The influence of ore grade decline on energy consumption and GhG emissions: The case of gold

Abstract

With the rush of metal consumption in the last decades and the expected raw material demand driven by the clean and digital transition, a growing concern has emerged about the decline of ore grades. Research of the effect of ore grade decline on energy consumption during the processing of metals has conventionally been addressed using historical data and LCA analyses. This paper provides another approach using a computational model developed with specialized software, HSC Chemistry, to analyse this relationship using gold as a case study. Gold was selected as it is a precious metal widely used in various applications, from jewellery to electronic circuits and will be key for digitalizing the economy. Considering all mineral processing stages, it was verified that the specific energy and associated environmental impact would experience exponential growth as ore grade in the mines decreases. As one of the most energy intensive stages is comminution, fuelled by electricity, the associated environmental impact is very much dependent on the electricity mix of the producing country. This approach allows for an evaluation of the future production's environmental impact for gold.