New Peruvian invention to cut mercury emissions from gold recovery

As International Mining finalises its article on innovations in gold recovery for the May issue of the magazine, Reuters’ World Environment News reports on a simple procedure. “A Peruvian engineer says he has come up with an environmentally sound way to isolate gold from clumps of sand without using toxic mercury that wildcat miners in the Amazon basin rely on to extract the precious metal, then dump into rivers.”

The small, cylindrical machine blends ore with jets of pressurised air, water and biodegradable chemicals in a centrifugal motion that produces a cocktail of thousands of bubbles that rise to the surface attached to specks of gold. “This is ethical gold, because it’s not using mercury. Small scale mining is a big employer, and the machine’s cost of operation is cheap,” Carlos Villachica, the engineer who developed the device, told Reuters at his small laboratory in Lima.

This follows closely on the news of the EPA in the US setting out tougher mercury emission regulations. Mercury is still used by millions of small, artisanal miners around the world. Reuters says “They buy hundreds of tonnes of it each year to extract gold. Environmentalists say much of it will eventually make its way into the food chain, causing health problems.”

In Peru, about 20% of the gold produced comes from the informal mining sector. The high concentration of gold produced by this device is reported to allows for direct smelting, according to Villachica, who says “it also conserves water, recycling up to 90% and as much as 70% of all chemicals used during the process.”

However, a report in the latest edition of MinerAndina.e says Peru produced a little more than 211.3 t of gold in 2009, and not the 182.4 t that the Ministry of Energy and Mines (MEM) indicated in its official statistics. This is according to a report by Hector Benavente, a consultant with Empresa Minera FIDAMI, which was constituted by artisanal miners in the process of being formalised in Ayacucho Region.

Benavente presented his report during the Jueves Minero conferences that are organized by the Institute of Mining Engineers of Peru (IIMP). The report indicated that the ‘hidden’ production, which was slightly more than 48.2 t of gold, comes mostly from informal mining. This amount is almost triple that indicated in MEM’s statistics, which only registered 29 kg from artisanal mining production and 17.2 t from medium informal mining in Madre de Dios.

Informal mining (illegal small and medium mining) could represent 22.8%, or more than one-fifth, of the national gold production. If the said difference in tonnes were to be produced formally, Peru would occupy third place in the global gold producers ranking, after China (300 t) and Australia (220 t), instead of the present sixth position, MinerAndina.e reports.

Of the 48.2 t that informal artisanal mining would have generated for the country in 2009, close to 31 t of gold comes from the main producing regions: Puno, Arequipa and Madre de Dios, with 12.5 t, 2.86 t and 2.75 t respectively.

The medium informal miners from Madre de Dios (17.2 t), who move more than 350 t/d without paying taxes, qualify as medium metal mining producers. On the other hand, artisanal miners move up to 25 t/d and small miners move between 25 and 350 t/d. With such levels of production, it is to be expected that many informal miners will continue to resist being formalised, in Benavente’s opinion.

Benavente estimates that the profits generated by informal artisanal mining nationally – not counting the medium informal mining of Madre de Dios – is around $987 million. Other figures indicated in his report show that nationally, Puno Region has the highest population of informal artisanal miners with 20,800, followed by La Libertad (7,500), Arequipa (7,080), Piura (6,600) and Madre de Dios (6,000).

In Madre de Dios, and that has been observed in recent weeks, the main cause for alarm is the degradation of the environment from the intensive use of heavy machinery by medium mining. This sector has invested huge amounts in the use of dredges and in the exploitation of open pits in the forest.

According to Benavente, informal artisanal mining in Peru directly employs 80,000 people and indirectly employs another 160,000. A population of close to 720,000 is dependent on such activity.

Also, the specialist does not attribute any production to Minera Laytaruma, the main broker and trader of artisanal production in Peru, as it only processes the ore exploited by the artisanal miners in the different regions of Peru. In the official statistics, Laytaruma appears as a small mining producer with 2.8 t produced in 2009.

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