Specialized metallurgical processes – compositions for use therei – Processes – Free metal or alloy reductant contains magnesium
Reexamination Certificate
2003-10-22
2009-02-10
King, Roy (Department: 1793)
Specialized metallurgical processes, compositions for use therei
Processes
Free metal or alloy reductant contains magnesium
C075S744000, C075S735000, C075S737000, C075S733000
Reexamination Certificate
active
07488370
ABSTRACT:
Precious metals such as gold can be extracted from a refractory ore using a conventional cyanide leaching step and with reduced cyanide consumption by pre-treating the ore prior to cyanide leaching. The refractory ore is pretreated by fine grinding and an initial leaching step which uses inexpensive limestone and lime to maintain the initial leach relatively alkaline. Oxygen is added to the initial leaching step and the conditions are carefully controlled to only partially oxidize the ground ore to between 9-15%. The initial leaching step can be carried out at temperatures of less than 100 degrees C. and at atmospheric pressures. The pre-treated ore is then leached by a conventional cyanide leaching step to recover the precious metal and cyanide consumption can be reduced by more than two thirds.
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Hourn Michael M
Ventura Rodrigo U
Willis John A
Winborne David
Hoffman Wasson & Gitler, P.C.
King Roy
McGuthry-Banks Tima M
Xstrata Queensland Ltd.
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