The International Nickel Company, Inc.

The United States of America As Represented by the Secretary of

Inco Limited

John A Thomas

Norman C Nissen

Malcolm C Bell

Victor A Ettel

Alexander Illis

Kohur N Subramanian

Kojur N Subramanian

David L Jones

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.

Hydrometallurgical processing of precious metal-containing materials

To recover chromium and other metals from scrap such as superalloy scrap, the scrap is sulfided to provide a molten matte which is cooled and fragmented, the fragments are leached selectively in an aqueous solution with chlorine at a controlled temperature and with agitation while controlling chlorine flow by redox potential to provide the major portion of the chromium in the leach residue and dissolving other valuable metals present as chlorides and thereafter recovering the chromium from the solid.

Chromium recovery from superalloy scrap by selective chlorine leaching

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.

Process for the recovery of metal values from anode slimes

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.

Growing community of inventors

Norval, Canada

John A Thomas