Enhancing Grade Engineering through multiple and high-speed collisions

Abstract

The head grades in mining operations have decreased globally, causing an increase in energy costs and a reduction in productivity due to the generation of more waste. Population growth and demand for more mineral resources whilst also striving for sustainable development, means that the mining industry is currently facing complex issues. One proposed solution is the early rejection of coarse gangue through pre-concentration of material after blasting or primary crushing. Separation occurs due to the uneven mineralisation distribution across particle sizes for some ores and can generate streams with different grades and consequently operational destinations. Sending less material to further stages of mineral processing reduces energy consumption and improves productivity. This grade by size deportment has been utilised by CRC ORE's Grade Engineering ® (GE) approach, which results in coarse gangue rejection.The usual pre-concentration methodology uses conventional crushing and does not exploit the use of technologies that can improve the concentration of minerals into specific size fractions. A more precise and selective breakage has the potential to further enhance the grade by size deportment of minerals. The Vertical Shaft Impactor (VSI) crusher was identified to potentially promote selective breakage of particles and the machine parameter settings are possibly related to the concentration of minerals. This research aims to investigate the influence of these parameters including throughput and rotor design on single and multiple particle breakage along with metal deportment in a laboratory-scale VSI unit.In addition, the laboratory-scale VSI is compared to a jaw crusher device, which is typically used in mining operations and it has inferior particle breakage control, with respects to the grade by size results to analyse the relationship between the crushing method and grade by size response.The more controlled breakage achieved by a VSI could potentially improve mineral deportment compared to conventional crushing. Furthermore, there could be a specific optimum VSI setting for gangue rejection. Additionally, modifications to the original rotor design could improve the preciseness of the breakage by decreasing secondary breakage of debris.