Abstract

Mineral and metal extraction often takes place in some of the World’s driest areas, including the southwest states of the United States of America, Northern Mexico, Western Australia, South Africa, Chile, and Peru among many others. In the majority of these areas, availability of water is low and expected to reduce as a result of climate change with expected outcomes such as higher incidences of local conflicts between water users, greater environmental damage and reduced productivity of operations. The mining industry, in general, is a large consumer of freshwater and the impact in arid areas can be extremely damaging, it is therefore necessary for operations in many circumstances to improve their water management or explore the potential for alternative water sources. Nevertheless, with the global economy preforming poorly and mineral prices low, mining companies are reluctant to invest in large scale projects to reduce their water consumption or source from alternative and more sustainable sources. This paper investigates the various options for reducing freshwater consumption in the mining industry and a cost benefit analysis is conducted to determine which are the most favourable options for particular operating variables. The methodology for the analysis is water balancing and cost analysis for typical mining operations using variables such as ore type, ore grade, throughput, climate and location among various others. Models have been developed to determine the operational consumption depending upon the variables and analysis of water saving techniques has been conducted to calculate the effectiveness of certain strategies such as improved on site water management, implementation of dewatering technologies and the use of seawater as an alternative water source. The cost per unit of water saved was then calculated to ascertain which strategy was most cost-effective for the base case. The variables were then modified to understand their importance upon the cost-effectiveness of each strategy. It was found that the most cost-effective strategies were improved on site water management through reduction of evaporation via the use of dust suppressants and the implementation of certain technologies to recycle water from tailings. These strategies were particularly important when the location of the mine was assumed to be isolated, i.e. in a location far from the coastline or at high altitude where the use of seawater was prohibitively expensive. In certain cases, however, when circumstances were such that a new source of water was imperative or the location was near to the coastline, the use of seawater as an alternative source was found to be comparatively feasible economically. In the current economic and environmental climate, mining companies are facing the necessary task of changing their water consumption habits to continue operation and avoid risks related to over extraction. This paper provides an analysis of the most cost-effective methods of achieving that goal under various circumstances.