2011 News Releases
Metallurgy Results Support In-Situ Recovery at Excelsior’s Gunnison Project
November 9, 2011
Excelsior Mining Corp. (TSX-V: MIN) (Frankfurt: 3XS) (OTCQX: EXMGF) (“Excelsior”) is pleased to announce results from the initial metallurgical tests on the 100% owned North Star Deposit of the Gunnison Copper Project, located in southern Arizona. Initial column leach tests indicated that acid consumption and copper recovery at North Star will support in-situ recovery (“ISR”) mining.
“We are very pleased that the results from the recent test work confirm our view that the recovery rate and acid consumptions are favorable for ISR mining of the North Star deposit,” says Stephen Twyerould, President and CEO of Excelsior. “These results, as well as the encouraging hydrological testing completed last month, will be used to complete our Preliminary Economic Assessment expected later this year.”
The North Star Deposit currently contains an indicated oxide copper resource of 3.21 billion pounds (511 million tons at 0.31% copper) and an additional inferred oxide copper resource of 0.88 billion pounds (159 million tons at 0.28% copper).
The metallurgical tests involved loading 6-inch diameter clear PVC pipe with three representative samples from the North Star deposit and leaching them with a dilute sulfuric acid solution for 164 days. The three samples were from the Martin formation (Met 1: high acid consumer), Upper Abrigo (Met 2: moderate acid consumer) and Lower Abrigo (Met 3: low acid consumer). The Martin formation sample is representative of the higher acid consuming rocks that make up approximately 50% of the mineralization; whereas, the Abrigo samples are representative of the lower acid consuming rocks (making up the remaining 50% of the mineralization). Given that the copper mineralization is essentially all chrysocolla and other silicates occurring on natural fracture planes and surfaces, the core fragments of the higher acid consuming rocks were epoxy-coated to seal off any unnatural surfaces and fractures created by drilling and core handling.
The results indicate that within the fractured oxide copper zone, approximately 65% to 80% of the copper will dissolve if contacted by dilute sulfuric acid solutions at a pH of approximately 1.5. These results are consistent with typical metallurgical recoveries of copper oxide deposits in the southwestern USA and northern Mexico. These results represent metallurgical recovery and not overall copper recovery, which is expected to be in the range of 40% to 50%, as is typical of ISR-based mining operations.
Estimates for acid consumption in terms of pounds of acid consumed per pound of copper recovered (lb/lb) were also completed for the recent test work. The results for each sample are as follows; Met 1, 8.9 lb/lb; Met 2, 5.0 lb/lb; and Met 3, 3.9 lb/lb. These results were very encouraging and generally superior to historical results, further demonstrating the potential for the Gunnison Project to become a low-cost copper producer.
The results of the recent metallurgical test work will be combined with historical test work and other important data to complete a Preliminary Economic Assessment on the North Star deposit scheduled to be completed later this year.
Hazen Research, Inc. of Golden, Colorado (“Hazen”), an independent contractor, conducted the metallurgical test work. Mr. Brian Cooper, Project Manager for Hazen Research, directly supervised the testing. The results of the Hazen tests, together with the historical test work were reviewed by Dr. Terry McNulty, President of T.P. McNulty and Associates, Inc. Both Mr. Cooper and Dr. McNulty are independent of Excelsior. Excelsior’s exploration work on the Gunnison Property is supervised by Dr. Stephen Twyerould, Fellow of AUSIMM, President and CEO of Excelsior, and a Qualified Person as defined by NI 43-101. Dr. Twyerould has reviewed and approved the technical information disclosed in this news release.
Excelsior is an exploration and development company with a copper project located within the copper porphyry belt of Arizona. The Gunnison Copper Project is located close to the required infrastructure and its oxide resource has the potential to be mined using in-situ recovery methods. The Excelsior team consists of experienced professionals with proven track records of advancing projects towards production.
Further details about Excelsior can be found at: http://www.excelsiormining.com. Further information about the Gunnison Copper Project can be found in the technical report filed on SEDAR at www.sedar.com entitled: Gunnison Copper Project, Cochise County, Arizona, USA, Mineral Resource of the North Star Deposit dated August 31, 2011, as revised October 25, 2011.
ON BEHALF OF THE EXCELSIOR BOARD
Cautionary Note Regarding Forward-Looking Information
Neither the TSX Venture Exchange nor its Regulation Services Provider (as that term is defined in the policies of the TSX Venture Exchange) accepts responsibility for the adequacy or accuracy of this release, and no securities regulatory authority has either approved or disapproved of the contents of this release.