SILICON RECOVERY PROCESS Russian patent published in 2002 - IPC

FIELD: phosphate production. SUBSTANCE: high-purity silicon is recovered from wastes issuing from sodium and potassium silicofluoride compounds (fertilizers) production via method involving reduction of alkali metal silicofluorides with reducing metals such as alkali metals at temperature superior to reducing metal melting point at least by 50K but below its boiling temperature, whereupon silicon is precipitated on a support at temperature by at least 10K below melt temperature but higher than melting point of chemically active reducing metal. Process is conducted within nonisothermal flow circuit. In precipitation zone, monocrystalline silicon seed with cooled surface can be used. EFFECT: increased productivity of process at lower expenses. 3 cl, 1 dwg