g of pre-chlorinated pellets into the furnace cavity; then wash the device pipeline with 500 sccm of inert gas continuously for 30 min; perform the second chlorination roasting on 100 g of pre-chlorinated pellets to generate gas-phase substances, liquid-phase substances, and unreacted residual solids.

[0259] In this step, the process of the second chlorination roasting is as follows: under an inert gas atmosphere, heat up at a heating rate of 10 °C / min to 1100 °C, then switch the gas to a mixed atmosphere of chlorine and inert gas, keep it warm for 10 min to obtain chlorinated black talc; after the heat preservation ends, switch the gas to inert gas, and close the inert gas when the temperature in the furnace drops below 200 °C.

[0260] In this step, the chlorination roasting is fluidized chlorination; the inert gas is argon; the volume ratio of chlorine to inert gas is 1:5.

[0261] S6, condense and recover the gas-phase substances at 20 °C to obtain silicon tetrachloride gas-phase substances. Collect the liquid-phase substances to obtain molten magnesium chloride.

[0262] Experimental results: Refer to Figure 11 , the detection result of gas chromatography-mass spectrometry shows that the purity of silicon tetrachloride in the silicon tetrachloride gas-phase substances is 99.96%. The calculated chlorination conversion rate of black talc by characterization is 98.12%.

[0263] Comparative Example 4

[0264] In this comparative example compared with Example 9, only the temperature of the first chlorination roasting is adjusted to 1000 °C, and other conditions remain unchanged. At this time, the temperature of the first chlorination roasting is too high, reducing the selectivity of the first chlorination roasting.

[0265] In this comparative example, the detection result of gas chromatography-mass spectrometry shows that the purity of silicon tetrachloride in the silicon tetrachloride gas-phase substances is 82.46%. The calculated chlorination conversion rate of black talc by characterization is 78.91%.

[0266] Comparative Example 5

[0267] In this comparative example compared with Example 10, only after the first chlorination roasting, there is no water washing, and other conditions remain unchanged. At this time, the generated magnesium chloride cannot enter the aqueous solution, hindering the subsequent second chlorination roasting.

[0268] In this comparative example, the detection result of gas chromatography-mass spectrometry shows that the purity of silicon tetrachloride in the silicon tetrachloride gas phase is 88.26%. The chlorination conversion rate of black talc characterized and calculated is 88.35%.

[0269] Comparative Example 6

[0270] Compared with Example 11, in this comparative example, petroleum coke is not added to the raw material of the first chlorination roasting, and other conditions remain unchanged. At this time, part of the carbon source is lacking in the first chlorination roasting, and the reaction cannot proceed fully.

[0271] In this comparative example, the detection result of gas chromatography-mass spectrometry shows that the purity of silicon tetrachloride in the silicon tetrachloride gas phase is 68.98%. The chlorination conversion rate of black talc characterized and calculated is 62.73%.

[0272] In the above technical solution of the present invention, the above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied to other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A method for chlorination of black talc minerals, characterized in that, It includes the following steps: First, crush the black talc and carbonaceous material in a mixed state to obtain a pretreated powder; the carbonaceous material contains elemental carbon; Then, carry out first chlorination roasting on the pretreated powder under the atmosphere of a chlorine mixed gas and at a first roasting temperature to obtain chlorinated black talc; wherein, the first roasting temperature is 700 - 800 °C, the chlorine mixed gas includes chlorine and carbon monoxide, and the volume ratio of chlorine to carbon monoxide is 2.5 - 5:

1.

2. The chlorination method of the black talc mineral according to claim 1, wherein, The mass ratio of the black talc to the elemental carbon in the carbonaceous material is 1:3 - 1.

3. The chlorination method of the black talc mineral according to claim 1, characterized in that, The carbonaceous material is petroleum coke.

4. The chlorination method of the black talc mineral according to claim 1, wherein The black talc and the carbonaceous material are first crushed by ball milling, the ball milling speed is 200 - 500 rpm, and the ball milling duration is 30 - 120 min.

5. The chlorination method of the black talc mineral according to claim 1, characterized in that, In the step of first roasting the pretreated powder, the first roasting duration is not less than 90 min.

6. The chlorination method of the black talc mineral according to claim 1, characterized in that, After the pretreated powder is heated to 700 - 800 °C, then the chlorine mixed gas is introduced for reaction.

7. The chlorination method of the black talc mineral according to any one of claims 1 to 6, characterized in that, In the step of first roasting the pretreated powder, the pretreated powder is first roasted under the condition of adding a chlorination catalyst, and the chlorination catalyst includes carbon tetrachloride or carbon disulfide.

8. Use of the method for chlorination of the black talc mineral according to any one of claims 1 to 7 in the preparation of nano-silica, characterized in that, It includes the following steps: React the chlorinated black talc obtained by the chlorination method with a hydrochloric acid solution, and collect the solid to obtain nano-silica.

9. Use of the method for chlorination of the black talc mineral according to claim 8 in the preparation of nano-silica, characterized in that, The concentration of the hydrochloric acid solution is 0.5 - 2 mol / L, and the liquid-solid ratio of the chlorinated black talc to the hydrochloric acid solution is 1:5 - 10.

10. Use of the chlorination method of the black talc mineral according to claim 9 in the preparation of nano-silica, characterized in that, The reaction duration of the chlorinated black talc and the hydrochloric acid solution is 30 min.

11. A deep chlorination process for black talc minerals, characterized in that, It includes the following steps: Immerse the chlorinated black talc obtained by the chlorination method according to any one of claims 1 - 7 in water to wash away water-soluble substances, and then dry it to obtain washed black talc; Second, crush the washed black talc and carbonaceous material in a mixed state to obtain a pre-chlorinated powder; Then, carry out second chlorination roasting on the pre-chlorinated powder under the atmosphere of chlorine and at a second roasting temperature, and collect the gas-phase substance to obtain a silicon tetrachloride gas-phase substance; the second roasting temperature is not lower than 850 °C.

12. The deep chlorination process of the black talc mineral according to claim 11, characterized in that, The mass ratio of the chlorinated black talc to the elemental carbon in the carbonaceous material is 3 - 1:

1.

13. The deep chlorination process of the black talc mineral according to claim 11, characterized in that, In the step of carrying out the second chlorination roasting, the second roasting temperature is 850 - 1300 °C, and the heat preservation duration is 10 - 120 min.

14. The deep chlorination process of the black talc mineral according to claim 11, characterized in that, In the step of carrying out second chlorination roasting on the pre-chlorinated powder under the atmosphere of chlorine and at a second roasting temperature, the chlorine and the inert gas are introduced in a volume ratio of (5 - 1):(5 - 1).

15. The deep chlorination process of the black talc mineral according to any one of claims 11 to 14, characterized in that, It further includes at least one of the following operations (1) - (2): (1) Collect the water leaching solution in the step of immersing the chlorinated black talc to obtain a magnesium chloride solution; (2) Collect the liquid-phase substance in the second chlorination roasting to obtain a molten magnesium chloride.

16. The deep chlorination process of the black talc mineral according to any one of claims 11 to 14, characterized in that, It further includes: Carry out first condensation on the silicon tetrachloride gas-phase substance to obtain a crude silicon tetrachloride liquid.

17. The deep chlorination process of the black talc mineral according to claim 16, characterized in that, The temperature of the first condensation is lower than 20 °C.

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