Treatment method of methyl chlorosilane monomer silicon slurry

Abstract

The invention belongs to the field of chemical engineering, and particularly relates to a treatment method of methyl chlorosilane monomer silicon slurry, which comprises the following steps: drying and crushing methyl chlorosilane monomer silicon slurry in a reaction kettle to obtain silicon slurry powder; and the silicon slurry powder is hydrolyzed, adsorbed and overflowed to obtain harmless silicon slag. According to the treatment method of the methyl chlorosilane monomer silicon slurry, the silicon slurry is dried through the hollow blades, a larger heat exchange area is achieved, evaporation of a liquid phase in the silicon slurry is facilitated, recovery of the methyl chlorosilane monomer is achieved, and the dried high-solid-content silicon slurry is smashed under conveying of the hollow blades; high-solid-content fine powder silicon slurry is hydrolyzed, the amount of residual copper in silicon slag is small, and harmless treatment of methyl chlorosilane monomer silicon slurry is achieved; by adding the chelating agent, copper ions in the filtrate are adsorbed, and water resources are recycled; and subsequently, a high-quality copper solution is obtained through chelating agent analysis, and the additional value of the copper solution is improved.

Description

Technical Field

[0001] The invention belongs to the field of chemical industry, and in particular relates to a method for treating methylchlorosilane monomer silicon slurry. Background Art

[0002] Methylchlorosilane monomer slurry (hereinafter referred to as slurry) is a fluid solid-liquid mixed waste produced during the monomer synthesis process, accounting for about 2-5% of the monomer output. The slurry is mainly composed of a large amount of high-boiling-point organochlorosilane and a small amount of unreacted silicon powder and copper powder brought out of the fluidized bed. It is flammable, easy to hydrolyze, highly irritating, and has poor fluidity. Direct discharge will cause serious pollution to the environment. Therefore, the resource utilization and harmless treatment of slurry are urgent problems to be solved by silicone manufacturers.

[0003] Chinese patent CN115672955A discloses a harmless treatment of methylchlorosilane monomer silicon slag, and the copper content of the silicon slag obtained by three washings is less than 100 mg / L specified in the leaching toxicity identification standard. However, due to the low solid content of the initial silicon slurry, this method leads to too much acid mist generation during the reaction, and the subsequent washing treatment requires multiple washing kettles, the process flow is cumbersome, and the filtration is time-consuming. Chinese patent CN110330521A discloses a method for treating organosilicon slurry, which obtains high-solid content silicon slag by heating and distilling high-boiling-point methylchlorosilane in a closed solid-liquid separator with scraper-type stirring. However, this method has poor heat exchange effect, and the high-solid content silicon slurry is in solid granular form, which is not easy to be harmlessly treated in the subsequent silicon slurry. Summary of the invention

[0004] In view of the shortcomings of the existing silicon slurry treatment technology, the present invention provides a method for treating methylchlorosilane monomer silicon slurry, which can reduce the amount of silicon slurry and achieve efficient and harmless treatment of silicon slurry.

[0005] A method for treating methylchlorosilane monomer silicon slurry, the method comprising the following steps: (1) Drying and crushing of methylchlorosilane monomer slurry. Add methylchlorosilane monomer slurry into the reactor, and the slurry is dried and crushed under the transportation of hollow paddles. The separated gaseous methylchlorosilane is collected by a condenser.

[0006] (2) Hydrolysis of silicon slurry powder: Add water and oxidant to the obtained silicon slurry powder, and stir the reaction at 60-90°C for 30-60 minutes.

[0007] (3) Silica slag filtration and heavy metal adsorption. The hydrolyzed silica slag is transported to the overflow tank, where heavy metal chelating agents are fixed to adsorb copper ions in the filtrate. The overflow tank is allowed to overflow for 12-24 hours. After the solid and liquid are completely separated, the slag is discharged in time to complete the treatment.

[0008] Specifically, the methylchlorosilane monomer slurry is mainly composed of organic chlorosilane, silicon powder, and copper, with a solid content of 25-45%, including but not limited to copper elements (copper element, cuprous, cupric ions) content of 3-8%; methylchlorosilane monomer accounts for 5-10% of the organic chlorosilane.

[0009] Specifically, the hollow blades are heated by heat transfer oil, and the temperature of the heat transfer oil is 200-270°C.

[0010] Specifically, after being transported by the hollow paddles of the reactor, the solid content of the silicon slurry is 80-90%.

