A method for the separation of a nonferrous material - metals from their nickel and / or cobalt containing ammoniacal solution

摘要

Metal values, especially copper, are separated from ammoniacal solutions, containing at least one salt of nickel and/or cobalt, free ammonia, and a salt of at least one metal which forms an insoluble sulphide more readily than nickel in said solution, said solution further being substantially free from polythionate and thiosulphate ions, by a process which comprises the steps of adjusting the free ammonia content of the solution to within the range of 2 to 4 mols per mol of dissolved nickel plus cobalt, dispersing particles of elemental sulphur in solution in an amount in excess of that required to combine with the metal values to be precipitated as sulphides, and actively agitating the dispersion at above 90 DEG C. to precipitate the insoluble metal sulphides, which precipitate is separated. The metal sulphide forming reaction may be initiated by the addition to the reaction mixture of a polythionate having more than two sulphur atoms, a thiosulphate, sulphur dioxide, matter, or a mineral sulphide. The solutions to be treated may be obtained by the aid of alkaline, especially ammoniacal, leaching of mineral sulphides, preferably at elevated temperature and pressure in the presence of an oxygen-containing gas. Metal values which may be separated include silver, gold, ruthenium, germanium, tungsten, bismuth, platinum, cadmium, rhodium, molybdenum, tin, osmium, vanadium, mercury, palladium, arsenic, antimony, and especially copper. Specifications 670,181, 722,373, 746,633, 761,129 and 791,916 are referred to.