Overcoming the challenges of mine dewatering

Every mine site faces a different challenge with water – it’s either scarce, or in excess and causing an issue, according to engineering solutions provider Weir Minerals.

Water is critical for its role in minerals processing, dust suppression and slurry transport, and without it the entire operation would stop.

A reliable dewatering plan is essential to ensuring a steady supply of process water throughout a mine site. Conversely, the removal of excess water from working areas to allow excavation also requires a dewatering plan.

Even though there is no ‘one size fits all’ approach to dewatering, below are major considerations common to any dewatering project.

Weather and environment

Each site’s dewatering requirements vary with environmental and geological considerations, as well as local climatic variations. Differences in weather conditions and environmental changes can have a significant effect on an operation.

Mine sites need to assess the permeability and porosity of the ground, the amount of surface water and geological features such as seasonal rainfall before starting a dewatering process.

The dewatering system put in place must be able to cope with this to provide a safe solution and minimise production delays.

“From designing and implementing a unified, fully-automated dewatering system in Czech Republic to delivering a dewatering system to withstand high wind speeds and tropical storms in Africa, we rarely meet a challenge we cannot overcome,” Weir Minerals global product manager for dewatering Ian Ross said.

Water composition

Temperature, pH range, corrosive and abrasive content in water all play a critical role in selecting the equipment to transport water effectively.

The presence of solids in the water, the specific gravity, size distribution and content percentage will determine the type of pumps required.

Pipework and valves are also subject to corrosion and abrasion from the products handled and must be designed accordingly, according to Weir Minerals.

“At Weir Minerals, we have a range of flexible solutions that allow us to use several types of pumping equipment, from self-primed diesel driven, submersibles, vertical turbine and multistage to high-wall pump designs for sites that have limited access due to high-sided mine pits,” Weir Minerals regional director of dewatering Cameron Murphy said.

“Our development of sophisticated pontoon and barge designs allows our equipment to float out over water bodies for easier access.”

Water reuse

With depleting ore grades around the world, there is an emphasis on turning waste into energy, and the dewatering process is no different, according to Weir Minerals.

Mine operators can reclaim water from their tailings and re-use it throughout the mine site by using pump house systems or customised barge solutions.

“These options can be complex, and we work with the customer to educate them on how the systems work and showcase the benefits,” Ross said.

Reclaiming process water for reuse through the plant can help overcome the issue of water scarcity, helping ensure an operation gains maximum use of its resources.

Streamlining dewatering process

Operators usually rely on multiple original equipment manufacturers (OEM) for dewatering projects and still have to ensure a solution comes together in a streamlined process.

Weir Minerals can eliminate this labour-intensive process by managing the entire dewatering solution, including a thorough assessment of site requirements, the mine plan, operating depths, existing infrastructure and required water in-flow.

“What we deliver is an optimal dewatering plan, backed up by recommendation for regular equipment maintenance to keep unscheduled stoppages to a minimum,” Ross concluded.

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