POLYCRYSTALLINE SILICON PREPARATION METHOD

摘要

Usage: the technical solution relates to a polycrystalline silicon preparation technique applicable, for instance, in the manufacturing of solar panels. Essence of the invention: a polycrystalline silicon preparation method includes mixing silicon dioxide with a reducing agent, subjecting the mixture to high-energy processing, and reacting the produced product with a chlorinating agent to form a chlorine-containing silicon compound which is used for producing polycrystalline silicon, wherein the byproducts are processed. The invention is novel in that quartz sand and/or an industrial silica-containing raw material is used as the silicon dioxide, the high-energy processing of the mixture is carried out at a temperature of between 1800°С and 2000°С in a solid phase, chlorine is used as the chlorinating agent so as to produce a chlorine-containing silicon compound - silicon tetrachloride, which is used for producing trichlorosilane by means of hydrogenation, said trichlorosilane being at least partially used for producing polycrystalline silicon by means of hydrogen reduction. Also novel is that the high-energy processing of the mixture is carried out in a fixed-bed resistance furnace, and that the produced product is sorted, crushed and a fraction of -50+10mm is isolated. The invention is also novel in that the high-energy processing of the mixture is carried out in an electrothermal boiling bed furnace, and in that the product produced therein has silicon dioxide and an organic binder added thereto and is then pelletized and annealed. Also novel is that hydrogen for hydrogenation and reduction, and chlorine, are obtained by the electrolytic decomposition of hydrochloric acid, which acid is produced during byproduct processing. The present invention is novel in that at least a portion of the trichlorosilane is used for producing monosilane, which then undergoes pyrolysis to produce polycrystalline silicon. The achieved technical result: intensifying the main technological processes, thus enabling an increase in the degree of silicon extraction into a useful product, while simultaneously providing for the high quality of the produced product with minimal energy and material outlay and, as a result, decreasing the price of the target product by almost 2 times.