Preparation of hyperpure metallurgy silicon

Abstract

A preparation method of ultrapure metallurgical silicon belongs to the purification technology of silicon, and the invention provides a primary purification method of a silicon material which totally contains less than 100ppma of impurities and is used for preparing solar cells. In the method, the physical metallurgical technology is used, industrial silicon powder (purity is higher than 99.5%) is taken as a raw material,, after being chemically pre-processed by acid, the silicon powder is evenly mixed with a slagging agent and put in a quartz crucible of a smelting furnace, protective gas is blown to the smelting furnace at micro-vacuum state or normal pressure; induction heating is carried out till the temperature of the smelting furnace is 1400-1700 DEG C, and the silicon metal is melted into a silicon melt; slagging is carried out to remove impurities; and finally directional solidification is carried out to obtain the ultrapure metallurgical silicon totally containing less than 100ppma of impurities. The method can remove most of metal impurity elements from silicon, especially can reduce the contents of B and P in the silicon effectively, and meet the demand of low-cost solar cells for silicon materials. The method saves equipment investment, reduces energy consumption, and has simple technology and easy operation in production.

Description

Technical field:

[0001] The invention relates to a method for preparing ultra-pure metallurgical silicon, belongs to the technical field of silicon purification, and specifically relates to a method for preparing ultra-pure metallurgical silicon by using a vacuum smelting furnace to add a slagging agent to purify industrial silicon. In particular, it can be used in the primary purification method of silicon for solar cells. Background technique:

[0002] Ultra-pure metallurgical silicon is generally used as silicon raw materials and silicon alloys for low-cost solar cell new processes. The purification of metallurgical silicon generally includes physical metallurgical methods and chemical methods. The ingredients are unchanged. The method of silicon purification using chemical principles is called chemical method. Its characteristic is that the composition of the silicon material changes during the purification process! The mature technology of chemical method is generall...