CN-119608080-B - Method and system for recycling polycrystalline silicon slag slurry

CN119608080BCN 119608080 BCN119608080 BCN 119608080BCN-119608080-B

Abstract

The invention provides a method and a system for recycling polycrystalline silicon slag slurry. The recycling method of the polycrystalline silicon slurry comprises the following steps of carrying out flash evaporation treatment on the slurry to obtain a first solid-liquid mixture and first gas-phase chlorosilane, carrying out sedimentation treatment on the first solid-liquid mixture to obtain a second solid-liquid mixture and supernatant, carrying out first drying treatment on the second solid-liquid mixture to obtain first dry powder and second gas-phase chlorosilane, and collecting the first gas-phase chlorosilane and the second gas-phase chlorosilane. The recovery method can efficiently separate the solid phase and the liquid phase in the slag slurry, realize the recovery of chlorosilane and dry powder in the slag slurry, and improve the utilization efficiency of resources.

Inventors

LIU JISAN
LIU MINGXIA
YAO YOUSHENG
TUO LINGHAN
LI DAN
HE ZHENJIANG
WU XIAOQIAN
CHEN WEIPING
LUO CAIPING

Assignees

华陆工程科技有限责任公司

Dates

Publication Date: 20260508
Application Date: 20241101

Claims (5)

1. The method for recycling the polycrystalline silicon slurry is characterized by comprising the following steps of: Flash evaporation treatment is carried out on the slag slurry to obtain a first solid-liquid mixture and a first gas phase; settling the first solid-liquid mixture to obtain a second solid-liquid mixture and a supernatant; Performing first drying treatment on the second solid-liquid mixture to obtain first dry powder and a second gas phase; collecting the first gas phase and the second gas phase; Performing first filtering treatment on the supernatant to obtain a first liquid phase and filter residues; performing second drying treatment on the filter residues to obtain second dry powder and a third gas phase; Collecting the first liquid phase and the third gas phase; performing a first condensation treatment on the first gas phase to obtain a fourth gas phase and a second liquid phase, collecting the fourth gas phase to enable the second liquid phase to participate in a flash evaporation treatment, and/or, Subjecting said second gaseous phase to a second condensation treatment obtaining a third liquid phase, collecting said third liquid phase, and/or, Performing third condensation treatment on the third gas phase to obtain a fourth liquid phase, and collecting the fourth liquid phase; making the first liquid phase, the fourth gas phase, the third liquid phase and the fourth liquid phase all enter a clear liquid tank to obtain a fifth liquid phase and a fifth gas phase; performing fourth condensation treatment on the fifth gas phase to obtain a sixth gas phase and a sixth liquid phase; Washing the sixth gas phase to return the sixth liquid phase to the clear liquid tank; Performing second filtering treatment on the fifth liquid phase to obtain a seventh liquid phase, and performing distillation treatment on the seventh liquid phase to obtain silicon tetrachloride; And enabling the silicon tetrachloride to participate in the sedimentation treatment.
2. The recovery method according to claim 1, wherein in the flash evaporation treatment, the temperature is 35 to 165 ℃ and the pressure is 0.05 to 1.5MPaG, and/or, In the sedimentation treatment, the temperature is 0-35 ℃, the time is 2-8 hours, the pressure is 0.05-0.7 MPaG, and/or, In the first drying treatment, the temperature is 70-120 ℃, the time is 2-8 hours, the pressure is 0.02-0.08 MPaG, and/or, In the second drying treatment, the temperature is 70-120 ℃, the time is 2-8 hours, the pressure is 0.02-0.08 MPaG, and/or, In the first filtering treatment, the filtering precision is 1-3 mu m, the temperature is 0-35 ℃, the pressure is 0.1-0.7 MPaG, and/or, In the first condensation treatment, the temperature is 40-80 ℃, the pressure is 0.04-1.5 MPaG, and/or, In the second condensation treatment, the temperature is 40-120 ℃, the pressure is 0.02-0.08 MPaG, and/or, In the third condensation treatment, the temperature is 40-120 ℃, the pressure is 0.02-0.08 MPaG, and/or, In the fourth condensation treatment, the temperature is-15-40 ℃, the pressure is 0.02-0.08 MPaG, and/or, In the second filtering treatment, the filtering precision is 1-3 mu m, the temperature is 0-50 ℃, the pressure is 0.1-1.5 MPaG, and/or, In the distillation treatment, the temperature is 80-150 ℃ and the pressure is 0.08-0.2 MPaG.
3. A recovery system for carrying out the recovery method according to any one of claims 1 to 2, comprising a flash tank, a settling tank, a dryer, and a clear liquid tank; The slurry enters the flash tank through the inlet of the flash tank, the solid-liquid mixture outlet of the flash tank is communicated with the inlet of the sedimentation tank, and the solid-liquid mixture outlet of the sedimentation tank is communicated with the inlet of the dryer; The gas phase outlet of the flash tank is communicated with the inlet of the clear liquid tank, and the gas phase outlet of the dryer is communicated with the inlet of the clear liquid tank.
4. The recovery system of claim 3, further comprising a supernatant filter, The supernatant outlet of the settling tank is communicated with the inlet of the supernatant filter, the filter residue outlet of the supernatant filter is communicated with the inlet of the dryer, and the liquid phase outlet of the supernatant filter is communicated with the inlet of the supernatant tank.
5. The recovery system of claim 3 or 4, further comprising a flash condenser; The vapor phase outlet of the flash tank is in communication with the inlet of the flash condenser, the liquid phase outlet of the flash condenser is in communication with the flash tank, the vapor phase outlet of the flash condenser is in communication with the inlet of the clear liquid tank, and/or, The dryer also comprises a dryer condenser; The gas phase outlet of the dryer is communicated with the inlet of the dryer condenser, the outlet of the dryer condenser is communicated with the inlet of the clear liquid tank, and/or, The device also comprises a refrigerator and a tail gas washing tower; the gas phase outlet of the clear liquid tank is communicated with the inlet of the refrigerator, the gas phase outlet of the refrigerator is communicated with the tail gas washing tower, the liquid phase outlet of the refrigerator is communicated with the clear liquid tank, and/or, The device also comprises a clear liquid distillation tower filter and a clear liquid distillation tower; the liquid phase outlet of the clear liquid tank is communicated with the inlet of the clear liquid distillation tower filter, the liquid phase outlet of the clear liquid distillation tower filter is communicated with the clear liquid distillation tower, and the silicon tetrachloride outlet of the clear liquid distillation tower is communicated with the settling tank.