[0011] Specifically, after being transported by the hollow paddles of the reactor, the particle size of the silicon slurry (D 50 ) at 20-100um.

[0012] Specifically, the reactor is a horizontal lining device with double-shaft hollow blades; the hollow blades are staggered and placed in parallel. During the rotation process at 200-300r / min, the materials between the double-shaft hollow blades rub against each other, achieving a process of drying and crushing, and quickly separating and treating the gaseous methylchlorosilane, and then collecting the gas phase.

[0013] In this process, a hollow paddle device that can be heated and crushed is used. In the early stage of silicon slurry hydrolysis treatment, the organic chlorosilane liquid phase is evaporated by high temperature, so that there is no organic matter wrapped during hydrolysis, and the subsequent copper precipitation is utilized, and the processing volume is reduced; the crushing allows a more complete reaction during hydrolysis.

[0014] Specifically, the mass ratio of the water to the methylchlorosilane monomer silicon slurry is 2-3:1.

[0015] Specifically, the oxidant is at least one of hydrogen peroxide and sodium hypochlorite, and the amount of the oxidant is 3-5 wt% of the mass of the methylchlorosilane monomer silicon slurry.

[0016] Specifically, the heavy metal chelating agent is a strongly acidic cation exchange resin, preferably at least one of CH-90Na, CH-95, A-21, T-IRR, LSC400, and ZGC.

[0017] Beneficial effects of this patent: 1. The present invention heats the silicon slurry through hollow blades, and utilizes its larger heat exchange area to efficiently dry the silicon slurry with high solid content. The high-boiling-point methylchlorosilane obtained by distillation can be converted into methylchlorosilane crude monomer after cracking and rearrangement. When the remaining silicon slurry with high solid content is harmlessly treated, the reaction is milder due to less organic matter, no acid mist is generated, and environmental damage is reduced.

[0018] 2. Since silicon slurry with high solid content is easy to agglomerate, the hollow blades can crush the solid phase silicon slurry while drying to obtain silicon slurry fine powder. At this time, there is no siloxane wrapped outside the silicon slurry fine powder, and the vast majority of copper in the silicon slurry can be better removed in subsequent treatment. The leaching toxicity of the hydrolyzed silicon slag obtained is less than 100ppm, and more preferably less than 50ppm, which meets the national standard for solid waste and reduces the operation of subsequent silicon slag resource utilization.

[0019] 3. The filtrate from the hydrolysis of silicon slurry is highly acidic and contains a variety of heavy metal ions such as copper, iron, nickel, and aluminum. The use of chelating agents is beneficial to the adsorption of copper ions in the filtrate, and the purification of the filtrate allows the water resources to be recycled; subsequently, the copper-containing solution is obtained through chelating agent analysis, which increases the added value of the filtrate and increases production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a schematic diagram of the structure of a reactor in a method for treating methylchlorosilane monomer silicon slurry, wherein: 1. a horizontal reactor, 2. a double-shaft hollow blade. DETAILED DESCRIPTION

[0021] The above-mentioned method for treating methylchlorosilane monomer silicon slurry includes drying and crushing the methylchlorosilane monomer silicon slurry, hydrolyzing the silicon slurry fine powder, and filtering the silicon slag. The methylchlorosilane monomer slurry is mainly composed of organic chlorosilane, silicon powder, and copper, with a solid content of 25-45%, including but not limited to copper elements (copper element, cuprous ions, cupric ions) content of 3-8%, and methylchlorosilane monomer accounts for 9.8% of the organic chlorosilane.

[0022] (1) Drying and crushing of methylchlorosilane monomer slurry. Add methylchlorosilane monomer slurry into the reactor, and the slurry is dried and crushed under the transportation of hollow paddles. The separated gaseous methylchlorosilane is collected by a condenser.

[0023] (2) Hydrolysis of silicon slurry powder: Add water and oxidant to the obtained silicon slurry powder, and stir the reaction at 60-90°C for 30-60 minutes.

[0024] (3) Silica slag filtration and heavy metal adsorption. The hydrolyzed silica slag is transported to the overflow tank, where heavy metal chelating agents are fixed to adsorb copper ions in the filtrate. The overflow tank is allowed to overflow for 12-24 hours. After the solid and liquid are completely separated, the slag is discharged in time to complete the treatment.

