| abstract |
Processing of solid metal-contg. residues from the direct synthesis of organochlorosilanes and/or chlorosilanes, comprising primarily reactor residues, filter dusts or hydrolysis sludges, is effected by treatment with dil. H2SO4 at elevated temp. without use of oxidising agents. Pref. the H2SO4 has a concn. of 20-70 (esp. 40-60) wt.%. The temp. is 20-150 (esp. 60-100) deg.C. USE/ADVANTAGE - Residues from direct synthesis processes using Cu/Si contact masses may be treated to remove Cu and impurities (e.g. Fe and Al), giving Si suitable for recycle, disposal or metallurgical use. In contrast to oxidative processes, all the Cu is removed in soluble form and may be recycled or used, e.g., as a wood preservative, fertiliser, feed additive, flotation activator, algicide or fungicide. In an example, spent contact mass contg. 5.5% Cu (300 g) was stirred with 300 g of 20% H2SO4 at 100-110 deg.C for 1 hr, and then filtered. The filter cake contained 1.7 g Cu, of which 100% was soluble |