Remote mining operations generally compete with local communities and agriculture for scarce water resources, often resulting in mines opting to pump in water from further afield to satisfy their demand, plastic piping systems manufacturer Polypipe export sales director Philip Wood says.

He notes that the uses of water in mining operations are varied and substantial.

“For example, in mineral processing applications, water is used to recover gold and copper from chemical solutions, to cool equipment, such as rock cutters, and to wash minerals once extracted,” says Wood.

Minerals can also be transported from mine sites through pipelines in slurry, which can substantially reduce costs associated with road or rail transport; however, this increases the amount of water used by a mine.

Further, arid climates often lead to dusty conditions, particularly on service roads, resulting in water being used to damp down and control dust. Finally, high-quality water is also required to meet the drinking, cooking and washing needs of workers throughout the life of the mine.

“As mining is one of the few industries that can use low-quality water – such as seawater for some mineral processing or dust control – it can draw water from a variety of unconventional sources, which is useful for more remote operations.

“Owing to the industry’s ability to use low-quality water, it is also possible that, beyond simply reducing the impact of mining on the local environment, mines in remote areas can actually have a positive effect by assisting with the provision of safe, clean drinking water to nearby communities,” Wood asserts.

He points out that French multinational Areva’s Trekkopje uranium mine, in Namibia, for example, boasts a water desalination plant which supplies both the mine and local communities with potable water, while diversified mining giant Anglo American’s eMalalheni water reclamation plant, in South Africa, takes in contaminated water from various mines, including its own, and delivers treated water into the municipality’s drinking water supply.

“Remote mines, which will often need to treat their own contaminated water, could easily operate in a similar way with the addition of potable water piping systems channelling water away from the mine to local villages and farms,” Wood posits.

Wood highlights that transporting water – whether fresh, saline or contaminated – over long distances and within the mine site itself can be challenging.

Far from alternative sources of water or replacement pipes, the materials chosen to transport the water have to be robust and durable, withstanding a variety of factors. For example, pipelines must have a tough exterior, which will not be perforated by rocks or damaged by slight land shifts above or beneath them.

“Pipes laid above ground will also need to withstand extreme temperatures and exposure to ultraviolet rays, and interior pipe surfaces should be resistant to the corrosive materials found in slurries or rock fragments within processing water, as well as the chemicals, salts and acids used in extraction, while pipes used for potable water must be able to resist bacterial growth,” says Wood.

He asserts that polyethylene (PE) pipes are an ideal solution for all aspects of mine water management and provide a lightweight, cost-effective and flexible alternative to traditional, heavy materials such as concrete and cast or ductile iron.

“With significant inherent strength and impact resistance, PE pipes can be installed above and below ground and can cope with temperatures ranging from -40 ºC to 60 ºC. This strength is achieved even with a very lightweight pipe, making PE pipes cheaper to transport, cutting fuel costs and the number of trips, and can be easily moved around site without heavy lifting equipment, a key consideration when planning a water management system for remote mines,” Wood states.

He highlights that PE also outperforms steel or concrete pipes when supplying potable water to mines, as PE is resistant to galvanic corrosion and bacterium sediment build-up – unlike traditional materials, which can be badly damaged.

While the chemicals used in mining and water treatment processes can have a corrosive effect on many traditional pipe materials, modern PE piping offers the resistance required to cope with even the most aggressive acids, bases and salts. Its inherent strength also offers protection against abrasion from metals or mineral particles, including rock fragments, which means it can also be used to transport ore away from the site in slurry.

Further, PE pressure pipes can be jointed using butt-welding or electrofusion techniques to form a continuous homogenous pipeline with no risk of leakage, which make them ideal for extended pipelines over long distances. In addition, the extremely smooth bore of PE pipes offers reduced friction – which means less drag and turbulence when large volumes of water are transported at high velocity.

Polypipe’s solutions for mine dewatering pipework include PE100, a polyethylene system, and Ridgidrain, a high-density polyethylene solution, which offer resistance to chemical corrosion and abrasive erosion required of a water treatment pipeline.