Presorting of high grade molybdenum ore - A case for enhanced small mine development

Michael Hitch, Andrew Bamber, Patricia Oka

With increasing energy and labour costs, and downward pressure on commodity prices, many mines are forced to extract higher grades to remain profitable. Additionally, pressure is increasing on mine operators to reduce their environmental footprint or face public censure, hence traditional approaches such as increasing the mining rate are not attractive. In this environment, operators must innovate to prevent smaller, or less profitable, mines from closing. Data from over eight years of research at the University of British Columbia, and ore recent data from customer studies at MineSense Technologies suggests that previously unrecognized quantities of barren or low grade waste is the norm, rather than the exception in mill feed material globally, therefore an approach that shows remarkable potential to address both of these issues is the pre-concentration of ore by sorting ahead of the mill. Through sensing of the physical, chemical or electromagnetic magnetic properties of ore on a by-particle basis, significant variations in grade can be measured; by exploiting this sensed data identification and rejection of up to 60% waste by mass prior to the expensive process of grinding is possible. Mill feed grade is increased, reducing transport and processing costs, potentially improving plant recoveries, and reducing the amount of waste being sent to the tailings pond. This paper presents the results of recent work undertaken to evaluate the potential of optical, x-ray, electromagnetic and density-based pre-concentration methods on ore from the Kuemseong molybdenum mine in South Korea. The work indicated technical and economic feasibility of pre-concentrating the Kuemseong ore. Using the preferred method of optical separation, overall extraction and recovery was vastly improved, with lower operating costs projected at the mine. The result confirms general potential for this strategy to enhance profitability while simultaneously improving environmental performance for small mine assets.