Method for preparing solar-grade silicon material by melt-salt electrolysis method

Abstract

The invention relates to a method for preparing the solar level polysilicon material, and specially relates to the method for using the craft of fusion electrolysis to three fluids fining and then to vacuum distillation to prepare the solar level polysilicon material. The invention first takes SiO2 or others compound of containing silicon as the raw material, and fusion electrolysis technology is adopted to prepare silicon containing alloy Si-M1. Three fluids fusion electrolysis fining technology is adopted to prepare high-purity silicon containing alloy Si-M2 with silicon containing alloy Si-M1 as anode and high-purity metal M2 as cathode. Finally, vacuum distillation technology is adopted to prepare solar level polysilicon material with high-purity silicon containing alloy Si-M2 as material. Compared with traditional Simens craft or improvement Simens craft, the invention has the superiority of high efficiency, low energy consumption, low cost, and low pollution.

Description

technical field [0001] The invention relates to the preparation of silicon materials, in particular to the preparation of solar-grade polysilicon materials by molten salt electrolysis-three-layer liquid refining-vacuum distillation. Background technique [0002] As a clean and sustainable energy source, solar energy has received extensive attention. High-purity polysilicon is the raw material used in silicon series solar cells. At present, the typical process for producing high-purity silicon at home and abroad is the Siemens process. More than 95% of the quartz ore is smelted into metallurgical-grade silicon at a high temperature of 1500°C in an electric furnace, and then smelted at a temperature of about 300°C and a pressure of 0.45MPa. Chlorination of metallurgical grade silicon to SiHCl with HCl 3 , followed by purification of SiHCl by rectification 3 , then use H 2 Reduced SiHCl 3 Electronic-grade silicon, and finally use electronic-grade silicon waste to manufactu...

AI Technical Summary

Problems solved by technology

[0003] Molten salt electrolysis is one of the silicon material preparation methods, which can be divided into the following categories for the preparation of solar-grade polysilicon: (1) at a temperature higher than the melting point of Si, high-purity SiO 2 As raw material, polysilicon is prepared by molten salt electrolysis; the process temperature is high, energy consumption is high, equipment corrosion is serious, and it is difficult to obtain solar-grade polysilicon; (2) High-purity fluorosilicate is used as raw material to prepare polysilicon by molten salt electrolysis , silicon is precipitated in solid form; the problem is that silicon is precipitated as dendrites, the conductivity is poor, the cathode solid-liquid interface is unstable, the deposition rate is slow, and continuous production cannot be performed; (3) high-purity SiO 2 As the cathode, through molten salt electrolysis, the electrochemical removal of cathode oxygen is realized, thereby preparing polysilicon; 2 Poor electrode conductivity, low current density and low efficiency during electrolysis