RIO DE JANEIRO - Brazil's largest mining company Vale has developed, in partnership with the University of São Paulo (USP), a method to identify bacteria and fungi capable of “eating” copper.
What exactly does that mean and why does it matter? Now with this process, waste generated by copper processing -- one of the steps involved in mineral extraction -- can thus be absorbed by these micro-organisms. The new technology could mean an extra gross income of $1.4 billion for Vale.
The project is being conducted at a tailings dam near Sossego mine, in Pará state, in northern Brazil. About 90 million tons of residue end up there, after valuable minerals have been separated from waste -- 0.07% of which is copper. The treatment would be worth some $600 million, more than twice the money invested on Sossego mine.
“This would be a revolutionary technology for the mining world. We would have a much higher copper recovery rate than today", says Eugênio Victorasso, director of copper operations in Vale.
However, the project is still far from being economically viable. The first step is to identify the most efficient copper-eating bacterium or fungus, that is, the one that can absorb it best.
So far, over 35 samples have been collected by USP researchers at the tailings dam. Scientists will be back there once more to look for other micro-organisms, hoping to increase the chances of selecting the very best. According to Victorasso, this is the trickiest part.
The second stage will focus on extracting copper from the bacteria and fungi, which will allow using the resulting material commercially. If it succeeds, Vale will be the first in the world to make profit out of milling copper and processing wastes.
Copper is a rare metal. For one ton of extracted ore, only 0.9% to 1.5% is pure copper -- in Sossego mine, the ratio is 1%. Today, one ton of copper is worth about $7,600.
Each year, Vale extracts 13 million tons of ore from the Sossego mine. To store more waste -- and maybe thanks to the copper-eating bacteria, more profits -- Vale is deepening its tailings dam by 4 meters.
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