Water is the lifeblood of our planet and a resource essential to minerals processing, which must be used conservatively. Itis critical for every mine site, and mine operators must be conscious of how they use it, as well as being innovative in its re-use and handling.

In operations, water is predominantly used for minerals processing in dust suppression and slurry transport. Without it, the entire operation would stop.

Every mine site faces a different challenge with water: it is either scarce or in excess, which causes various issues respectively.

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

“There is no ‘one size fits all’ approach to dewatering,” states Ian Ross, Global Product Manager for Dewatering at Weir Minerals.

“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.”

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, for example, 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 (-500C) arctic operations in Northern Canada that operate year-round. All of them, irrespective of their varying challenges, require effective water management systems and a strong partner to support them.

“We have extensive experience helping either open pit or underground mine sites with their water management challenges,” comments Mr Ross.

“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 – including the permeability and porosity of the ground, the amount of surface water, and geological features such as seasonal rainfall – which must all be assessed and factored into a detailed dewatering system before work can begin.

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

The composition of water being moved has a notable impact on the equipment and materials used. 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.

The pipework and valves are also subject to corrosion and abrasion from the products handled and must be designed accordingly.

To deliver the optimal solution for every dewatering project, it is important the original equipment manufacturer (OEM) understands the environment before developing the strategy.

The pitfalls of over or undersized equipment include excessive energy use, high cost investment and maintenance, 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 says the Company can supply a vast range of flexible solutions that allows Weir to use several types of pumping equipment.

“We can offer a selection ranging 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.

“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,” states Mr Murphy.

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 that not only dewaters mine sites, but also enables the operator to recycle and re-use back through the plant.

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 we can help our customers reclaim water from their tailings and re-use it throughout the mine site. 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,” says Mr Ross.

Operators usually rely on multiple OEMs for dewatering projects, which is a labour intensive task dealing with different providers and ensuring a solution comes together in a streamlined process.

Weir Minerals can remove this headache by project managing the entire dewatering solution, utilising products from its 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.

“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,” Mr Ross concludes.

Weir Minerals use expertise in both process and products to maximise efficiency and help operators take control of their water. Visit www.dewateringsolutions.weir for more information.

*Article published in the July-September 2019 issue of The Asia Miner

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