A harmless treatment method and device for methyl chlorosilane monomer silicon slurry

Abstract

The present application belongs to the field of chemical industry, and particularly relates to a harmless treatment method of methyl chlorosilane monomer silicon slurry. The methyl chlorosilane monomer silicon slurry is hydrolyzed under an oxidizing agent, and then solid-liquid separation is performed to obtain silicon residue. The silicon residue is crushed by a ball mill. The crushed silicon residue is continuously washed, purified, pressure-filtered and dried to obtain harmless silicon residue. The harmless treatment method and device of the methyl chlorosilane monomer silicon slurry have high residual acid removal rate, and the amount of residual copper in the silicon residue is small, so that the harmless treatment of the methyl chlorosilane monomer silicon slurry is realized. The silicon residue after the crushing treatment has a large contact area with the washing liquid, so that the washing and purification are easier. A solid-liquid separation module is arranged at the bottom of the purification kettle device, three layers of stirring and a variable-diameter inclined connection are arranged in the purification kettle device, so that the washing and solid-liquid separation efficiency of the silicon residue is improved. The washing liquid is recycled after treatment, so that the water consumption for treating the silicon slurry is reduced by 70%, and the environmental benefits are significant. The continuous reaction of the purification kettle improves the production efficiency obviously.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of chemical industry, and particularly relates to a harmless treatment method and device for methyl chlorosilane monomer silicon slurry. BACKGROUND

[0002] Methyl chlorosilane monomer silicon slurry (hereinafter referred to as silicon slurry) is discharged from the bottom of a fluidized bed in the process of catalytic reaction of silicon powder and chloromethane to generate methyl chlorosilane monomer, accounting for about 2-5% of the monomer yield. Since the silicon slurry is mainly composed of a large amount of high-boiling organic chlorosilane and a small amount of unreacted silicon powder and copper catalyst brought out by the fluidized bed, it has the characteristics of flammability, easy hydrolysis, strong irritation, poor flowability and serious environmental pollution. Therefore, the resource utilization and harmless treatment of silicon slurry have become a problem that needs to be solved by organic silicon production enterprises, and the progress and development of silicon slurry treatment process must be continuously promoted to lay a foundation for the healthy development of the organic silicon industry.

[0003] Chinese patent CN215757543 discloses a copper-containing waste silicon slag reprocessing device, which can effectively remove copper from the waste silicon slag by adding an acid solution and an oxidizing agent to the copper-containing waste silicon slag and then adding iron powder for stirring and reaction. However, the silicon slag treated by this method is strongly acidic and cannot be directly discharged, and it cannot treat silicon slag with high copper content (content higher than 5%). Chinese patent CN115672955A discloses a harmless treatment of methyl chlorosilane monomer silicon slag, which obtains silicon slag with a copper content less than 100 mg / L of the leaching toxicity identification standard through three times of washing. However, this method needs to treat the silicon slag by a washing kettle, and the process flow is complicated and time-consuming. SUMMARY

[0004] The present application provides a harmless treatment method and device for methyl chlorosilane monomer silicon slurry, which can realize continuous purification and harmless treatment of a large amount of silicon slurry, aiming at the deficiencies of existing silicon slurry treatment technologies.

[0005] A harmless treatment method and device for methyl chlorosilane monomer silicon slurry, characterized in that the method steps are as follows:

[0006] (1) Hydrolysis of methyl chlorosilane monomer silicon slurry. Methyl chlorosilane monomer silicon slurry, water and oxidizing agent are added to a hydrolysis kettle, and stirring and reaction are carried out for 10-20 min to obtain silicon slag and washing liquid through solid-liquid separation. The washing liquid is reused after treatment.

[0007] (2) Silicon slag crushing. The silicon slag is conveyed to a ball mill for crushing.

