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

Abstract

The invention provides a chlorination method of black talc mineral, a deep chlorination process and application. The chlorination method comprises the following steps: crushing black talc and a carbon substance in a mixed state to obtain pretreated powder; the carbon substance contains elemental carbon; roasting the pretreated powder in the atmosphere of chlorine gas mixture to obtain chlorinated black talc; wherein the roasting temperature is 700-800 DEG C, and the chlorine gas mixture comprises chlorine gas and carbon monoxide. According to the chlorination method of the black talc mineral, part of carbon substances enter a black talc structure through crushing to form intercalated carbon. And the composition of the chlorine gas mixture and the selection of the roasting temperature are combined, so that the magnesium component is chloridized, but the silicon component is not chloridized. Therefore, the chlorination efficiency of the black talc is improved, the air permeability of the black talc chlorination method is enhanced, magnesium resources in the black talc are fully converted and utilized, the magnesium conversion rate in the black talc mineral chlorination process can reach 77% or above, and part of 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 (4SiO 2 ·3MgO·2H 2 O) is a layered talc structure, and the interlayer carbon (C) is the main cause of blackness. 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 are difficult to break the silicon-oxygen tetrahedral structure, which makes 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. 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: 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; 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.

[0006] 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.

[0007] According to an embodiment of the present application, the carbon-based substance is petroleum coke.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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: 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.

[0013] 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.

[0014] According to an embodiment of the present application, the reaction time of the chlorinated black talc and the hydrochloric acid solution is 30 minutes.

[0015] The present application also provides a deep chlorination process of black talc mineral, comprising the following steps: 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; The washed black talc and the carbonaceous material are crushed for the second time in a mixed state to obtain a pre-chlorinated powder; 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.

[0016] 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.

[0017] 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 time is 10-120 min.

[0018] According to an embodiment of the present application, in the step of subjecting the pre-chlorinated powder to a second chlorination roasting in a chlorine atmosphere at a second roasting temperature, the chlorine and inert gas are introduced in a volume ratio of (5-1):(5-1).

[0019] According to the implementation of the present application, at least one of the following operations (1) to (2) is also included: (1) collecting the water extract from the black talc chloride soaking step to obtain a magnesium chloride solution; (2) Collecting the liquid phase in the second chlorination roasting to obtain a magnesium chloride melt.

[0020] According to the implementation mode of the present application, it also includes: The silicon tetrachloride gas phase is subjected to a first condensation to obtain a crude silicon tetrachloride liquid.

[0021] According to an embodiment of the present application, the temperature of the first condensation is lower than 20°C.

[0022] The above-mentioned chlorination method of black talc mineral, in the process of crushing, some carbonaceous substances 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, the full conversion and utilization of magnesium resources in black talc is achieved, and the magnesium conversion rate of the black talc mineral chlorination process is high, which can reach more than 77%, and can reach 90% under some conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0024] FIG1( a ) is an X-ray diffraction (XRD) diagram of Example 1 according to an embodiment of the present invention.

[0025] FIG1( b ) is a SEM image of Example 1 of the embodiment of the present invention. In the image, “X5,000” means “magnification 5000 times”. “WD” is the abbreviation of “Working Distance”. JEOL indicates the instrument model.

[0026] FIG1( c ) is an EDS graph of Example 1 according to an embodiment of the present invention.

[0027] Figure 2This is an X-ray diffraction (XRD) chart of Example 2 according to an embodiment of the present invention.

[0028] Figure 3 This is an X-ray diffraction (XRD) chart of Example 3 according to an embodiment of the present invention.

[0029] Figure 4 This is an X-ray diffraction (XRD) chart of Example 8 according to an embodiment of the present invention.

[0030] Figure 5 is an X-ray diffraction (XRD) diagram of Comparative Example 1 according to an embodiment of the present invention.

[0031] Figure 6 is an X-ray diffraction (XRD) diagram of Comparative Example 2 according to an embodiment of the present invention.

[0032] Figure 7 It is a gas chromatography-mass spectrometry (GC-MS) chart of silicon tetrachloride gas phase in Example 9 according to an embodiment of the present invention.

[0033] Figure 8 It is a gas chromatography-mass spectrometry (GC-MS) chart of the silicon tetrachloride gas phase of Example 10 according to the embodiment of the present invention.

[0034] Fig. 9 It is a gas chromatography-mass spectrometry (GC-MS) chart of the silicon tetrachloride gas phase of Example 11 according to the embodiment of the present invention.

[0035] Fig.10 It is a gas chromatography-mass spectrometry (GC-MS) chart of the silicon tetrachloride gas phase of Example 12 according to the embodiment of the present invention.

[0036] Fig.11 It is a gas chromatography-mass spectrometry (GC-MS) chart of the silicon tetrachloride gas phase of Example 13 according to the embodiment of the present invention.

[0037] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0038] 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.

[0039] 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.

[0040] The present invention provides a chlorination method of black talc mineral, comprising the following steps: 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.

[0041] The main component of the black talc is 4SiO 2 ·3MgO·2H 2 O, 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] The overall reaction equation is: 4SiO 2 ·3MgO·2H 2 O(s)+11Cl 2 (g)+5.5C(s)=3MgCl 2 (l)+4SiCl 4 (g)+5.5CO 2 (g)+H 2 O(g). Specifically, the chlorination temperature of the magnesium component of black talc is 700°C, and the chlorination temperature of the silicon component is 900°C. That is, at 700°C, the hypothetical reaction occurs: MgO·xH 2 O(s)+Cl 2 (g)+0.5C(s)=MgCl 2 (l) +0.5CO 2 (g)+xH 2 O(g), hypothetical reaction at 900℃: SiO 2 ·xH2 O(s)+2Cl 2 (g)+C(s)=SiCl 4 (g)+CO 2 (g)+xH 2 O(g). The silicon-magnesium components in black talc belong to the TOT structure, and there is no separate SiO 2 ·xH 2 O(s) and MgO·xH 2 O(s) exists, and the above assumption only describes the temperature difference. By controlling the chlorination temperature below 900°C, only the magnesium component can be chlorinated without chlorinating the silicon component. It should be noted that carbon monoxide can also replace carbon substances for reaction, and since the effect of gas-solid mass transfer is significantly better than solid-solid mass transfer, the addition of carbon monoxide can promote the chlorination reaction. The reaction equation is: 4SiO 2 ·3MgO·2H 2 O(s)+11Cl 2 (g)+11CO(g)=3MgCl 2 (l)+4SiCl 4 (g)+11CO 2 (g)+2H 2 O(g).

