Tuesday, 8 June 2021

Biomining '21 Day 2

Dr. Chris Bryan has been a consultant to MEI’s biomining conferences for several years. Formerly a senior lecturer at Camborne School of Mines, he is now head of the Geomicrobiology and Environmental Monitoring Unit at BRGM in France.

Chris got the day off to a fine start with a keynote lecture “Bridging the gaps in biomining research and application”.  He highlighted that, despite the excitement of 40 years ago, biohydrometallurgy remains a niche technology, applied where it offers unique advantages or no alternative exists. Advances in competing hydrometallurgical processes, such as chloride leaching and HPAL, mean bioleaching is at risk of losing ground. To halt this potential decline, and to make biomining more competitive in an increasingly busy space, serious scientific and technological advances are required. 

Chris feels that biohydrometallurgy is incredibly exciting. Few other technologies combine so many different disciplines. However, research is rather disparate, with relatively few resources. More than ever, as a community we need to consider how best to advance the state of the art: how to avoid the no-man’s land between academic knowledge and industrial needs and what are the key research questions.

Chris’s provocative keynote was followed by three presentations  from South Africa on biooxidation.

Metso Outotec's BIOX® process was developed for the pre-treatment of refractory concentrates ahead of conventional cyanide leaching for gold recovery. As the gold is encapsulated in sulfide minerals such as pyrite and arsenopyrite, the gold is prevented from being leached by cyanide. The BIOX® process destroys sulfide minerals and exposes the gold for subsequent cyanidation, thereby increasing the achievable gold recovery.

BIOX® has gained wide range acceptance due to its relatively lower operating cost and environmental friendliness. However, with uncertainties in gold prices, depletion of near-surface ores and dwindling gold grades coupled with high reagent cost, some BIOX® processes are becoming uneconomically viable, and Jakolien Strauss, of Metso Outotec, South Africa, described how the BIOX® technology solution offerings have been expanded in recent years to cater for the treatment of complex base metal sulphides. 

The search for more useful microorganisms continues, as there are areas in which those currently available are inadequate for industrial use, solids tolerance in stirred tanks being a notable area, particularly at high temperature, and microorganisms was the subject of 11 diverse presentations in the 2nd session of the day, showing the diversity and capabilities of microbes from a broad range of environments from the Northern Hemisphere to the Antarctic.

Back in 2014 (posting of 28 July 2014) Dr. Paul Norris said that academics should look at relevant natural and mining sites in their countries. He said that it is not difficult to find new microorganisms and then to screen them to assess their effectiveness. Academics at the TU Bergakademie Freiberg, Germany have done just that, and Dr. Götz Haferburg showed how the Reiche Zeche mine, one of the most famous historic polymetallic mines in the Freiberg area, proved to be a treasure trove of acidophilic microorganisms.

All presentations and discussions are available on demand to registered delegates until December 31st, but abstracts are freely available on the conference website


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