Metallurgical Review Of Northumberland Gold Deposit
The review, commissioned as part of Fronteer's overall development strategy for the project, has identified proven processing methods for the various mineralization types, which will be systematically evaluated as part of Northumberland's multi-phase metallurgical program. Historical metallurgical studies were narrow in scope and did not provide recommendations for sequential processing of all Northumberland mineralized material.
Fronteer commissioned Gary Simmons, of GL Simmons Consulting LLC and former Newmont Mining Senior Technical Director - Metallurgy & Technology, to conduct the review. Simmons' work experience includes metallurgical analysis of ores for Newmont and Santa Fe Pacific Gold that are similar to Northumberland mineralization.
"The processing options identified in the review show Northumberland has good potential for economic development within the current and potentially extended gold price environment," said Simmons.
Northumberland has an indicated resource of 36.5 million tonnes at 1.9 grams per tonne gold and 7.7 g/t silver (2,388,000 ounces gold equivalent - calculated using a 70:1 ratio for price of the two metals and assumes 100% recovery), and an additional inferred resource of 6.9 million tonnes at 3.49 g/t gold and 6.3 g/t silver (796,000 ounces gold equivalent). Approximately 20% of the gold ounces are oxide, with the balance comprising transitional or sulfide material.
The review recommends processing oxide and transition mineralization through either run-of-mine heap leaching, crushed ore heap leaching and/or milling.
Based upon the evidence contained in 19 metallurgical reports that were reviewed, and other related experience in this field of refractory ore processing, expectations are that Whole Ore Alkaline Pressure Oxidation will produce good gold extraction results - greater than 80% -- on moderately cyanide soluble (>45% range) materials. N2TEC flotation results showed high gold recovery, as well as lower mass and higher grade concentrate. On two highly refractory samples, from the Zanzibar Formation, N2TEC flotation achieved 90% gold recovery in a combined rougher/scavenger flotation concentrate.
Fronteer's multi-phased, metallurgical testing program will be carried out through to 2010. Planned metallurgical activities are to be undertaken in conjunction with a broader advancement program, which includes identifying preferred mine development options. The metallurgical program will initially test mildly refractory and primary sulfide mineralization process alternatives.
As part of Phase 1, Fronteer completed six PQ core holes of metallurgical drilling in 2008. Twenty metallurgical composites have been identified, including 13 representing mildly refractory and primary sulfide mineralization. These 13 composites have been condensed into three master composites for metallurgical characterization and alkaline pressure oxidation testing. Testing will be conducted at Dawson Metallurgical Laboratories in
Design of the metallurgical program's second phase will be based on the analysis of Phase 1 data, and ongoing R&D activities conducted by Simmons.
Northumberland produced more than 230,000 ounces of gold and 485,000 ounces of silver from oxide and mildly transitional ores via milling, ROM leaching and crushed ore heap leaching, during historical operations. Gold production ceased in 1991 due to lower gold prices.
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