Good day.
As a result of the development of minerals, wastes containing huge amounts of heavy metals remain. After completion of their work (waste) must be reclaimed. Basically, there are two stages: technical and biological. How is the biological stage of reclamation in you? (except for filling with potentially fertile soils)
In some tailings dams, phytostabilization with native metalliferous plants is used, to minimize environmental damage.
Hello Dmitry Golubev
In Canada we use a variety of approaches at varying scales. Among the most popular is the use of sulphide to precipitate minerals out of solution. While this can be achieved using sulphide salts, some companies actually use sulphide producing bacteria to produce this chemical which can be applied in tailings ponds.
Alternatively, biomining is also becoming more and more popular. Some microbes have developed extremely high resistance to metals of value, such as copper (among many others) that allow them to hyperaccumulate the metals. This means the metals stays in biomass that is heavier than water which can be separated using gravimetric techniques (simply letting it settle or in a large centrifuge). Many of these microbes are already present in these contaminated sites so sometimes it is simply a question of stimulating this community by the addition of nutrients to give them a competitive advantage (biostimulation). Alternatively, isolated microbial cultures can also be directly amended to mining waste to compliment the existing microbial community (bioaugmentation).
Some approaches that have yet to scale also rely on microbes that carry out a redox transformation that can favour precipitation or, dissolution of a metal that can later be recovered or removed from waste. These approaches tend to be a little more specific for 1 metal. I have studied the feasibility of using such an approach in the context of mercury pollution, a common contaminant found in mining waste all over the world:
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Solutions that rely on microbes are getting increased traction because of they can be scaled and generate a much smaller volume of waste, at least in the context of tailings dams (I am not as familiar with dry trailings). To the best of my knowledge while Marcelo Eduardo Rojas Vidal recommendation of phytostabilization/phytoremediation is often considered attractive namely because it can allow for revegetation of contaminated sites, these solutions have yet to be widely adopted because of cost and the long term management of plants contaminated with high concentrations of metals.
I hope you found this helpful and please do not hesitate to reach out on this message board for further discussion.
Our legislation requires that they leave the place occupied by the mining company, with the conditions that are most similar to what they were before the exploitation, but our law is not retroactive, and there are still many tailings dams from the past, that no one has taken charge. Only in a few, we are working with phytostabilization.
Dear Marcelo Eduardo Rojas Vidal and Daniel Gregoire , thank you very much for the information. We will try to evaluate this direction in the reclamation!
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