Method for preparing elemental silicon

Abstract

The invention discloses a method for preparing elemental silicon. The method comprises the following steps of: dissolving SiO2 in an alkali metal or alkaline earth metal oxide-containing chloride molten salt, or dissolving alkali metal or alkaline earth metal silicate in the chloride molten salt, wherein the temperature of the chloride molten salt is 600 to 1,000 DEG C, electrolyzing by using graphite or silicon or a metal as a cathode and using graphite or an inert material as an anode to electrically deposit siliconic acid radicals at the cathode, and separating the electrodeposition to obtain the elemental silicon. In the method, the operation temperature is low; raw materials are cheap and available; the molten salt is stable; and the purity of the product is high. The process can be controlled through consistent current; continuous production is easy to be realized; the current efficiency is high; and the production energy consumption and cost of silicon can be obviously reduced.

Description

technical field [0001] The invention belongs to the technical field of metallurgy and relates to a new method for preparing metal silicon. Background technique: [0002] Elemental silicon has very important applications in the fields of materials, information and energy, and its demand continues to expand with the development of the solar photovoltaic industry. At present, the carbothermal reduction method for producing crude silicon has serious pollution, high energy consumption, and high content of impurities such as boron and phosphorus. Electrolytic silicon smelting is a silicon smelting method with low energy consumption and low carbon emissions that may replace carbothermal reduction. In 2003, Kyoto University Nohira and Ito et al. (Nat.Mater.2003, 2, 397-401) reported that in CaCl 2 However, the serious ohmic polarization and concentration polarization in the solid-state cathode lead to slow reduction, and the cathode potential must be finely controlled, which is dif...

AI Technical Summary

Problems solved by technology

At present, the carbothermal reduction method for producing crude silicon has serious pollution, high energy consumption, and high content of impurities such as boron and phosphorus. Electrolytic silicon smelting is a silicon smelting method with low energy consumption and low carbon emissions that may replace carbothermal reduction.

In 2003, Kyoto University Nohira and Ito et al. (Nat.Mater.2003, 2, 397-401) reported that in CaCl 2 However, the serious ohmic polarization and concentration polarization in the solid-state cathode lead to slow reduction, and the cathode potential must be finely controlled, which is difficult Realize industrial production

However, due to the high electrolysis temperature, it is still difficult to industrialize