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Vista Gold Corp. Announces Mt Todd Met Testing Results with Significantly Improved Gold Recoveries
DENVER, Aug. 2, 2018 /CNW/ -- Vista Gold Corp. (TSX & NYSE American: VGZ) ("Vista" or the "Company") today announced results of its ongoing grinding and leachin
About this update from Vista Gold Corp
[{"type":"text","content":"DENVER, Aug. 2, 2018 /CNW/ -- Vista Gold Corp. (TSX & NYSE American: VGZ) (\"Vista\" or the \"Company\") today announced results of its ongoing grinding and leaching tests indicating that gold recoveries exceeding 90% may be achieved for the Mt Todd gold project, depending on final grind size. Recently completed tests of the second stage grinding circuit undertaken by Core Metallurgy and FLSmidth, under the direction of Resource Development Inc. (\"RDi\"), suggest that the Mt Todd ore can be ground to a finer final product size with lower power consumption than previously estimated. Leaching the finer final product size material has again confirmed higher recoveries at finer grind sizes. Based on these initial results, Vista now plans to undertake additional testing to: confirm results over a broad range of feed grades, justify design changes and support a possible update of the project economics. Leach Test Results Leach tests were completed on two low-grade composites of ore from Mt Todd. Composite 1 had an average head grade of 0.66 g Au/t (individual head grades ranging from 0.64 to 0.69 g Au/t), while Composite 4 had an average head grade of 0.65 g Au/t (individual head grades ranging from 0.60 to 0.79 g Au/t). Leach tests were completed in triplicate on the product from each grinding test. The following table summarizes the leach test results at various final grind sizes for the two types of stirred media mills tested, compared to the results of previous tests where the samples were prepared in a ball mill. Composite 2nd Stage Grinding Mill 80% Passing Product Size Average Gold Recovery 1 VXPmill 57 µm 89.67% 1 IsaMill 38 µm 90.60% 1 IsaMill 25 µm 92.40% 4 IsaMill 57 µm 84.77% 4 VXPmill 38 µm 90.03% 4 IsaMill 25 µm 91.30% Previous Test Results 1 Ball Mill 57 µm 87.35% 4 Ball Mill 57 µm 86.69% Frederick H. Earnest, President and Chief Executive Officer, commented, \"The implementation of stirred media grinding technology in the design of the 2nd stage grinding circuit has allowed us to achieve significant energy efficiency improvements. We believe that we may be able to achieve another significant reduction in final particle size without any increase in power consumption. These test results are based on ...