[0054] The magnesium element in the chlorinated black talc mainly exists in the form of magnesium chloride, and most of the silicon element in the chlorinated black talc still exists in the form of silicate. The mass fraction of the magnesium element existing in the form of magnesium chloride to all the magnesium elements is the magnesium conversion rate. Referring to the subsequent embodiments, under different conditions, the magnesium conversion rate reaches more than 77%.

[0055] The present invention realizes 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 being able to prepare porous nano-silicon dioxide from hard-to-treat silicates such as black talc and fully recover magnesium resources in the black talc mineral.

[0056] The above-mentioned chlorination method of black talc mineral, in the process of crushing, some carbonaceous substances 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, the full conversion and utilization of magnesium resources in black talc is achieved, and the magnesium conversion rate of the black talc mineral chlorination process is high, which can exceed 90%.

[0057] In some embodiments, the mass ratio of the black talc to the carbon in the carbon-based 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, and a large amount of reducing agent carbon is introduced and enriched between the black talc TO layers; by introducing the petroleum coke, sufficient amorphous carbon source can be provided for the black talc as a reducing agent.

[0058] In some embodiments, the carbonaceous material is petroleum coke, which is porous and irregular particles with disordered carbon structure, has a high carbon content and low cost.

[0059] In some embodiments, 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.

[0060] The mechanical energy input during the ball milling process can cause the chemical bonds on the surface of the material particles to break and recombine. This energy input not only helps the mixing of materials, but also allows the particles of different substances to interact physically or chemically, further strengthening their contact and bonding, that is, achieving the effect of activation. Under the above process parameters, the particle size of the pre-treated powder is made appropriate by ball milling, which allows the particles of black talc and the carbonaceous material to have more contact points and a larger contact area, thereby achieving close contact without excessive grinding, which produces adverse effects such as particle agglomeration.

[0061] In some embodiments, in the step of first calcining the pretreated powder, the calcination time is not less than 90 minutes.

[0062] In some more specific embodiments, after the pretreated powder is heated to 700-800° C., the chlorine gas mixture is introduced to react.

[0063] Since chlorine reacts with carbon at 200-500℃ to produce phosgene (COCl 2 ), which is ten times more toxic than chlorine and poses a hidden danger to production safety. Therefore, after the pretreated powder is heated to 700-800°C, the chlorine mixed gas is introduced into the reaction to avoid the production of phosgene.

[0064] Exemplarily, before the chlorination roasting, the pretreated powder is heated to 700-800°C in an inert gas atmosphere, such as at a heating rate of 10°C / min; and then the gas is switched to a mixed atmosphere of chlorine and inert gas. The magnesium conversion rate of the chlorination process of the talc mineral is high, exceeding 90%; the chlorination roasting in the present invention is molten pool smelting or boiling chlorination; the inert gas in the present invention includes one or more of argon and nitrogen.

[0065] In some embodiments, 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. The reaction rate of calcination is accelerated by adding the chlorination catalyst. The amount of the chlorination catalyst added is: pretreated powder: carbon disulfide = 10-5: 1, or pretreated powder: carbon tetrachloride = 8: 3-1.

[0066] In some embodiments, the method further includes pelletizing the pretreated powder to obtain pretreated pellets.

[0067] In some embodiments, before the step of first calcining the pretreated powder, the pretreated powder is further dried.

[0068] This operation removes moisture from the talc raw material and reduces the effect of moisture on the chlorination reaction, because silicon tetrachloride reacts with water to form silicon dioxide, which will prevent the chlorination reaction from proceeding further. In addition, moisture will consume chlorine to form hydrogen chloride byproduct. 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 ball milled product is dried at 90-120°C for 30-90 minutes.

[0069] In some embodiments, before the step of first calcining the pretreated powder, the step further includes drying the calcining device and introducing an inert gas to remove air and moisture therein.

[0070] This operation removes moisture from the calcining device, reduces the effect of moisture on the chlorination reaction, and can also increase the amount of silicon tetrachloride obtained in the reaction.

[0071] Exemplarily, the furnace chamber and the device pipelines are kept at 200° C. for 1 hour for drying, and the pretreated powder and the chlorination catalyst are fed into the furnace chamber; then the device pipelines are purged with 500 sccm of inert gas for 30 minutes.

[0072] In some embodiments, the chlorine gas mixture also includes an inert gas; the volume ratio of the chlorine gas to the inert gas is 5:1.

[0073] On the one hand, the use of inert gas can reduce the amount of chlorine consumed per unit time; on the other hand, compared with the use of low-flow pure chlorine alone, the use of inert gas will reduce the activity of chlorine, making the reaction more controllable and production safer.

[0074] In some embodiments, after the first roasting is completed, the chlorine mixed gas is switched to an inert gas, and the inert gas is turned off when the temperature in the furnace drops below 200°C.

[0075] Switching to inert gas to cool down is because chlorine will react with carbon to produce phosgene (COCl 2 ), so after the chlorination reaction is completed, the temperature cannot be lowered in the presence of chlorine and carbon at the same time, and inert gas needs to be replaced for cooling.

[0076] The inert gas is turned off when the temperature in the furnace drops below 200°C to protect the generated product and prevent magnesium chloride from being oxidized to magnesium oxide by oxygen. If the inert gas is turned off in advance, the air above 200°C, especially the oxygen in the air, will oxidize the generated product magnesium chloride to magnesium oxide.

[0077] 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: The chlorinated black talc obtained by the chlorination method is reacted with hydrochloric acid, and the solid matter is collected to obtain nano silicon dioxide.

[0078] The residual solid obtained by the chlorination method is stirred for a period of time with hydrochloric acid of a certain concentration and a certain volume solid-liquid ratio, and then filtered to obtain a solid.

