The Asia Miner

JUN 2018

The ASIA Miner - Reporting Important Issues to Mining Companies in the Asia Pacific Region

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the asia miner • volume 15 • issue 2 20 WASTE TO ENERGY Former mining communiƟes across UK could find a new lease of life – with old mine shaŌs turned into hi-tech green energy stores. This is the plan of energy start-up Gravitricity, which has received a £650,000 grant from Innovate UK, the UK Government's innovaƟon agency, for their plan to harness the power of gravity to store renewable energy. Their technology uses a massive weight suspended in mine shaŌs to capture green power, and then release it in seconds. If Gravitricity's plan succeeds, their technology could breathe new life into former mining communiƟes, adding jobs and economic acƟvity. The UK funds will enable them to start building a scale demonstrator later this year and find a site to install a full- scale prototype by 2020. They are now on the look-out for investors, including those who can bring mining experience to the team, and suitable shaŌs to trial their technology. And once they have proven the technology in old mines, they then plan to sink new shaŌs to store energy wherever it is required. "As we rely more and more on renewable energy, there is an increasing need to find ways to store that energy – so we can produce quick bursts of power exactly when it is needed," explains company managing director Charlie Blair. "So far there is a lot of focus on baƩeries, but our idea is quite different. Gravitricity uses a heavy weight – up to 2000 tonnes – suspended in a deep shaŌ by cables aƩached to winches. "When there is excess electricity the weight is winched to the top of the shaŌ ready to generate power. "This weight can then be released when required – in less than a second – and the winches become generators, producing either a large burst of electricity quickly, or releasing it more slowly depending on what is needed," Blair explains. Unlike baƩeries, the Gravitricity system can operate for decades without any degradaƟon or reducƟon in performance, Blair states. The idea of using gravity to store energy is not new. Britain already relies on a number of pumped storage hydro schemes, such as Ben Cruachan, where water is pumped uphill to be released when required. "The difference is we don't need a mountain with a loch or lake at the top, and we can react much faster," says Blair. He says the biggest single cost is the hole, and that is why the start-up is developing their technology uƟlising exisƟng mine shaŌs, both in the UK and also in South Africa. As the technology advances, the cost of drilling will reduce significantly and will allow them to sink purpose-built shaŌs wherever they are required, the company claims. The start-up plans to build models from 1 to 20MW, and esƟmates each 'Gravitricity Energy Storage System' will last up to 50 years. Disused mine shafts to become green energy stores of the future Barrick's Lagunas Norte turns its waste to energy Barrick's Lagunas Norte operaƟon has used an Ohio based modular thermal waste to energy specialist – Eco Waste SoluƟons (EWS) – to install an energy recovery system. The Lagunas Norte operaƟon is located on the western flank of the Peruvian Andes at an elevaƟon of over 4,000 meters above sea level. The open-pit, crush, valley-fill heap leach operaƟon produced 387,000 ounces of gold in 2017, with producƟon in 2018 anƟcipated to reach 230,000-270,000 ounces of gold. As much as the rise in mining in Peru over the last 15 years has been seen as a posiƟve impetus in improving the country's economic posiƟon and the welfare of its people, it did also create a problem of increased and varied waste streams in an area that makes landfills unfeasible and the transportaƟon of waste too expensive. When the Canadian owned gold mining company opened its Lagunas Norte site, it knew that it would not be able to rely on a convenƟonal waste disposal and treatment soluƟon. Rather, it would require an on-site waste management system capable of handling waste generated by 1,600 residents including domesƟc waste and special wastes like by-products from equipment servicing, oily rags, filters and various liquids. EWS provided a soluƟon to Barrick's problem by supplying the mining company with its ECO 2TN-25LPH model. It was selected by Barrick for its ability to process all the idenƟfied target waste streams, as well as its ability to meet strict environmental standards. It processes up to 2 tonnes of solid waste and 250l of liquids per day. To simplify the waste tracking, operaƟons and air emission monitoring requirements, it was concluded that a combinaƟon system that could process both solid and liquid waste would be ideal. The ECO model with an integrated liquid waste combusƟon system was selected. It can process all the target waste streams that would otherwise leave a legacy long aŌer the mine closes and is well suited to the mining environment. Liquids such as glycol and used lubricaƟng oils are eliminated. This reduces the clean fuel requirements for processing the solid waste – a significant cost savings in a remote locaƟon where fuel costs are much higher. Gravitricity's technology uses a massive weight suspended in mine shafts to capture green power, and then release it in seconds

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