The deep challenges of deeper mining

Mines are getting deeper. As a consequence, the costs of ventilation and cooling, the time required to get workers to the face, and the distance required to transport ore to the mill are all increasing.

Some of the biggest recent trends in the industry have arisen in response to these challenges. For example, ventilation on demand and emission-free battery-electric vehicles (BEVs) are being adopted to keep a lid on the cost of ventilation in underground mines. The introduction of BEVs also avoids adding the heat generated by diesel powered machines into an already high-temperature environment, potentially cutting the energy costs required for cooling.

And of course, the promise of automation is to one day remove workers from the inherent dangers of working underground.

Continuous mining – which has the potential to dramatically increase productivity by shortening or eliminating the lag time between each part of the drill-blast-muckground support cycle of underground mining – may also be part of the solution.

At the Future of Deep Mining conference in September, organized by the Centre for Excellence in Mining Innovation (CEMI), Vale principal mining engineer Andy Charsley, noted that industry and OEM efforts to develop mechanical rock excavation technology are intensifying.

“We at Vale certainly see mechanical rock excavation having a future in deep mining, where we’ve got very deep mines that are hot, and broad horizontal extents where it takes time to get people out to them,” Charsley said.

Continuous mining machines already work well for rock of up to 150 MPa. In the near term, OEMs are focusing on machines that can handle slightly harder ore, such as sulphide ores, which have a rock strength of around 200 MPa, rather than harder, more challenging ores of 250-300 MPa, Charsley said.

Further into the future – and not unique to underground operations – the mining sector needs to grapple with waste and the opportunity to eliminate tailings before they are even produced, said Janice Zinck, director of green mining innovation at CanmetMining.

How? Through looking at the whole mining process holistically instead of considering mining, milling, and tailings disposal separately.

“The whole mine-to-mill integration is critical in terms of looking at opportunities around selective mining and waste recovery and intelligent recovery of the ore itself,” Zinck said. “A lot of these pieces are not standalone.”

Lastly, as we at CMJ, continue to cover the challenges, trends and innovations that are transforming the mining sector, we are preparing to wish a happy retirement to a colleague who has seen a lot of change over her 45 years as a mining reporter. I want to wish the very best to our news editor, Marilyn Scales. Marilyn has been a valuable resource to me since I joined the CMJ team nearly three years ago, and to our readers for the past four decades and more. It’s been a pleasure working with you, Marilyn – you will be missed!