698638 Alberta Ltd.

Donald K Kofluk

Michael J Collins

There is provided a novel class of additives, specifically coals, which are useful in zinc extraction processes involving one or more pressure leach stages carried out at temperatures above the melting point of sulphur. Such processes may include those incorporating a single stage pressure leach, a process involving two stage countercurrent or cocurrent pressure leaches or a multistage leach process for recovering zinc, lead and silver from zinc bearing sulphidic materials which also contain lead and silver.

Recovery of zinc from sulphidic concentrates

There is provided a novel hydrometallurgical process for the extraction of copper from sulphidic concentrates involving an oxidizing pressure leach using dilute sulphuric acid and a carbonaceous additive. The leaching step is carried out preferably at temperatures above the melting point of sulphur but below about 200.degree. C.

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Fort, Canada

Donald K Kofluk