Method and equipment for intermittently recycling waste liquid of chlorosilane during polycrystalline silicon production

Abstract

The invention discloses a method for intermittently recycling chlorosilane in discharged waste liquid in a washing tower during polycrystalline silicon production, and the method the following steps of: intermittently charging a chlorosilane waste liquid produced in polycrystalline silicon production into an evaporation device at different places, evaporating trichlorosilane and silicon tetrachloride with lower boiling point into a gas state when the temperature of the evaporation device is controlled at 120-180DEG C and the pressure of the evaporation device is controlled at 0.1-0.6MPa, and charging the gaseous trichlorosilane and silicon tetrachloride into a rectifying tower so as to be purified and recycled. The invention further provides the evaporation device used in the method. The invention has the beneficial effects that the method is simple in process, the process condition is easy to realize, and the method is convenient to operate; and the treatment difficulty of the chlorosilane waste liquid during polycrystalline silicon production in the process of production can be improved, the discharge quantity of exhaust liquor can be mainly reduced, the waste of the chlorosilane can be reduced, the treatment load of an alkali liquor pond can be reduced, the environment pollution problem can be remitted, the labor quantity can be reduced, the production cost can be reduced, the complete recycle of the chlorosilane can be realized, and the phenomenon of equipment blockage can be avoided.

Description

technical field [0001] The invention relates to material recycling in the field of polysilicon preparation, in particular to a method and special equipment for recycling chlorosilane waste liquid in polysilicon production. Background technique [0002] Chlorosilane waste liquid from polysilicon production includes metal chlorides, polymers, high boilers and chlorosilane compounds. Described metal chloride is aluminum chloride and / or calcium chloride; Described polymer is the polymer of phosphorus trichloride and / or the polymer of boron trichloride; Described high boiler is aluminum chloride, chlorine Iron chloride and / or calcium chloride; The chlorosilane compound is trichlorosilane and / or silicon tetrachloride. These substances are all mixed in the waste liquid, and the chlorosilane compounds can be separated and reused after purification, and the metal chlorides, polymers, and high boiling substances are separated and treated as waste materials. [0003] At present, in t...

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Problems solved by technology

[0006] However, these evaporation methods currently used have many deficiencies in the implementation process: the evaporation effect is poor, it is easy to cause pipeline blockage, and chlorosilane cannot be completely recovered, part of the chlorosilane waste liquid still needs to be rinsed, and the amount of residual liquid is large. The discharge liquid contains a large amount of chlorosilane, which causes problems such as large residual liquid treatment load, waste of chlorosilane, environmental pollution, high energy consumption, high cost, and large amount of human labor.

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