Patent ID: 6953565

Claim:
A process for producing an ammonium polythiomolybdate of the formula (NH 4 ) 2 Mo 3 S 13 .n H 2 O where n is 0, 1 or 2 comprising: (a) reacting an aqueous ammoniacal molybdate solution with hydrogen sulfide gas in a closed system at superatmospheric pressure until the H 2 S is no longer absorbed by the solution, to form a slurry of solid ammonium tetrathiomolybdate containing a portion of the starting molybdenum in a mother liquor containing the balance of the molybdenum; (b) heat soaking the slurry of step (a) in a closed reactor in the presence of elemental sulfur at a pressure of 600-1000 psig whereby the ammonium tetrathiomolybdate is converted to (NH 4 ) 2 Mo 3 S 13 .n H 2 O; (c) cooling the slurry of step (b) to ambient temperature; (d) separating said solid from the major portion of said mother liquor; (e) washing said solid with water to remove the remaining portion of said mother liquor and soluble impurities from said solid; and (f) drying the resulting washed solid.