COST-EFFECTIVENESS OF TAILINGS DEWATERING AND STACKING

Over the last one hundred years, tailings dams have failed globally at a rate of 2 to 5 per annum. This failure rate is considered unacceptable by the community and by the mining industry. The conventional transport of slurry or thickened tailings and their storage in a tailings dam, requires low capital and operational expenditure, as slurry tailings can be transported by pipeline using relatively inexpensive and robust centrifugal pumps. Recently, the filtration of tailings, their transport by conveyor or truck, and "dry" stacking have been seen as an alternate method of tailings management. However, filtration and dry stacking are considered expensive. Over the full life cycle, including post-closure, of filtration and a dry stack facility, the potential to increase water recovery for recycling and increased options post-closure can lead to a reduction in the total expense of a dry stack facility. This study aimed to contribute to understanding of the cost-effectiveness of tailings dewatering and dry stacking as a tailings management method. Various tailings samples from different locations and with different characteristics were tested for their filtration potential. The potential for monetary savings through the reuse/recycling of the water recovered from the tailings through filtration was a particular focus. While tailings with higher clay mineral contents had more potential for water recovery than coarser-grained tailings, they were also more difficult to dewater. Tailings with lower clay mineral contents were relatively easy to dewater, requiring a short residence time, leading to increased water recovery and volume reduction potential. The results identified that there is significant potential for water recovery, leading to monetary savings through the reuse/recycling of water, potential for storage volume reduction, and potential for higher value post-closure uses.