Method for efficiently preparing silicon fluoride by using fluorite

Abstract

The application discloses a method for efficiently preparing fluorinated silicon by using fluorite, which comprises the following steps: firstly, finely grinding and preheating silicon dioxide, and then chlorinating the finely ground and preheated silicon dioxide into chlorinated silicon by using carbon tetrachloride; and then, finely grinding and preheating fluorite, and then chlorinating the finely ground and preheated fluorite into fluorinated silicon by using the chlorinated silicon. The method uses silicon dioxide as a silicon source, does not need to prepare carbon, directly chlorinates the silicon dioxide into chlorinated silicon by using carbon tetrachloride, and significantly improves the reaction activity of the chlorinated silicon by finely grinding and activating, so that the process is efficient and environment-friendly. The method uses chlorinated silicon as a chlorinating agent, fluidizes and chlorinates fluorite powder in a gas-solid fluidized bed provided with inner members to obtain fluorinated silicon products, the inner members can prevent fine particles from agglomerating and breaking bubbles, and can strengthen the gas-solid contact, so that the reaction efficiency is high, the products are easy to separate and purify, the process flow is simple, the operation is simple, and the method is convenient for continuous operation. The method can realize large-scale and efficient preparation of fluorinated silicon by using fluorite, meanwhile, the system has high energy utilization rate, and has good economic and social benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical nonferrous metallurgy and environmental protection, and particularly relates to a method for efficiently preparing silicon fluoride by using fluorite. BACKGROUND

[0002] Silicon fluoride (SiF4) is an electronic special gas used in the processing of semiconductors and optical fibers, and is a synthetic material of organosilicon compounds, and is often used as an important component in the ion implantation method used in the production process of silicon-based semiconductor devices. In addition, silicon fluoride can also be used to treat dry concrete parts, and can well improve their waterproofness, corrosion resistance and wear resistance.

[0003] The synthesis methods of silicon fluoride mainly include the synthesis method of Si source-containing substances and F group-containing substances, sulfuric acid method, fluorosilicate pyrolysis method and fluorosilicic acid method, among which the commonly used methods are the synthesis method of Si source-containing substances and F group-containing substances and the sulfuric acid method. The synthesis method of Si source-containing substances and F group-containing substances usually refers to the preparation of silicon fluoride by directly reacting Si with F2 or HF. This method is simple to operate, and silicon fluoride can be obtained through one-step reaction. However, the raw material and equipment costs are high, the product purity is low, and the subsequent impurity removal process is complex. The sulfuric acid method mainly includes fluorite-concentrated sulfuric acid method, fluorosilicic acid-sulfuric acid method and fluorosilicate-concentrated sulfuric acid method. The preparation of silicon fluoride by the sulfuric acid method needs concentrated sulfuric acid under heating conditions, which has high requirements for the corrosion resistance of the equipment. At the same time, there are problems such as low conversion rate, many by-products, large amount of waste liquid and difficult impurity removal. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application aims to provide a method for efficiently preparing silicon fluoride by using fluorite, which has a simple process flow, is simple to operate, is efficient and environmentally friendly, is convenient for continuous operation, and can realize large-scale and efficient preparation of silicon fluoride from fluorite.

[0005] In order to achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0006] A method for efficiently preparing silicon fluoride by using fluorite, comprising the following steps:

[0007] S1, finely grinding I: grinding silicon dioxide to obtain fine powder I;

[0008] S2, preheating I: preheating the fine powder I obtained in step S1 to obtain hot fine powder I;

[0009] S3, gasification I: gasifying liquid carbon tetrachloride to obtain gaseous carbon tetrachloride, and the gaseous carbon tetrachloride is sent to the combustion preheating I process of step S4;

[0010] S4, combustion preheating I: using combustion of air and fuel, heating the gaseous carbon tetrachloride obtained in step S3 to obtain high-temperature carbon tetrachloride and combustion tail gas I, and the high-temperature carbon tetrachloride is sent to the chlorination I process of step S5;

[0011] S5, chlorination I: using the high-temperature carbon tetrachloride obtained in step S4 and the hot fine powder I obtained in step S2 to carry out a chlorination reaction to obtain high-temperature chlorination flue gas I, and the high-temperature chlorination flue gas I is sent to the preheating I process of step S2 to preheat the fine powder I by heat exchange, and the low-temperature chlorination flue gas I obtained after heat exchange is sent to the condensation I process of step S6;

[0012] S6, condensation I: condensing the low-temperature chlorination flue gas I obtained in step S5 to obtain a liquid-phase mixture of carbon dioxide, chlorinated silicon and carbon tetrachloride;

