Method for recovering silicon carbide, high-purity silicon and dispersion liquid from silicon material linear cutting waste mortar

Abstract

The invention relates to a method for recovering silicon carbide, high-purity silicon and dispersion liquid from silicon material linear cutting waste mortar, which is characterized in that the solid and liquid separation on the waste mortar is carried out, recovered dispersing agents are obtained after the liquid is refined, solid is washed by water for further removing residual dispersing agents, then, flotation liquid is used for carrying out floatation for many times, crude silicon carbide and crude silicon powder are separated, the recovered silicon carbide is obtained after the crude silicon carbide is refined, the crude silicon powder is treated through acid cleaning, drying, melting, plasma refining, vacuum refining, unidirectional solidification and the like, and the solar grade polysilicon is obtained. The method has the advantages that the important indexes such as the viscosity, the acid-base degree and the like of the recovered dispersing agents are more similar to those of the novel dispersing liquid, more cutting capability of the silicon carbide can be recovered after the silicon carbide is subjected to the silicon corrosion treatment, metal impurities in high-purity silicon powder are removed, an important index of the phosphorus and boron content of the solar grade silicon is reduced to a value conforming to the solar grade silicon requirements that the phosphorus is lower than 0.01 ppmw and the boron is lower than 0.16ppmw, and the attenuation of the photoelectric conversion efficiency is greatly reduced after solar batteries are made.

Description

technical field [0001] The invention relates to the field of recovery and reuse of silicon wire cutting waste mortar, in particular to a method for recovering silicon carbide, high-purity silicon and dispersion liquid from silicon wire cutting waste mortar. Background technique [0002] Whether it is monocrystalline silicon or polycrystalline silicon, semiconductor silicon or crystalline silicon for solar energy, it must be cut before it flows into the next step of use. In the existing cutting technology, wire cutting is the best choice. High rate, high efficiency, low loss and so on. [0003] The principle of wire cutting is: use silicon carbide and polyethylene glycol dispersion to prepare a mortar with a certain viscosity. Driven by the high-speed moving steel wire, the silicon carbide in the mortar will rub against the material to be cut at a high speed locally. The hardness of silicon is much higher than that of the material to be cut. Silicon carbide can scrape off a ...

AI Technical Summary

Problems solved by technology

[0016] To sum up the various methods, it is known that silicon carbide, dispersion liquid and silicon with limited purity can only be recovered from waste wire cutting mortar (although individual patents claim to be high-purity polysilicon, in fact, the high content of phosphorus and boron in it is not treated. )

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