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Project Topic
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Biomining is the biotechnological process for metal extraction from sulphidic ores. This process exploits the ability of acidophilic microorganisms (optimum pH < 3) to catalyse chemical oxidation of insoluble metal sulphides to acid soluble sulphates. Today, increasing amounts of metals are extracted by biomining technologies in many countries that include Finland, Chile and South Africa. Bioleaching of copper minerals is usually performed in engineered heaps and this technology accounts for approximately 15-20% of the worldwide copper production. Presently there is an increase in the European demand for metals. However, commercial biomining of chalcopyrite (CuFeS2; the largest copper resource in the world) is not extensively employed due to slow metal release and limited copper recoveries. Instead, chalcopyrite is generally treated by environmentally polluting and energy demanding ore concentration followed by high temperature metallurgical processes. In previous projects, the applicants have performed two laboratory-scale, proof-of-concept experiments to increase the efficiency of industrial bioleaching of chalcopyrite. The first strategy is to maintain the redox potential of a chalcopyrite bioleaching system in the favourable range for copper dissolution by using ‘weak’ iron oxidising microbes such as Sulfobacillus thermosulfidooxidans and to exclude strong iron oxidisers such as Leptospirillum ferriphilum from the consortium. The second strategy exploits the lower tolerance of the strong iron oxidizer, L. ferriphilum to chloride ions as compared to S. thermosulfidooxidans. In addition, it has been demonstrated that signal molecules control biofilm formation for pyrite and it will now be tested if they suppress the growth of L. ferriphilum when grown on chalcopyrite. Although the applicants have proof-of-concept strategies to suppress L. ferriphilum, how the desired microbial consortium can be maintained in the several square kilometre bioheaps employed by industry is unknown. In this study, these two proof-of-concept strategies will be scaled up to ultimately reach demonstration in an industrial pilot bioheap. The applicants will use stirred tank and column reactors to move to larger scale before the most promising strategy will be tested in the pilot plant. These experiments will be evaluated using state-of-the-art interdisciplinary analytical techniques in molecular biology, ‘omics’, and chemistry. Thus, the consortium will interdisciplinary cover the process in terms of innovation and research and will comprehensively study engineering, chemical, microbiological, molecular biological and 'omics' methods. This project contributes to the RMI and EIP strategies on raw materials through the enhanced resource efficiency achieved for both copper resources in Europe and those globally with potential to supply Europe, while at the same time reducing the environmental footprint of copper extraction. In achieving this, the project addresses the circular economy as well as the implementation of low carbon process options for copper recovery. Through its potential for application to both low-grade copper deposits and smaller deposits, the project has potential to create new resource opportunities and reduce barriers to their exploitation. Further, the nature of the technology to be developed allows it to be evaluated for its potential innovation capacity to replace traditional processing options, even for high-grade ores. By incorporating a German company into the consortium and having two associated companies providing minerals and facilities, the knowledge of these stakeholders will contribute to the progress in the project. In turn, this also results in new insights from the project having a substantially greater probability to be applied through the companies involved and the mining sector in general.
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