Tuesday November 9, 9:16 am Eastern Time
Company Press Release
Expatriate and Atna Planning Prefeasibility Study for Wolverine Project, Yukon
VANCOUVER, BRITISH COLUMBIA--Expatriate Resources Ltd. (EXR.V) and Atna Resources Ltd. (ATN.T) are pleased to provide an update on the metallurgical study that commenced in June by the Wolverine Joint Venture (60% Expatriate and 40% Atna). The study was undertaken to address concerns as to the marketability of concentrates from Wolverine due to unusually high levels of selenium.
The Joint Venture's metallurgical team, led by Brad Marchant, evaluated various possible metallurgical processes and selected several for more detailed study. The Wolverine Joint Venture commissioned AGRA Simons Ltd. to conduct a scoping study on these selections to evaluate the technical viability, capital requirements and operating costs. Results indicate two of these metallurgical processes would produce readily saleable products and are economically attractive. The preferred process options use proven technology and require minimal additional infrastructure cost beyond that required for mine development.
Several Established Metallurgical Processes Potentially Viable
Of the various on-site metallurgical treatment options considered for zinc processing, the conversion of zinc sulphide concentrate to a high-grade clean zinc oxide using traditional roasting is preferred. This treatment eliminates the selenium, allows slightly higher zinc recoveries to concentrates, and reduces transportation and marketing costs, partially offsetting higher operating costs. The selenium and other contaminants are captured through standard recovery technology. Two on-site treatment options are being evaluated for processing the precious metal rich bulk copper-lead concentrate: firstly, bioleaching of bulk concentrate to recover the precious metals by conventional cyanidation; and secondly, bioleaching to reduce selenium levels to produce an attractive precious metal rich copper concentrate for shipment to smelters.
Application of these processes should ensure saleable products are produced that maximize recovery and payment for zinc, silver and gold, which make up 88% of the gross metal value of the high grade Wolverine ores. Work is continuing to evaluate minor variations in the zinc oxide process and leaching of the precious metal rich copper-lead concentrate to improve technical understanding and cost estimates.
On-site leaching of bulk concentrates, using conventional pressure-leach hydrometallurgical processes, followed by copper and zinc refining, do not appear economic at this time due to high capital and infrastructure costs. These alternatives are not being considered further at this time.
Concentrate Marketing Investigations
Marketing studies are in progress with several smelters to evaluate concentrate sales opportunities. The investigations include the marketing of concentrates with selenium levels reduced by on-site treatment, and the possibility of a smelter increasing its ability to recover selenium from the processing of untreated concentrates.
A cost-benefit analysis between on-site treatment and additional treatment at smelter sites is planned over the next few weeks, as the marketing information becomes available. On completion, a decision can be made as to which alternatives merit detailed investigation and engineering.
Prefeasibility Study Planned
Sensitivity analysis of key project parameters indicates that the project has potential to produce a significant positive net present value if target parameters can be confirmed. As part of the scoping study, capital and operating costs were estimated by AGRA Simons using available factored mine development cost data. These estimates provide a rough guide to capital and operating costs but do not take into account the unique characteristics of the project. Detailed engineering of ore processing, mine development and infrastructure is warranted to improve cost estimates and better define project components.
The Wolverine Joint Venture is pleased with the metallurgical team's progress and the positive results obtained. Planning for start of the prefeasibility study and a review of exploration and permitting requirements is in progress.
This press release may contain forward looking statements based on assumptions and judgements of management regarding future events or results that may prove to be inaccurate as a result of exploration and other risk factors beyond its control and actual results may differ materially from the expected results.
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