[0079] In some embodiments, the concentration of the hydrochloric acid solution is 0.5-2 mol / L, exemplified by 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.

[0080] In some embodiments, the liquid-to-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-to-solid ratio of the chlorinated black talc to the hydrochloric acid solution is 1:10.

[0081] In some embodiments, the reaction time of the chlorinated black talc and the hydrochloric acid solution is 30 minutes. For example, a magnetic stirring of 500 rpm is used for 30 minutes during the reaction.

[0082] In the subsequent process, the leachate was collected for inductively coupled plasma optical emission spectrometry (ICP-OES) to test the magnesium concentration, the filtered solid was collected and dried for X-ray diffraction (XRD) to test whether the talc structure was destroyed, and the scanning electron microscope-energy dispersive spectrometer (SEM-EDS) was used to test its morphology and microstructure.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] A deep chlorination process of black talc mineral comprises the following steps: S10: soaking the chlorinated black talc in water to wash away water-soluble substances, and drying to obtain washed black talc.

[0087] 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.

[0088] 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.

[0089] S20: performing a second crushing on the washed black talc and the carbonaceous material in a mixed state to obtain a pre-chlorinated powder.

[0090] The chlorination method of black talc mineral destroys the black talc structure, but the Si-O bond in the black talc still needs the participation of C to react with the Si-Cl bond in silicon tetrachloride, so it is necessary to add carbon substances to the reactants. The purpose of the carbon substances in this step is also to form interlayer carbon in the water-washed black slip. The carbon substances and the second crushing operations in this step can refer to the carbon substances and the first crushing operations 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 carbon substances in step S20 can be the same or different from the carbon substances in step S100.

[0091] S30: subjecting the pre-chlorinated powder to a second chlorination roasting in a chlorine atmosphere at a second roasting temperature, collecting a gas phase to obtain a silicon tetrachloride gas phase. The second roasting temperature is not less than 850°C.

[0092] In this step, SiO 2 ·xH 2 O(s)+2Cl 2 (g)+C(s)=SiCl 4 (g)+CO 2 (g)+xH 2 The reaction of O(g) causes the silicon element to generate silicon tetrachloride gas, and also generates a small amount of liquid phase (mainly molten magnesium chloride) and unreacted residual solid.

[0093] In the present invention, the first chlorination roasting and the second chlorination roasting in the present invention are molten pool smelting or boiling chlorination. The second chlorination may include multiple roasting cycles, and the roasting time of each roasting cycle is not less than 8 minutes, and further 8-150 minutes; or, the roasting time of each roasting cycle is not less than 10 minutes, further 10-120 minutes, further 15-120 minutes, and can also be 15-30 minutes or 60-120 minutes or 100-150 minutes; after completing the previous roasting cycle, in the next roasting cycle, the next batch of pretreated powder is directly roasted; the residual solid can also be repeatedly roasted with the next batch of pretreated powder.

[0094] The above-mentioned deep chlorination process of black talc mineral first forms intercalated carbon by allowing some carbonaceous substances to enter the black talc structure during the crushing process. Then, the magnesium component is chlorinated without chlorinating the silicon component in combination with the composition of the specific chlorine gas mixture and the selection of the roasting temperature. Then, the generated magnesium chloride is removed by soaking, which greatly reduces the encapsulation of the silicon component by the molten magnesium chloride in the subsequent chlorination process, so that the silicon element can be better chlorinated, thereby improving the overall chlorination efficiency of the black talc and improving the comprehensive utilization rate of silicon and magnesium elements in the black talc.

[0095] In some embodiments, the mass ratio of the chlorinated black talc to the carbon in the carbon-based substance is 3 to 1: 1. In some specific embodiments, the carbon-based substance is petroleum coke.

[0096] The chlorinated black talc and the carbon in the carbon material are crushed at a mass ratio of 3 to 1: 1. Since the first chlorination roasting destroys the black talc structure, the difficulty of the carbon to form intercalated carbon is reduced, so the amount of the carbon material is relatively reduced.

[0097] In some embodiments, the second crushing is performed by ball milling, the ball milling speed is 100-600 rpm, and the ball milling time is 20-130 min.

[0098] In some embodiments, in the step of performing the second chlorination roasting, the second roasting temperature is 850-1300°C, and the heat preservation time is 10-120 minutes. Further, the second roasting temperature is not less than 900°C or not less 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.

[0099] In some embodiments, in the step of subjecting the pre-chlorinated powder to a second chlorination roasting in a chlorine atmosphere at a second roasting temperature, the chlorine and the inert gas are introduced in a volume ratio of (5-1):(5-1).

[0100] Similarly, in the second chlorination roasting step, the introduction method of the chlorine and the inert gas can refer to the first chlorination roasting, when the temperature in the reaction furnace rises to the second roasting temperature, and then introduced. Before this, the pre-chlorination powder is in an inert gas atmosphere.

[0101] In some embodiments, the method further includes at least one of the following operations (1) to (2): (1) Collecting the water extract from the chlorinated black talc soaking step to obtain a magnesium chloride solution.

[0102] (2) Collecting the liquid phase in the second chlorination roasting to obtain a magnesium chloride melt.

[0103] In some specific embodiments, the liquid phase is subjected to molten salt electrolysis to obtain crude metallic magnesium.

[0104] In some embodiments, it also includes: The silicon tetrachloride gas phase is subjected to a first condensation to obtain a crude silicon tetrachloride liquid. In some specific embodiments, the temperature of the first condensation is lower than 20°C.

[0105] The crude silicon tetrachloride liquid can be further refined by distillation to obtain refined silicon tetrachloride liquid.

[0106] The following are specific examples of the present invention: Example 1 A chlorination method for black talc mineral, comprising the following steps: S1, ball-milling the crushed black talc and petroleum coke together, and drying the ball-milled product to obtain a pretreated powder; and pelletizing the pretreated powder to obtain pretreated pellets.

[0107] In this embodiment, the main component of black talc is 4SiO 2 ·3MgO·2H 2 O (content greater than 90%), contains 0.67wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0108] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of the ball mill is 500 rpm, and the ball milling time is 120 min; the drying temperature is 120° C., and the drying time is 90 min.

