The production method of silicon micro powder

Firstly, the trichlorosilane method adds dry silicon powder to the synthesis furnace and undergoes chlorination reaction with the introduced dry hydrogen chloride gas in the presence of cuprous chloride catalyst at 280-330 ℃. The reaction gas is separated by cyclone to remove impurities, and then the gaseous trichlorosilane is condensed into a liquid using calcium chloride frozen salt water. It is distilled and condensed in a crude distillation tower to remove high boiling and low boiling substances, and then distilled and condensed in a distillation tower to obtain a refined trichlorosilane liquid. The purity should reach 7 or more "9", the impurity content should be less than 1 × 10-7, and the boron requirement should be below 0.5 × 10-9. The purified trichlorosilane is sent into a stainless steel reduction furnace, where ultrapure hydrogen gas is used as a reducing agent to reduce it to silicon at 1050-1100 ℃. The silicon core rod is used as a carrier to deposit polycrystalline silicon products.

Secondly, mix silica with approximately 95% SiO2 content and coke with low ash content, heat to around 1900 ℃ for reduction. The purity of silicon produced by this method is 97%~98%, which is called metallic silicon. After melting the metallic silicon, it undergoes recrystallization and impurities are removed with acid to obtain metallic silicon with a purity of 99.7%~99.8%. To make it into semiconductor silicon, it is necessary to convert it into a liquid or gas form that is easy to purify, and then obtain polycrystalline silicon through distillation and decomposition processes. To obtain high-purity silicon, further purification treatment is required.

Thirdly, mix silica with approximately 95% SiO2 content and coke with low ash content, and use a 1000-3000kVA open arc furnace to heat to around 1900 ℃ for reduction.