JSE-listed Master Drilling is currently developing a new Shaft Boring System (SBS) that aims to revolutionise shaft sinking in hard rock by eliminating the need for conventional blasting in hard rock material.

The system is designed to bore shafts of varying diameters, which range from 4 m to 11.5 m, depending on the client's requirements.

The SBS is currently being tested at a site in Fochville, Gauteng, where it is boring a shaft with a diameter of 4.3 m to depths between 50 m and 100 m.

The machine uses a specialised patented cutter head, known as the W-cutter head, which has been specifically developed to drill through extremely hard rock, such as 320 MPa norite.

The machine's average advance rate is about 1 m an hour, although achieving a consistent rate has been identified as a key challenge.

"If you look at this technology and compare it to what's out there in the market, there isn't really something in the market that can do hard rock, and that's really the difference," Master Drilling new business development manager Izak Bredenkamp said during a live demonstration of the machine on September 6, which Mining Weekly attended.

The SBS has been designed to enhance safety and efficiency by reducing the need for human presence in the shaft during the boring process. The machine can theoretically operate 24 hours a day without the need for personnel to physically enter the shaft, as is necessary with conventional methods.

In traditional shaft sinking, people are required to drill, blast and excavate the material manually, which can be dangerous.

"It's going to be safer. In conventional shafting, you’ve got about 50 people working on it at any given time and it would take anywhere between seven and eight years to complete," Bredenkamp noted.

Master Drilling’s latest machine is capable of boring at depths of up to 3 000 m, with the possibility of achieving a diameter of up to 11.5 m in future iterations.

Currently, the machine is configured for a 4.5-m-diameter shaft at the test site, with an average progress rate of about 5 m to 6 m a day, compared with the 1.5 m a day typically achieved using conventional methods.

"If you look at conventional shaft sinking, they're doing 1.5 m a day. That’s why it takes seven years to do the shaft. However, even if we only achieve 3 m a day, it's still half the time it takes to sink a shaft through conventional means, and it's obviously safer," Bredenkamp said.

The development of the SBS has required capital expenditure (capex) of about R200-million so far.

Master Drilling CFO Andre van Deventer reveals that about R2-million a month is spent on testing and running costs.

“The big thing we're talking about now is the commercialisation of this, because we're not going to do it with this [testing] machine. We’ll need to spend new capex of between R600-million and R700-million for the real McCoy," Van Deventer said.

Bredenkamp also pointed out that the commercial version of the SBS would likely be designed to bore shafts with a diameter of between 7.5 m and 10 m, which would meet the majority of clients’ needs.

"That seems to be the sweet spot for most of the client requirements," he said.