Mines change approach to water management

12th May 2023 By: Bonginkosi Tiwane - Creamer Media Reporter

Water is a crucial resource and plays a vital role in the mining sector, but climate change and sustainability challenges have forced mines to reconsider their approach to water management. Various factors, such as urbanisation, deforestation, contamination of water resources and overallocation, have resulted on a water shortage in various mining catchments.

Experts, such as consulting firm WSP in Africa, are able to provide consulting services on water management across the mining cycle, providing a complete perspective to allow for efficient and effective design and strategy.

“We’re seeing increasingly that water security is being evaluated as one of the major risks when looking at prefeasibility studies,” says WSP in Africa principal associate Priyal Dama-Fakir.

She says that, previously, project development was predominantly driven by capital. While capital is still the key determining factor, water is demanding more attention in project evaluation, in terms of not only potential environmental impacts but also whether the mine will have sufficient water throughout its life.

Even with brownfield or expansion projects, clients are required to consider project viability in relation to water stewardship, particularly in terms of improving efficiencies to enhance water consumption.

For example, if a mine site is allocated 10-million litres of water a day, and it cannot increase that allocation, then more efficient and innovative means of operating must be considered if it wants to increase production.

“It would need to expand in a way that reduces water consumption, ensuring that it isn’t increasing its overall water needs,” adds Dama-Fakir.

WSP in Africa assists mining companies in implementing innovative workflows to improve operational performance by enhancing understanding on surface and subsurface conditions and implementing practical solutions.

The consultancy’s experienced teams have provided surface water, groundwater, geochemistry, water treatment and water engineering consulting services and have developed fit-for-purpose solutions focused on mine water management and subsurface characterisation.

Dama-Fakir defines fit-for-purpose solutions as those that incorporate an understanding of where water is being consumed and what the restrictions are in terms of water-quality requirements, enhancing reuse whilst reducing treatment requirements.

“For example, mines should try to use poorer-quality water in areas that aren’t impacted on by water quality and save better-quality water for the sensitive areas.”

This approach often results in improved equipment longevity and water reuse and recycling while reducing municipal water consumption on site.

Responsible Water Management

One of the drivers for responsible water management is the liability associated with poor water management.

“Water liability will continue long after mining activities have ceased, especially for opencast mines,” says Dama-Fakir, adding that South African legislation is stringent in terms of outlining a mine’s water-related obligations.

“The legal consequences for failing to comply with this legislation is what’s driving a lot of the responsible behaviour,” she says, adding that mines must account for their water-related activities to the regulator and, in many instances, to shareholders. There is also a cost implication, as mines are required to manage and treat their water long after mining ceases to prevent contamination of the water resources, and demonstrate that this will continue to obtain a closure certificate.

She believes that the need to comply with water-use licence conditions encourages better behaviour across the industry, but suggests that mines across the continent invest in functional water and salt balances, and improve monitoring throughout their sites.

“We often see that flow monitoring on site is primarily focused on streams that cost the mines money, like mines monitoring the potable line coming onto site, but not monitoring the reuse streams.”

She quotes the late Professor Chris Buckley, who stressed that “one cannot manage what they do not measure”, and comments that they have seen various case studies where improved flow monitoring and data interpretation have resulted in new water savings and improved water management.

Further, typical water-saving initiatives currently being implemented include the use of improved density control on tailings thickeners, evaporative covers, side-stream treatment processes to allow for improved reuse on mine impacted water streams, dust-suppression additives, dry stacking for tailings and waterless cooling systems.

“Ideally, simulation modelling and conceptual-level engineering studies are needed to assess these opportunities. These are site specific and there is no one-size-fits-all solution,” says Dama-Fakir.

Meanwhile, opportunities to prevent noncontact water mixing with mine-affected water, such as active dewatering, water separation and continuous rehabilitation, can also reduce long-term water liabilities.

Mines in arid areas tend to be more efficient when using water, says Dama-Fakir.

“However, there has certainly been a mind shift around responsible mine water management over the past five years. Water and salt balances, and water management plans are no longer seen as grudge purchases, but rather management tools used to aid compliance.”

Environment, social and corporate governance reporting, and initiatives from the International Council on Mining and Metals (ICMM), are also key drivers for facilitating a broader change in industry, in light of concerns about the impact of mining on the environment. But ICMM goes far beyond climate change impacts. In 2003, ICMM published its ten principles for sustainable development to set a standard of ethical performance for its members. Over time, they have worked to expand on these with eight position statements on key issues, such as water stewardship and transparency of mineral revenues.

Further, improved data management and tools, such as business intelligence tool Power BI, enable companies to present water losses, reuse efficiency and new water consumption figures from various sites on a single platform, creating a healthy competition between sites and driving better behaviour.

WSP in Africa can also help mines responsibly navigate some of the effects of climate change, with Dama-Fakir noting that it recently aided water management activities for a Ghanaian mine’s processing plant, tailings dams and return water facilities. The company also sized a treatment plant, and recommended wet and dry season operating levels for the return water facilities to reduce the risk of spillage in the wet season while ensuring water security in the dry season.