[0013] S7, rectification: rectifying the liquid-phase mixture of chlorinated silicon and carbon tetrachloride obtained in step S6 to obtain gaseous chlorinated silicon and recycled carbon tetrachloride, and the gaseous chlorinated silicon is sent to the heat exchange cooling process of step S11;

[0014] S8, grinding II: grinding fluorite to obtain fine powder II;

[0015] S9, preheating II: preheating the fine powder II obtained in step S8 to obtain hot fine powder II;

[0016] S10, chlorination II: using high-temperature chlorinated silicon and the fine powder II obtained in step S8 to carry out a chlorination reaction to obtain high-temperature chlorination flue gas II and hot chlorination residue, and the hot chlorination residue is sent to the heat exchange cooling process of step S11; the high-temperature chlorination flue gas II is sent to the preheating II process of step S9 to preheat the fine powder II obtained in step S8 by heat exchange, and the low-temperature chlorination flue gas II obtained after heat exchange is sent to the condensation II process of step S13;

[0017] S11, heat exchange cooling: using the gaseous chlorinated silicon obtained in step S7 to cool the hot chlorination residue obtained in step S10 by heat exchange to obtain tail residue and hot chlorinated silicon, and the hot chlorinated silicon is sent to the combustion preheating II process of step S12;

[0018] S12, combustion preheating II: using combustion of air and fuel to heat the hot chlorinated silicon obtained in step S11 to obtain high-temperature chlorinated silicon and combustion tail gas II, and the high-temperature chlorinated silicon is sent to the chlorination II process of step S10;

[0019] S13, condensation II: condensing the low-temperature chlorination flue gas II obtained in step S10 to obtain liquid-phase chlorinated silicon and fluorinated silicon product;

[0020] S14, gasification II: the liquid phase silicon chloride obtained in step S13 is gasified to obtain recycled silicon chloride, which is sent to the heat exchange and cooling process in step S11 to cool the hot chlorination residue obtained in step S10 by heat exchange.

[0021] Further, in step S1, the particle size of the fine powder I is <1 μm.

[0022] Further, in the chlorination I process in step S5, the temperature of the chlorination reaction is 400-700 DEG C, and the time is 0.5-1 h.

[0023] Further, in the condensation I process in step S6, the condensation temperature is 20-50 DEG C.

[0024] Further, in step S8, the particle size of the fine powder II is <1 μm.

[0025] Further, in the chlorination II process in step S10, the temperature of the chlorination reaction is 500-800 DEG C, the time is 0.5-1 h, and a fluidized bed reactor is used; the fluidized bed reactor is provided with internal members, which are in the form of a perforated plate structure, a paddle structure or a hole-paddle structure.

[0026] Further, in the condensation II process in step S13, the condensation temperature is 20-50 DEG C.

[0027] The present application has the following beneficial effects:

[0028] 1. The present application does not need balling, and the grinding and activation can significantly improve the activity of silicon dioxide in the chlorination reaction, reduce the reaction temperature, save energy, and does not need to be carbonized, and uses carbon tetrachloride to directly chlorinate silicon dioxide into silicon chloride, which is simple to operate;

[0029] 2. The present application uses a fluidized bed provided with internal members to perform the fluidization chlorination of fluorite fine powder, the internal members can inhibit the agglomeration of fine particles, break bubbles, and strengthen the mass and heat transfer between the gas and solid phases, effectively improving the reaction efficiency and the stability of the system operation;

[0030] 3. The present application uses a gas-solid fluidized bed to prepare silicon fluoride by reacting fluorite fine powder with silicon chloride, compared with the concentrated sulfuric acid method, the process flow is simple, the safety is high, and the continuous operation is convenient, the large-scale and efficient preparation of silicon fluoride from fluorite can be realized, and the reaction product is easy to separate and purify, and the product purity is high;

[0031] 4. The present application has high waste heat recovery utilization rate, effectively improving the thermal efficiency of the overall process system;

[0032] 5. The present application uses silicon dioxide as a silicon source, which is widely available and inexpensive. The silicon chloride required for the preparation of fluorinated silicon is obtained by chlorinating silicon dioxide with CCl4, an industrial by-product of chlorination of alkanes, which has significant economic and social benefits.

[0033] In summary, the present application provides a method for preparing fluorinated silicon from fluorite, which is simple, easy to operate, efficient, environmentally friendly, and easy to control, and can realize large-scale continuous and efficient production of fluorinated silicon. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 Method flowchart for each embodiment of the present application. DETAILED DESCRIPTION

[0035] The present application will be further described below with reference to the accompanying drawings. It should be noted that the present embodiment is based on the present technical solution, and provides detailed implementation and specific operation process, but the protection scope of the present application is not limited to the present embodiment.