Description

Method and system for recycling polycrystalline silicon slag slurry Technical Field The invention relates to a method and a system for recycling polycrystalline silicon slag slurry, and belongs to the technical field of chemical separation. Background As demand increases, the photovoltaic industry and the integrated circuit industry are rapidly evolving. Polysilicon is a core raw material for the photovoltaic industry and the integrated circuit industry, and thus more and more enterprises begin to produce polysilicon. Currently, the polysilicon production enterprises almost all adopt an improved Siemens method, and a large amount of slag slurry is generated in the process of producing polysilicon by the improved Siemens method. The method mainly comprises the steps of treating polycrystalline silicon slag slurry mainly by two modes, namely, carrying out rough hydrolysis treatment on part of the slag slurry to cause a great deal of chlorosilane material waste and environmental pollution, and sending part of the slag slurry to a vacuum drum filter to carry out solid-liquid separation by utilizing an adsorption layer formed by mixing diatomite and chlorosilane, wherein the separated solid phase is simply treated and then sent to a hydrolysis system for treatment, and the liquid phase is further purified and recycled. Disclosure of Invention The invention provides a recycling method of polycrystalline silicon slurry, which can efficiently separate solid and liquid phases in the slurry, recycle chlorosilane and dry powder in the slurry, and improve the utilization efficiency of resources. The invention provides a recycling system of polysilicon slag slurry, which is used for implementing the recycling method, has a simple structure, can efficiently separate solid and liquid phases in the slag slurry, realizes recycling of chlorosilane and dry powder in the slag slurry, and improves the utilization efficiency of resources. The invention provides a method for recycling polycrystalline silicon slag slurry, which comprises the following steps: Flash evaporation treatment is carried out on the slag slurry to obtain a first solid-liquid mixture and a first gas phase; settling the first solid-liquid mixture to obtain a second solid-liquid mixture and a supernatant; Performing first drying treatment on the second solid-liquid mixture to obtain first dry powder and a second gas phase; collecting the first gas phase and the second gas phase. The recovery method as described above, further comprising: Performing first filtering treatment on the supernatant to obtain a first liquid phase and filter residues; Performing second drying treatment on the filter residues to obtain second dry powder and a third gas phase; collecting the first liquid phase and the third gas phase. The recovery method as described above, further comprising: Performing a first condensation treatment on the first gas phase to obtain the fourth gas phase and a second liquid phase, collecting the fourth gas phase to enable the second liquid phase alkane to participate in a flash evaporation treatment, and/or, Subjecting said second gaseous phase to a second condensation treatment, obtaining said third liquid phase, collecting said third liquid phase, and/or, And carrying out third condensation treatment on the third gas phase to obtain the fourth liquid phase, and collecting the fourth liquid phase. The recovery method as described above, further comprising: making the first liquid phase, the fourth gas phase, the third liquid phase and the fourth liquid phase all enter a clear liquid tank to obtain a fifth liquid phase and a fifth gas phase; performing fourth condensation treatment on the fifth gas phase to obtain a sixth gas phase and a sixth liquid phase; And washing the sixth gas phase to return the sixth liquid phase to the clear liquid tank. The recovery method as described above, further comprising: and carrying out second filtering treatment on the fifth liquid phase to obtain a seventh liquid phase, and carrying out distillation treatment on the seventh liquid phase to obtain silicon tetrachloride. The recovery method as described above, wherein the silicon tetrachloride is caused to participate in the sedimentation treatment. The recovery method as described above, wherein in the flash evaporation treatment, the temperature is 35 to 165 ℃, the pressure is 0.05 to 1.5MPaG, and/or, In the sedimentation treatment, the temperature is 0-35 ℃, the time is 2-8 hours, the pressure is 0.05-0.7 MPaG, and/or, In the first drying treatment, the temperature is 70-120 ℃, the time is 2-8 hours, the pressure is 0.02-0.08 MPaG, and/or, In the second drying treatment, the temperature is 70-120 ℃, the time is 2-8 hours, the pressure is 0.02-0.08 MPaG, and/or, In the first filtering treatment, the filtering precision is 1-3 mu m, the temperature is 0-35 ℃, the pressure is 0.1-0.7 MPaG, and/or, In the first condensation treatment, the temperature is 80-40 ℃, the p