Mining cleans up its act

Materials World magazine
3 Oct 2016

Could mining be going green? Rhiannon Garth Jones looks at areas where the industry has made changes in the past few years.

The sub-Arctic location of Diavik Diamond Mine, Canada, is remote enough that its workers are regularly treated to some of the most stunning views of the Aurora Borealis in the world. Temperatures reach –50°C and supplies are brought in by truck along a 340-mile long ice road to Yellowknife that is only accessible for 10 weeks a year. In 2016, the weather was so severe that the road was impassable for all but six weeks and the workers were unable to transport all the supplies needed for the rest of the year. 

To solve this problem, Rio Tinto, the owners of the mine, built a four turbine, 9.2 megawatt wind power facility that supplies 11% of the mine's annual power needs and operates at 98% availability. The wind turbines are specially designed, because the low temperatures mean that the standard lubricant used would freeze. Diavik now operates the world's largest wind diesel hybrid power facility at its remote off-grid mine. 

Mining companies and renewable energy technologies might seem unlikely partners, but this isn’t the only example. In fact, it’s not even the only example at Rio Tinto. The mineral extraction industry is quietly making some surprising forays into environmentally friendly territory. 

A business approach

Matthew Bateson, Head of Environment and Legacy Management at Rio Tinto, makes clear the motivation that led to the windfarm at Diavak. ‘It wasn't directly motivated by addressing a greenhouse gas emissions issue – although it has a tremendous environmental benefit and was the right thing to do – but it was driven by a strong business case.’ The inability to supply the site with fuel was the primary consideration, although the company is certainly proud of the successful technically challenging project.  

That attitude is also clear in his assessment of the company’s other major renewable energy project, Weipa. Bateson acknowledges that solar panel manufacturers have argued for many years that remote diesel could be substituted by solar panels, and that this was an area the company had considered and monitored but noted, ‘For years, it hasn't been economic, and we've had issues about integrating solar into the grid – we would need a hybrid system or battery storage to ensure continuous operation and that hasn't existed. But we've kept an eye on the technology for years as it improved, and the costs have come down. 

‘A few years ago, we started to look at sites where it could best be used. When it became viable, we worked with the business to make sure the costs added up – we didn't want to spend millions of dollars on solar panels if it didn't make sense. Eventually, a company came in and offered to put up the capital expenditure, and the Australian Government were providing subsidies, both of which helped make a clear business case. We've had some teething problems, but we have learnt a lot from it.’

Around 10 years ago, Bateson acknowledges, Rio Tinto had a different approach – not necessarily better or worse, but certainly different. ‘The approach then was for the company to take an industry leadership position on a number of issues. We had subject matter experts, people with a very high degree of technical competence on issues such as water and land management, biodiversity and emissions, to lead across the group. There was aspiration for leadership in the mining sector and beyond, which was seen as enhancing our reputation and license to operate. There was an attempt to build a business case for this. I think then we were seen as the leading company in this area. We were learning from the oil and gas industry but, certainly in mining, we were pushing the boundaries.’

Although the approach is different now, Bateson makes clear that he doesn’t think it’s a step backwards. Instead, he says, ‘The focus is on how we operate ourselves, rather than leading others’. He adds, ‘The environmental consequences at Diavik and Weipa are positive, but they're not the driver until such a time when carbon emissions have such a high price that it's automatically a business decision and, hopefully, at that time, we'll be ahead of the curve.' 

An industry shift

The 6.7MW off-grid farm at Weipa is not the only solar project to supply a mine. German company Cronimet Mining AG launched a subsidiary, Cronimet Mining Energy AG, in 2010 by commissioning a 1MW intelligent hybrid solar system for a chrome ore mine in Limpopo, South Africa. The system includes diesel generators to back up performance when the weather conditions mean the system can’t provide sufficient power. Keith Richards, Director of Projects and Power Systems at Cronimet, has publicly said that it makes sense for mining companies to use solar power, especially since, once the capital costs are paid off, the operating cost is much less than the price of diesel. 

Elsewhere, Barrick Gold has been investing in wind projects in both Argentina and Chile – where it also owns a small solar test plant. Scott Fraser, Barrick Gold’s Director of Power Projects publicly noted that the mining industry’s increased interest had contributed to the decision, as well as ‘the increased demand for renewable energy due to government regulations and the recent cost reduction in [those] technologies.’ However, he has also made clear that ‘one of the biggest challenges for completing renewable energy projects [is] the strong demands for capital at this point in time.’

In an article published in Energy and Mines, Fraser suggested that declining ore grades, necessitating more sophisticated refining processes, will cause the energy used per unit of production to increase further – a factor that could make renewable technologies more tempting in future.

And that’s not all...

As Bateson made clear, the cases above have had a clear business argument – energy is, overall, becoming more expensive, especially as regulations come in to make emissions costly. In these circumstances, renewable energy is likely to make increasing sense for many companies. But this is not the only area where the mining industry is burnishing its environmental credentials. Rio Tinto’s environmental policy covers water, air emissions and the management of land, chemically reactive materials and waste. 

Zero discharge water programmes are becoming common, such as those provided by Condorchem Envirotech, which works across the industry. The water discharged at mines can have serious consequences because of the contaminents it often contains. Processes such as vacuum evaporation and crystallisation remove this problem and aim to make the water reusable – removing both the need for costly disposal processes and increasing the efficiency of water use.

Reclamation of legacy sites can be an expensive business, although, when done well, it can restore a site to its former beauty, preventing aesthetic scars on the landscape and any possible future safety concerns. The National Mining Association estimates that USA-based mining companies have reclaimed more than 2.8 million acres of previously mined land, creating recreation areas, parks and even wildlife reserves. The reclamation work at Richards Bay, South Africa, by Rio Tinto is a well-known example of how well this type of work can be done, but it is far from the only one. 

The former Ereen coal mine in Mongolia, operated by USA-based Peabody Energy, was transformed into 44 acres of grassland for traditional livestock grazing in a US$1 million project that consulted the local nomadic communities, kept their cultural practices and land uses in mind and employed local families as caretakers. The project also provided a source of fresh drinking water in an area that did not previously have easy access to potable water.

Although the public perception might be that the mining industry is not the best place to find environmentally friendly practices, it has made huge strides in recent years and is well worth keeping an eye on for the future, particularly in those areas where a financial case can be made.