[0036] Embodiment 1

[0037] The present embodiment provides a method for efficiently preparing fluorinated silicon from fluorite, as shown in the following steps: Figure 1

[0038] S1, finely ground I: grinding silicon dioxide to obtain fine powder I with a particle size of less than 1 μm;

[0039] S2, preheating I: preheating the fine powder I obtained in step S1 to obtain hot fine powder I;

[0040] S3, gasification I: gasifying liquid carbon tetrachloride to obtain gaseous carbon tetrachloride, which is sent to the combustion preheating I process of step S4;

[0041] S4, combustion preheating I: using the combustion of air and fuel to heat the gaseous carbon tetrachloride obtained in step S3 to obtain high-temperature carbon tetrachloride and combustion tail gas I, and the high-temperature carbon tetrachloride is sent to the chlorination I process of step S5;

[0042] S5, chlorination I: using the high-temperature carbon tetrachloride obtained in step S4 to react with the hot fine powder I obtained in step S2, the chlorination reaction temperature is 400℃, and the time is 1h, to obtain high-temperature chlorination flue gas I, which is sent to the preheating I process of step S2 for preheating the fine powder I by heat exchange, and the low-temperature chlorination flue gas I obtained after heat exchange is sent to the condensation I process of step S6;

[0043] S6, condensation I: condensing the low-temperature chlorination flue gas I obtained in step S5 at a condensation temperature of 20℃ to obtain a liquid mixture of carbon dioxide, chlorinated silicon, and carbon tetrachloride;​

[0044] S7, rectification: rectifying the liquid-phase mixture of silicon chloride and carbon tetrachloride obtained in step S6 to obtain gaseous silicon chloride and circulating carbon tetrachloride, and sending the gaseous silicon chloride to the heat exchange cooling process in step S11;

[0045] S8, grinding II: grinding the fluorite to obtain fine powder II with a particle size less than 1 μm;

[0046] S9, preheating II: preheating the fine powder II obtained in step S8 to obtain hot fine powder II;

[0047] S10, chlorination II: performing a chlorination reaction between high-temperature silicon chloride and the fine powder II obtained in step S8, with a chlorination reaction temperature of 500°C and a reaction time of 1 h, to obtain high-temperature chlorination flue gas II and hot chlorination residue, and sending the hot chlorination residue to the heat exchange cooling process in step S11; sending the high-temperature chlorination flue gas II to the preheating II process in step S9 to preheat the fine powder II obtained in step S8 by heat exchange, and sending the low-temperature chlorination flue gas II obtained after the heat exchange to the condensation II process in step S13; the chlorination reaction is performed in a fluidized bed reactor, and a porous plate type internal component is arranged in the fluidized bed reactor to break up clusters, eliminate bubbles and strengthen gas-solid contact;

[0048] S11, heat exchange cooling: cooling the hot chlorination residue obtained in step S10 by heat exchange using the gaseous silicon chloride obtained in step S7 to obtain tail residue and hot silicon chloride, and sending the hot silicon chloride to the combustion preheating II process in step S12;

[0049] S12, combustion preheating II: heating the hot silicon chloride obtained in step S11 by combustion of air and fuel to obtain high-temperature silicon chloride and combustion tail gas II, and sending the high-temperature silicon chloride to the chlorination II process in step S10;

[0050] S13, condensation II: condensing the low-temperature chlorination flue gas II obtained in step S10 at a condensation temperature of 20°C to obtain liquid-phase silicon chloride and silicon fluoride product;

[0051] S14, gasification II: gasifying the liquid-phase silicon chloride obtained in step S13 to obtain circulating silicon chloride, and sending the circulating silicon chloride to the heat exchange cooling process in step S11 to cool the hot chlorination residue obtained in step S10 by heat exchange.

[0052] Example 2

[0053] The method flow of the embodiment is basically the same as that of Embodiment 1, except that in step S5, the temperature of the chlorination reaction is 700℃, and the time is 0.5h; in step S6, the condensation temperature is 50℃; in step S10, the temperature of the chlorination reaction is 800℃, the time is 0.5h, and the inner member in the fluidized bed reactor is in the form of a paddle structure; and in step S13, the condensation temperature is 50℃.

[0054] Embodiment 3

[0055] The method flow of the embodiment is basically the same as that of Embodiment 1, except that in step S5, the temperature of the chlorination reaction is 600℃, and the time is 0.7h; in step S6, the condensation temperature is 35℃; in step S10, the temperature of the chlorination reaction is 680℃, the time is 0.7h, and the inner member in the fluidized bed reactor is in the form of a hole-paddle structure; and in step S13, the condensation temperature is 40℃.

