Sterling Mining Receives Positive Results of Agglomeration Leach Tests at San Acacio Silver Project in Mexico
Thursday January 13, 3:05 pm ET
WALLACE, Idaho--(BUSINESS WIRE)--Jan. 13, 2005--Sterling Mining Company (OTC:SRLM - News) announced today that it has received results from samples from its San Acacio silver project in Mexico that were sent to Degerstrum Metallurgical for grinding, agglomeration and cyanide leaching. The tests were positive with 86.7% recovery on silver and 87.3% recovery on gold.
In July 2004, Sterling began metallurgical testing on dumps and backfill (gob) material from its San Acacio Mine in Zacatecas State, Mexico. The San Acacio had been mined historically by Spanish and British operators with mill-feed ore averaging 32 ounces of silver per ton silver. The high grades were necessary for the high-cost amalgamation process that was used at the time to recover the silver. All ore mined at the San Acacio was oxide ore and the dumps and backfills are considered, metallurgically, to be representative of unexplored and unmined ore in the mine.
Initial testing by Sterling was initiated to assess recoveries from a two-stage crush/cyanide leach circuit, as previously reported. Samples were sent to Degerstrum Metallurgical, crushed to 100% passing 3/4 inches and column leached using cyanide. The results were poor with only 21.8% silver recovery. However, screen classification of the leached material showed that the finer fractions had leached well.
With a requirement for a larger sample, Sterling collected a composite from a backfilled stope open to surface. Grinding and agglomeration/cyanide leach testing by Degerstrum resulted in recoveries of 86.9% silver and 87.3% gold. These results were positive given the lower relative capital costs of agglomerated heap leaching versus agitated tank leaching.
Sterling has over 14,000 acres of mineral concessions in Mexico containing long vein strikes that contain oxide ores similar to San Acacio.
This process also gives better recovery, at lower cost than flotation concentration, which according to historical data on flotation milling of dumps from the property, and tests done by Intermountain Mineral Engineers gave an average recovery 62% and a concentrate grade of 85 ounces of silver per ton.
Sterling Mining is conducting these tests in conjunction with selective drilling, which should result in the necessary data to permit a preliminary scoping study to determine projected capital and operating costs for the San Acacio property. In addition, this will have applicability to Sterling's other properties in the area.
Sterling has also commissioned 'Thiosulfate' column leach testing by McClelland Metallurgical in Sparks, Nevada, on San Acacio vein material ground to between 100 and 150 mesh, the same process Sterling will incorporate at the Baroness Vat Leaching Plant, which is in the process of being commissioned.
Sterling Mining Company controls the legendary Sunshine Mine, the richest silver mine in American history with more than 360 million ounces of production over the past century. Sterling offers investors superior leverage to silver price increases through its extensive portfolio of "Silver Valley" landholdings in Idaho and through strategic alliances and equity stakes in neighboring companies. The Company also holds several advanced properties in Mexico, including the Baroness Tailings Project in the Zacatecas silver district. Sterling stock trades on the OTC Market Exchange under the symbol "SRLM". Please visit the Sterling website at http://www.sterlingmining.com for more information.
Certain statements contained in this press release are "forward- looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements are based on beliefs of management as well as assumptions made by and information currently available to management. Forward-looking statements are subject to risks, uncertainties and other factors that could cause actual results to differ materially from expected results.
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Sterling Mining Company
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http://www.sterlingmining.com
or
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Cavalcanti Hume Funfer Inc. (CHF Inc.)
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or
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