[0008] (3) Silicon slag purification. The ball mill crushed silicon slag is transported to the purification kettle, and the pickling solution is supplemented in the purification kettle. After stirring for 10-20 min, the solid-liquid separation is carried out in the purification kettle, the pickling solution is transported to the pickling solution buffer tank, and after treatment, it is reused, and the silicon slag is left in the purification kettle; the recycled water is supplemented, stirred for 10-20 min, and the solid-liquid separation is carried out in the purification kettle, the water washing solution is sent to the water washing solution buffer tank, and after treatment, it is reused, and the silicon slag is left in the purification kettle; the alkali washing solution is supplemented, stirred for 10-20 min, and the solid-liquid separation is carried out in the purification kettle, the alkali washing solution is filtered and sent to the alkali washing solution buffer tank, and the silicon slag is transported to the filter press.

[0009] (4) Silicon slag pressure filtration and drying. The silicon slag is subjected to pressure filtration, the pressure filtration pressure is 5-8 MPa, and the reverse washing is carried out through clean water-dilute alkali solution, the washing water is transported to the water washing solution buffer tank, and the silicon slag after pressure filtration is dried by the drying machine.

[0010] Specifically, the methyl chlorosilane monomer slag mainly consists of organic chlorosilane, silicon powder and copper catalyst, and the solid content is 20-50%, including but not limited to the copper element (the copper element is selected from one or more of elemental copper, cuprous, and copper ions) content of 3-8%.

[0011] Specifically, the amount of water is 2-3:1 of the mass ratio of methyl chlorosilane monomer silicon slurry.

[0012] Specifically, the oxidizing agent is at least one of hydrogen peroxide and sodium hypochlorite, and the amount of oxidizing agent is 3-5wt% of the mass of methyl chlorosilane monomer silicon slurry.

[0013] Specifically, the average particle size of the silicon slag crushed by the ball mill is 5-20 mm.

[0014] Specifically, the purification kettle is a vertical three-layer stirring lining device; the lower part and the upper part are connected through a variable diameter connection, and the variable diameter connection is inclined at 40-50°; there are three discharge ports on the side of the bottom of the kettle, and the discharge ports have filter plates with pores to realize solid-liquid separation, the diameter of the filter plate is 800-1000 mm, the diameter of the filter hole is 1-2 mm, and the center of the bottom stirring center is parallel to the center of the side discharge port of the kettle bottom.

[0015] Specifically, the reaction temperature of the purification kettle is 30-40℃, and the stirring speed of the purification kettle is 70-200 r / min.

[0016] Specifically, the amount of acid washing solution / water washing solution / alkali washing solution is 2-3:1 of the mass ratio of methyl chlorosilane monomer silicon slag.

[0017] Specifically, the acid washing solution is hydrochloric acid, and the concentration of hydrochloric acid in the acid washing solution is 3-5%.

[0018] Specific, the alkali solution is sodium hydroxide, the amount of alkali is 1-2.5wt% of the mass of methyl chlorosilane monomer silicon residue, and the pH value is kept at 3.0-4.0.

[0019] The patent has the following advantages:

[0020] 1. The present application can remove most of the copper in the silicon slurry by hydrolyzing the silicon slurry under a strong oxidizing agent, making the copper in the silicon slurry exist in the form of copper ions, and then combining three times of washing of acid washing, water washing and alkali washing, so that the final treated silicon residue is neutral, reducing the subsequent operation of resource utilization of the silicon residue.

[0021] 2. The purification kettle is used to wash the silicon residue, the lower part and the upper part of the kettle are connected through variable-diameter inclined connection, the silicon residue can be fully contacted with the washing liquid during washing, the silicon residue is easy to be separated from the liquid during filtration, the bottom stirring is parallel to the center of the discharge port, which can make the silicon residue layer rotate during solid-liquid separation, and accelerate the solid-liquid separation, and the solid-liquid separation module exists in the kettle, so that the silicon residue washing is continuous.

[0022] 3. After the filtrate of the washed silicon residue is treated, the washing liquid can be recycled, the water consumption for treating the silicon slurry can be reduced by 70%, the water resource can be greatly saved, and the environmental hazards can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a process flow chart of a harmless treatment method of methyl chlorosilane monomer silicon slurry.

[0024] Figure 2 is a structure schematic diagram of a purification kettle of a harmless treatment method and device of methyl chlorosilane monomer silicon slurry.

