METHOD OF PREPARING HIGH-PURITY SILICON POWDER FROM SILICON PERFLUORIDE WITH SIMULTANEOUS PREPARATION OF ELEMENTARY FLUORINE, METHOD OF SEPARATING SILICON FROM SALT MELT, SILICON POWDER AND ELEMENTARY FLUORINE OBTAINED BY INDICATED METHOD, AND SILICON TETRAFLUORIDE PREPARATION PROCESS Russian patent published in 2006 - IPC C01B33/02 C01B33/08 C01B7/20 C25B1/24 C25B1/00 

FIELD: semiconductor engineering and silicon compounds technology.

SUBSTANCE: invention relates to production of electrolytic-grade silicon appropriate for use in sun power engineering and in semiconductor engineering. Group of inventions comprises a method for preparing high-purity silicon powder and elementary fluorine as well as a method for preparing silicon tetrafluoride used to saturate melt of salts to perform electrolysis. Silicon is isolated during electrolytic decomposition of melt of eutectic of alkali metal fluoride salt systems saturated with silicon tetrafluoride. Silicon is then discharged from electrolyzer in the form of silicon powder slurry and eutectic melt. Thereafter, silicon is separated from molten eutectic by dissolving this melt in anhydrous hydrogen fluoride. Resulting composition HF+(LiF-KF-NaF) in the form of liquid phase and silicon particles is filtered. Liquid phase is subjected to distillation of hydrogen fluoride, which is reused in dissolution stage. Silicon tetrafluoride is prepared via two-stage fluorination of silicon dioxide with elementary fluorine, which process is conducted in two flame reactors wherein excess elementary fluorine is conveyed from first stage to second stage.

EFFECT: enabled continuous process mode, increased yield and improved quality of product.

21 cl, 4 dwg, 2 tbl