This industrial research project is directed at the use of therrnophilic bacteria for the bioleaching of sulphide minerals and has been designated the "HIOX" process. Although a considerable amount of research work has been carried out on mesophiles and several plants have been installed for Au bearing materials, there has to date been no significant commercial breakthroughs in the use of thermophilic bacteria. In addition, the technology of bacterial leaching is dominated by South Africa and Australia and it is the intention of this project to establish the EU as a major technology base for bioleaching, by using the expertise in the field of thermophilic bacterial leaching which presently exists within Europe.

Two types of thermophiles will be considered: the moderate/high temperature thermophiles which operate at 55 75 C and the extreme thermophiles which operate above 75 C. The work will be arranged so that all aspects of the process flowsheet are covered i.e. the bioleaching and downstream process steps will be tested so that an integrated industrial application can be finally evaluated For all of the process steps the focus will be on the practical parameters required for the optimisation of an industrial application based on the "HIOX" process. The industrial objectives will be to develop a new bioleaching process: for the treatment of chalcopyrite, which at present is only treatable by pyrometallurgical methods or by high pressure leaching, both with environmental disadvantages; for metal production from complex sulphide concentrates which are presently untreatable by conventional means; which is more economic and environmentally friendly, for metal production from a range of other base metal and Au bearing sulphide minerals and which can operate on a small scale; for metal production from low grade concentrates (e.g. rougher flotation concentrates) and therefore obtain higher metal recoveries from the mine; that is environmentally friendly and leaves a low grade inert residue and which does not produce SO₂, H₂SO₄ or As₂O₃; that is an integrated hydrometallurgical process based on thermophilic bacterial leaching that can be economically used to produce Cu, Ni and Zn of 99.99% purity and Au suitable for further refining; with process flowsheets and plant designs to meet the above targets; which will make the European mining industry world leaders in the field of bioleaching, based on thermophilic bacterial mineral oxidation.

The work will involve:

• Collection and Characterisation of Samples
• Sample Selection and Preparation
• Bacteriological Testwork
• Laboratory testwork with thermophiles
• Large scale Contiinuous Testwork
• Down Stream Processing
• Reactor Scale-up
• Environmental Studies
• Process Design Study
• Economic Study and,
• Exploitation Plan

The mining companies involved have each indicated one ore deposit in which they have an immediate interest and which cannot presently be exploited with existing technology. Most of these are located within the EU, namely Ireland, Spain, Sweden and Greece. If the "HIOX" process can be successfully demonstrated and is exploited commercially then these projects alone could generate over ECU 1.5 billion per annum of income from metal sales. The mining companies have combined annual sales of over ECU 8 billion so if this is extrapolated throughout the EU and worldwide then it is evident that the high temperature bioleaching of sulphide minerals has an enormous commercial potential.

Contacts

Coordinator

• Christopher BONNEY / Mineral Industry Research Organisation UNITED KINGDOM

Participant

• Jan-Eric SUNDKVIST / Boliden Mineral AB SWEDEN
• Georges MORIZOT / Bureau de Recherches Géologiques et Minières Organisation / FRANCE
• Peter SINCLAIR BRIDGES / Greenwich Resources plc UNITED KINGDOM
• Werner SCHWAB / Henkel KG AA GERMANY
• Roger CRADDOCK / LaSource Compagnie Minière SAS FRANCE
• Luleaa University Of Technology SWEDEN