Chlorosilane-containing slurry treatment method and chlorosilane-containing slurry treatment system

Abstract

The invention belongs to the technical field of polycrystalline silicon production, and relates to a chlorosilane-containing slurry treatment method and a chlorosilane-containing slurry treatment system. The chlorosilane-containing slurry treatment method disclosed by the invention comprises the following steps: chlorosilane-containing slurry gets into a slurry collection tank, and is kept still,and by utilizing the incompatibility and density difference between components in the slurry, the slurry is formed into supernate and bottom turbid liquid in the slurry collection tank; the supernateis discharged out from a plurality of chlorosilane outlets which are arranged at different heights on the slurry collection tank, sequentially passes through a filter and a delivery pump, and gets into a chlorosilane recovery device; and the bottom turbid liquid gets into a washing device from the bottom outlet of the slurry collection tank under the effect of pressure difference and is washed. According to the invention, the chlorosilane recovery rate is high, the quality of recovered chlorosilane is better, and the requirement of electronic-grade polycrystalline silicon production on qualitycan be met. Moreover, the investment of the process is low, safety is good, the continuous operation period is long, later operation and maintenance costs are low, the investment recovery period is short, and risk is low.

Description

technical field [0001] The invention belongs to the technical field of polysilicon production, and relates to the technical field of slag slurry treatment in the polysilicon production process, in particular to a chlorosilane-containing slag slurry treatment method and a treatment system. Background technique [0002] In the production process of electronic grade polysilicon, the slag slurry mainly comes from the hydrogenation reduction of silicon tetrachloride, the synthesis of trichlorosilane, the separation and purification of chlorosilane, etc., especially the cold hydrogenation process, the slag discharged from the cold hydrogenation unit and the separation and purification unit The amount of slurry is greatly increased. During the production process of the cold hydrogenation process, a slag slurry mainly composed of chlorosilane, silicon powder and metal chloride will be produced. There are currently four main methods for the treatment of the slag slurry: direct hydrol...

AI Technical Summary

Problems solved by technology

After the slurry is concentrated, due to the reduction of liquid phase chlorosilane and the presence of silicon powder and high-boiling metal chlorides, its fluidity becomes poor, especially under the conditions of long pipelines and low temperatures, metal chlorides And silicon powder will be deposited on the pipe wall of the conveying pipeline, often causing the blockage of conveying equipment and pipeline, affecting the normal process operation; (2) In the dry hydrolysis method, the metal chloride in the slurry is also evaporated and recovered in large quantities, so that the subsequent The product quality of the rectification unit is reduced

This method is acceptable in the production process of solar-grade polysilicon, but in the production process of electronic-grade polysilicon, because electronic-grade polysilicon has very strict requirements on the surface metal and bulk metal content of the product, this method cannot meet its production requirements; (3) Due to the particularity of the properties of chlorosilane, the safety requirements of the equipment in the production process are high

In the application of this method, the shaft end seal of the dryer is often not tightly sealed, causing chlorosilane leakage, which has certain safety hazards and causes the system to run continuously for a short period; (4) in the drying hydrolysis method, the dryer is The core components of this technology have relatively high prices and post-maintenance costs. For polysilicon manufacturers with small production capacity, the investment recovery period is too long

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