Who we are
Waste
In using our resources wisely, we ensure we also manage our mineral and non mineral wastes in a socially responsible way.
Mining activities require large quantities of rock to be moved to access economic resources. Mineral processing activities result in generation of slags and tailings. These materials, commonly termed mineral wastes, can pose environmental hazards if poorly managed. Through improvements in mine planning we are improving the efficiency with which we mine and process ore leading to reduced material movements, fuel consumption and greenhouse gas emissions.
We produced 1,904 million tonnes of mineral waste in 2007, about two per cent more than in 2006. Much of this material was moved within mined areas and placed as in-pit backfill (66 per cent) or was stored in engineered piles (31 per cent) close to where it was generated.
The acquisition of Alcan is expected to have marginal impact on our mineral waste profile. Alcan operations generated 3.2 million tonnes of Bauxite waste in 2007.
One of the most serious environmental risks for the mining industry is "acid rock drainage" (ARD) from mineral waste. When sulphide containing rocks are disturbed and exposed to air and water, they may release acidity, metals and sulphate. Left unchecked, this can reduce water quality in the long term.
We minimise the potential for ARD generation by adopting leading practices in mine planning, operation and waste management. Only about 11 per cent of Rio Tinto's mineral waste generated was considered to have acid generating potential or to pose other geochemical hazards in 2007. Kennecott Utah Copper contributed 63 per cent of this total. To minimize water contact chemically reactive mineral waste is covered or capped and vegetated wherever possible.
Rio Tinto's ARD review programme is regarded as the industry benchmark for this key risk area. Since 2004 we have completed 22 ARD risk reviews, including reviews of all of our operations and advanced projects that pose high ARD hazards. In 2007 we focussed on the ARD risks and management programs for our La Granja copper project in Peru. Rio Tinto continues to play a leading role in the International Network for Acid Prevention.
This year we rolled out a new diagnostic tool to improve the management of all types of chemically reactive mineral waste. In addition to ARD, this programme also focuses on wastes that pose salinity, radioactivity, metals soluble or bioavailable at neutral pH and naturally occurring asbestos risks. Four mines and advanced projects have now completed this diagnostic program.
Non mineral waste includes materials that are used in mining and processing, such as tyres, oils, refractory lining and domestic rubbish. We re-use and recycle these materials, where possible. If recycling is not an option, we burn, store or dispose of waste in engineered landfills in an environmentally responsible way and in accordance with local regulations. In 2007, non mineral waste generation was 288 thousand tonnes, 11 per cent lower than in 2006.
With an increased exposure to smelting and other downstream packaging activities, the inclusion of Alcan is expected to have a significant impact on our non mineral waste profile. Alcan operations generated 1.09 million tonnes of non mineral waste in 2007.
