METHOD FOR PRODUCING TECHNICAL SILICON (VERSIONS) Russian patent published in 2022 - IPC C01B33/23 C01B33/37 C30B29/06 

FIELD: chemistry.

SUBSTANCE: invention relates to a technology of obtaining silicon raw materials of different grades: solar quality (99.9999% Si), high-purity silicon (99%+ Si) and ordinary metallic silicon (96-99% Si) by reducing calcium silicate slag using an aluminum source. One of options for obtaining metallic silicon includes: (I) combining silicon dioxide and calcium oxide in a vessel at a temperature sufficient to form molten calcium-silicate slag; (II) introducing a metallic aluminum source into molten calcium-silicate slag to reduce calcium-silicate slag to metallic Si and form calcium-aluminate slag; (III) separating metallic Si from calcium-aluminate slag; and optionally (IV) further purifying metallic Si; where the reduction stage (II) is carried out in a series of reduction furnaces, in which the specified slag is moved in a countercurrent direction relatively to metallic Si, or where the reduction stage (II) is carried out in a series of furnaces, in which calcium-silicate slag is moved in a countercurrent direction relatively to metallic Al. The technology is characterized by low energy consumption, almost zero dust, low CO₂ and NO_x emissions, simplicity and low capital costs.

EFFECT: invention provides the production of high-purity silicon with concentrations of B and P below 1 ppmw.

14 cl, 12 dwg, 2 tbl, 7 ex