Copper North Updates Improved Processing Plan at Carmacks Project

Copper North Mining Corp. (TSXV:COL) provided an update on the metallurgical work for copper, gold and silver at its Carmacks project.
As quoted in the press release:

The new processing plan consists of crushing to minus 19mm, followed by rod mill grinding to minus 1mm then acid leaching copper in an agitated leach tank, followed by gold and silver leaching in similar tanks, and cyanide destruction for final waste materials. The copper leachate is to be processed in a standard solvent extraction electro-winning (SXEW) plant to produce cathode copper sheets, and gold and silver will be recovered using Merrill Crowe to produce doré bars.
Test work indicates that raising the temperature of the acid leach for copper improves the overall recovery and significantly shortens the leach time. With a grind size of minus 1mm and a leach temperature of 40 degrees Celsius, recoveries of 88% were achieved within 4 to 6 hours, less than half the time for a coarser grind of 2mm at ambient temperature. Waste heat from the manufacturing of sulphuric acid will be used to heat the leach tanks.

The residue in the copper circuit is washed to remove residual acid and the slurry is pumped into the gold-silver circuit for cyanidation; also an agitated tank leach. Optimal leach time for a two stage cyanidation circuit is approximately 12 hours with recoveries of approximately 80% gold and 62% for silver.Leachate from the cyanide tanks is sent to a Merrill Crowe circuit to recover gold and silver as a doré bar for refining. A SART circuit is used to remove copper cyanates from leach fluids to recover cyanide and thereby manage cyanide consumption. The SART circuit will produce a small amount of copper-rich sulphide that will add to the total copper recovery.

Dr. Harlan Meade, President and CEO of Copper North Mining, commented:

The metallurgical test results have been very instructive; a finer crush on leach materials coupled with increased temperatures in the leach circuit, results in much improved leach kinetics. Leach times are very fast. The test work has yielded much improved leach efficiency and reduction of operational and environmental risks.

Click here to read the Copper North Mining Corp. (TSXV:COL) press release