New way to mine hard rock impresses veteran researcher

JOHANNESBURG (miningweekly.com) – A new way of breaking rock in Southern Africa’s narrow-reef mines is seen as safety and production enhancing.

Veteran researcher Rod Pickering, who spent 20 years at the Chamber of Mines Research Organisation (Comro) running the stoping technology laboratory, says he has yet to come across a better rockbreaking solution.

After leaving Comro in 1996, he has spent another couple of decades focused on the adoption of better mining methods in the narrow-reef space.

“Moving to nonexplosive mining is where we need to be going,” says Pickering, who has witnessed controlled foam injection (CFI) in action in Colorado, where it has been developed by fellow researcher Chapman Young, the president of CFI Technologies.

Using it would mean that Southern Africa’s hard-rock gold, platinum and chrome mines could operate around the clock, twenty-four hours a day, seven days a week, which current drill-and-blast technology does not allow.

“There’s no loud bang, no dust. It’s a gentle way of breaking the rock, and that’s one of the important things about the use of foam,” he says. (Also watch attached Creamer Media video).

But how does a mixture of air and water with a little bit of soapy material manage to break hard rock?

In much the same way as explosives do, except it happens in a totally inert way, with no chemical reaction whatsoever.

A probe placed into the drilled hole is sealed to keep the foam in the hole under pressure, and out pops a large slab of rock.

CFI is seen as a replacement for small-diameter, short-hole drilling and blasting and a new way of mining the hard rock, both for tunnel development and stoping.

“It would come with mechanisation. This is not going to be someone out there with a hand drill, drilling a hole and then taking this big cylinder and pushing it in the hole. A machine will drill the hole, index round, insert the foam injector probe, seal it, release the high pressure foam and break the rock,”  says Pickering, who spoke to Creamer Media’s Mining Weekly Online on the sidelines of last week’s Southern African Mining and Metallurgy Institute’s minerals colloquium.

CFI has broken every rock type encountered during trials and it could be used in place of all mining and civil engineering rockbreaking processes that use explosives in short and small-diameter blast-holes.