Method of separating metal values from ammoniacal solutions

Claim 1

IN A METHOD OF SEPARATING VALUES OF METALS THE SULPHIDES OF WHICH ARE OF LOWER SOLUBILITY IN AMMONIACAL SOLUTION THAN NICKEL SULPHIDE FROM AN AMMONIACAL SOLUTION WHICH CONTAINS, IN SOLUTION, FREE AMMONIA IN EXCESS OF ABOUT 1 GRAM PER LITRE FOR EACH GRAM PER LITRE OF NICKEL PLUS COBALT, A SALT OF AT LEAST ONE SUCH LOWER SOLUBILITY METAL, AT LEAST ONE SALT OF A METAL OF THE GROUP CONSISTING OF NICKEL AND COBALT, AND AT LEAST ONE SULPHUR COMPOUND OF THE GROUP CONSISTING OF POLYTHIONATES HAVING MORE THAN TWO SULPHUR ATOMS IN THEIR MOLECULAR STRUCTURE AND THIOSULPHATE, THE IMPROVEMENT WHICH COMPRISES THE STEPS OF ADJUSTING THE FREE AMMONIA CONTENT OF THE SOLUTION TO NOT LESS THAN THAT WHICH WHEN REACTED WITH SULPHURIC ACID WILL PRODUCE IN THE AMMONIACAL SOLUTION A TOTAL AMMONIUM SULPHATE CONCENTRATION NOT LESS THAN ABOUT 5 GRAMS PER LITRE FOR EACH GRAM PER LITRE OF DISSOLVED NICKEL PLUS COBALT, ADDING SULPHURIC ACID TO THE SOLUTION IN AMOUNT SUFFICIENT TO REDUCE THE AMMONIA CONTENT THEREOF TO NOT LESS THAN ABOUT 2.0 MOLS PER MOL OF NICKEL PLUS COBALT AND THE PH VALUE OF THE SOLUTION TO NOT LESS THAN ABOUT PH 7.2, WHEREBY VALUES OF METALS OF LOWER SOLUBILITY THAN NICKEL SULPHIDE ARE PRECIPITATED FROM THE SOLUTION, AND SEPARATING PRECIPITATED METAL VALUES FROM THE SOLUTION.