Mine water treatment innovations turn a liability into an asset
What to do with contaminated mine water has been a question as long as large-scale mining has existed. After mineral processing and slurry transport, the water is often left as a waste product, harming the environment and sitting as a sunk cost for the mining company. But new water treatment solutions are finding creative ways to remove contaminants and recycle the water for other uses, saving mining companies money and in some cases even adding revenue.
Using reverse osmosis and deionisation, New H2O Resources offers mobile water treatment plants that can be scaled to fit the needs of a particular mine, allowing for faster processing times than fixed treatment stations. As mines are often in remote areas with little access to fresh water, cleaning contaminated water is critical for sustainability.
Not only is the process environmentally friendly, having a ready supply of clean water can be a boon to mining companies selling the water to agricultural interests. New H2O’s filtration plants yield Environment Authority-approved levels of water quality, suitable for crop irrigation adjacent to mines. With bulk water valued at approximately $4,000 per megalitre, this could prove quite lucrative.
Another focus of New H2O is reducing evaporation. Anywhere from 10-14 per cent of stored mine water is lost to evaporation. New H2O’s technology accurately measures evaporation rates and reduces evaporation by up to 90 per cent. This saves money on financial assurance bonds that often overestimate rates and limits the number of new dams that need to be built.
The Mount Piper power station, about 165 kilometres west of Sydney, supplies 15 per cent of Sydney’s electricity. Mount Piper uses coal from the nearby Springvale mine to produce that electricity. When it opens later this year, Veolia’s mine water treatment plant at Springvale will take water from the mine, clean it, and deliver it via pipeline 16 km away to Mount Piper, where the water will help run the power plant.
In addition to creating a sustainable loop between the mine and power station, Veolia’s treatment plant promises to divert contaminated water from Coxs River, a source of Sydney’s drinking water. Without an agreement to build the treatment plant, the mine and power station may have had to shut down. Keeping them open saved Centennial Coal and EnergyAustralia millions of dollars and ensured continued prosperity while taking the operations in a greener direction with lowered health risk for Sydneysiders.
“Job security in a regional area is absolutely paramount, as is energy reliability, and I’m sure that the Lithgow community is going to be very pleased with this outcome,” Centennial Coal communications director Katie Brassil told the ABC when the deal was struck.
Environmentalists long concerned about the impact on Sydney’s water supply are also pleased to have a solution sorted. “We’re very happy about that; we just wish that it happened many years ago,” Colong Foundation director Keith Muir said.
Reduce, Reuse, Recycle
Rio Tinto’s Argyle diamond mine in the Kimberley region of Western Australia is consistently among the world’s leading diamond producers. It also used to be one of the biggest consumers of water. In 2005, Argyle used more than 3,500 megalitres from Lake Argyle. In an arid region where temperatures routinely reach 40 degrees, that had a big impact on groundwater levels. With a concentrated effort to capture and recycle, that number dropped steadily. In 2017, it was 447 megalitres, and 91.4 per cent of the water was recycled. As water use has gone down, Argyle’s annual revenues have doubled to more than $300 million.
As Rio Tinto prepares to close Argyle next year, it is installing water monitoring bores to monitor groundwater levels at the site as part of an agreement with Traditional Owners who have inhabited the area for thousands of years. The agreement includes a plan for continued water management at Devil Devil Springs, an important cultural site which was previously drained completely as a result of Argyle’s operations.
With creative green solutions such as these, mining companies are figuring out how to be more friendly to the environment and surrounding communities while reducing costs. That makes for better treatment of water and people.