Method for preparing high-purity silicon by recovering diamond wire cutting silicon powder through electric field coupling directional solidification technology

Abstract

The invention discloses a method for preparing high-purity silicon by recovering diamond wire cutting silicon powder through an electric field coupling directional solidification technology, which comprises the following steps: grinding a diamond wire cutting silicon powder waste material, preparing a solution from HF, H2O and C2H5OH in a ratio of 1: 3: 1, pickling, centrifugally drying, and briquetting; the silicon powder block is subjected to vacuum induction melting, after heat preservation is finished, an electric field is introduced in the solidification process, the temperature gradient at the solid-liquid cross section is controlled, some protruding parts at the solid-liquid interface are remelted, the stability of the solid-liquid interface is kept, growth of dendrites is restrained, and the yield in the recovery process is remarkably increased. The introduction of the electric field can promote the convection of the silicon liquid, can ensure the uniformity of impurities and temperature in the silicon liquid, enables the segregation effect of the impurities in the solidification process to be more obvious, further improves the purity of the silicon ingot, and improves the purity of the recovered silicon to 5N. According to the technology, environmental pollution caused by the silicon powder waste can be prevented, silicon resources can be reused, and the industrial cost of the crystalline silicon solar cell industry is further saved.

Description

technical field [0001] The invention relates to a method for recovering diamond wire-cut silicon powder to prepare high-purity silicon by electric field coupling directional solidification technology, and belongs to the technical field of photovoltaic solid waste resource recycling and silicon material preparation. Background technique [0002] As a clean and renewable energy, solar energy has broad prospects for development. Among them, crystalline silicon solar cells have maintained a market share of more than 90%, and crystalline silicon has become a strategic resource in the new century. However, as the current mainstream silicon ingot processing method, diamond wire cutting silicon ingot technology, about 30-35% of ultra-fine silicon particles are lost to silicon powder waste in the production process. High-purity silicon accounts for about 90% of these wastes, which has important Recycling value. Since the technology for recycling silicon fume waste is not perfect, a ...

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Problems solved by technology

[0004] In order to overcome the above-mentioned defects in the prior art, the present invention aims at reclaiming and preparing high-purity silicon from silicon powder waste generated during the production of crystalline silicon solar cells through electric field coupling directional solidification technology, which can not only prevent environmental pollution caused by silicon powder waste , and can re-use silicon resources, save industrial costs in the crystalline silicon solar cell industry, and solve the problems of insufficient purity and low yield in the prior art when recycling high-purity silicon

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