METHOD producing high-purity silicon tetrafluoride TETRAFLUORIDE method of separating from oxygen and silicon fluorides highly volatile impurities, a production method of silicon powder FROM SILICON TETRAFLUORIDE

摘要

1. A method of producing silicon tetrafluoride, comprising in that the fluorination is carried out with natural siliceous concentrates 97,0-99,998 wt.% SiOv two subsequent independently flowing step without separation of the reaction products in the 1st stage fluorination is carried out in a torch at 1500-2000 ° C with elemental fluorine an excess of 15-20 wt% relative to the stoichiometry of the reactions with the fluorination process of the terminal non-volatile fluorides at 100-350 ° C and of moderately - at -40 -60 ° C. for 2 minutes fluorination stage is carried out at 300-500 ° C in excess of the initial silicon ontsentratov in an amount of 60-70% relative to stoichiometric excess with the absorption of elemental fluorine from the 1st stage ftorirovaniya.2. A method of silicon tetrafluoride and oxygen separation from highly volatile impurities fluoride obtained according to claim 1, comprising contacting them with molten fluoride eutectic salts of alkali metals LiF (0,465 M) - KF (0,420 M) - NaF (0,115 M) at 430-550 ° C with evolution of oxygen and carbon tetrafluoride in the gas phase, and silicon tetrafluoride - the melt elektrolita.3 complex salts. A method of producing silicon powder from the silicon tetrafluoride obtained according to claim 2, comprising the steps that produce electrolytic reduction of silicon cations (Si) on a liquid zinc cathode and oxidation of the anions fluorine (F) - on a graphite anode in the molten electrolyte LiF (0.465 M ) - KSiF (0,401 M) - NaSiF (0,134 M) at 500-550 ° C with the output of the cell in the silicon powder mixture elektrolitom.4. A method of washing the silicon powder obtained from the electrolyte according to claim 3 and impurities of subjecting the mixture of silicon powder and electrolyte solution of ammonium hydrofluoride at a concentration of 140-160 g / l at pH = 3.5, temp