Method for preparing high-purity silicon from silicon carbide sliced crystalline silicon waste mortar

Abstract

The invention discloses a method for preparing high-purity silicon from silicon carbide sliced crystalline silicon waste mortar and belongs to the technical field of high-purity silicon preparation. The method comprises the following specific steps: 1, smashing a silicon carbide sliced crystalline silicon waste mortar raw material; 2, performing chemical processing and purification; 3, sorting; 4,utilizing a sheet frame to dewater the raw material and a bipyramid vacuum rotary drying machine to dry the raw material; 5, utilizing a pressing and forming machine to press the raw material in to blocks; 6, utilizing one or more combinations of an intermediate frequency furnace, an intermediate frequency electric arc furnace and an electromagnetic induction furnace to melt the raw material; 7,utilizing a breaking machine to smash the raw material; 8, utilizing one or more combinations of sulfuric acid, hydrochloric acid, hydrofluoric acid and nitric acid to perform purification and removeimpurities; 9, utilizing the bipyramid vacuum rotary drying machine to dry the raw material and drying to obtain a high-purity silicon product. The method disclosed by the invention can be used for purifying and recycling silicon powder in a mortar cutting waste material, the silicon powder is applied to a solar-grade silicon industry chain again, and great significance in resource reutilization,cost reduction and environmental protection is achieved.

Description

technical field [0001] The invention specifically relates to a method for preparing high-purity silicon by using silicon carbide cutting crystal silicon waste mortar, and belongs to the technical field of high-purity silicon preparation. Background technique [0002] In the production process of solar-grade crystalline silicon wafers, multi-line mortar cutting is a commonly used method. During the cutting process, the high-speed reciprocating motion of the metal wire is used to grind silicon carbide as the abrasive and polyethylene glycol as the dispersion and suspension agent. The silicon ingot can be cut into hundreds of pieces at the same time. With the accumulation of silica fume in the mortar, the cutting ability of the mortar gradually decreases and eventually becomes waste mortar that loses the cutting ability. The prior art can recycle the cutting fluid of the waste mortar and the SiC abrasive > 7mm, and the non-recyclable tailings are processed to obtain the mor...

AI Technical Summary

Problems solved by technology

For example, using the difference in the melting points of Si and SiC to directly smelt silicon ingots, however, due to the high melting point of SiC, the content of SiC will cause the problem of furnace bottom rise

Using the low melting point of Si-Cu alloy, the melting temperature can be lowered, but the problem of rising the bottom of the furnace is still unsolved, and the separation of Si / Cu will also cause additional energy consumption

Using the difference of Zeta on the surface of Si and SiC to separate Si / SiC by electrophoresis; using the difference of contact angle between Si and SiC to separate Si / SiC by froth flotation and extraction, but these methods have not been scaled up and verified

Using the difference in particle size distribution to separate Si / SiC by cyclone separation and sedimentation methods, however, due to the serious crossover of Si and SiC particle sizes, the separation of Si and SiC is not complete, and it cannot be melted in the melting furnace

Due to the above reasons, there is currently no mature technology for preparing high-purity silicon from silicon carbide cutting crystal silicon waste mortar