Introduction
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 decrease as a result of climate change. Examples of expected outcomes are: a higher incidence of local conflicts between water users, greater environmental damage and reduced productivity of operations. In many cases, governments are making policies to reduce consumption in certain industries. The mining industry, in general, is a large consumer of freshwater and the impact in arid areas can be extremely damaging. Therefore, it is necessary for operations in many circumstances to improve their water management or explore the potential for alternative water sources. Nevertheless, with the global economy performing poorly and mineral prices attaining low levels, mining companies are reluctant to invest in large scale projects to reduce their water consumption or, in other cases, use water from alternative and more sustainable sources. This paper assesses options for reducing freshwater consumption in the mining industry by cost benefit analysis to determine which are the most favourable options for particular operating variables.
Methodology
The methodology for the analysis is water budget 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.
Results
It was found that the most cost-effective strategies were: (1) improving on site water management through reduction of evaporation via the use of dust suppressants, and (2) the implementation of 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 due to pumping cost. 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.
Implications
In the current economic and environmental landscape, mining companies and governments are facing the necessary task of adopting new operating strategies and regulations to change water consumption habits in the mining industry to continue operating whilst avoiding conflicts, environmental damage and the associated risks. This paper provides an analysis of the most cost-effective methods of achieving that goal under various circumstances.