The RE-MINING Approach - Utilization and Rehabilitation of Tailings through Bioleaching and Metal Recovery

The extraction of metals such as copper or indium is essential for the economy, but inevitably associated with the generation of vast amounts of tailings. Especially flotation tailings lead to huge land consumption and are a potential source of environmental hazards. However, due to limited processing technologies in the past such mining waste typically contains remarkable concentrations of valuable elements. Therefore, it is sensible to combine modern resource with environmental technologies to supplement the recovery of valuables with the removal of hazardous substances such as arsenic or cadmium. In the ideal scenario the residues can be utilized for underground backfilling or dump construction.
The project partners GEOS, SAXONIA and HIF have started to develop, build and optimize a pilot plant for the processing of material from primary and secondary sources using bioleaching, metal extraction and elimination of hazardous components based on various research projects. The pilot plant, consisting of different modules, combines biotechnology with physical separation and processing technologies in an innovative and sophisticated way to recover valuables and remove pollutants. The bioleaching module leaches tailings in an airlift reactor by means of selected microorganisms under specific process conditions (pH, temperature, etc.). The obtained yields of up to 90% indium and 85-90% copper indicate the promising potential of this bioleaching technique. For the metal recovery module, it is planned to integrate the following main processing stages: solvent extraction, absorber columns (e.g. activated carbon, IX resin) and electrolysis. The so-called environmental module is designed as classical precipitation, flocculation and sedimentation unit for treatment of remaining process streams from the metal recovery module to eliminate hazardous substances. A future aim is running the mobile pilot plant directly at the tailings site.
An overview on the development of the modules, the equipment and the results that were obtained so far will be presented.