[0025] Figure 1 In the figure: 1. Hydrolysis kettle, 2. Plate and frame filter press, 3. Ball mill, 4. Purification kettle, 5. Plate and frame filter press, 6. Dryer, 7. Acid washing liquid buffer tank, 8. Water washing liquid buffer tank, 9. Alkali washing liquid buffer tank.

[0026] Figure 2 In the figure: 4-1 first layer stirring paddle, 4-2 second layer stirring paddle, 4-3. Third layer stirring paddle, 4-4. Kettle bottom side discharge port, 4-5. Kettle lower part and upper part are connected through variable-diameter inclined connection, 4-6. Filter plate with pores in the discharge port, 4-7. Filter hole. Specific implementation method

[0027] As shown in Figure 1 A harmless treatment method and device of methyl chlorosilane monomer silicon slurry, including hydrolysis kettle 1, plate and frame filter press 2, ball mill 3, purification kettle 4, plate and frame filter press 5, dryer 6, acid washing liquid buffer tank 7, water washing liquid buffer tank 8, alkali washing liquid buffer tank 9.

[0028] The hydrolysis kettle 1 is connected with the plate and frame filter press 2 through a pipeline; the plate and frame filter press 2 is connected with the ball mill 3 and the pickling liquid buffer tank 7 through a pipeline respectively; the ball mill 3 is connected with the purification kettle 4 through a pipeline; the purification kettle 4 is connected with the pickling liquid buffer tank 7, the water washing liquid buffer tank 8, the alkali washing liquid buffer tank 9 and the plate and frame filter press 5 through a pipeline respectively; the filtrate outlet of the plate and frame filter press 5 is connected with the water washing liquid buffer tank 8 through a pipeline, and the filter residue outlet of the plate and frame filter press 5 is conveyed to the drying machine 6 through a belt; the pickling liquid buffer tank 7 and the water washing liquid buffer tank 8 are connected with the purification kettle 4 after being treated by copper extraction and salt removal; the alkali washing buffer tank 7 is connected with the purification kettle 4 after being filtered and supplemented with alkali liquid.

[0029] As shown in Figure 2 The kettle body part of the purification kettle 4 is connected with the discharge port 4-4 through a variable-diameter inclined connecting end 4-5, and the discharge port 4-4 is provided with a filter plate 4-6 with pores.

[0030] The purification kettle 4 is internally provided with three layers of stirring paddles from top to bottom, namely a first layer of stirring paddles 4-1, a second layer of stirring paddles 4-2 and a third layer of stirring paddles 4-3, wherein the third layer of stirring paddles 4-3 is parallel to the center of the discharge port 4-4 of the kettle bottom part of the purification kettle 4.

[0031] The inclined angle of the variable-diameter inclined connecting end 4-5 is 50°; the diameter of the filter plate 4-6 with pores in the discharge port 4-4 is 800 mm; and the diameter of the filter hole 4-7 on the filter plate 4-6 is 2 mm.

[0032] The above-mentioned harmless treatment method and device for methyl chlorosilane monomer silicon slurry include hydrolysis of the methyl chlorosilane monomer silicon slurry, crushing of silicon residue, purification of the silicon residue and pressure filtration and drying of the silicon residue.

[0033] (1) Hydrolysis of the methyl chlorosilane monomer silicon slurry. The methyl chlorosilane monomer silicon slurry, water and an oxidizing agent are added to a hydrolysis kettle, and stirred and reacted for 10-20 min to obtain silicon residue and washing liquid through solid-liquid separation. The washing liquid is reused after treatment.

[0034] (2) Crushing of the silicon residue. The silicon residue is conveyed to a ball mill for crushing.