[0025] In the embodiment of the present invention, Figure 1 The reactor is a horizontal lining device with double-shaft hollow blades; the hollow blades are placed in a staggered and parallel manner. The hollow blades are heated by heat transfer oil, and the temperature of the heat transfer oil is 200-270°C. The stirring speed of the hollow blades is 200-300r / min.

[0026] Specific examples of the above process are given below.

[0027] Example 1 (1) Drying and crushing of methylchlorosilane monomer slurry. 500 kg of methylchlorosilane monomer slurry with a solid content of 25% was added to a horizontal reactor. The temperature of the heat transfer oil of the double-shaft hollow blade was set to 250°C and the stirring speed was set to 200 rpm. The slurry was transported and stirred by the double-shaft hollow blade to obtain a solid content of 83%, D 50 The separated gaseous methylchlorosilane was collected by a condenser to obtain 8.6% methylchlorosilane monomer.

[0028] (2) Hydrolysis of silicon slurry powder: Add 300 kg of water and 4.5 kg of sodium hypochlorite to 150 kg of silicon slurry powder, and stir at 90 °C for 60 min.

[0029] (3) Silicon slag filtration. The hydrolyzed silicon slag is transported to the overflow tank, where the resin CH-90Na is fixed. It is allowed to settle for 12 hours. After the solid and liquid are completely separated, it is discharged in time. The leaching toxicity of the silicon slag is 85 ppm, which meets the national solid waste standard. The copper content in the filtrate is 120 ppm and can be recycled.

[0030] Example 2 (1) Drying and crushing of methylchlorosilane monomer slurry. 500 kg of methylchlorosilane monomer slurry with a solid content of 28% was added to the reactor. The temperature of the heat transfer oil of the double-shaft hollow blade was set to 270°C and the stirring speed was set to 250 rpm. The slurry was transported by the hollow blade to obtain a solid content of 90%, D 50 The separated gaseous methylchlorosilane was collected by a condenser to obtain 9.4% methylchlorosilane monomer.

[0031] (2) Hydrolysis of silicon slurry powder: Add 465 kg of water and 4.5 kg of sodium hypochlorite to the obtained 155 kg of silicon slurry powder, and stir the reaction at 90°C for 60 minutes.

[0032] (3) Silicon slag filtration. The hydrolyzed silicon slag is transported to the overflow tank, where the resin CH-90Na is fixed. It is allowed to settle for 12 hours. After the solid and liquid are completely separated, it is discharged in time. The leaching toxicity of the silicon slag is 78 ppm, which meets the national solid waste standard. The copper content in the filtrate is 169 ppm and can be recycled.

[0033] Example 3 (1) Drying and crushing of methylchlorosilane monomer slurry. 500 kg of methylchlorosilane monomer slurry with a solid content of 32% was added to the reactor. The temperature of the heat transfer oil of the double-shaft hollow blade was set to 210°C and the stirring speed was set to 250 rpm. The slurry was transported by the hollow blade to obtain a solid content of 89%, D 50 The separated gaseous methylchlorosilane was collected by a condenser to obtain 7.1% methylchlorosilane monomer.

[0034] (2) Hydrolysis of silicon slurry powder: 450 kg of water and 4.5 kg of hydrogen peroxide were added to the obtained 180 kg of silicon slurry powder, and the mixture was stirred and reacted at 90°C for 60 minutes.

[0035] (3) Silicon slag filtration. The hydrolyzed silicon slag is transported to the overflow tank, where the resin CH-90Na is fixed. It is allowed to settle for 12 hours. After the solid and liquid are completely separated, it is discharged in time. The leaching toxicity of the silicon slag is 54 ppm, which meets the national solid waste standard. The copper content in the filtrate is 137 ppm and can be recycled.

[0036] Example 4 (1) Drying and crushing of methylchlorosilane monomer slurry. 500 kg of methylchlorosilane monomer slurry with a solid content of 41% was added to the reactor. The temperature of the heat transfer oil of the double-shaft hollow blade was set to 210°C and the stirring speed was set to 250 rpm. The slurry was transported by the hollow blade to obtain a solid content of 89%, D 50 The separated gaseous methylchlorosilane was collected by a condenser to obtain 8.7% methylchlorosilane monomer.

[0037] (2) Hydrolysis of silicon slurry powder: Add 690 kg of water and 11.5 kg of hydrogen peroxide to the obtained 230 kg of silicon slurry powder, and stir the reaction at 60°C for 45 minutes.

