Evaluation of energy-efficiency, emission pricing and pre-concentration for the optimised development of a Au-Cu deposit

Abstract

In 2009-10, fifty percent more energy was required by the Australian mining industry to generate a unit of output compared with just ten years earlier. The escalating energy intensity being experienced by the mining industry has been largely attributed to a significant deterioration in the quality of the resources available for production. However, the Australian mining industry also remains heavily reliant on energy sourced from the combustion of fossil fuels and the recent introduction of emission pricing in Australia has placed greater importance on improvements to the energy-efficiency of operations.The thesis demonstrates that improvements in the energy-efficiency of current mining and mineral processing equipment have the potential to reduce the energy and emission intensities of production and improve the value of operations. In contrast, the introduction of emission pricing in Australia is shown to significantly reduce the value of the operation and the conversion of resources to reserves with negligible reductions in energy and emission intensities of production. The energy reductions required to offset the impact of emission pricing at an operation exceeded the capabilities of the most energy-efficient equipment currently available to the mining industry.A promising path to significantly improve the value and energy intensity of metalliferous mining involves the adoption of pre-concentration strategies that reject uneconomic material from processing streams and increase the grade of ore prior to treatment at the processing plant. These strategies introduce significant complexity into the optimisation of the cut-off grade policy for the development of resources.This thesis examines the economic and production impacts of improved energy-efficiency in metalliferous mining operations, the introduction of emission pricing in Australia and the application of pre-concentration strategies for the optimal development of a low-grade AuCu deposit. A novel methodology has been derived from the optimal cut-off grade policy incorporating pre-concentration and stockpiling strategies to evaluate the economics, energy consumption and associated emissions attributable to production over the life of a mining operation.iii The examination of pre-concentration strategies confirms their potential to create considerable value for treatment constrained operations, increasing the conversion of resources to reserves and decreasing the energy and emission intensities of production.As the industry continues toward the development of lower quality resources and maintains a strong reliance on fossil fuels, the energy and emission intensities of metal production will continue to rise. Innovative solutions that seek to upgrade ore prior to energy intensive grinding can significantly improve the economics of an operation and the energy and emission intensities of production.iv

Enhancing Grade Engineering through multiple and high-speed collisions

“…The advantages of pre-concentration in the industry include reduction of material handling, improvement in resource utilisation and environmental conformity due to improved operation sustainability (Carrasco et al 2014). Reduction in water consumption and tailings are also potential contributions of this technology (Scott 2013) and this benefit is especially advantageous where water is a scarce resource or costly, such as in arid regions (Scott 2018). Despite the advantages of pre-concentration, it is essential to evaluate the cost of losing value when applying this technique and how the generated material will be classified (for instance, stockpile, completely barren or potential to heap leaching) (McGrath et al…”