[0056] Embodiment 4

[0057] The method flow of the embodiment is basically the same as that of Embodiment 1, except that in step S5, the temperature of the chlorination reaction is 500℃, and the time is 0.9h; in step S6, the condensation temperature is 46℃; in step S10, the temperature of the chlorination reaction is 730℃, the time is 0.6h; and in step S13, the condensation temperature is 30℃.

[0058] For those skilled in the art, various corresponding changes and modifications can be made according to the above technical solutions and concepts, and all of these changes and modifications should be included in the protection scope of the claims of the present application.

Claims

1. A method for efficiently preparing silicon fluoride using fluorite, characterized by, The method comprises the following steps: S1, grinding I: grinding silica to obtain fine powder I; S2, preheating I: preheating the fine powder I obtained in step S1 to obtain hot fine powder I; S3, gasification I: gasifying liquid phase carbon tetrachloride to obtain gaseous phase carbon tetrachloride, which is sent to the combustion preheating I process of step S4; S4, combustion preheating I: using the combustion of air and fuel to heat the gaseous phase carbon tetrachloride obtained in step S3 to obtain high-temperature carbon tetrachloride and combustion tail gas I, and the high-temperature carbon tetrachloride is sent to the chlorination I process of step S5; S5, chlorination I: using the high-temperature carbon tetrachloride obtained in step S4 to react with the hot fine powder I obtained in step S2 to obtain high-temperature chlorination flue gas I, which is sent to the preheating I process of step S2 to preheat the fine powder I by heat exchange, and the low-temperature chlorination flue gas I obtained after heat exchange is sent to the condensation I process of step S6; the temperature of the chlorination reaction is 400-700℃, and the time is 0.5-1h; S6, condensation I: condensing the low-temperature chlorination flue gas I obtained in step S5 to obtain a liquid phase mixture of carbon dioxide, chlorinated silicon and carbon tetrachloride; S7, rectification: rectifying the liquid phase mixture of chlorinated silicon and carbon tetrachloride obtained in step S6 to obtain gaseous phase chlorinated silicon and circulating carbon tetrachloride, and the gaseous phase chlorinated silicon is sent to the heat exchange cooling process of step S11; S8, grinding II: grinding fluorite to obtain fine powder II; S9, preheating II: preheating the fine powder II obtained in step S8 to obtain hot fine powder II; S10, chlorination II: using high-temperature chlorinated silicon to react with the fine powder II obtained in step S8 to obtain high-temperature chlorination flue gas II and hot chlorination residue, and the hot chlorination residue is sent to the heat exchange cooling process of step S11; the high-temperature chlorination flue gas II is sent to the preheating II process of step S9 to preheat the fine powder II obtained in step S8 by heat exchange, and the low-temperature chlorination flue gas II obtained after heat exchange is sent to the condensation II process of step S13; the temperature of the chlorination reaction is 500-800℃, and the time is 0.5-1h, and the reactor used is a fluidized bed reactor; the fluidized bed reactor is provided with an inner member, and the inner member has a porous plate structure, a paddle structure or a hole paddle structure; S11, heat exchange cooling: using the gaseous phase chlorinated silicon obtained in step S7 to cool the hot chlorination residue obtained in step S10 by heat exchange to obtain tail residue and hot chlorinated silicon, and the hot chlorinated silicon is sent to the combustion preheating II process of step S12; S12, combustion preheating II: using the combustion of air and fuel to heat the hot chlorinated silicon obtained in step S11 to obtain high-temperature chlorinated silicon and combustion tail gas II, and the high-temperature chlorinated silicon is sent to the chlorination II process of step S10; S13, condensation II: condensing the low-temperature chlorination flue gas II obtained in step S10 to obtain liquid phase chlorinated silicon and fluorinated silicon product; S14, gasification II: gasifying the liquid phase chlorinated silicon obtained in step S13 to obtain circulating chlorinated silicon, which is sent to the heat exchange cooling process of step S11 to cool the hot chlorination residue obtained in step S10 by heat exchange.

2. The method of claim 1, wherein, The particle size of the fine powder I in step S1 is <1 μm.

3. The method of claim 1, wherein, The condensing temperature in the condensing I step of step S6 is 20-50°C.

4. The method of claim 1, wherein, The particle size of the fine powder II in step S8 is <1 μm.

5. The method of claim 1, wherein, The condensing temperature in the condensing II step of step S13 is 20-50°C.

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