Saturday, 16 July 2011

What is the future for heap bioleaching?

The use of a leaching solution to extract valuable minerals from ore is not new, and has been taking place, by accident and design, for many hundreds of years. However, advances in process technology and equipment are continuously improving efficiency, mineral recovery and quality, in keeping with rising costs and increasing complexity of ores (see MEI Online).

Bioleaching is increasing in importance as ore grades fall and metal prices rise. Heap bioleaching of primary copper ores has great potential for low grade ores not amenable to processing by other means, but there are also limited applications for heap bioleaching of refractory gold ores, low grade nickel sulphide deposits and low grade sulphidic uranium ores.

The time frame required for recovery of the metal inventory in heap bioleaching of sulphidic minerals has significant impact on the economic analysis of the process. One factor influencing this time frame is the time required from construction of the heap to achievement of an active bioleaching system. This is affected to a large extent by the microbial colonisation of the low grade sulphide ores.

Factors impacting this colonisation will be considered by Prof. Sue Harrison, of the University of Cape Town South Africa, in her keynote lecture at next year’s Biohydrometallurgy ’12 conference in Falmouth. These factors include initial microbial attachment to the ore, the development of firmly attached biofilms, the location of the microbial community with respect to the ore, the kinetics of microbial growth on the ore surface and its subsequent impact on microbial ecology.

Sue will address the manner in which physico-chemical conditions and availability of the sulphide mineral phase influence attachment, and the effect of heap hydrology, through solution-ore and microbe-mineral contacting, on microbial colonisation.
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3 comments:

  1. Chandra Sekhar Gahan18 July 2011 at 16:51

    Heap bioleaching optimisation and feasibility studies especially on chalocpyrite and ability to get rid of passivation layer due to Jarosite and iron hydroxide precipitation would be of great importance and a bright future for bioleaching application as this is one of the major challenge faced by any pilot scale heaps or lab scale columns today. Probably heap leaching of refractory gold would follow up if the conditions are amenable considering the economics and recovery together with its g
    feasibility. Desulphurisation of coal is another aspect where lots of research with regards to biooxidation of pyritic sulphur has been done but still under process to be a full scale operation until today. Well Heap bioleaching has a bright future even though we are half way now but its never late.

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  2. Anonymous26 July 2011 at 16:58

    Bioleaching... likely to become a new economical processing technology for some ores. Dealing with living organisms is more challenging but with proper tecchnology might be possible to ensure their survival in a continuously channging micro-environment.
    Alexey Duarte, Colombia

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  3. Anonymous26 July 2011 at 16:59

    I am particularly interested in seeing someone do a further work in in cost/benefits of forced aeration in heap bioleaching. My personal feel is that it is worth while at higher sulphide grades, or in during the establishment of lower grade heaps ( first month), but may be getting used beyond the point of economic benefit.

    I would like to hear other peoples experiences and comments.
    Roger Strickland, Australia

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