Advancing Together With Barrick Gold

Environment A perspective on water and mining

We speak with an expert who says there's growing interest in how mining companies use water, and how those choices affect local water resources

As part of our effort to keep you informed about our industry, we are launching a new feature called “Broadening Borders.” We will regularly publish feature interviews with, or articles by, third-party thought leaders on subjects that are important to you, our stakeholders. This includes innovation and technology, gender and human rights, community relations, energy, and the environment.

Today we cover one of the hot-button issues in mining: water. It is a critical resource that touches virtually every aspect of the mining process. It is also a shared resource that is critical to life. It is, as Laurie Reemeyer explains, something that people expect as a right. Stakeholders want to know how the industry is using water, and what we're doing to mitigate potential impacts.

Reemeyer is well-placed to address these and other questions about water in mining. He is Founder and Principal Consultant of Resourceful Paths, a Vancouver-based consultancy that helps clients develop an integrated design approach to reduce energy and water consumption, and waste footprints, from tailings disposal. He has more than 20 years of experience in metallurgy, operations, project management, and consulting. He has worked at base metals mining and smelting operations throughout Australia, and led studies for the Oyu Tolgoi copper-gold project in Mongolia, and the Blackwater gold project in British Columbia. He has also led sessions and roundtables on water use in mining at a number of conferences, including the Global Water Summit, one of the world’s biggest annual conferences on the water industry. He holds a Bachelor of Engineering (Minerals Process) from the University of Queensland, and an MBA from the University of California, Berkeley.

Beyond Borders: Water is invariably at or near the top when mining industry stakeholders are asked to list their top priorities and challenges. Why is water such a critical issue?

Laurie Reemeyer: Water is very closely associated with life. It’s essential for drinking, crops, livestock, and so forth. It’s something people expect as a right. Many regions in the world are increasingly water stressed. So there is heavy competition for water.

When it comes to mining, stakeholders want to know how water is being used, and how mining activities affect water quality. They want to know how water interacts with materials from a mine, such as waste rock or tailings, and how that might impact other water users in the region. There’s a growing acceptance that climate change is having a significant effect on water resources. In Chile, for example, climate change is understood to be behind a shift from snow precipitation to rainfall in the mountains, where the country’s big copper mines are located. Stakeholders are concerned about how this affects water flows and water storage, the security of water supplies, and the potential for flooding events and mudslides. Miners have to address all of these concerns, and there are obviously a lot of complexities.

As regulations around fresh water usage become more stringent globally, the mining industry is looking to alternative water sources. One option is desalination. What are some of the more promising developments in this area?

Desalination is definitely on the rise in mining, and some operators are even using raw seawater to process certain ores. Most modern desalination facilities use reverse osmosis. This involves pumping saline water at high pressure through semipermeable membranes to filter out salt and other minerals. It’s an expensive and energy-intensive process. The main focus, therefore, in desalination is finding ways to do it with less energy, and make it more economic. In the last 10 years, there has been quite a lot of development in this area. The main innovation has been around pressure recovery devices, which have made the desalination process more efficient and affordable.

What a lot of people don’t realize is that the most expensive part of the desalination process is transporting the water to a mine. You may have a mine in the mountains of Chile, for example, located 150 kilometers from the sea. The cost of getting water to a site like that can run as high as $3.00-per- meter cubed, more than the cost of desalinating the water itself. So the real questions are, can the volume of water used be reduced, can water-pumping systems be made more efficiently, and/or can mine processing facilities be built in locations that reduce the cost of pumping these alternative water sources? We may soon see companies locating processing plants more strategically to minimize the distance or elevation that water needs be moved.

What proportion of water do you think will come from ocean or sea water in the next five to 10 years?

The Chilean Copper Commission, Cochilco, recently issued a report predicting that seawater will account for 50 percent of water used by the mining industry in Chile by 2026. That compares to about 19 percent today. That’s a significant increase and gives a sense of where things may be headed. Obviously, usage levels may differ in other parts of the world due to distance from the sea—think of places like central Australia—but companies are certainly looking at desalination because there’s just not the security of supply from fresh water sources anymore. Having said that, it’s not as simple as a company saying, “We’re going to switch over to seawater and everything will be okay.” Mineral processing with seawater can impact recoveries and maintenance costs due to corrosion. Companies must do their research and test work to understand the potential issues, mitigation measures, and costs.

Are mining companies doing enough to engage stakeholders when it comes to water-related issues?

Expectations are very, very high and, quite frankly, stakeholders always believe companies can do more. That may seem a little unfair at times to those in the industry, but it’s the reality of the world we live in. I think what stakeholders generally expect is transparency. They want to know how mining companies evaluate the design and choices they make around the use of water, and how those choices affect local water resources. Companies need to educate communities about what happens in the mining process, and how the industry manages water responsibly. That takes time, and while most companies understand this, things aren’t always perfect. Tensions, for example, can arise when metal prices trend higher and companies look to expedite projects. Stakeholders may want more information about the potential impacts of such projects, and expect companies to provide it. Water is invariably a primary concern, and companies who hope to secure their license to operate would do well to take the necessary time to properly address the community’s concerns.

In the wake of the Samarco and Mount Polley tailings dam failures, companies are taking a closer look at dry stacking—tailings disposal that does not require large volumes of water. However, dry stacking is expensive. Is it a viable option for large mines?

Some companies say it’s too expensive to dry stack tailings, but that view has to be considered in the context of the capital costs and risks associated with conventional tailings disposal. Samarco and Mount Polley underscored the massive costs if mining companies don’t, for whatever reason, properly design or manage conventional tailings facilities. Dry stack offers a way to dramatically reduce tailings failure risk and increase water recycling, so companies may be starting to realize that there’s an economic case for this investment. 

As it stands, the scale of equipment required to filter water out of tailings has not kept pace with the other types of processing units. Crushers, SAG [semi-autogenous grinders] and ball mills, and flotation cells, have gotten much bigger, but filtration units, not so much. And it’s a bit of a chicken and egg situation. Equipment manufacturers will respond with larger equipment if the industry shows a willingness to invest in it, and the industry will only invest after someone successfully uses the large-scale equipment first. So it’s a race to be second.

Are data analytics becoming more evident in water management? How might this improve the industry’s ability to monitor and manage water?

Water companies are increasingly using data analytics to manage networked water infrastructure, particularly for detecting leaks, minimizing pumping costs and capacity bottlenecks, optimizing predictive maintenance, and understanding effects of droughts on water supply. Companies such as Rio Tinto are investing in data analytics across wider parts of their businesses. Mine fleet optimization is typically where mining companies would start to use data analytics. The generally high level of instrumentation at most mining sites, coupled with an increased use of data analytics in operational areas, should allow companies to extend these methods to improve decision-making in areas such as water management.