Is biomining the future? As global demand for minerals continues to rise, how can we maximize extraction from deposits with low grades? And is it possible to do so in a way that’s economically viable? Is there a way for us to tap into supposedly exhausted mines, using new technologies? Can we do this more sustainably, limiting the impact on our fragile environment? For some, biomining is the answer.
Biomining and bioleaching, have been heralded as methods of increasing extraction levels, while limiting the use of toxic chemicals used in traditional processes. They also reduce CO2 emissions and lower the carbon and water footprint of the entire process. The ‘bio’ element of this method is the use of microbes to break down the minerals or mineral ores.
Biosigma, established in 2002, is a joint venture between Codelco (Chile’s state-controlled producer) and Nippon Mining and Metals. The JV experimented with microbes which break down copper ore at higher recovery rates (up to 90% as opposed to 60% by conventional methods) and reduce operating costs. Ores are placed into acid and then acidithiobacillus ferroxidans and thiobacillus ferroxidans bacteria are used for extraction. The bacteria use CO2 and the mineral itself as a source of energy. After a year-long trial in 2012, copper extraction was up 30 to 50%. In 2014, Biosigma launched a commercial application of biomining technology, with 85 patents.
Biomining isn’t limited to copper. Nor is it limited to an experiment in Chile (albeit in the world’s biggest copper mine, known as The Escondida, majority owned by BHP Biliton NYSE:BHP, LSE:BLT). It has also been used to extract gold and uranium – effectively anything where the concentration of the mineral in the ore is low, or hard to access. And its use has spread to South Africa, Australia, Brazil and even Finland (which we’ll come back to in a moment).
Biomining is slower than traditional extractive processes but balanced against low or impossible extractions, the time span can work commercially. However, we must be cautious when celebrating this bacterial extraction as being entirely environmentally friendly. Toxic chemicals such as sulphuric acid and heavy ions are still sometimes by-products and bioheap leaching cannot be stopped quickly, if there’s a problem.
Which brings us back to Finland and the cautionary tale of Ahtium Plc (formerly known as Talvivaara Mining and previously listed on the London and Nasdaq Helsinki Stock Exchanges). The Finnish mining company filed for bankruptcy in March 2018, leaving embarrassed stock exchanges, a total loss of the equity value, political scandals, criminal charges and a trail of environmental devastation in its wake after its gypsum pond metal tailings leaked into the environment and its Sulfate emissions poisoned water courses over a two-year period.
At first, using bioleaching to access deposits of rare minerals (in this case nickel, cobalt and uranium) too poor in concentration (Ni 0.22%, Co 0.02% and Cu 0.13% and Zn 0.5%) to extract by traditional methods looked like a sustainable plan. Leaks, contamination, army reservists called in to manage toxic spills and a 100 million Euro bill to clean up the environment, are the legacy that’s left.
Biomining and bioleaching clearly have a role to play in a world of scarcer or harder to access resources. And eliminating toxic chemicals used in extraction and environmental footprints is a positive move. But the industry needs to heed the lessons of Ahtium and ensure that by-products of leaching are contained and cleaned – perhaps even using microbes – to ensure broader support from Civil Society and Governments.