WATER MANAGEMENT & TREATMENT
Water wins
BQE
From holistic water management approaches to dewatering pumps and technologies to water treatment including a specific focus on selenium , Paul Moore takes in a bit of everything in this water in mining focus
Looking at water management in mining , it is good to look at the big picture and the overall approach . A holistic , multidisciplinary and integrated approach to water stewardship provides the most effective and defensible route to setting and achieving water saving targets , argues Grace Yungwirth , Technical Director – Mine Water at WSP .
She adds : “ The equitable and sustainable use of water is one of the key challenges facing mining companies around the world , and one that touches upon many aspects of environmental , social and governance ( ESG ) performance . In areas of water scarcity , reliable and sustainable access to a suitable supply of water is critical , not just for mining companies but all local water users , whether for communities , agriculture , or other applications . Meanwhile , commitments to positively support local ecosystems and nature-positive outcomes place additional demands on water priorities .”
Against this background , mining companies are committing to reduce their water consumption and improve their water recycling and reuse metrics . Yungwirth : “ There is a business imperative here : reliable access to water of suitable quality is frequently identified as a key risk to the continuity of mining operations . But companies also recognise that water is an essential communal resource and are committed to its equitable and sustainable use by all of the catchment stakeholders .”
This is a complex undertaking . Water stewardship investments must be balanced against financial costs and other objectives , such as decarbonisation , net zero and energy use targets . Yungwirth : “ In addressing this challenge with WSP ’ s mining clients , we have found the best solutions are developed through a holistic and collaborative approach . Forming a multidisciplinary team of technical experts , operational staff and project stakeholders , we brainstorm potential opportunities and are able to innovate solutions drawing on different areas of expertise . Identified opportunities can then be evaluated at a high level and developed through to concept level engineering and costing to allow evaluation of the options on a cost per megalitre saved basis , alongside other local and projectspecific priorities .”
She argues that a particular benefit of this multidisciplinary approach is seen when identifying potential technologies and solutions for delivering water savings . “ Because these will encompass the integrated expertise of all stakeholders , the result is a more comprehensive assessment than could otherwise be achieved and that moves beyond the typical approach of interrogating the water balance . Results will certainly include technologies that are widely known , such as evaporative covers or dewatered tailings . But novel options will also rise to the surface , like replacement of pump gland seal water with mechanical seals , as seen in the oil and gas industry .”
The ultimate outcome is a well-documented , defensible and inclusive plan for targeted
investment in water stewardship programmes at the site or across a portfolio of sites . “ This is an incredibly powerful tool for the operator , bringing
Water specialises in providing innovative wastewater treatment solutions to the global mining industry
transparency to decision making , with key stakeholders clearly able to see why certain projects are prioritised over others . These key decisions can then feed into both corporate target setting and reporting .”
She concludes : “ There is little doubt that mining and mineral processing operations will require an increasingly proactive approach to water stewardship , including a focused approach to water savings , to meet ESG targets and mitigate water-related risks . We have seen the benefit of close collaboration between a mining company ’ s technical teams , multidisciplinary consultancy teams , and engagement with all relevant stakeholders , to develop a comprehensive and integrated assessment of solutions . Such an approach offers the potential to expedite the mining industry ’ s ability to meet their ESG commitments while promoting transparency and trust with stakeholders , advancing water stewardship priorities , and of course saving water .”
Optimal results and operational flexibility in underground dewatering
Underground water management in mining can be challenging . Looking at this topic we talked to Nick Lancaster , Weir Minerals , Product Manager – Mine Water , Thickened Tailings and Paste Pumps . He says that in the past , the majority of underground mine dewatering systems were clean water systems , requiring large sumps to settle out solids . “ However , there ’ s now more of a focus on quicker implementation of dewatering systems and an understanding among mine operators that mine water is never really clean – that it always has some solids in it and that needs to be planned for .”
As a result , underground mine dewatering systems are increasingly being designed to handle dirty water from the outset . Lancaster says this might mean using more robust materials within a clean water pump or simply designing a pumping system that ’ s capable of handling dirty water .
This latter option has advantages in terms of space and capital expenditure . “ Put simply , there are obviously space constraints in underground mines and if the pumping system requires additional space to be excavated for settling sumps or vertical dams , these works are both capital and time intensive . Moreover , dirty water pumps have been specifically designed for higher wear and abrasive duties .”
Another common issue Lancaster says is that the sumps are almost always neglected and are rarely cleaned as frequently as they need to be , if
International Mining | MARCH 2024