[0035] (3) Purification of the silicon residue. The silicon residue crushed by the ball mill is conveyed to a purification kettle, acid washing liquid is supplemented into the purification kettle, stirred and reacted for 10-20 min, and then solid-liquid separation is performed through the purification kettle, the acid washing liquid is conveyed to an acid washing liquid buffer tank and reused after treatment, and the silicon residue remains in the purification kettle; reused water is supplemented, stirred and reacted for 10-20 min, and then solid-liquid separation is performed through the purification kettle, the water washing liquid is sent to a water washing liquid buffer tank and reused after treatment, and the silicon residue remains in the purification kettle; alkali washing liquid is supplemented, stirred and reacted for 10-20 min, and then solid-liquid separation is performed through the purification kettle, the alkali washing liquid is filtered and sent to an alkali washing liquid buffer tank, and the silicon residue is conveyed to a pressure filter.

[0036] (4) Silicon slag filter pressing drying. The silicon slag is filter pressed, the filter pressing pressure is 5-8 Mpa, the backwashing is carried out by clean water-dilute alkali solution, the washing water is transported to the washing liquid buffer tank, and the silicon slag after filter pressing is dried by the drying machine.

[0037] The following gives the above device and process as follows specific embodiments.

[0038] Example 1

[0039] (1) Methyl chlorosilane monomer silicon slurry hydrolysis: 200 kg of methyl chlorosilane monomer silicon slurry, 400 kg of water and 10 kg of 3% hydrogen peroxide solution are added to the hydrolysis kettle, stirred for 20 min, and then silicon slag and washing liquid are obtained by solid-liquid separation. The washing liquid is reused after treatment.

[0040] (2) Silicon slag crushing: the obtained silicon slag is put into the ball mill and crushed to an average particle size of 15 mm.

[0041] (3) Silicon slag purification: 200 kg of silicon slag obtained by ball mill crushing is added to the purification kettle, 400 kg of 3% hydrochloric acid is added to the purification kettle, the stirring speed is set to 70 revolutions per minute, the reaction temperature is 30°C, and the stirring is carried out for 20 min. After stirring, solid-liquid separation is carried out, the acid washing liquid is transported to the acid washing liquid buffer tank, and the silicon slag is left in the purification kettle; 400 kg of recycled water is added to the purification kettle, and stirring is carried out for 20 min. After stirring, solid-liquid separation is carried out, the washing liquid is transported to the acid washing liquid buffer tank, and the silicon slag is left in the purification kettle; 400 kg of 2.5 wt% sodium hydroxide solution is added to the alkali washing reaction kettle, stirring is carried out for 20 min, and then solid-liquid separation is carried out. After stirring, the alkali washing liquid is transported to the alkali washing liquid buffer tank, and the silicon slag is transported to the plate and frame filter press.

[0042] (4) Silicon slag filter pressing drying: the silicon slag after alkali washing is in the plate and frame filter press, the squeezing pressure is 8 Mpa, the backwashing is carried out by clean water-dilute alkali solution after squeezing, the washing water is transported to the washing liquid buffer tank, and the silicon slag after filter pressing is dried by the drying machine.

[0043] After the toxicity leaching experiment, the copper content in the leaching liquid is 81.2 mg / L, which is less than the minimum standard (leaching method refers to HJ 557-2007, identification standard refers to GB 8979) of 100 mg / L of hazardous waste, the pH of the silicon slag is 6.5, and the harmless treatment of the methyl chlorosilane monomer silicon slurry is achieved.

[0044] Example 2

[0045] The parameters of this embodiment are basically the same as those of Example 1, and the difference is that sodium hypochlorite is used as the oxidizing agent. After the toxicity leaching experiment, the copper content in the leaching solution is 68.4 mg / L, which is less than the minimum standard of 100 mg / L of hazardous waste, and the pH of the silicon residue is 7.0, reaching the harmless treatment of methyl chlorosilane monomer silicon slurry.

[0046] Example 3

[0047] The parameters of this embodiment are basically the same as those of Example 1, and the difference is that the mass ratio of methyl chlorosilane monomer silicon slurry to acid washing solution is 1:3. After the toxicity leaching experiment, the copper content in the leaching solution is 42.6 mg / L, which is less than the minimum standard of 100 mg / L of hazardous waste, and the pH of the silicon residue is 8.0, reaching the harmless treatment of methyl chlorosilane monomer silicon slurry.

