US 4,384,889 A · Simultaneous leaching and cementation of precious metals

Abstract

A method for the recovery of precious metals such as gold and silver from various ore types is disclosed which involves subjecting a slurry of the ore to a simultaneous leaching and cementation process with a reagent such as an alkaline cyanide solution providing for the leaching requirement and a reducing metal affording cementation. The reducing metal is selected from the group consisting of cadmium, copper, iron, lead, molybdenum, tin, zinc and alloys and mixtures comprising at least two of these metals. The simultaneous leaching and cementation occur under conditions controlled to afford at least partial dissolution of the precious metal values from the ore, whereby continuous transfer of these values from the ore onto the surface of the reducing metal is promoted. The resultant cementation product, i.e., the reducing metal with precious metal values cemented thereon, is separated from the ore slurry and subjected to a subsequent precious metal recovery step by conventional methods.

Claims28

Dependent claims

Process for the recovery of a precious metal or metals from an ore selected from the group consisting of a carbonaceous ore and a mixture of a carbonaceous ore and an oxide ore, comprising:

(a) preparing an aqueous slurry of said ore in ground form;
(b) simultaneously leaching and cementing said precious metal or metals from said aqueous slurry of ore in ground form at an elevated temperature by:
(i) adding sufficient alkaline material to said aqueous slurry to maintain the liquid phase of said aqueous slurry at a pH higher than 9;
(ii) adding an effective amount of a precious metal-complexing agent to said aqueous slurry;
(iii) contacting said slurry with an effective amount of a reducing metal selected from the group consisting of cadmium, copper, iron, lead, molybdenum, tin, an alloy of at least two of such metals and a mixture of at least two of such metals, whereby simultaneous leaching and cementation of said precious metal or metals occur;
and
(c) separating said reducing metal and cemented precious metal or metals from said aqueous slurry.

4 more elements

Dependencies are inferred from the claim text.

Simultaneous leaching and cementation of precious metals

Life of this patent

Simultaneous leaching and cementation of precious metals

Life of this patent

Abstract

Claims28