PROCESS OF LEACHING SULFIDE-CONT AINING MATERIALS WITH HOT, STRONG SULFURIC ACID

摘要

1,254,119. Leaching materials containing metal sulphides. TREADWELL CORP. 5 Dec., 1968 [18 Dec., 1967; 29 Nov., 1968], No. 57775/68. Heading C1A. Materials containing metal sulphides are reacted with hot sulphuric acid at a temperature below 250‹ C., the reaction proceeding in at least one stage at a temperature above 160‹ C., heat being supplied to the reaction to maintain the temperature, the sulphuric acid concentration being maintained above 80% for long enough to convert a major amount of the sulphides to the corresponding sulphates and the amount of sulphuric acid being sufficient to react with the metal sulphides but not present in sufficient excess to produce a slurry in the later stages, so that the reaction is effected in substantially solid form. Preferably, water formed in the reaction is removed by evaporation as it is formed. Specified metal sulphates which may be obtained by the process of the invention are copper, lead, zinc, nickel and ferrous sulphates. A preliminary treatment with weaker acid may be used to convert certain sulphides such as lead sulphide, to their sulphates. The uniformity of distribution of reactants in the process of the invention may be improved by providing particles which are large relative to the particles of the sulphides reacted, upon which a coating of reactants is formed, or by forming balls of the feed material, including the acid. The sulphates obtained by the process of the invention may be recovered by conventional procedures such as electrowinning and cyanidation.