Monday, 9 May 2016
During the final panel discussion at Biohydromet '14 (posting of 28th July 2014) Dr. Jim Brierley, of Brierley Consultancy, USA, felt that future mines might utilise some form of a process similar to the hydrofracturing technology developed by petroleum engineers to release shale gas, thus opening up a buried resource. Benefits could include reducing the footprint of mining and development of new technologies for extraction of critical earth resources.
Now, as described in more detail on MEI Online, BIOMOre, funded by the EC/EU "Horizon 2020" Research and Innovation Program, intends to be a cost efficient and ecological answer to this problem. Its main objective is to develop new technological concepts for the in-situ recovering of metals from deep deposits using controlled stimulation of pre-existing fractures in combination with in-situ bioleaching. Within the scope of this project, methods and procedures of the process will be designed, tested and evaluated in laboratories and in a small test facility in an operating underground mine in Poland. BIOMOre is an ambitious approach including quite a lot of environmental benefits (no waste heaps, no dust exposure, minimum infrastructure on surface, less noise and chemical impact etc.).
At next month's Biohydromet '16 in Falmouth, Prof. Barrie Johnson's team from Bangor University will present a paper discussing the BioMOre design concept, which involves: (i) opening flow channels within the ore body; (ii) acid leaching to dissolve acid-labile minerals; (iii) oxidative leaching under anoxic conditions using a microbially-generated ferric iron lixiviant; (iv) decommissioning to eliminate introduced bacteria and to seal flow channels. Data will be presented from experiments in which a polymetallic ore (Talvivaara, Finland) and copper-rich kupferschiefer (Rudna mine, Poland) have been subjected to indirect bioleaching under laboratory conditions. Results confirm the possibility of using such an approach for deep in situ biomining of base metal ores.
So could this be the future for the minerals industry? As Jim Brierley said two years ago it would need a new mind-set, and how would we manage it to make it work? Biohydrometallurgists would play an important role in advancing new technologies, but obviously not working alone in developing such in situ technology- it would need the involvement of metallurgists, geologists, rock engineers and others. To prepare for this he said that we should be researching how microorganisms behave under high hydrostatic pressures, anaerobic and other conditions yet to be defined. This would be a complex technology only applicable for use with highly specific amenable ore bodies and would need to meet all economic, environmental and safety concerns.
And of course, societal concerns- fracking for shale gas has received tremendous opposition in UK, not only because of a perceived earthquake risk, but also, more reasonably, because of potential groundwater contamination by the reletively benign fluids that are used to open up the cracks. But here we are talking of fracking with acids and bacteria, so there is likely to be a lot ot opposition to be overcome.