[0109] S2, the furnace chamber and the device pipeline are kept at 200°C for 1h for drying, and 100g of pretreated pellets and 10g of carbon disulfide are fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30min; 100g of pretreated pellets and 10g of carbon disulfide are subjected to chlorination roasting; in this embodiment, the process of chlorination roasting is: in an inert gas atmosphere, the temperature is increased to 800°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and the temperature is kept for 120min to obtain residual solids; after the insulation is completed, 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.

[0110] In this embodiment, the chlorination roasting is boiling 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.

[0111] S3, acid leaching and testing of residual solids: The residual solids were subjected to magnetic stirring at 500rpm for 30min with 1mol / L hydrochloric acid and a solid-liquid ratio of 1:10, and then filtered, and repeated three times. The leachate from the first two and third times was collected and the total volume was recorded respectively. The collected leachate was diluted to an appropriate multiple and fed into an inductively coupled plasma optical emission spectrometer (ICP-OES) to test the magnesium concentration; the filtered solids were dried and X-ray diffraction (XRD) was performed to test whether the talc structure was destroyed, and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) was used to test its morphology and microstructure.

[0112] Experimental results: 100g of pretreated pellets contain 35.09g of black talc, of which magnesium accounts for 16% (5.61g). The total magnesium mass obtained by ICP-OES test after acid leaching is 5.31g, and the magnesium conversion rate of black talc chlorination process is calculated to be 94.65%; see Figure 1 (a), the XRD test talc peak intensity is low, indicating that the black talc structure is largely destroyed, see Figure 1 (b) and Figure 1 (c), SEM-EDS test shows that the filtrated solid is porous nano-silicon dioxide.

[0113] Example 2 A chlorination method for black talc mineral, comprising the following steps: S1, ball-milling the crushed black talc and petroleum coke together, and drying the ball-milled product to obtain a pretreated powder.

[0114] In this embodiment, the main component of black talc is 4SiO 2 ·3MgO·2H 2 O (content greater than 90%), contains 0.64wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0115] 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.

[0116] S2, the furnace chamber and the device pipeline are kept at 200°C for 1h for drying, and 80g of pretreated powder and 30g of carbon tetrachloride are fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30min; 80g of pretreated powder and 30g of carbon tetrachloride are subjected to chlorination roasting; in this embodiment, the process of chlorination roasting is: in an inert gas atmosphere, the temperature is increased to 750°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and the temperature is kept for 90min to obtain residual solid; after the insulation is completed, 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.

[0117] In this embodiment, the chlorination roasting is boiling 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.

[0118] S3, acid leaching and testing of residual solids: The residual solids were subjected to magnetic stirring at 500rpm for 30min with 1mol / L hydrochloric acid and a solid-liquid ratio of 1:10, and then filtered, and repeated three times. The leachate from the first two and third times was collected and the total volume was recorded respectively. The collected leachate was diluted to an appropriate multiple and fed into an inductively coupled plasma optical emission spectrometer (ICP-OES) to test the magnesium concentration; the filtered solids were dried and X-ray diffraction (XRD) was performed to test whether the talc structure was destroyed, and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) was used to test its morphology and microstructure.

[0119] Experimental results: 80g of pre-treated powder contains 28.07g of black talc, of which magnesium accounts for 16% (4.49g). After acid leaching, ICP-OES test shows that the total magnesium mass is 4.26g, and the calculated percentage of black talc chlorination process is 94.88%; see Figure 2 The XRD test showed that the talc peak intensity was low, indicating that the black talc structure was largely destroyed, indicating that most of the black talc participated in the chlorination reaction, so the chlorination conversion rate was high. SEM-EDS test showed that the filtrated solid was porous nano-silica.

[0120] Example 3 A chlorination method for black talc mineral, comprising the following steps: S1, ball-milling the crushed black talc and petroleum coke together, and drying the ball-milled product to obtain a pretreated powder.

[0121] In this embodiment, the main component of black talc is 4SiO 2 ·3MgO·2H 2 O (content greater than 90%), contains 0.55wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0122] 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.

[0123] S2, the furnace chamber and the device pipeline are kept at 200°C for 1h for drying, and 80g of pretreated powder and 50g of carbon tetrachloride are fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30min; 80g of pretreated powder and 50g of carbon tetrachloride are subjected to chlorination roasting; in this embodiment, the process of chlorination roasting is: in an inert gas atmosphere, the temperature is increased to 750°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and the temperature is kept for 90min to obtain residual solid; after the insulation is completed, 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.

[0124] In this embodiment, the chlorination roasting is boiling 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.

[0125] S3, acid leaching and testing of residual solids: The residual solids were subjected to magnetic stirring at 500rpm for 30min with 1mol / L hydrochloric acid and a solid-liquid ratio of 1:10, and then filtered, and repeated three times. The leachate from the first two and third times was collected and the total volume was recorded respectively. The collected leachate was diluted to an appropriate multiple and fed into an inductively coupled plasma optical emission spectrometer (ICP-OES) to test the magnesium concentration; the filtered solids were dried and X-ray diffraction (XRD) was performed to test whether the talc structure was destroyed, and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) was used to test its morphology and microstructure.

[0126] Experimental results: 80g of pretreated powder contains 28.07g of black talc, of which magnesium accounts for 16% or 4.49g. The total magnesium mass obtained by ICP-OES test after acid leaching is 4.32g, and the magnesium conversion rate of black talc chlorination process is calculated to be 96.21%; see Figure 3 The XRD test showed that the peak intensity of talc was almost zero, indicating that the structure of black talc was completely destroyed, indicating that almost all black talc participated in the chlorination reaction, so the chlorination conversion rate was very high. SEM-EDS test showed that the filtrated solid was porous nano-silica.

[0127] Example 4 A chlorination method for black talc mineral, comprising the following steps: S1, ball-milling the crushed black talc and petroleum coke together, and drying the ball-milled product to obtain a pretreated powder; and pelletizing the pretreated powder to obtain pretreated pellets.

[0128] In this embodiment, the main component of black talc is 4SiO 2 ·3MgO·2H 2O (content greater than 90%), contains 0.67wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0129] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of the ball mill is 500 rpm, and the ball milling time is 120 min; the drying temperature is 120° C., and the drying time is 90 min.

