Estimating an upper limit for primary copper supply using empirically derived mineral resource-to-production rate relationships

A theoretical upper limit for the annual primary supply rate of copper is estimated under the overoptimistic assumption that all known mineral deposits can be mined simultaneously. Factors for mineral resource and reserve-to-production relationships – often referred to as Taylor’s rule – were derived for specific copper deposit types and mining methods based on data for existing mining operations. These were used to estimate potential production rates with uncertainty bounds for the remaining set of known deposits that are not currently being mined. A Monte-Carlo analysis was performed and the 90% confidence intervals for the upper limit of primary supply were determined. For the deposits (n = 407) with defined mineral reserves in 2015 (640.9 Mt Cu) this was found to be 22–27 Mt Cu/year. For the broader set of deposits (n = 2296) with resource estimates in 2015 (3,054 Mt Cu) this was found to be 59–69 Mt Cu/year. Published scenarios indicate that annual primary copper demand may reach the upper primary supply limit derived from mineral reserves by the middle of this century, but not the upper limit derived from identified mineral resources. This suggests that successful conversion of mineral resources to reserves and subsequent mine development may be able to bridge potential supply-demand gaps. Further analysis of factors not considered by this study such as social and environmental considerations and the availability of labour, equipment, energy and capital into the sector may provide further insight into the upper limits of primary copper supply.