The contemporary African copper cycle: One year stocks and flows

The characterization of material flows within and between countries and continents has the potential to inform analysis of resource availability, energy consumption, environmental degradation, and governmental policy. Quantification of flows (and the accompanying changes in resource stocks) has been accomplished for grouped resources largely for a small number of countries in Western Europe. Regularizing these approaches, directing them to specific industrial metals, and applying them to all the world’s continents is the goal of the Stocks and Flows (STAF) project at Yale University, USA. In this paper, we treat the contemporary annual flows of copper on the African continent. Copper has been selected as the first case study material being investigated by the STAF project, the reason being that copper has been widely used for several thousand years, is stored in several different chemical and physical forms and has an estimated depletion time of less than 80 years1. Material Flow Accounting (MFA) is the technique used for estimating and analysing flows of material within a geographic boundary2. Our copper-focused MFA goals are fourfold: the assessment of the magnitude of copper uses during the mid-90s, the estimation of the amount of copper leaving African economies in various waste streams, the determination of the amount of copper recovered, and the estimation of the amounts of copper accumulating in specific reservoirs. A comprehensive approach was developed by Graedel et al.3 for the evaluation of all relevant aspects of the copper cycle, especially stock build-up and draw-down and material flow magnitudes. If this approach is applied over an extended period, it has the potential to identify opportunities for resource strategies, assessment of associated environmental impacts, and policy developments. Spatari et al.4 applied this comprehensive approach to compile a contemporary European copper cycle. A static flow model represents a snapshot in time, and assesses the current (contemporary) epoch flows of materials. These flows result in changes of reservoir stocks over time unless inputs and outputs to the various reservoirs are in balance. If the results of a set of static models are integrated, a dynamic model is generated which includes an assessment of the total stocks in each reservoir and the inter-reservoir flow at any epoch within the time limits of the model. A dynamic model also assesses the age distribution for The contemporary African copper cycle: One year stocks and flows