[0130] S2, the furnace chamber and the device pipeline are kept at 200°C for 1h for drying, and 100g of pretreated pellets and 20g of carbon disulfide are fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30min; 100g of pretreated pellets and 20g of carbon disulfide are subjected to chlorination roasting; in this embodiment, the process of chlorination roasting is: in an inert gas atmosphere, the temperature is increased to 800°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and the temperature is kept for 120min to obtain residual solids; after the insulation is completed, 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.

[0131] In this embodiment, the chlorination roasting is boiling 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.

[0132] S3, acid leaching and testing of residual solids: The residual solids were subjected to magnetic stirring at 500rpm for 30min with 1mol / L hydrochloric acid and a solid-liquid ratio of 1:10, and then filtered, and repeated three times. The leachate from the first two and third times was collected and the total volume was recorded respectively. The collected leachate was diluted to an appropriate multiple and fed into an inductively coupled plasma optical emission spectrometer (ICP-OES) to test the magnesium concentration; the filtered solids were dried and X-ray diffraction (XRD) was performed to test whether the talc structure was destroyed, and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) was used to test its morphology and microstructure.

[0133] Experimental results: 100g of pretreated pellets contained 35.09g of black talc, of which magnesium accounted for 16% (5.61g). After acid leaching, the total magnesium mass obtained by ICP-OES test was 5.51g, and the magnesium conversion rate of black talc chlorination process was calculated to be 98.22%; the talc peak intensity of XRD test was basically zero, indicating that the black talc structure was completely destroyed, and SEM-EDS test showed that the filtered solid was porous nano-silicon dioxide.

[0134] Example 5 A chlorination method for black talc mineral, comprising the following steps: S1, ball-milling the crushed black talc and petroleum coke together, and drying the ball-milled product to obtain a pretreated powder; and pelletizing the pretreated powder to obtain pretreated pellets.

[0135] In this embodiment, the main component of black talc is 4SiO 2 ·3MgO·2H 2 O (content greater than 90%), contains 0.67wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0136] In this embodiment, the mass ratio of black talc to petroleum coke is 1:3; the rotation speed of the ball mill is 500 rpm, and the ball milling time is 120 min; the drying temperature is 120° C., and the drying time is 90 min.

[0137] S2, the furnace chamber and the device pipeline are kept at 200°C for 1h for drying, and 100g of pretreated pellets and 10g of carbon disulfide are fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30min; 100g of pretreated pellets and 10g of carbon disulfide are subjected to chlorination roasting; in this embodiment, the process of chlorination roasting is: in an inert gas atmosphere, the temperature is increased to 800°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and the temperature is kept for 120min to obtain residual solids; after the insulation is completed, 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.

[0138] In this embodiment, the chlorination roasting is boiling 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.

[0139] S3, acid leaching and testing of residual solids: The residual solids were subjected to magnetic stirring at 500rpm for 30min with 1mol / L hydrochloric acid and a solid-liquid ratio of 1:10, and then filtered, and repeated three times. The leachate from the first two and third times was collected and the total volume was recorded respectively. The collected leachate was diluted to an appropriate multiple and fed into an inductively coupled plasma optical emission spectrometer (ICP-OES) to test the magnesium concentration; the filtered solids were dried and X-ray diffraction (XRD) was performed to test whether the talc structure was destroyed, and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) was used to test its morphology and microstructure.

[0140] Experimental results: 100g of pretreated pellets contain 25.00g of black talc, of which 4.00g is magnesium, accounting for 16%. The total magnesium mass obtained by ICP-OES test after acid leaching is 3.83g, and the magnesium conversion rate of black talc chlorination process is calculated to be 95.75%; the talc peak intensity of XRD test is basically zero, indicating that the black talc structure is completely destroyed, and SEM-EDS test shows that the filtrated solid is porous nano-silicon dioxide.

[0141] Example 6 Compared with Example 1, in this example, only the mass ratio of black talc to petroleum coke is adjusted to 1:1, and other conditions remain unchanged.

[0142] In this embodiment, the magnesium conversion rate of the chlorination process is reduced to 80.34%.

[0143] Example 7 Compared with Example 2, in this example, only the amount of carbon tetrachloride added is adjusted to 10 g, and other conditions remain unchanged.

[0144] In this embodiment, the magnesium conversion rate of the chlorination process is reduced to 82.13%.

[0145] Example 8 Compared with Example 2, in this example, only the chlorination roasting process is heated to 700° C. at a heating rate of 10° C. / min, and other conditions remain unchanged.

[0146] In this example, the magnesium conversion rate of the chlorination process was reduced to 77.06%. Figure 4 , the product of Example 8 was subjected to XRD test. After the chlorination process, the structure of the black talc was partially destroyed, indicating that part of the black talc participated in the chlorination reaction, so the chlorination conversion rate was high.

[0147] Comparative Example 1 Compared with Example 1, in this comparative example, only the co-ball milling of the crushed black talc and petroleum coke is adjusted to the ball milling of the black talc alone without adding petroleum coke, and other conditions remain unchanged.

[0148] In this comparative example, the magnesium conversion rate of the chlorination process was reduced to 72.50%. The product of comparative example 1 was subjected to XRD test. Figure 5 ,The talc peak intensity in the XRD test is relatively high, indicating that the black talc structure is rarely destroyed after the chlorination process, and only some black talc participates in the chlorination reaction, so the chlorination conversion rate is medium.

[0149] Comparative Example 2 Compared with Example 2, in this comparative example, only the chlorination roasting process was heated to 600° C. at a heating rate of 10° C. / min, and other conditions remained unchanged.

[0150] In this comparative example, the magnesium conversion rate of the chlorination process was reduced to 60.57%. The product of comparative example 2 was subjected to XRD test. Figure 6 ,The talc peak intensity in the XRD test is relatively high, indicating that the black talc structure is rarely destroyed after the chlorination process, and only some black talc participates in the chlorination reaction, so the chlorination conversion rate is medium.

