Method for recovering silicon powder from monocrystalline and polycrystalline silicon cutting wastes by utilizing potential adjustment centrifugal process

Abstract

The invention discloses a method for recovering a silicon powder from monocrystalline and polycrystalline silicon cutting wastes by utilizing a potential adjustment centrifugal process. The method comprises the following steps of: firstly, performing pretreatment on the cutting wastes to remove a polyethylene glycol solution; drying to obtain a mixed powder of silicon and silicon carbide; adding water to the mixed powder and stirring; regulating a pH value to 6-9 by acid and base; performing centrifugal separation for a plurality of times, and then, adding the acid to an isolated upper layer suspension to regulate the pH value to 1-3 so as to enable a silicon powder aggregate to grow up; and performing standing settling for 30min or centrifugal settling for 5min to collect the silicon powder, wherein the purity of the silicon powder can reach more than 80 percent.

Description

[0001] technical field [0002] The invention relates to a method for recovering silicon powder in monocrystalline silicon and polycrystalline silicon wire cutting waste. [0003] Background technique [0004] The utilization of solar energy has become an important direction of new energy development. The research and development of various solar photovoltaic cells is in full swing, and more than 80% of solar cells are made of high-purity polysilicon as the basic raw material. At present, various photovoltaic cells The product occupies an absolute dominant position. Generally, when making silicon wafers for solar cells, high-purity crystalline silicon must first be cast into ingots and then sliced. During the slicing process, the part accounting for more than 30% of the weight of the silicon ingot will be multi-wire cut into fine-sized silicon powder waste, which is used as a cutting abrasive silicon carbide powder, metal shavings generated by grinding, and as a cutting ab...

AI Technical Summary

Problems solved by technology

[0007] A comprehensive evaluation of the technical characteristics of the above separation and recovery of silicon shows that the process flow is generally long and the operation is complicated. Some methods even convert silicon from a simple substance into a compound, and it is more difficult to further recover the principle.

In addition, most separation methods use some toxic and polluting reagents

Although silicon is the most valuable component of monocrystalline silicon and polycrystalline silicon wire cutting waste slurry, there is currently no simple and mature separation technology that can realize its industrial regeneration cycle into high-purity polycrystalline silicon, and then manufacture into solar-grade polycrystalline silicon

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