[0048] Example 4

[0049] The parameters of this embodiment are basically the same as those of Example 1, and the difference is that the mass ratio of methyl chlorosilane monomer silicon residue to acid washing solution / water washing solution / alkali washing solution is all 1:3. After the toxicity leaching experiment, the copper content in the leaching solution is 46.5 mg / L, which is less than the minimum standard of 100 mg / L of hazardous waste, and the pH of the silicon residue is 6.5, reaching the harmless treatment of methyl chlorosilane monomer silicon slurry.

[0050] Example 5

[0051] The parameters of this embodiment are basically the same as those of Example 1, and the difference is that the stirring and washing time is 15 min. After the toxicity leaching experiment, the copper content in the leaching solution is 78.4 mg / L, which is less than the minimum standard of 100 mg / L of hazardous waste, and the pH of the silicon residue is 8.5, reaching the harmless treatment of methyl chlorosilane monomer silicon slurry.

[0052] Example 6

[0053] The parameters of this embodiment are basically the same as those of Example 1, and the difference is that the concentration of the acid washing solution is 4%. After the toxicity leaching experiment, the copper content in the leaching solution is 47.3 mg / L, which is less than the minimum standard of 100 mg / L of hazardous waste, and the pH of the silicon residue is 7.5, reaching the harmless treatment of methyl chlorosilane monomer silicon slurry.

[0054] Example 7

[0055] The parameters of this embodiment are basically the same as those of Example 1, and the difference is that the concentration of the alkali washing solution is 1.0%. After the toxicity leaching experiment, the copper content in the leaching solution is 68.0 mg / L, which is less than the minimum standard of 100 mg / L of hazardous waste, and the pH of the silicon residue is 7.5, reaching the harmless treatment of methyl chlorosilane monomer silicon slurry.

[0056] Example 8

[0057] The embodiment is basically same as the parameters of example 1, the difference is that the average particle size of the silicon slag after crushing is 20mm. After the toxicity leaching experiment, the copper content in the leaching solution is 75.7mg / L, which is less than the minimum standard of 100mg / L of hazardous waste, and the pH of the silicon slag is 7.5, which reaches the harmless treatment of methyl chlorosilane monomer silicon slurry.

[0058] Example 9

[0059] The embodiment is basically same as the parameters of example 1, the difference is that the stirring speed of the purification kettle is 150r / min. After the toxicity leaching experiment, the copper content in the leaching solution is 48.2mg / L, which is less than the minimum standard of 100mg / L of hazardous waste, and the pH of the silicon slag is 8.0, which reaches the harmless treatment of methyl chlorosilane monomer silicon slurry.

[0060] Example 10

[0061] The embodiment is basically same as the parameters of example 1, the difference is that the reaction temperature of the purification kettle is 40℃. After the toxicity leaching experiment, the copper content in the leaching solution is 39.8mg / L, which is less than the minimum standard of 100mg / L of hazardous waste, and the pH of the silicon slag is 7.0, which reaches the harmless treatment of methyl chlorosilane monomer silicon slurry.

