Highlights

Precipitation in the area of the Oyu Tolgoi mine averages just 57mm per year

Oyu Tolgoi carried out detailed hydrogeological investigations in the region to find a sustainable source

Mine is implementing innovative and highly-efficient recycling and conservation practices

We are committed to protecting the quality and the quantity of water that is available here

Mark Newby, Environment manager, Oyu Tolgoi

Water is the most precious resource in the South Gobi province of Mongolia, where the Rio Tinto-managed Oyu Tolgoi copper-gold mine began production last year.

Precipitation in the area of the mine averages just 57mm per year and local herders rely on shallow groundwater from springs and wells for their animals. With water also a critical resource for the Oyu Tolgoi operations – for the mine, the processing plant and for the workforce – it requires careful management and close engagement with community and government to ensure that everyone’s needs can be met.

“We are committed to protecting the quality and the quantity of water that is available here, and to supporting the development of water supplies in local communities,” said Oyu Tolgoi Environment manager Mark Newby.

Oyu Tolgoi carried out detailed hydrogeological investigations in the region to find a source that would balance the needs of an operational mine and the current and future populations. The surveys led to the discovery of the Gunii Hooloi aquifer, which sits more than 150 metres below the surface – far deeper than the water sources used by local herders.

The Government of Mongolia has permitted Oyu Tolgoi to use 20 per cent of the aquifer’s 6.8 billion cubic metre capacity, which will be sufficient to supply all of the company’s current water needs for more than 40 years. The water reserve that will be left would be big enough to supply Mongolia’s capital city, Ulaanbaatar, for the same period of time.

84%

of water used in production at Oyu Tolgoi in 2013 was reused

Innovative approaches

Thanks to the innovative and highly-efficient recycling and conservation practices in which Oyu Tolgoi has invested, the company uses just 520 litres of water to process each tonne of ore. This is less than half the global average amount of water consumed by similar mines.

And in 2013, out of all the water used for production at Oyu Tolgoi, 84 per cent was reused. Most of the water is required by the concentrator, where the mined ore is transformed into the saleable product: copper concentrate.

Water is recycled across many parts of the operation, including from truck washing and cooling systems. Household wastewater is treated at the seven wastewater treatment plants. Some of the recycled water is used to spray on roads for dust suppression, and in the concentrator.

Among other water management procedures in place, Oyu Tolgoi is recovering groundwater that surfaces when ore is removed in the open-pit mine. High-efficiency thickeners are being used to reclaim water from tailings – the mixture of process water and finely-ground rock that is left over after the valuable minerals have been removed. A floating cover has been installed on the lagoon that holds water piped from the aquifer, to prevent evaporation.

To make sure that it understands and can manage any impacts of its operations on the surrounding water resources, Oyu Tolgoi has been monitoring the levels and quality of water in herders’ hand-dug wells since 2003. And since 2011, herders have been making their own records for comparison with Oyu Tolgoi’s. The data has not demonstrated negative impact on the wells due to the project.

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Herders rely on shallow groundwater springs and wells for their animals. Close engagement with the community ensures everyone's needs can be met.