Elemental measurement of conveyed flows in real time - ore/waste sorting, ore blending, and more


Henry Kurth, Scantech International Pty Ltd

Mining geologists utilise many technologies to map, sample, measure, model and plan before and during the mining process. Predicted ore quality rarely corresponds with feed quality determined by process operators. Objectively measuring conveyed material quality accurately in real time avoids disagreements over mined ore quality and generates opportunities to improve mill feed quality. This presentation discusses the well proven PGNAA (Prompt Gamma Neutron Activation Analysis) technology used in the GEOSCAN-M elemental analyser that is ideally suited to measuring composition of primary crushed conveyed material in real time. Representative, continuous, fully penetrative measurements are unaffected by particle size, belt speed, mineralogy, dust or layering on the conveyor. Material can be directed to processes or stockpiles by utilising measurement increments of 30 seconds to five minutes and then activating diverters to direct increments to the correct location. Waste, low grade or deleterious material can be rejected to waste dumps or stockpiled for later processing. Material meeting a product specification can bypass unnecessary processing. Paybacks in weeks have been achieved for such applications. Process operators are able to control the blend of ores fed into the mill to improve processing performance and use measurements for ore reconciliation and metal accounting. Utilising the technology to upgrade ore quality after mining and before processing is beneficial in improving plant economics. The technology has been successfully utilised in base metals, ferrous metals and industrial minerals.  Ore feed quality measurements are used by process operators in optimising plant performance. The elemental content can help identify geometallurgical domains as well as other major changes in quality which may affect processing. The presentation outlines proven applications and case studies and proposes some innovative applications.
Keywords: PGNAA, ore sorting, real time analysis, pre-concentration, reconciliation, metal accounting