[0038] (3) Silicon slag filtration. The hydrolyzed silicon slag is transported to the overflow tank, where the resin CH-90Na is fixed. It is allowed to settle for 24 hours. After the solid and liquid are completely separated, it is discharged in time. The leaching toxicity of the silicon slag is 77 ppm, which meets the national solid waste standard. The copper content in the filtrate is 126 ppm and can be recycled.

[0039] Example 5 (1) Drying and crushing of methylchlorosilane monomer slurry. 500 kg of methylchlorosilane monomer slurry with a solid content of 36% was added to the reactor. The temperature of the heat transfer oil of the double-shaft hollow blade was set to 210°C and the stirring speed was set to 250 rpm. The slurry was transported by the hollow blade to obtain a solid content of 90%, D 50The separated gaseous methylchlorosilane was collected by a condenser to obtain 9.3% methylchlorosilane monomer.

[0040] (2) Hydrolysis of silicon slurry powder: Add 600 kg of water and 8 kg of sodium hypochlorite to the obtained 200 kg of silicon slurry powder, and stir the mixture at 90°C for 30 minutes.

[0041] (3) Silicon slag filtration. The hydrolyzed silicon slag is transported to the overflow tank, where resin A-21 is fixed. The slag is allowed to settle for 12 hours. After the solid and liquid are completely separated, it is discharged in time. The leaching toxicity of the silicon slag is 24 ppm, which meets the national solid waste standard. The copper content in the filtrate is 46 ppm and can be recycled.

[0042] Example 6 (1) Drying and crushing of methylchlorosilane monomer slurry. 500 kg of methylchlorosilane monomer slurry with a solid content of 30% was added to the reactor. The temperature of the heat transfer oil in the double-shaft hollow blade was set to 250°C and the stirring speed was set to 250 rpm. The slurry was transported by the hollow blade to obtain a solid content of 80%, D 50 The separated gaseous methylchlorosilane was collected by a condenser to obtain 8.5% methylchlorosilane monomer.

[0043] (2) Hydrolysis of silicon slurry powder: Add 570 kg of water and 7.6 kg of sodium hypochlorite to the obtained 190 kg of silicon slurry powder, and stir the reaction at 90°C for 60 minutes.

[0044] (3) Silicon slag filtration. The hydrolyzed silicon slag is transported to the overflow tank, where the resin LSC400 is fixed. It is allowed to settle for 20 hours. After the solid and liquid are completely separated, it is discharged in time. The leaching toxicity of the silicon slag is 25ppm, which meets the national solid waste standard. The copper content in the filtrate is 54ppm and can be recycled.

[0045] Example 7 (1) Drying and crushing of methylchlorosilane monomer slurry. 500 kg of methylchlorosilane monomer slurry with a solid content of 35% was added to the reactor. The temperature of the heat transfer oil of the double-shaft hollow blade was set to 250°C and the stirring speed was set to 250 rpm. The slurry was transported by the hollow blade to obtain a solid content of 87%, D 50 The separated gaseous methylchlorosilane was collected by a condenser to obtain 9.5% methylchlorosilane monomer.

[0046] (2) Hydrolysis of silicon slurry powder: Add 500 kg of water and 10 kg of sodium hypochlorite to the obtained 200 kg of silicon slurry powder, and stir the mixture at 90°C for 60 minutes.

[0047] (3) Silicon slag filtration. The hydrolyzed silicon slag is transported to the overflow tank, where the resin ZGC is fixed. It is allowed to settle for 12 hours. After the solid and liquid are completely separated, it is discharged in time. The leaching toxicity of the silicon slag is 28 ppm, which meets the national solid waste standard. The copper content in the filtrate is 51 ppm and can be recycled.

[0048] Comparative Example 1 (1) Drying and crushing of methylchlorosilane monomer slurry. 500 kg of methylchlorosilane monomer slurry with a solid content of 25% was added to a horizontal reactor. The temperature of the heat transfer oil of the double-shaft hollow blade was set to 150°C and the stirring speed was set to 250 rpm. The slurry was transported and stirred by the double-shaft hollow blade to obtain a solid content of 63%, D 50 The separated gaseous methylchlorosilane was collected by a condenser to obtain 3.2% methylchlorosilane monomer.

[0049] (2) Hydrolysis of silicon slurry powder: Add 300 kg of water and 4.5 kg of sodium hypochlorite to 150 kg of silicon slurry powder, and stir at 90 °C for 60 min.

