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MEI Online: Environmental Issues: Latest News: April 24th 2015


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:: BacTech Environmental Targets Mercury Reduction in Mining


BacTech Environmental Corporation has announced that in addition to its tailings activity in Bolivia, the Company has launched a new initiative to reduce the amount of mercury used in artisanal/small mining operations.

There are areas of northern Peru and southern Ecuador where artisanal miners are mining complex sulphide (refractory) mineralized material as the near-surface oxidized material becomes depleted. In many instances, mercury is used by the miners, who obtain as little as 10% of the contained gold from this difficult-to-treat mineralized material. The remainder of the material is then sold for little value and/or trucked 1,100 km to the southern region for eventual smelting. This presents a real opportunity for BacTech to make a large contribution to the reduction of mercury, arsenic and cyanide contamination in the environment while giving substantial increases in gold recovery. This is achievable through the use of relatively simple gravity and flotation circuits and BacTech's bioleaching technology to process the mineralized material, without using mercury and reducing other chemical requirements.

Recently the government of Peru enacted legislation to encourage artisanal miners to apply for legal mining licenses, stating that artisanal miners have been contributing up to one million ounces of gold production annually. The origin of much of this gold has been difficult for government authorities to ascertain. Peru has initiated a formalization process designed to register all small-scale and artisanal mining operations. The registration allows the government to monitor and regulate health and safety, and environmental issues for miners, and will allow these operations to legally sell their mineralized material to toll-milling facilities approved by the government.

This has led to increasing interest, predominantly among Canadian companies, to set up processing facilities for conventional processing. All of these facilities have been designed to process oxide material and "easy" or non-refractory sulphide material. The resulting sulphide concentrates are then treated with cyanide to liberate the precious metal, but often results in poor gold recovery due to the presence of refractory gold that is not recovered by such processing. Dynacor, Inca One, Standard Tolling and Anthem United are examples of companies either processing material today or planning to build processing facilities in Peru.

The grades of the refractory arsenopyrite-rich material in this area are very high. It has been reported that arsenopyrite gold concentrate grades of 150 gpt (5 ounces) and higher are common, given the high grade material that is processed. There is a strong business case to establish a gravity/flotation plant and a bioleach processing facility in a strategic location to address these refractory issues. The plant would eliminate the need to deliver arsenic sulphides 1,100 km on public highways to the south for processing.

This problem is not limited to Peru and Ecuador as there are other countries, such as Colombia and Nicaragua, that have similar issues. There is no doubt that bioleaching can play a big part in alleviating the mercury issues related to artisanal mining. BacTech will be aggressively pursuing these opportunities as they are presented.




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