Oxidation/reduction process for recovery of precious metals from

Details Oxidation/reduction process for recovery of precious metals from Oxidation/reduction process for recovery of precious metals from

1992-03-03

1993-08-03

Lewis, Michael

Specialized metallurgical processes, compositions for use therei

Processes

Free metal or alloy reductant contains magnesium

75736, 75744, 423 27, 423 38, 423 40, 423 41, C01G 500, C01G 700, C22B 1100

Patent

active

052324907

ABSTRACT:
A process for separating precious metals from an MnO.sub.2, sulfidic or carbonaceous refractory ore or refractory feed such as tailings is provided. The process includes the step of leaching a feed with a leach liquor that includes an acid selected from the group of HCl and H.sub.2 SO.sub.4 in the presence of MnO.sub.2 and a reductant. A source of chloride ion is added to the leach sufficient to dissolve at least about 50% of the precious metals present in the ore. A portion of the leach is removed and precious metals are recovered from the removed portion. A portion of the chloride carrier is recycled to the leach to carry chloride values to the leach. In one embodiment, HCl is regenerated by pyrohydrolysis, which minimizes harmful waste products. The present process can advantageously avoid the use of noxious reagents.

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