[0050] (3) Filtration of silicon slag. The hydrolyzed silicon slag is transported to the overflow tank, where the resin CH-90Na is fixed. It is allowed to settle for 12 hours and is discharged in time after the solid and liquid are completely separated. Since the heat exchange efficiency and crushing degree of the hollow blades are not high at this time, the leaching toxicity of the silicon slag is 214ppm, which is higher than the national standard for solid waste.

[0051] Comparative Example 2 (1) Drying and crushing of methylchlorosilane monomer slurry. 500 kg of methylchlorosilane monomer slurry with a solid content of 25% was added to a horizontal reactor. The temperature of the heat transfer oil of the double-shaft hollow blade was set to 250°C and the stirring speed was set to 150 rpm. The slurry was transported and stirred by the double-shaft hollow blade to obtain a solid content of 82%, D 50 The separated gaseous methylchlorosilane was collected by a condenser to obtain 8.4% methylchlorosilane monomer.

[0052] (2) Hydrolysis of silicon slurry powder: Add 300 kg of water and 4.5 kg of sodium hypochlorite to 150 kg of silicon slurry powder, and stir at 90 °C for 60 min.

[0053] (3) Filtration of silicon slag. The hydrolyzed silicon slag is transported to the overflow tank, where an anion resin 4200CI is fixed. It is allowed to settle for 12 hours and is discharged in time after the solid and liquid are completely separated. Since the copper ions in the filtrate are poorly purified by this resin, a large amount of copper solution adheres to the surface of the silicon slag, resulting in a silicon slag leaching toxicity of 206ppm, which is higher than the national solid waste standard; the copper content in the filtrate is 593ppm, which is relatively high and affects the reuse of the filtrate.

Claims

1. A method for treating methylchlorosilane monomer silicon slurry, characterized in that: The steps include: (1) Drying and crushing the methylchlorosilane monomer slurry. Add the methylchlorosilane monomer slurry into the reactor. The slurry is dried and crushed under the conveying and stirring of the hollow paddle blades. The separated gaseous methylchlorosilane monomer is collected through a condenser; (2) hydrolyzing the silicon slurry powder, adding water and an oxidant to the obtained silicon slurry powder, and stirring the reaction at 60-90°C for 30-60 minutes; (3) Silica slag filtration and heavy metal adsorption. The hydrolyzed silica slag is transported to the overflow tank. The heavy metal chelating agent is fixed in the overflow tank to adsorb the copper ions in the filtrate. The overflow tank overflows for 12-24 hours. After the solid and liquid are completely separated, it is discharged in time to complete the treatment.

2. The method for treating methylchlorosilane monomer silicon slurry according to claim 1, characterized in that: The methylchlorosilane monomer slurry is mainly composed of organic chlorosilane, silicon powder and copper, with a solid content of 25-45%, including copper element, cuprous ions and cupric ions with a content of 3-8%; the methylchlorosilane monomer accounts for 5-10% of the organic chlorosilane.

3. The method for treating methylchlorosilane monomer silicon slurry according to claim 1, characterized in that: The hollow blades are heated by heat transfer oil, and the temperature of the heat transfer oil is 200-270°C.

4. The method for treating methylchlorosilane monomer silicon slurry according to claim 1, characterized in that: After being transported by the hollow paddles of the reactor, the solid content of the silicon slurry is 80-90%.

5. The method for treating methylchlorosilane monomer silicon slurry according to claim 1, characterized in that: After being transported by the hollow paddles of the reactor, the obtained silicon slurry particle size D 50 In 20-100um.

6. The method for treating methylchlorosilane monomer silicon slurry according to claim 1, characterized in that: The reactor is a horizontal lined device with double-shaft hollow blades; the hollow blades are placed in a staggered and parallel manner.

7. The method for treating methylchlorosilane monomer silicon slurry according to claim 1, characterized in that: The mass ratio of the water to the methylchlorosilane monomer silicon slurry is 2-3:

1.

8. The method for treating methylchlorosilane monomer silicon slurry according to claim 1, characterized in that: The oxidant is at least one of hydrogen peroxide and sodium hypochlorite, and the amount of the oxidant is 3-5wt% of the mass of the methylchlorosilane monomer silicon slurry.

9. The method for treating methylchlorosilane monomer silicon slurry according to claim 1, characterized in that: The heavy metal chelating agent is a strongly acidic cation exchange resin, preferably at least one of CH-90Na, CH-95, A-21, T-IRR, LSC400 and ZGC.

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