Biomining

From left to right: Dr David Dew, Dr Paul Norris and Dr Chris Bryan. Image: Toby Weller.

Cornwall team investigates potential for bacteria to boost Europe’s metal production

By using bacteria to recover metals from mine by-products, Europe could move towards a more sustainable treatment of ores and mine waste to provide an alternative supply of metals such as copper, zinc, nickel and gold.

The application of ‘biomining’ could help companies reduce hazardous waste and produce more valuable metals, many of which are imported because they are scarce in Europe.

Research into this technique led by Dr Chris Bryan of the University of Exeter’s Environment and Sustainability Institute (ESI) in Penryn, is attracting interest from mining companies operating in Europe.

As well as making mines more productive, biomining can also be used to clean up sites, which are often left with traces of dangerous heavy metals that present a hazard to humans and wildlife. This means that companies could revisit historic mine wastes with abandoned low grade mineral deposits, some of which have been present for hundreds of years.

Dr David Dew of Dewality Consultants Limited, based near Truro, is providing his expertise to help Dr Chris Bryan develop a centre of excellence for biomining at the ESI. Dr Dew has worked for a major mining company for over 20 years in the development of biomining technology for the treatment of ores and concentrates.

Dr Paul Norris, a leading researcher in the field of biomining microbiology, has relocated to Cornwall from the University of Warwick and joined the ESI as an Honorary Research Associate to expand the ESI’s biomining research and development capability. He has brought an extensive range of microbial cultures, collected during almost 40 years of research on microbial mineral-processing with industrial partners.

From the ESI laboratory, the team is testing the ability of strains of algae and cultures of microbes isolated from Cornish mine wastes, including Wheal Jane and Wheal Maid, to recover metals, while establishing links with European mining companies to get samples to test the technique.

The microorganisms used in commercial biomining are derived from natural, often volcanic, environments or mining sites and are sometimes adapted for processing a particular mineral.  The bacteria oxidise iron and sulphur in some minerals, dissolving valuable metals so they can be recovered. The success of biomining is dependent on selecting and adapting microbial cultures for the treatment of different ore types and establishing the best environment for them to thrive.

Commercial scale biomining has been practised for 30 years and is now regarded as a developed technology. However, the focus on the molecular biology of the microorganisms is adding new insight into the metabolism and function of microorganisms that can improve process performance and range of applications. 

With the capability to carry-out molecular studies, the ESI research aims to reveal more about the metabolism and function of the bacteria so this knowledge can be used by mining companies. 

Dr Chris Bryan said: “Wherever you have mining, you have mining waste, which can present a hazard for hundreds of years. While there are examples of biomining across the world, it is hardly used in Europe. We believe there is a real opportunity for Cornwall, with its fascinating history of mining and innovation, to develop and promote this technique.”

David Dew said: “Biomining gives mining companies the opportunity to get value from something that would otherwise be disposed of as waste. European mines are facing a growing number of challenges – chief of which include scarcity of viable resources and compliance with environmental legislation – which could make biomining attractive as a process option to increase metal recovery.

“Biomining is a technique with specific niche applications, particularly in Europe. Strategic issues have made certain metals scarcer and Europe is increasingly dependent on imports. Biomining presents a real opportunity for some of Europe’s smaller mines, particularly in Scandinavia and Eastern Europe to produce more metals.

“The research of Dr Chris Bryan at the ESI could make a significant contribution to the commercial application of bioleaching in Europe. The challenge is to encourage the participation of companies in the evaluation of the process, in order to focus research to areas that have commercial potential.”

Date: 8 August 2014

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