Claims

1. A method for detoxifying methylchlorosilane monomer slurry, characterized by, The method comprises the following steps: (1) methyl chlorosilane monomer silicon slurry hydrolysis, methyl chlorosilane monomer silicon slurry, water, oxidant are added to the hydrolysis kettle, after stirring reaction, the silicon residue and washing liquid are obtained by solid-liquid separation, the washing liquid is recycled after treatment; (2) silicon residue crushing, the silicon residue is transported to the ball mill for crushing; (3) silicon residue purification, the silicon residue crushed by the ball mill is transported to the purification kettle, acid washing liquid is supplemented in the purification kettle (4), after stirring reaction, solid-liquid separation is carried out, the acid washing liquid is transported to the acid washing liquid buffer tank, and is recycled after treatment, the silicon residue remains in the purification kettle; the recycled water is supplemented, after stirring reaction, solid-liquid separation is carried out, the water washing liquid is sent to the water washing liquid buffer tank, and is recycled after treatment, the silicon residue remains in the purification kettle; the alkali washing liquid is supplemented, after stirring reaction, solid-liquid separation is carried out, the alkali washing liquid is filtered and sent to the alkali washing liquid buffer tank, the silicon residue is transported to the filter press, the kettle body part of the purification kettle (4) is connected with the discharge port (4-4) through a variable-diameter inclined connecting end (4-5), the filter plate (4-6) with pores is arranged in the discharge port (4-4), and three layers of stirring paddles are arranged in the purification kettle (4) from top to bottom, namely the first layer of stirring paddles (4-1), the second layer of stirring paddles (4-2) and the third layer of stirring paddles (4-3), wherein the third layer of stirring paddles (4-3) is parallel to the center of the discharge port (4-4) of the kettle bottom of the purification kettle (4); (4) silicon residue filter pressing and drying, after the silicon residue is filter pressed, reverse washing is carried out through clean water-dilute alkali liquid, the washing water is transported to the water washing liquid buffer tank, and the silicon residue after filter pressing is dried through the drying machine.

2. The method for the detoxification of methylchlorosilane monomer slurry according to claim 1, characterized by: The methyl chlorosilane monomer residue slurry mainly comprises organic chlorosilane, silicon powder and copper, the solid content is 20-50 %, and the copper element content is 3-8 %.

3. The method for the detoxification of methylchlorosilane monomer slurry according to claim 1, characterized by: The mass ratio of the amount of water to the methyl chlorosilane monomer silicon slurry is 2-3:1; 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 methyl chlorosilane monomer silicon slurry; the average particle size of the silicon residue crushed by the ball mill is 5-20 mm.

4. The method for the detoxification of methylchlorosilane monomer slurry according to claim 1, characterized by: The reaction temperature of the purification kettle is 30-40 DEG C, and the stirring speed of the purification kettle is 70-200 r / min.

5. The method for the detoxification of methylchlorosilane monomer slurry according to claim 1, characterized by: The mass ratio of the amount of the acid washing liquid / water washing liquid / alkali washing liquid to the methyl chlorosilane monomer silicon residue is 2-3:1; the acid washing liquid is hydrochloric acid, the concentration of hydrochloric acid in the acid washing liquid is 3-5 %, the alkali washing liquid is sodium hydroxide, the amount of the alkali is 1-2.5 wt% of the mass of the methyl chlorosilane monomer silicon residue, and the pH value is maintained at 3.0-4.

0.

6. The method for the detoxification of methylchlorosilane monomer silicon slurry according to any one of claims 1 to 5, characterized by: The harmless treatment device used in the method is as follows: the hydrolysis kettle (1) is connected with the plate and frame filter press (2) through a pipeline; the plate and frame filter press (2) is connected with the ball mill (3) and the acid washing liquid buffer tank (7) through pipelines; the ball mill (3) is connected with the purification kettle (4) through a pipeline; the purification kettle (4) is connected with the plate and frame filter press (5) through a pipeline; and the filter residue port of the plate and frame filter press (5) is transported to the drying machine (6) through a belt.

7. The method for the detoxification of methylchlorosilane monomer slurry according to claim 6, characterized in that, The purifying kettle (4) is connected with the pickling liquid buffer tank (7) and the water washing liquid buffer tank (8) through pipelines respectively, the filtrate outlet of the plate-and-frame filter press (5) is connected with the water washing liquid buffer tank (8) through a pipeline, the pickling liquid buffer tank (7) and the water washing liquid buffer tank (8) are connected with the purifying kettle (4) respectively, and the alkaline washing liquid buffer tank (9) is connected with the purifying kettle (4), the pickling liquid buffer tank (7) and the water washing liquid buffer tank (8) through pipelines respectively.

8. The methyl chlorosilane monomer slurry detoxification method according to claim 6, characterized by, The inclination angle of the tapering and inclined connecting end (4-5) is 40-50°; the diameter of the filter plate (4-6) with pores in the discharge port (4-4) is 800-1000mm; and the diameter of the filter hole (4-7) on the filter plate (4-6) is 1-2mm.

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