METHOD OF SILICON-BEARING RESIDUES POWDERS RECOVERY Russian patent published in 2009 - IPC B22F8/00 B22F3/23 

FIELD: metallurgy.

SUBSTANCE: for recovery there are chosen powdered silicon-bearing residues, including no less than 30% of silicon alloys, and alloys contains no less than 10% of silicon. Initial charge of powdered residues with grain size no more than 5.0 mm are dried with receiving of moisture content less than 0.2% and porosity from 30 till 80%. Dried charge is placed into the gaseous nitrogen atmosphere with oxygen concentration no more than 7.0 volume % under pressure from 0.2 till 20.0 MPa. It is implemented short-term local heating till the temperature of the beginning of exoergic chemical reaction of nitriding and oxidation. After lighting process proceed in mode of layerwise and volume combustion at the temperature 1500-2300°C. In the issue of burning major part of silicon transforms into nitride, oxynitride and/or carbide, and initial charge into sintered material, containing 30-80% of silicon, 7.0-39.0% nitrogen, 0.01-17.0 carbon and 0.01-7.0% oxygen. Sintered product allows compactness from 1.1 till 4.6 g/cm³.

EFFECT: high-quality nitrogen-containing products for metallurgy.

23 cl, 1 tbl, 4 ex