The acquisition by United Commodity was cause for celebration in the Cobalt area as 46 employees were hired and several million dollars were invested in upgrading the plant's Merrill-Crowe process
to produce nickel, cobalt, silver and gold from otherwise difficult to process concentrate.
Precipitation of the metal values is accomplished using the Merrill-Crowe process
. Homogenized zinc dust slurry is added to the de-areated solution in the suction of the filter press feed pump.
It has since added a Merrill-Crowe process for gold and silver recovery and struck some long-term deals for processing concentrate.
With the addition of the Merrill-Crowe process, the refinery is able to produce nickel, cobalt, silver and gold from otherwise difficult to process concentrate.
Silver will then be extracted from the pregnant leach solution using the Merrill-Crowe process
to produce silver-rich dore bars.
Gold-silver dore will be produced using a combination of conventional bulk sulphideflotation, gravity concentration and cyanidation, with gold and silver recovery by the Merrill-Crowe process
Harris defended the use of the Merrill-Crowe process
for gold recovery, which, he observed, some operators feel is inferior to carbon adsorption recovery.
Here, the Merrill-Crowe process
first deoxgenates the pregnant solution.
Cominco originally planned to use the Merrill-Crowe process
to recover 96-97% of the gold values contained in ore, but environmental concerns and the prospect of permitting delays over the use of cyanide in close proximity to major waterways (Bronson Creek empties into the Iskut River, which joins the Stikine River near the coast) eventually forced the company to switch to less controversial gravity separation and flotation techniques.