Tuesday, 12 June 2018

Namibia 2018 off to a good start

MEI’s Jon Wills opened Biohydromet '18 this morning, welcoming the 50 delegates from 12 countries to the Windhoek Country Club, and thanking Outotec for their corporate support. Many of the delegates we met yesterday at the late afternoon welcoming reception.
This week is MEI’s first outing in Namibia and we are pleased to be associated with the relatively newly formed Namibia University of Technology. Following Jon’s opening remarks, the Vice-Chancellor of the University Prof. Tjama Tjivikua gave his own words of welcome to this friendliest of African countries.
Of the 52 delegates, 32 will be staying on for Sustainable Minerals ’18 which begins on Thursday, the two conferences having a common informal dinner tomorrow evening.
Appropriately the first presentation of the day was a keynote lecture by one of our conference consultants, Prof. Sue Harrison, of the University of Cape Town, who talked about the role of biohydrometallurgy in the sustainable development of mineral resources. 
Sue, Jon and Tjama
Over the past 40 years, biohydrometallurgy has been recognised increasingly as an emerging technology for extraction of metal values from recalcitrant minerals, low grade ores or mineral resources carrying penalty metals.  This has led to the development of commercial tank and heap leaching processes, processing concentrates and crushed ores to liberate metals of interest through bioleaching of base metals and biooxidation to enable subsequent recovery of gold and PGMs.  The potential of in situ leaching of mineral reserves is under consideration with biohydrometallurgy of key interest owing to the potential for ongoing regeneration of leach agents.  
Processes based on biohydrometallurgy have potential to deliver environmental benefits over competing extraction approaches and to enhance the degree of extraction from the overall resource. While many of the commercial applications of biohydrometallurgy for recovery of metal values use solvent extraction and electrowinning for metal recovery, the importance of biohydrometallurgy in the recovery of metals or, mainly, the removal of metals from aqueous solutions has been considered from the environmental perspective through, for example, biological sulfate reduction with associated metal precipitation.  
Currently, the recognition of the relevance of biohydrometallurgy in a broader context is growing.  Key aspects include the need to account for unintentional bioleaching reactions on the disposal of waste rock and tailings and the need for the long term prevention of such reactions to enable appropriate handling of waste rock and restoration and rehabilitation of prior mine sites with associated protection of water resources.  Further, limited global resources of key metals highlight both the need to process mineral resources of decreasing grade, smaller size of deposit and increasing complexity and the ability to extract metals from secondary sources for re-use.  In the former, biohydrometallurgy has potential to expand technological approaches.  In the latter, with an increasing focus on the circular economy, the sources of metals or modern-day ‘ores’ are changing to include secondary resources such as waste electrical and electronic equipment (WEEE) and municipal solid waste (MSW). These present new challenges for biohydrometallurgists.  
Sue’s presentation provided the ideal start to a day of papers dealing with innovative bioleaching of low grade compex ores, such as copper, zinc, nickel laterites, rare earths and and precious metal ores.
Twitter @barrywills

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