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:: Bioleach Study Advances at Tonkin
BACTECH Mining, 55% owner and project manager, and U.S. Gold, 45% owner, have received positive results from an internal study by BacTech for the Tonkin Springs gold project in north-central Nevada.
The study helped identify a production strategy at Tonkin Springs to maximise use of the infrastructure and resources and to address the metallurgical issues identified by BacTech.
Metallurgical testing, including diagnostic leaching to establish bioleach parameters, has shown gold recoveries of 86-95% can be achieved using a coarse grind of 300 microns from the TSP-1 deposit. TSP-1, containing refractory gold sulphides amenable to bioleaching, was defined in the Micon International feasibility study completed last year.
Metallurgical tests were conducted on drill-core composites derived from the recent BacTech drilling programme at TSP-1. A production proposal includes contract mining of 1,500 t/d from TSP-1 to use the existing mine and plant infrastructure and produce around 30,000 oz/y, assuming 85% gold recovery. During the initial production, the oxide material from the Rooster deposit would be mined at a rate of 2,000 t/d and placed on an established heap leach pad. The oxide heap leach is estimated to produce 17,000 oz/y of gold, assuming 65% of gold recovery. Once the oxides are mined, the refractory sulphides from the Rooster pit can be scheduled for milling at 1,500 t/d.
The plan calls for eight years of production.
For permitting purposes, BacTech plans to withdraw the current plan of operations and submit a revised plan incorporating the new production proposal to modify the existing operating permit, previously established for a 1,500 t/d open pit and bioleach operation, to allow for an accelerated return to production at Tonkin Springs.
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