Victoria Kenrick explores the challenges of water management within the mining industry
Our planet is facing a real crisis in water resources. Climate change and population increases are changing the balance of supply and demand. According to predictions, by 2030 the world’s population will be over 8.1 billion. Since 1950, the need for water has trebled and it will double again by 2050. It is water management that is emerging as the pre-eminent sustainability issue within the Global Energy and Mining Resource Industries. With water being the most important resource in all mining and quarrying developments and operations; it can be used and abused. With hard rock mines in particular using water in all steps of the mining process, from cooling equipment, separating waste from valuable minerals to controlling dust - working with such large volumes of water presents a variety of risks.
In recent years there has been a renewed public debate surrounding the mining industry and its sustainability, due to strong public sentiment on environmental and social issues surrounding the mining industry globally, most specifically, in Australia:
Whilst in Africa, there are also ambitions for a sustainable mining industry; with the growth rate projected to average 6.4 per cent between now and 2014 , partnerships and sustainable development in the mining sector is vital.
Tackling water pollution
Water-pollution problems which can often be caused by mining include acid mine drainage, metal contamination and increased sediment levels in streams. Changes in laws, technologies and attitudes have begun to address some of the most immediate threats posed by mineral development, but there are still many areas of mining practices and regulations that need to be addressed. A number of preventable accidents that have occurred recently include massive sediment loading into fish-bearing streams, the building of roads with acid generating waste rock, non-compliance with waste handling plans, and repeated violations of water quality standards.
To avoid these accidents, mining corporations need to ensure the best pollution prevention strategies are employed in cases where the risks can be managed. Another question that should be raised is to whether there is a need to recognise that in some places mining should not be allowed to proceed because the identified risks to other resources, such as water, are too great. In the right place – and with conscientious companies, new technologies and good planning – many of the potential impacts are avoidable. In fact, it has also been argued that most water pollution that is caused by mining arises from negligence not necessity .
Managing risks requires dedicated environmental mining specialists. The traditional mining industry in Australia requires large amounts of water, which must be treated. Christopher Ouizeman, Australasia Recruitment Manager at International Sustainability Recruitment Consultancy, Allen & York outlines that there are high demands for tailings specialists to manage the mining operations by-products.
In addition to the traditional mining sector, Australia also mine for Coal Seam Gas (often methane). To extract the gas requires the use large amounts of water which must then be treated. As such this sector also requires more and more water specialists, as suggested by Christopher Ouizeman.
Driving sustainable water management in mining
There’s increasing competition for water usage within mining – steps towards a more sustainable mining industry should involve promotion of the use of poor-grade water, usually underground or sea water, which agriculture and municipality do not want. This recovered water does not have to be first grade; in fact many mining processes can tolerate high saline water. In addition, by encouraging water recycling as much as possible, companies can move towards a zero water discharge mine.
Patrick McKelvey Principal Hydrogeologist at Schlumberger Water Services, confirms this view; highlighting that the water management industry in mining is beginning to make use of non optimal water, ie saline instead of fresh, using recycled/treated water as a means of becoming more sustainable.
Dr Hal Aral, Stream Leader for Waste Water Treatment at CSIRO has achieved this at CSIRO. Dr Hal Aral recommends companies take a scientific approach - knowing the volume and composition of the process and amount of fresh water running in every unit operation in the plant provides a mine with the knowledge to be able to minimise the use of fresh water. The scientific approach involves computer modelling and optimisation of the flows plant-wide. There are newly emerging computer modelling approaches, Water Pinch Modelling is the most advanced approach to optimise water use and recycling. Water Pinch Modelling includes a detailed study of the water processes and water pollution prevention and enables production of a full report on the schemes for wastewater reuse.
Utilising the scientific approach are CONSOL Energy Inc and Veolia Water Solutions & Technologies, who announced in June 2011, an agreement to design and build a state-of-the-art Zero Liquid Waste Discharge system to treat mine water. As Australia lacks water, reuse and recycling is an area of constant investment, as is identifying underground sources of water to use once it has been treated. Reflecting this, there is a demand for hydrogeologists and hydrologists for both the mining corporations and engineering consulting firms who service the Australian mining sector.
Preventing water pollution in mining
One organisation that is leading the way in tackling water pollution within mining is The Environment Agency in Wales, who are working at Cwm Rheidol mine near Aberystwyth as part of a unique pilot scheme. The mine has historically discharged large amounts of zinc and other metals into the River Rheidol which means it is failing to meet the good water quality standards required by the European Union's Water Framework Directive. The new scheme will mean that toxic metals will be stripped out of the mine water before it enters the River Rheidol, using an environmentally friendly method that requires only gravity, as an energy source. The treatment system will use a mixture of waste products, including cockle shells and compost, to encourage natural biological and chemical processes that clean the mine water, making for more sustainable mining.
Meanwhile, mining corporations in Australia are taking a more preventative approach and are currently adopting best practices aimed at preventing environmental damage, rather than repairing damage already done. These such programmes include borehole extraction to help contain the pollution plume, the containment of seepage and the pre-treatment of all water, that is to be released into streams, to correct levels.
Progress is also being seen in Africa; environmental solutions company Procon Environ-mental Technologies has been awarded a $1-million contract by mining giant Vale to install a hydro cyclone oily water separation system at the Moatize coal mine, in Mozambique. Whilst in the U.S a major public hearing in West Virginia took place in June 2011 where after a review of more than 50,000 public comments, the US Environmental Protection Agency (EPA) announced that it will use its authority under the Clean Water Act to halt the proposed disposal of mining waste into local streams.
To conclude, Water resource management is an integral part of mining, regulators, industry and the community are increasingly recognising the importance of managing water resources in a responsible way. In brief the three areas of concern in sustainable water management within the mining sector are 1) Finding adequate sources of water to use, 2) Minimising water consumption wherever possible and therefore reusing water where possible, 3) Managing waste and remediating contamination.
Victoria Kenrick is with International Sustainability Recruiters, Allen & York, Wimborne, Dorset, UK. www.allen-york.com
References: Mudd, G M, 2009, The Sustainability of Mining in Australia: Key Production Trends and Their Environmental Implications for the Future. Research Report No RR5, Department of Civil Engineering, Monash University and Mineral Policy Institute, Revised - April 2009.