Sec. aluminium@ smelter and refiner residue and filter dust detoxification - to remove poly:halogenated organic cpds. with recovery of aluminium cpds. by lixiviation and hydrothermal or thermal treatment with alkali

摘要

Removal of toxic polyhalogenated organic cpds. (I) from filter dust (IIA) and residues (IIB) from metallurgical smelters and refiners for the mfr. of sec. Al, with recovery of Al cpds. (III), comprises (a) lixiviating (II) with water to remove soluble smelting salts; (b) subjecting filter-moist or dry (II) to hydrothermal treatment with addn. of alkali and under reducing conditions in aq. soln. at temps. up to 250 deg.C or thermal treatment with addn. of alkaline earths in the solid phase at temps. up to 1000 deg.C so that (I) are largely or completely decomposed, whilst the Al and Al cpds., esp. Al2O3 phases remaining in (II) are converted to soluble alkali(ne earth) aluminate; and (c) after sepg. the remaining residues, which are no longer ecotoxic, working it up to Al2O3 (hydrate) or other pure Al cpds.. USE/ADVANTAGE - The technique is useful for treating (II) from processes utilising scrap metal or similar industrial or communal residues contg. Al. (I) are eliminated economically and useful (III) are recovered. Hydrothermal treatment with alkali gives an inert residue contg. silicate, which may be dumped or used in ceramics mfr.; and thermal treatment with alkaline earths gives e.g., useful Ca cpds. and a residue contg. CaCO3, which can be partly recycled, dumped or used in silicate mfr..atme