[0151] Comparative Example 3 Compared with Example 3, in this comparative example, only the chlorination roasting process was heated to 650° C. at a heating rate of 10° C. / min, and other conditions remained unchanged.

[0152] In this comparative example, the magnesium conversion rate in the chlorination process was reduced to 69.46%.

[0153] From the results of Examples 1 to 8 and Comparative Examples 1 to 3, the chlorination method of 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, which can reach more than 77%, and can reach 90% under some conditions, thereby realizing the full conversion and utilization of magnesium resources in black talc.

[0154] In the following embodiments and comparative examples: The main component of black talc is 4SiO 2 ·3MgO·2H 2 O (content greater than 90%), contains 0.67wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0155] Example 9 A deep chlorination process of black talc mineral, the steps are: S1, ball-milling the crushed black talc and petroleum coke together, and drying the ball-milled product to obtain a pretreated powder.

[0156] In this embodiment, the main component of black talc is 4SiO 2 ·3MgO·2H 2 O (content greater than 90%), contains 0.67wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0157] 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.

[0158] S2, the furnace chamber and the device pipeline are kept at 200°C for 1h for drying, and 80g of pretreated powder and 30g of carbon disulfide are fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30min; 80g of pretreated powder and 30g of carbon disulfide are subjected to the first chlorination roasting; in this embodiment, the process of the first chlorination roasting is: in an inert gas atmosphere, the temperature is increased to 750°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and the temperature is kept for 90min to obtain chlorinated black talc; after the insulation is completed, 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.

[0159] In this embodiment, the chlorination roasting is boiling 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.

[0160] S3, soaking the chlorinated black talc in water to wash away water-soluble substances, taking out and drying, and obtaining water-washed black talc, wherein the water soaking liquid is a magnesium chloride solution.

[0161] S4, ball-milling the washed black talc and the petroleum coke together, and drying the ball-milled product to obtain a pre-chlorinated powder.

[0162] In this step, the mass ratio of washed 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.

[0163] S5, the furnace chamber and the device pipeline are kept at 200°C for 1 hour for drying, and 100g of pre-chlorinated powder is fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30 minutes; the pre-chlorinated powder is subjected to a second chlorination roasting to generate a gas phase, a liquid phase and unreacted residual solids.

[0164] In this step, the second chlorination roasting process is: in an inert gas atmosphere, the temperature is increased 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 mixture is kept warm for 20 minutes to obtain chlorinated black talc; after the insulation is completed, 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.

[0165] In this step, the chlorination roasting is boiling chlorination; the inert gas is argon; and the volume ratio of chlorine gas to the inert gas is 1:1.

[0166] S6, condensing and recovering the gas phase at -20°C to obtain silicon tetrachloride gas phase, and collecting the liquid phase to obtain molten magnesium chloride.

[0167] Experimental results: see Figure 7 The results of gas chromatography-mass spectrometry showed that the purity of silicon tetrachloride in the silicon tetrachloride gas phase was 99.93%. The characterization calculation showed that the chlorination conversion rate of black talc was 96.32%.

[0168] The calculation method of the chlorination conversion rate of black talc is: chlorination conversion rate η=(1-(mass of unreacted residual solids after the second chlorination roasting / mass of black talc ore before chlorination))×100%; wherein, in order to eliminate the influence of excessive petroleum coke on the calculation, the mass of the unreacted residual solids after the second chlorination roasting is washed with water and then calcined at 600°C for 2h in an air atmosphere is counted as the mass of the unreacted residual solids after the second chlorination roasting.

[0169] Because black talc (4SiO 2 ·3MgO·2H 2 O) in which silicon and magnesium are in the form of 4SiO 2 The chlorination reaction is carried out in a fixed stoichiometric ratio of MgO:3, so the chlorination conversion rate of silicon and the chlorination conversion rate of magnesium in the black talc are numerically equal to the chlorination conversion rate of the black talc.

[0170] Example 10 A deep chlorination process of black talc mineral, the steps are: S1, ball-milling the crushed black talc and petroleum coke together, and drying the ball-milled product to obtain a pretreated powder; and pelletizing the pretreated powder to obtain pretreated pellets.

[0171] In this embodiment, the main component of black talc is 4SiO 2 ·3MgO·2H 2 O (content greater than 90%), contains 0.67wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0172] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of the ball mill is 500 rpm, and the ball milling time is 120 min; the drying temperature is 100° C., and the drying time is 90 min.

[0173] S2, the furnace chamber and the device pipeline are kept at 200°C for 1h for drying, and 100g of pretreated pellets and 20g of carbon disulfide are fed into the furnace chamber; then the device pipeline is purged with 500sccm of inert gas for 30min; 100g of pretreated pellets and 20g of carbon disulfide are subjected to the first chlorination roasting; in this embodiment, the process of the first chlorination roasting is: in an inert gas atmosphere, the temperature is increased to 800°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and the temperature is kept for 120min to obtain chlorinated black talc; after the insulation is completed, 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.

[0174] In this embodiment, the chlorination roasting is boiling 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.

[0175] S3, soaking the chlorinated black talc in water to wash away water-soluble substances, taking out and drying, and obtaining water-washed black talc, wherein the water soaking liquid is a magnesium chloride solution.

[0176] S4, ball-milling the washed black talc and the petroleum coke together, and drying the ball-milled product to obtain a pre-chlorinated powder; and pelletizing the pre-chlorinated powder to obtain pre-chlorinated pellets.

[0177] In this step, the mass ratio of washed 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.

[0178] S5, the furnace chamber and the device pipeline are kept at 200°C for 1 hour for drying, and 100g of pre-chlorinated pellets are fed into the furnace chamber; then the device pipeline is purged with 500sccm of inert gas for 30 minutes; the 100g of pre-chlorinated pellets are subjected to a second chlorination roasting to generate gas phase, liquid phase and unreacted residual solid.

[0179] In this step, the second chlorination roasting process is: in an inert gas atmosphere, the temperature is increased to 1200°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 120 minutes to obtain chlorinated black talc; after the insulation is completed, 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.

[0180] In this step, the chlorination roasting is boiling chlorination; the inert gas is argon; and the volume ratio of chlorine gas to the inert gas is 5:1.

