As public scrutiny over the mining sector’s use of water continues to grow amid global shortages, Weir Minerals has issued its own guide on how to optimise the dewatering component of a mine site.

“Water is critical for every mine site, it’s used for minerals processing to dust suppression and slurry transport, and without it the entire operation would stop,” Weir said. “Every mine site faces a different challenge with water; it’s either scarce, or in excess and causing an issue.”

A comprehensive, reliable and flexible dewatering plan is essential to ensuring there is a steady supply of process water throughout the site, according to Weir. Conversely, the removal of excess water from working areas to allow excavation to continue while safeguarding the operators and maintaining productivity also requires a dewatering plan.

Ian Ross, Global Product Manager for Dewatering at Weir Minerals, said: “There is no ‘one size fits all’ approach to dewatering. It can be an expensive and complex challenge, which is why we deliver bespoke strategies that are cost effective and manageable.

“At Weir Minerals our strength lies in our engineering and project management capabilities. We have the knowledge, expertise and range of equipment to optimise the entire dewatering component of a site.”

Major considerations for any dewatering project

Weather and environment

Each site’s dewatering requirements vary and present unique challenges, 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. The challenges operators face with water will change from region to region.

“From the outback of Australia where water is scarce, the recovery of water is desperately required compared to the tropical climates of Brazil, where open pits rapidly fill with water, or sub-zero (-50°C) arctic operations in northern Canada that operate year-round – they all require effective water management systems,” Weir said. “Every site, in every country, experiences varying issues with water management and requires a strong partner to support them, whatever the issue.”

Ross said: “We have extensive experience helping either open-pit or underground mine sites with their water management challenges. 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.”

There are also a number of factors affecting the dewatering system, from the permeability and porosity of the ground, the amount of surface water, and geological features such as seasonal rainfall.

All of these must all be assessed and factored into a detailed dewatering system before work can begin, Weir said. The dewatering system put in place must be able to cope with this to provide a safe solution and minimise production delays.

What’s in the water?

The composition of water being moved has a notable impact on the equipment and materials used, according to Weir. “The pH range, temperature, corrosive and abrasive content 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.”

Equally, the pipework and valves are also subject to corrosion and abrasion from the products handled and must be designed accordingly, the company said.

“For every dewatering project, it’s important the original equipment manufacturer (OEM) understands the environment before developing the strategy, to deliver the optimal solution,” Weir said.

“The pitfalls of over- or under-sized equipment include excessive energy use, high cost investment and maintenance and also risk to equipment and personnel, as well as lost production in the case of insufficient capacity.”

Cameron Murphy, Regional Director of Dewatering for Weir Minerals, said the company has a range of flexible solutions that allow it to use several types of pumping equipment, from self-primed diesel driven, submersibles, vertical turbine and multi-stage to high-wall pump designs for sites that have limited access due to high-sided mine pits.

“Our development of sophisticated pontoon and barge designs allows our equipment to float out over water bodies for easier access. All designs are rigorously tested and include safety features to help prevent risk to operators. Each of our pontoons is designed with a fully-tested anchoring system and can be customised for extreme weather conditions,” he said.

Waste not, want not

With depleting ore grades around the world, there is an emphasis on turning waste into energy, and the dewatering process is no different. Weir Minerals produces equipment which not only dewaters mine sites, but also enables the operator to recycle and re-use back through the plant, it said.

Weir said: “Reclaiming process water for reuse is an increasing demand from operators as it can help overcome the issue of water scarcity, and ensure the operation is gaining maximum use of its resources. Weir Minerals has successfully partnered with a number of customers around the world to make this happen.”

There are multiple ways in which Weir can help its customers reclaim water from their tailings and re-use it throughout the mine site, according to Ross. “From pump house systems to innovative and customised barge solutions, we find a solution that is right for the customer. These options can be complex, and we work with the customer to educate them on how the systems work and showcase the benefits, it’s a collaborative approach,” he said.

More than just equipment

“Operators usually rely on multiple OEMs for dewatering projects; a labour intensive task dealing with different providers and ensuring a solution comes together in a streamlined process,” Weir said.

“Weir Minerals can remove this headache by project managing the entire dewatering solution, utilising products from our extensive dewatering range. This involves a thorough assessment of the requirements of the site, including the mine plan, operating depths, and existing infrastructure, as well as required water in-flow.”

Ross concluded: “We provide a resilient process against the backdrop of increasingly difficult conditions in which many of our customers operate. What we deliver is an optimal dewatering plan, backed up by recommendation for regular equipment maintenance to keep unscheduled stoppages to a minimum.”