METHOD OF OBTAINING POLYCRYSTALLINE SILICON Russian patent published in 2018 - IPC C30B28/14 C30B29/06 C01B33/03 C01B33/35 C01B33/107 C01B7/01 C01B7/03 C25B1/26 C01B33/12 

FIELD: technological processes.

SUBSTANCE: invention relates to the technology of semiconductor materials and can be used in the production of polycrystalline silicon. Method includes the production of hydrogen chloride from chlorine and hydrogen; obtaining trichlorosilane in a fluidized bed reactor of metallurgical silicon with a catalyst using synthesized hydrogen chloride and circulating hydrogen chloride from the condensation system after hydrogen reduction of trichlorosilane with the formation of a vapor-gas mixture 1 containing chlorosilanes and hydrogen; condensation of chlorosilanes from vapor-gas mixture 1 to produce condensate 1 and with the separation of hydrogen; rectification separation of chlorosilanes from condensate 1 and their purification; processing of silicon tetrachloride to trichlorosilane; hydrogen reduction of purified trichlorosilane in precipitation reactors to produce polycrystalline silicon and a vapor-gas mixture 2 containing chlorosilanes, hydrogen, and hydrogen chloride; condensation of chlorosilanes from vapor-gas mixture 2 to produce condensate 2 and with the separation of hydrogen and hydrogen chloride; rectification separation of chlorosilanes from condensate 2 and their purification; processing of silicon-containing waste to produce silicon dioxide and sodium chloride solution, to obtain chlorine using electrolysis of sodium chloride solution obtained during the processing of silicon-containing waste, while producing hydrogen, which is sent to obtain hydrogen chloride, and sodium hydroxide solution, which is sent to the waste treatment system; to obtain hydrogen chloride, dry chlorine and hydrogen from the chlorine electrolysis system and additional hydrogen from the hydrogen station are used, and the synthesis of hydrogen chloride is carried out with simultaneous absorption by water and further evolution of gaseous hydrogen chloride on the stripping column, with simultaneous production of hydrochloric acid, which is sent to the waste treatment system; the direct synthesis of trichlorosilane and the processing of silicon tetrachloride to trichlorosilane are carried out jointly in a reactor, in which, in addition to metallurgical silicon, a catalyst and hydrogen chloride, hydrogen is extracted, separated from vapor-gas mixture 1, part of the hydrogen separated from vapor-gas mixture 2, hydrogen from the hydrogen station, purified after distillation separation of condensate 1 silicon tetrachloride and the main part of silicon tetrachloride after distillation separation of condensate 2; in the process of hydrogen reduction of silicon, trichlorosilane, purified after distillation separation of chlorosilanes from condensate 1, is fed to the reactor, trichlorosilane, purified after distillation separation of chlorosilanes from condensate 2, and working hydrogen from condensation system 2, temperature gradient in the space from the cooling zone of the reactor wall to the heaters is reduced to 250–300 °C due to the introduction of composite heat shields; after distillation separation of condensate 1 and distillation separation of condensate 2, dichlorosilane is brought into the system for conversion of dichlorosilane to trichlorosilane, from which trichlorosilane is then returned to distillation separation of chlorosilanes from condensate 1 and their purification.

EFFECT: technical result of the invention is to increase the productivity of the enterprise for the production of GLC 1,3–1½ times without a significant change in capital and operating costs compared with the unit (base) power, as well as the implementation of a fully closed cycle in chlorine with a 2–2½ times decrease in the amount of waste (by-products); as a result of the use of this technical solution, the cost of polycrystalline silicon is reduced by a factor of 1,2–1,4.

1 cl, 1 ex, 1 dwg