Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/1085636
March 2019 Water. desalination + reuse In Site 27 The mining industry has a bad reputation on water. The tail- ings dam collapse at Córrego de Feijão mine in Minas Gerais state, southeastern Brazil, in January 2019, killed 169 people and le‚ 141 missing. The col- lapse of the 86-metre high iron ore tailings follows a similar incident in Minas Gerais state in November 2015, at a site owned by Vale and BHP. That disaster killed 19 and destroyed the vil - lage of Bento Rodrigues, near the town of Mariana. "Tailings ponds are the high- est profile, particularly when they leak. They are spectacular and that's the problem," says Hu Fleming, chief executive of Anglo American. Such high pro - file failures combined with the water scarcity affecting many mining regions are driving up water management to the top of the industry's agenda. Stakeholder concern "Historically I spent all my time focused internally, looking at the sites, supporting and leading our operations and strategy. Now I spend half my time with stakeholders, investors, share - holders, government agencies and lots of other public interest groups that have an interest in water management and manag - ing risk. Water has become very out-facing as an issue whereas 10 years ago it wasn't," says Fleming. He continues: "We need a 'social licence to operate'. We had a leak in Brazil: it wasn't toxic, no-one was hurt, no veg - etation damaged. But the gov- ernment pulled our operating permit and it cost us $1 billion. These are big numbers. You can get a fine of $5 million or $10 million. But if you threaten to pull an operating permit that's big. Governments are sensi- tive. Many of the international mining companies are focused on making sure that doesn't happen." The mining industry's response has been to begin developing a more risk-based approach to water manage- ment. This combines measures from minimising freshwater abstractions to improving water efficiency in mining operations to reusing and recycling water to developing alternative water sources. Technology-wise, it in- cludes process water, monitor- ing and analysis and wastewa- ter treatment. Water efficiency Mining uses about four per cent of global freshwater abstrac- tions each year. However mines o‚en consume a much higher proportion than this in the catchments where they operate. New projects are now likely to be developed hand-in-glove with local communities. "The majority of new mines in the next several years are in water stressed regions. Demand is growing for metals used in batteries - lithium, nickel, copper and gold. Those are all southern hemisphere, mean - ing South America, Africa, Australia and China. All tend to be low water areas. Miners are increasingly in competi - tion with local communities for water resources," says Fleming. "We have to modify how much water we're taking out, how we are taking it out and how we are processing it - all because of water availability." One part of the answer is alternative water sources which are now used at a third of Anglo's sites globally. "There are only so many freshwater sources. We can't compete for lakes or sub-surface sources because in most countries the public has priority. The obvious one is desalination - going to the sea or a brackish source somewhere. There is a big push on desalination in certain parts of the world. We along with other miners are building desalination plants," says Flem - ing. The other commonly used alternative sources include raw or treated sewage and industrial effluent such as power plant wastewater. The challenge for technol - ogy vendors is that the water element of a new mine is one part of an overall much bigger project that typically comprises power plants and pipelines, monitoring capability, sump collection and geotechnical railways. Says Fleming: "We are looking for firms that can pro - vide a solution, the total pack- age. They may say 'I did this municipal desalination project and therefore I can do a project for Anglo'. No, not even close. You can build the desalination plant at the coast, but that's a tiny part of the project. Who's going to do the rest? To a miner, the rest is the project." Miners' other water risk abatement measures include improving water efficiency within the mining operation. "We have a number of process - es that are proprietary - we're progressing to simply not bring- ing in this massive amount of rock and processing it. We have found ways to extract the met- als right at the mine site before bringing it to an extraction plant. The net effect is to mas- sively reduce the total solids and total water generated. For us that's a big one. It involves advanced filtration, directed laser cutting in the mining pro- cess and hydro-blasting," says Fleming. "Generally - the larger miners anyway - are reducing the amount of water they need in the mining operation. They're getting smarter, more efficient," he adds. Reuse technology Vendors may get a warmer reception from miners on water reuse. "Mining is considered a small market for water treat - ment. It's actually not, it's very large," says Fleming. "Vendors tend to say 'I have this kit or this filtration device that we use in chemical processing and you can apply it.' Well fine, but we are really pretty complex in terms of our water use. These are really complex streams. We tend not to get products specific to our need. So you have to adapt or modify or work with them to build something that's unique. Technology for miners is very specific. It has to be one-off per site and it requires a partner - ship in development." On tailings, the industry has zero liquid discharge in its sights. "Major miners have moved to risk-based water management. With tailings, we know it's an issue and as an industry we are putting more effort, energy and money into addressing that. There is a set of technology in treatment where you say, 'Okay, I have a certain amount of water in the processing circuit. I am going not to discharge any of it. I'm going to recycle.' We and oth - ers are going to near complete recycle. We're about 65 per cent now and we're going to 80 per cent in the next couple of years. Eventually, nearing 100 per cent." The result could be a solids-only tailings product that would be welcomed by all. 'We and others are going to near complete recycle' Anglo American's head of water management Hu Fleming on mining's water challenges and how demand for metals found in the water-scarce southern hemisphere is growing Mining is considered a small market for water treatment. It's actually not, it's very large.