Strong Metallurgy Results At Kilgore Mine Ridge Deposit
VANCOUVER, BC - Otis Gold Corp. reported the receipt of additional positive gold recoveries from column leach tests performed on bulk samples from the Company's Kilgore Mine Ridge gold deposit in Clark County, Idaho. These results, in conjunction with historic column leach testing from the deposit, provide continuing support that the deposit is readily amenable to standard heap-leach process technology.
The column leach tests were run by McClelland Laboratories, Inc. of Sparks, Nevada, on composites of the three main host rock types collected throughout the deposit area. Column percolation tests demonstrate that three composites are amenable to simulated heap-leach cyanidation treatment at the 80% -1/2 inch feed size. The bulk of the Mine Ridge mineralization occurs in two rock types, felsic dikes and lithic tuff, which together comprise an estimated 93% of the deposit and exhibit column leach recoveries of 85.3% and 81.0% respectively. The tests performed indicate that up to 77% of the gold was recovered within 30 days.
Craig Lindsay, President, said, "We have achieved excellent metallurgical recovery rates at Kilgore which are a critical component in the overall economics of developing a profitable gold deposit. Further, the results confirm and expand on the favorable metallurgical tests that were historically performed by Echo Bay Mines." The results Otis obtained confirm and expand upon the favorable metallurgical tests that were historically obtained by Echo Bay, which ranged from 64% to 94%, based on oxidation type. Otis geologists believe that it was advantageous to run tests based on host rock type in addition to oxidation type because oxidation state is related to dike emplacement, which are responsible for the introduction of the gold-bearing ore fluids. Recoveries based on rock type will feed directly into Otis' deposit modeling that is being performed this year. Tests were conducted on between 93 and 123 kg composite samples from a variety of drill holes scattered throughout the deposit from split HQ-3 drill core. Each composite was stage crushed in its entirety to 80% -1/2" in size. Crushed composites were each thoroughly blended and split to obtain approximately 68 kg for a column leach test and each sample was blended and split to obtain 1 kg for triplicate head assays. Column tests were not optimized for sodium cyanide ("NaCN") consumption and used 3.1 to 3.9 lbs NaCN; however, projected NaCN consumption in production heaps is typically 25 to 33% of the NaCN consumption achieved in laboratory testing. McClelland reports, "Column test cyanide consumptions encountered during commercial production would probably not exceed 1.3 lbs NaCN/ton of ore." Lime additions of 2.0 to 4.5 lbs/ton were sufficient for maintaining protective alkalinity during leaching. Otis plans on performing large diameter column leach tests, during its 2011 Kilgore program, on a coarser crush size conducting additional analytical and characterization work to better understand the leach parameters and to optimize leach results for use in designing full scale operations. Upon completion of these large diameter column tests, McClelland will be providing the Company with an independent certified report of the results. The company's address is 880-609 Granville Street, PO Box 10321, Pacific Centre Vancouver, BC V7Y 1G5, 604-683-2507, fax: 604-683-7589, email: [email protected].