Method for recovering solar-grade polysilicon from single crystal silicon/polysilicon cutting slurry

Abstract

The invention relates to a method for recovering solar-grade polysilicon from single crystal silicon / polysilicon cutting slurry, belonging to the technical field of silicon material. The method comprises: first, drying the slurry and preparing polyethylene glycol water solution; then, carrying out physical settlement to obtain crude powder material; pickling, filtering and drying the obtained crude powder material, and obtaining refined powder material; carrying out fusion casting on the obtained refined powder material at 1500-1600 DEG C, and obtaining metallic silicon ingots and silicon carbide powder; and finally, purifying the metallic silicon ingots by directional solidification and zone fusion casting technology, and obtaining the solar-grade polysilicon. The method does not introduce impurity elements which are harmful to the performance of high-purity silicon when the high-purity silicon is purified, has simple and easy technique and experienced equipment, is easy for realizingindustrialization, and becomes one of the effectively way for solving the shortage of the silicon material.

Description

technical field [0001] The invention belongs to the technical field of silicon materials, and in particular relates to solar-grade polysilicon technology. Background technique [0002] Global resources such as oil and coal are increasingly tense, the energy crisis is looming, and the environment is deteriorating. Therefore, renewable energy has received great attention, and solar energy has become the focus of attention of the world because of its unique advantages such as inexhaustible, inexhaustible, clean, safe and cheap. The developed countries in the world and our country are competing to vigorously develop the photovoltaic industry. The global solar energy industry has entered a period of rapid development, and photovoltaic energy has become the most important new energy in the 21st century. [0003] But at present, the cost of solar power generation is still high, because the polysilicon used to make solar cells is very expensive. At present, the main method of pre...

AI Technical Summary

Problems solved by technology

There are many steps in this method, and the liquid used with a density between Si and SiC will inevitably pollute the silicon powder to a certain extent, and the obtained silicon cannot reach the 6N purity of solar-grade polysilicon.

At present, most enterprises only recycle the silicon carbide in the cutting waste, and can reclaim the large particle silicon carbide, but there is no good way to reclaim the silicon in it, and the benefits produced are also small. Patent application (application number: 200610058746.3 ) discloses a recovery method for reclaiming silicon carbide micropowder, but the silicon therein is not effectively recovered

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