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MEI Online: Commodities: Metallic Ores: Nickel: Latest News: November 27th 2007


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:: ExtrEL Leaching System for Nickel Sulphide Mine Tailings

ENPAR Technologies Inc. recently announced that it has entered into a definitive patent and technology license agreement with Dundarave Resources Inc. . The Agreement provides Dundarave with an option to acquire an exclusive worldwide license to ENPAR’s ExtrEL leaching system technology and all related intellectual property as it relates to the recovery and the extraction of nickel and associated by-products contained in the nickel sulphide mine tailings

The ExtrEL process promises to be a cost-effective and very energy efficient solid sulphur-rich mining waste dissolution technology. The process produces a uniform acidic matrix which can then be blended with appropriate metal, acid and water recovery technologies to develop an integrated processing circuit. This circuit could be modular in design, and thus relatively easily transported and installed to function on small remote sites with easy waste resource access, perhaps even powered by a local Green Energy source. The process applies basic acid dissolution chemistry with minimal energy input to drive combination oxidation-reduction reactions which dissolve the sulphur-rich pyrite and pyrrhotite minerals in the tailings wastes. The combined reactions produce a process stream high in dissolved iron, and a waste stream of hydrogen sulphide which can be converted using existing technologies to either elemental sulphur or sulphuric acid.

The breakthrough ExtrEL process dissolves nickel from tailings. The nickel, in concentrations approaching 1.0% in both active and closed mill wastes, can be separated from the acidic solution matrix. Unoptimized bench-scale trials of ExtrEL to date have provided over 75% recoveries of nickel occluded in the pyrrhotite waste from a Sudbury Tailings stream sample.

Dundarave Resources has engaged Dr. Graeme A. Spiers, C. Chem., the Chair of Environmental Monitoring at Laurentian University, to conduct due diligence on the ExtrEL process. Dr. Spiers has 25 years of research and facilities management experience in academic, government and commercial laboratory environments. His research has focused on effects of acidification and extreme metal insult on pedologic processes, particularly as these relate to seasonal metal fluxes to water bodies. He is the author of over 100 publications, including 35 journal papers, that have contributed to the understanding of metal translocation in soil-plant systems, and have also included pioneering work in development of slurry analytical methodologies for mineral materials. According to Dr. Spiers, the ExtrEL technology has two major benefits: potential economic advantages and potential solution to environmental issues faced by the mining industry.

The target feedstock for the ExtrEL process is not an expensive new ore body to be developed, but the sulphur-rich tailings waste streams from the concentrate mills of the modern and closed sulphidic-feed smelter operations at any location around the globe. The ExtrEL technology has the potential to revolutionize the modern mining industry by:

  • Recovering economically significant tonnages of base metals such as nickel from surface mining industry waste dumps at relatively low costs
  • Producing economically significant tonnages of elemental sulphur or sulphuric acid from surface waste dumps as a by-product of the base metal extraction process
  • Recovering precious metals such as rhodium from pyrrhotite-rich surface waste dumps at relatively low costs
  • Converting environmental liabilities into more benign neutral drainage generation surface materials such as a building aggregate (fine sand for concrete and road construction usage) of minimal sulphur and metal content

The other significant benefit of further developing the ExtrEL technology into an integrated metal, acid, gas and water recovery system could be the potential reduction of environmental liabilities for the mining industry. The modern metal mining industry is essentially one of the largest waste management industries in the world. Mill tailings materials are a potential major environmental legacy and liability to the industry because of acid mine drainage. The impacts of acid mine drainage can be long-term, lasting for decades or perhaps even centuries. The mining industry in Canada spends $100 million annually to control acid mine drainage, with liabilities potentially reaching several billion dollars. Modern mill technologies continue creating waste streams containing in excess of 0.8% nickel. Metal recovery from such metal and sulphur-rich wastes could become a stand-alone profit centre while reducing the environmental liability facing the mining industry.

As part of the Agreement, Dundarave will fund an optimization and design program and the full cost of the construction of the test pilot plant to process a significant amount of nickel tailings. Dundarave is actively seeking a suitable nickel sulphide tailings deposit for the demonstration plant.




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