[0181] S6, condensing and recovering the gas phase at -40°C to obtain silicon tetrachloride gas phase, and collecting the liquid phase to obtain molten magnesium chloride.

[0182] Experimental results: see Figure 8 The results of gas chromatography-mass spectrometry showed that the purity of silicon tetrachloride in the silicon tetrachloride gas phase was 99.99%. The characterization calculation showed that the chlorination conversion rate of black talc was 99.78%.

[0183] Embodiment 11 A deep chlorination process of black talc mineral, the steps are: S1, ball-milling the crushed black talc and petroleum coke together, and drying the ball-milled product to obtain a pretreated powder.

[0184] In this embodiment, the main component of black talc is 4SiO 2 ·3MgO·2H 2 O (content greater than 90%), contains 0.67wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0185] 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.

[0186] S2, the furnace chamber and the device pipeline are kept at 200°C for 1h for drying, and 80g of pretreated powder and 50g of carbon tetrachloride are fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30min; 80g of pretreated powder and 30g of carbon disulfide are subjected to the first chlorination roasting; in this embodiment, the process of the first chlorination roasting is: in an inert gas atmosphere, the temperature is increased to 750°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and the temperature is kept for 90min to obtain chlorinated black talc; after the insulation is completed, 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.

[0187] In this embodiment, the chlorination roasting is boiling 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.

[0188] S3, soaking the chlorinated black talc in water to wash away water-soluble substances, taking out and drying, and obtaining water-washed black talc, wherein the water soaking liquid is a magnesium chloride solution.

[0189] S4, ball-milling the washed black talc and the petroleum coke together, and drying the ball-milled product to obtain a pre-chlorinated powder.

[0190] In this step, the mass ratio of washed 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.

[0191] S5, the furnace chamber and the device pipeline are kept at 200°C for 1 hour for drying, and 100g of pre-chlorinated powder is fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30 minutes; the pre-chlorinated powder is subjected to a second chlorination roasting to generate a gas phase, a liquid phase and unreacted residual solids.

[0192] In this step, the second chlorination roasting process is: in an inert gas atmosphere, the temperature is increased 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 chlorinated black talc; after the insulation is completed, 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.

[0193] In this step, the chlorination roasting is boiling chlorination; the inert gas is argon; and the volume ratio of chlorine gas to the inert gas is 2:1.

[0194] S6, condensing and recovering the gas phase at -40°C to obtain silicon tetrachloride gas phase, and collecting the liquid phase to obtain molten magnesium chloride.

[0195] Experimental results: see Fig. 9 The results of gas chromatography-mass spectrometry showed that the purity of silicon tetrachloride in the silicon tetrachloride gas phase was 99.97%. The characterization calculation showed that the chlorination conversion rate of black talc was 96.40%.

[0196] Example 12 A deep chlorination process of black talc mineral, the steps are: S1, ball-milling the crushed black talc and petroleum coke together, and drying the ball-milled product to obtain a pretreated powder; and pelletizing the pretreated powder to obtain pretreated pellets.

[0197] In this embodiment, the main component of black talc is 4SiO 2 ·3MgO·2H 2 O (content greater than 90%), contains 0.67wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0198] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of the ball mill is 500 rpm, and the ball milling time is 120 min; the drying temperature is 100° C., and the drying time is 90 min.

[0199] S2, the furnace chamber and the device pipeline are kept at 200°C for 1h for drying, and 100g of pretreated pellets and 10g of carbon disulfide are fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30min; 100g of pretreated pellets and 10g of carbon disulfide are subjected to the first chlorination roasting; in this embodiment, the process of the first chlorination roasting is: in an inert gas atmosphere, the temperature is increased to 800°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and the temperature is kept for 120min to obtain chlorinated black talc; after the insulation is completed, 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.

[0200] In this embodiment, the chlorination roasting is boiling 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.

[0201] S3, soaking the chlorinated black talc in water to wash away water-soluble substances, taking out and drying, and obtaining water-washed black talc, wherein the water soaking liquid is a magnesium chloride solution.

[0202] S4, ball-milling the washed black talc and the petroleum coke together, and drying the ball-milled product to obtain a pre-chlorinated powder; and pelletizing the pre-chlorinated powder to obtain pre-chlorinated pellets.

[0203] In this step, the mass ratio of washed black talc to petroleum coke is 1:1; the rotation speed of the ball mill is 200 rpm, and the ball milling time is 30 min; the drying temperature is 150° C., and the drying time is 120 min.

[0204] S5, the furnace chamber and the device pipeline are kept at 200°C for 1 hour for drying, and 100g of pre-chlorinated pellets are fed into the furnace chamber; then the device pipeline is purged with 500sccm of inert gas for 30 minutes; the 100g of pre-chlorinated pellets are subjected to a second chlorination roasting to generate gas phase, liquid phase and unreacted residual solid.

[0205] In this step, the second chlorination roasting process is: in an inert gas atmosphere, the temperature is increased to 900°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 10 minutes to obtain chlorinated black talc; after the insulation is completed, 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.

[0206] In this step, the chlorination roasting is boiling chlorination; the inert gas is argon; and the volume ratio of chlorine gas to the inert gas is 1:5.

[0207] S6, condensing and recovering the gas phase at 20°C to obtain silicon tetrachloride gas phase, and collecting the liquid phase to obtain molten magnesium chloride.

[0208] Experimental results: see Fig.10 The results of gas chromatography-mass spectrometry showed that the purity of silicon tetrachloride in the silicon tetrachloride gas phase was 99.91%. The characterization calculation showed that the chlorination conversion rate of black talc was 95.52%.

[0209] Example 13 A deep chlorination process of black talc mineral, the steps are: S1, ball-milling the crushed black talc and petroleum coke together, and drying the ball-milled product to obtain a pretreated powder; and pelletizing the pretreated powder to obtain pretreated pellets.

[0210] In this embodiment, the main component of black talc is 4SiO 2 ·3MgO·2H 2 O (content greater than 90%), contains 0.67wt.% interlayer carbon (C); the particle size of the crushed black talc is less than 10μm; the carbon content in petroleum coke is greater than 97%.

