Application of the water footprinting method and water accounting framework to a base metal refining process

Abstract

The key to a sustainable future lies in understanding and utilising resources more efficiently. This holds especially for industries that seek to minimise water usage through better management of resources. Most mineral processing plants have high water requirements, yet often function in an environment where water is becoming increasingly scarce. Further, an increase in population will result in an even greater demand for water, potentially beyond the limits of supply. This would lead to even greater competition for the resource. In South Africa, Gauteng and the North West Provinces are likely to be the first to experience a shortage of potable water. A base metals refinery in Rustenburg sought to understand and minimise its potable water usage, as well as report its usage using global tools and frameworks. The two tools used in this study were the Minerals Council of Australia’s ‘Water Accounting Framework for the Minerals Industry’ (WAF) and the Water Footprinting method (WF). The potable water and stormwater systems were surveyed to assess and determine methods to improve water accountability. Using information from the survey, monthly and yearly water balances were presented in the form of a water balance sheet. Using data from the water balance, an input-output and operational model were drawn up in accordance with the WAF. The WAF models assisted in reporting data in a universally consistent manner. Blue, green and grey WFs were calculated for the refinery and recommendations were made to achieve savings in water consumption.

Keywords: water, base metals, water footprint, water accounting framework