Abstract: A hydrometallurgical process is provided for separating heavy metal nuisance elements such as As, Sb, Bi, Sn and Pb from precious metals and/or selenium. The process can be used as a step in an overall hydrometallurgical process for treating refinery residues such as anode slimes for the separation and recovery of valuable metal values.

Abstract: A process is provided for treating a matte for selective extraction of nonferrous metals using a single stage oxidative pressure leach wherein leaching is carried out in a continuous manner and relatively mild conditions on an aqueous slurry of the matte having a specific sulfur adjustment, having copper present in the aqueous phase, and having a final pH of less than .about.4 but not less than .about.3.

Abstract: A process for treating anode slimes containing silver in which the silver is converted to a form soluble in dilute nitric acid, and in which after dissolution in dilute nitric acid, the silver is electrowon from solution. The process can be carried out by a route which is entirely hydrometallurgical. In addition to recovery silver, other values such as Se, Te, Ni and precious metals can be recovered.

Abstract: A nickel matte in which the atomic ratio of S:(Ni+Co+Cu) is less than 0.7 is fragmented and slurried with water or an aqueous nickel sulfate solution to ensure that the S:(Ni+Co+Cu) ratio for the slurry as a whole exceeds 0.4, the slurry is heated under pressure in the presence of oxygen to form a basic nickel sulfate and the reacted slurry is treated with lime to convert the basic nickel sulfate to nickel hydroxide. The nickel hydroxide is then separated from gypsum by physical separation and thereafter dissolved in spent sulfate electrolyte to generate fresh electrolyte from which nickel can be electrowon.

Abstract: A hydrometallurgical process for treating copper refinery anode slimes containing selenium, lead and precious metals in which a selenium product of better than 99.7% purity can be produced and the final residue is suitable for smelting to produce anodes for silver refining.

Abstract: A process for the precipitation of metallic sulfides, e.g., nickel, cobalt or zinc sulfides, from aqueous metal-ion-containing solution comprising passing hydrogen sulfide through the metal-containing solution while the solution is at a temperature of about 75.degree. C. and at a pH of about 2 to about 3 and maintaining said pH during the time of hydrogen sulfide addition by continuous addition of alkali to the solution. The precipitated metal sulfide is characterized by a relatively large particle size by a high settling rate and by ease of filterability.