Method for recycling waste silicon powder in production process of trichlorosilane

Abstract

The invention discloses an equipment for producing trichlorosilane by comprehensively utilizing waste silicon powder. The equipment comprises a trichlorosilane synthetic furnace mixed gas outlet pipe connected with a high-efficiency cyclone separator; wherein a material discharge port of the high-efficiency cyclone separator is connected with a silicon powder recovery tank; a gas outlet of the high-efficiency cyclone separator is connected with a primary cyclone separator; a primary slag storage tank is arranged below the primary cyclone separator; the gas outlet of the primary cyclone separator is connected with a secondary cyclone separator; a secondary slag storage tank is arranged below the secondary cyclone separator; the gas outlet of the secondary cyclone separator is connected with a primary bag-type dust remover and a secondary bag-type dust remover in turn; both the material discharge ports of the primary bag-type dust remover and the secondary bag-type dust remover are connected with the silicon powder recovery tank through slag blowing pipes; and the material discharge port of the silicon powder recovery tank is connected with a recovery port of the trichlorosilane synthetic furnace. The equipment has the characteristics of obvious energy conservation effect, high environmental protection benefit, high safety factor, unique process, simplicity and long service life, and is easy to operate and the like.

Description

technical field [0001] The invention belongs to the technical field of trichlorosilane production, and in particular relates to a method for recycling waste silicon powder in the trichlorosilane production process. Background technique [0002] Judging from the development of my country's trichlorosilane industry, most enterprises have not installed waste silicon powder recovery devices. In most enterprises, the waste silicon powder generated after the mixed gas dedusting is directly discharged to the leaching tower, and a few manufacturers use the waste silicon powder to be discharged into a large-capacity ash storage tank, and then manually discharged regularly. [0003] The first method is equivalent to the wet dust removal method. The circulating water pump pumps the water into the leaching tower in multiple layers, and the gas containing silicon powder enters from the middle and lower part of the tower, and is absorbed by the liquid sprayed from the multi-layer spraying...

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Problems solved by technology

This method can ensure the regeneration effect of the dust removal equipment, but because the dust gas contains a small amount of trichlorosilane, and trichlorosilane meets water to form silicon dioxide solids and hydrogen chloride gas

Silica will block the nozzle of the spraying device in the tower, and in severe cases, it will cause no water spraying in the washing tower, and the silicon powder will be discharged directly from the top of the washing tower, causing serious environmental pollution; the generated hydrogen chloride gas dissolves in water to form hydrochloric acid , the spray liquid of the leaching tower is acidic, causing certain corrosion to the circulating water pump, and the generated hydrochloric acid needs to be treated before being discharged, resulting in secondary pollutants

Because the surface of waste silicon powder is stained with a small amount of hydrogen chloride, trichlorosilane and other gases, and trichlorosilane meets the moisture in the air and generates pungent hydrogen chloride gas, which affects the environment of the factory area and the health of employees; Because of the fine particle size, temperature of 100~200℃, and flammable trichlorosilane gas attached to the surface, waste silicon powder is easy to catch fire when it is discharged and stacked, and there are certain safety hazards.

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