Sulphur recovery from residual aqs. solns. - which contain ammonium sulphate, sulphuric acid and metal salt impurities

摘要

A process is claimed for producing S is produced from aqs. solns. of H2SO4 and/or (NH4)2 SO4 contg. heavy metal salts. The soln. is treated with NH3, (NH4)2 S and/or H2S to form ppts. of heavy metal hydroxides and/or sulphides which are separated and a soln. contg. H2SO4 and/or (NH4)2SO4 which is treated with BaS to form (a) a BaSO4 ppte. which is reduced by a C-contg. cpd. (pref. charcoal or coke) to regenerate BaS, (the gaseous effluent being purified before disposal), and (b) a soln. contg. H2S and/or (NH4)2S which is heated to obtain a gas contg. H2S from which S is produced and separated by reaction with SO2. S may be recovered from industrial residual waters such as obtd. from plants of TiO2 prodn. metal cleaning, caprolactam prepn. and purification of industrial gases contg. SO2. The process also allows recovery of commercially valuable metal.