Method for preparing ultra-metallurgical grade silicon from crystalline silicon cutting waste

Abstract

A method for preparing ultra-metallurgical grade silicon from crystalline silicon cutting waste, the method comprising: performing the first pretreatment on the crystalline silicon cutting waste to obtain a crystalline silicon roughing slurry, and subjecting the roughing slurry to a second pretreatment to obtain Purify and select the material; process the obtained purified and selected material through briquetting to obtain the first selected material block, and then separate the slag and silicon after the first selected block is subjected to oxygen-controlled smelting and refining treatment to obtain the first molten silicon and the first refining slag; the first modified solid silicon and / or the second modified solid silicon are obtained after the first molten silicon and / or the first refining slag are subjected to impurity chemical reconstruction; the obtained first modified solid The silicon and / or the reconstructed impurity phase in the second modified solid silicon is removed to obtain the ultra-metallurgical grade silicon. The method has the advantages of short process, cleanliness, and low cost, and is easy to realize the large-scale application of high-value regeneration cycle of crystalline silicon cutting silicon material.

Description

technical field [0001] The invention belongs to the technical field of secondary resource utilization, and in particular relates to a method for preparing ultra-metallurgical grade silicon from crystalline silicon cutting waste. Background technique [0002] Nearly 40% of the silicon in the crystalline silicon cutting process becomes waste, and there is an urgent demand for the recycling of low-end silicon materials such as crystalline silicon cutting waste. Crystalline silicon cutting waste mainly comes from the cutting process of solar cells, which also includes scraps from silicon ingot cutting. Solar cells are generally cut with a multi-wire saw and mortar, and the mortar is usually a mixture of mineral oil or polyethylene glycol (PEG) and SiC (silicon carbide) particles. During the cutting process, nearly 50% of the cutting silicon material enters the mortar in the form of fine silicon powder and becomes waste. The cutting fluid, SiC particles and silicon powder in the...

AI Technical Summary

Problems solved by technology

However, the traditional UMG-Si preparation method relies too much on the "concentrated material principle" and multiple directional solidification processes. The existing silicon purification method needs to combine multiple metallurgical separation technologies, resulting in long process, high energy consumption, and low efficiency.

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