Patent ID: 7837960

Claim:
A method of recovering metals from a used catalyst comprising the steps of: (a) leaching a Group VB metal, a Group VIB metal and a Group VIII metal from the used catalyst with an ammonia containing leach solution at a temperature and a pressure sufficient to form a pressure leach slurry comprising at least a Group VIB soluble metal complex and at least a Group VIII soluble metal complex and a first solid residue; (b) separating and removing the first solid residue from the pressure leach slurry to form a first pressure leach solution comprising the Group VIB soluble metal complex and the Group VIII soluble metal complex; (c) precipitating from the first pressure leach solution, at a first pre-selected pH, a second solid residue comprising at least a portion of the Group VIB soluble metal complex to form a first slurry comprising the second solid residue and at least a portion of the Group VIII soluble metal complex; (d) separating from the first slurry the second solid residue and a primary filtrate substantially free of Group VB, Group VIB and the Group VIII metals; (e) dissolving the second solid residue at a second pre-selected pH to form a group VIB metal precipitate and a group VIII metal containing solution; (f) separating the group VIB metal precipitate from the Group VIII metal containing solution of step (e); (g) dissolving said Group VIB metal precipitate in a dilute base at a sufficient temperature to form a Group VIB soluble metal product.