[0211] In this embodiment, the mass ratio of black talc to petroleum coke is 1:1.85; the rotation speed of the ball mill is 500 rpm, and the ball milling time is 120 min; the drying temperature is 100° C., and the drying time is 90 min.

[0212] S2, the furnace chamber and the device pipeline are kept at 200°C for 1h for drying, and 100g of pretreated pellets and 10g of carbon disulfide are fed into the furnace chamber; then the device pipeline is washed with 500sccm of inert gas for 30min; 100g of pretreated pellets and 10g of carbon disulfide are subjected to the first chlorination roasting; in this embodiment, the process of the first chlorination roasting is: in an inert gas atmosphere, the temperature is increased to 800°C at a heating rate of 10°C / min, and then the gas is switched to a mixed atmosphere of chlorine and carbon monoxide, and the temperature is kept for 120min to obtain chlorinated black talc; after the insulation is completed, 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.

[0213] In this embodiment, the chlorination roasting is boiling 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.

[0214] S3, soaking the chlorinated black talc in water to wash away water-soluble substances, taking out and drying, and obtaining water-washed black talc, wherein the water soaking liquid is a magnesium chloride solution.

[0215] S4, ball-milling the washed black talc and the petroleum coke together, and drying the ball-milled product to obtain a pre-chlorinated powder; and pelletizing the pre-chlorinated powder to obtain pre-chlorinated pellets.

[0216] In this step, the mass ratio of washed black talc to petroleum coke is 1:1; the rotation speed of the ball mill is 200 rpm, and the ball milling time is 30 min; the drying temperature is 150° C., and the drying time is 120 min.

[0217] S5, the furnace chamber and the device pipeline are kept at 200°C for 1 hour for drying, and 100g of pre-chlorinated pellets are fed into the furnace chamber; then the device pipeline is purged with 500sccm of inert gas for 30 minutes; the 100g of pre-chlorinated pellets are subjected to a second chlorination roasting to generate gas phase, liquid phase and unreacted residual solid.

[0218] In this step, the second chlorination roasting process is: in an inert gas atmosphere, the temperature is increased 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 10 minutes to obtain chlorinated black talc; after the insulation is completed, 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.

[0219] In this step, the chlorination roasting is boiling chlorination; the inert gas is argon; and the volume ratio of chlorine gas to the inert gas is 1:5.

[0220] S6, condensing and recovering the gas phase at 20°C to obtain silicon tetrachloride gas phase. Collecting the liquid phase to obtain molten magnesium chloride.

[0221] Experimental results: see Fig.11 The results of gas chromatography-mass spectrometry showed that the purity of silicon tetrachloride in the silicon tetrachloride gas phase was 99.96%. The characterization calculation showed that the chlorination conversion rate of black talc was 98.12%.

[0222] Comparative Example 4 Compared with Example 9, in this comparative example, 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, which reduces the selectivity of the first chlorination roasting.

[0223] In this comparative example, the gas chromatography-mass spectrometry test results show that the purity of silicon tetrachloride in the silicon tetrachloride gas phase is 82.46%. Characterization calculation shows that the chlorination conversion rate of black talc is 78.91%.

[0224] Comparative Example 5 Compared with Example 10, this comparative example does not wash with water only after the first chlorination roasting, and other conditions remain unchanged. At this time, the magnesium chloride generated cannot enter the aqueous solution, which hinders the subsequent second chlorination roasting.

[0225] In this comparative example, the gas chromatography-mass spectrometry test results show that the purity of silicon tetrachloride in the silicon tetrachloride gas phase is 88.26%. The characterization calculation shows that the chlorination conversion rate of black talc is 88.35%.

[0226] Comparative Example 6 Compared with Example 11, this comparative example does not add petroleum coke to the raw materials of the first chlorination roasting, and other conditions remain unchanged. At this time, the first chlorination roasting lacks part of the carbon source, and the reaction cannot be fully carried out.

[0227] In this comparative example, the gas chromatography-mass spectrometry test results show that the purity of silicon tetrachloride in the silicon tetrachloride gas phase is 68.98%. The characterization calculation shows that the chlorination conversion rate of black talc is 62.73%.

[0228] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification 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 chlorinating black talc mineral, characterized in that: The following steps are involved: 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; 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.

2. The chlorination method of black talc mineral according to claim 1, characterized in that: The mass ratio of the black talc to the carbon element in the carbon-based material is 1:3-1.

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

4. The chlorination method of black talc mineral according to claim 1, characterized in that: 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.

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

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

7. The chlorination method of black talc mineral according to any one of claims 1 to 6, characterized in that: 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.

8. Application of the chlorination method of black talc mineral according to any one of claims 1 to 7 in the preparation of nano silicon dioxide, characterized in that: The following steps are involved: 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.

9. The use of the chlorination method of black talc mineral according to claim 8 in the preparation of nano silicon dioxide, characterized in that: 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.

10. The use of the chlorination method of black talc mineral according to claim 9 in the preparation of nano silicon dioxide, characterized in that: The reaction time of chlorinated black talc and hydrochloric acid solution is 30 minutes.

11. A deep chlorination process of black talc mineral, characterized in that: The following steps are involved: The chlorinated black talc obtained by the chlorination method according to any one of claims 1 to 7 is soaked in water to wash away water-soluble substances, and dried to obtain washed black talc; The washed black talc and the carbonaceous material are crushed for the second time in a mixed state to obtain a pre-chlorinated powder; 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.

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

1.

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

14. The deep chlorination process of black talc mineral according to claim 11, characterized in that: In the step of subjecting the pre-chlorinated powder to a second chlorination roasting in a chlorine atmosphere 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 black talc mineral according to any one of claims 11 to 14, characterized in that: It also includes at least one of the following operations (1) to (2): (1) collecting the water extract from the black talc chloride soaking step to obtain a magnesium chloride solution; (2) Collecting the liquid phase in the second chlorination roasting to obtain a magnesium chloride melt.

16. The deep chlorination process of black talc mineral according to any one of claims 11 to 14, characterized in that: Also includes: The silicon tetrachloride gas phase is subjected to a first condensation to obtain a crude silicon tetrachloride liquid.

17. The deep chlorination process of 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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