• Core innovation

    With the ever-growing spotlight on environmental accountability, miners look to solutions that ensure their operations are cost effective and energy efficient.

    Core innovation

    The global mining industry in general – and coal miners in particular – will not look back on the final months of 2015 with a great amount of fondness.

    At the UN conference on climate change (COP21) in Paris, diplomats thrashed out a deal that called for a shift in energy supplies – away from high-carbon sources and towards cleaner, non-coal alternatives.

    The news could not have come at a darker time, as coal-mining companies around the world were – as with so many other minerals – still reeling from a year of plummeting prices and rising debt.

    For ‘coal’ you could read any mineral, from platinum to gold. All mining activities have been guilty of environmental- and energy-related inefficiencies – but coal is certainly the worst offender.

    Just ask Greenpeace. According to the global environmental NGO: ‘Coal-fired power plants are the biggest source of man-made CO2 emissions. This makes coal energy the single greatest threat facing our climate.’

    Coal production gets a similarly grim review. For the best illustration of the environmental impact of coal mining, one need look no further than the mammoth Carmichael coal mine. If it goes ahead, this project – proposed by Adani Mining and located in the Galilee basin in central Queensland, Australia – will be the biggest coal mine in the country, and one of the largest in the world. It will also be one of the world’s heaviest polluters.

    ‘Reducing usage by just one light bulb keeps a half ton of CO2 out of the atmosphere through the LED’s life cycle’

    New figures from the Australia Institute think tank show that Carmichael will emit 79 million metric tons of CO2 equivalent every year. To put that into perspective, Carmichael’s annual emissions will be about double the levels of Tokyo, three times as much as New Delhi, and six times as much as Amsterdam.

    According to the report: ‘Adani expects Carmichael will output 2.3 billion [metric tons] of coal over its lifetime: enough to build a road – 1m thick, 10m wide – wrapped around the world five times.’

    Faced with numbers like that, the mining industry as a whole is being forced to comply with ever-stricter environmental regulations.

    In November 2015, as South Africa entered a summer of deepening droughts and water shortages, water restrictions were imposed on Rustenburg, the hub of the country’s platinum mining industry.

    Residents asked – reasonably so – why those restrictions didn’t also apply to the mines. South Africa’s Minister of Water and Sanitation Nomvula Mokonyane responded by urging mining companies to use water sparingly.

    ‘Every mining company has water usage licences,’ Mokonyane told South Africa’s national broadcaster. ‘There are conditions that go with that licence. Among those are water conservation and management. So every mining house has to make sure that it does not only depend on additional supply, but also has systems to preserve water.’

    Continuing the shift to more efficient energy usage, renewables such as solar have an increasingly important role to play in the sector. Mines across the country are also moving to LED-based lighting.

    It uses 60% to 90% less energy than incandescent lighting and is more durable, and while LED products are more expensive, they last about a hundred times longer than an equivalent halogen light.

    ‘As one of the most energy-efficient light bulbs on the market, LED is the most environmentally friendly because it has a lower carbon footprint and, when discarded, does not leach poisonous mercury into the ground,’ says Leonard Chester, product manager at Torre Automotive, distributor of VisionX Lighting’s Cannon LED light.

    ‘LEDs last 35 to 50 times longer than incandescent lighting, and about four to 10 times longer than fluorescent lighting. Reducing usage by just one light bulb keeps a half ton of CO2 out of the atmosphere through the LED’s life cycle,’ he says, adding that LEDs are also 98% recyclable.

    Meanwhile, Impala Platinum (Implats) announced in April last year that it would use fuel cells to provide energy at its platinum group metals refinery in Springs, beginning in early 2016.

    ‘We are very excited about the prospects of fuel cells,’ Implats CEO Terence Goodlace said at the announcement. ‘Albeit early days, we’re starting to see the roll-out of fuel cells in fairly large numbers in niche uses as the energy solution of choice.

    ‘On the mining front, we are working to convert our underground LHDs from diesel-driven power into fuel-cell hybrid configurations. Here we are collaborating with local mobile mining equipment manufacturers, Mitochondria and our international fuel-cell partner, SerEnergy, to integrate solutions that offer a superior cost and carbon solution for underground mining. We expect that this conversion will provide Implats a competitive advantage in underground materials movement, and provide our miners a healthier and safer working environment.’

    When it comes to energy efficiency in mining operations, however, water and lighting are not the real issues.

    According to Van Zyl Brink, researcher at the CSIR in South Africa, overall energy usage isn’t the most effective way to look at energy efficiency. Instead, ‘you need to determine which areas would yield the greatest gains if you changed the way you work’, he says.

    ‘In fact, lighting is a very small component of energy usage, and there’s also very little scope for improvement. [In terms of] water, there’s very little you can do to reduce the cost of taking a litre of water and pumping it 2 km up to the surface. So again, that’s not really an area that you would look at if you wanted to optimise your energy usage.’

    The biggest potential gains in terms of energy consumption lie in optimising the processes around ventilation and cooling

    The main scope for improvement, Brink says, lies in ventilation and cooling. To understand this, you have to understand the working environment in a mine.

    As part of the research for his book, Gold: the Race for the World’s Most Seductive Metal, US journalist Matthew Hart spent time in the world’s deepest gold mine – Mponeng, in South Africa’s North West Province. Here, the shafts drop 4 km into the Earth and the rock faces reach temperatures of 60°C.

    ‘You can imagine what it’s like to crawl into a cavity there,’ Hart told NPR in an interview. ‘It’s like crawling into a pizza oven.’

    To keep those temperatures fit for human habitation, an ice slurry mixed with salt is pumped down from the surface. Large fans then blow air over the ice to form a controlled cold-air system within the mine. The ice-making plant goes through about 6 000 tons of ice a day – all to keep the temperatures in the mine at a liveable 29°C.

    ‘In a deep-level mine especially, there is a huge amount of wastage when it comes to cooling,’ says Brink. ‘Often you’re cooling areas that don’t need to be cooled, because there’s no mining activity happening there.

    ‘There’s also very little in terms of so-called “ventilation on demand”. Mines are maintaining the environment down there continually – 24 hours a day, seven days a week – and if you wanted to close an area down, for example over a long weekend, there’s no facility to stop that ventilation process.’

    Brink agrees with the notion that the biggest potential gains in terms of energy consumption lie in optimising the processes around ventilation and cooling in mining operations.

    ‘It’s been recognised as a major issue,’ he says. ‘To some extent, it’s habit – in that we don’t have efficient monitoring systems in all our mines. You really need to know the quality and the temperature of the air before you send people back in there – and those kinds of monitoring systems would enable you to make decisions around redirecting the cold air or switching it off.’

    Ironically, then, as the mining industry comes under pressure around its CO2 emissions and its effects on the air on the Earth’s surface, the biggest challenges in terms of energy efficiencies lie in the air below the ground. The air that its miners are breathing. 

    By Mark van Dijk
    Image: Gallo/GettyImages