Development and Implementation of Thickened Discharge at

Abstract: Osborne Mine is an underground copper-gold operation in Northern Queensland that mines an ironstone deposit which hosts magnetite and silica with chalcopyrite, pyrite, and pyrrhotite. The mine setting is arid with the majority of make-up water being supplied from boreholes located on the edge of the Great Artesian Basin, some 28 km away. The development and implementation of thickened discharge for tailings management was initially motivated on the basis of potential water savings as well as the potential to reduce wall raising costs on the tailings dam. As trials progressed however, it became apparent that thickened discharge would not only achieve these but also would enable reductions in operating costs, improved rehabilitation potential, and more efficient use of available storage capacity. This paper describes the development and implementation of thickened discharge at Osborne. The operating strategy and the operating cost savings that have been realised are discussed, as is the design philosophy for a new tailings storage facility to accommodate the new method of deposition. The economic, geotechnical and rehabilitation assessments necessary to obtain regulatory approvals and to proceed with this method of deposition on a long term basis are also detailed