JSE-listed drilling solutions provider Master Drilling celebrated the manufacture of its one-hundredth raiseboring rig at its head office in Fochville, Gauteng, last month.

The RD8 raiseboring rig was designed specifically for larger-diameter raise boring applications and can drill shafts with a diameter of up to 8 m, and to a depth of up to 1.5 km in hard rock.

Master Drilling executive director Koos Jordaan told Engineering News during a site visit of its manufacturing facilities at its head office that the one-hundredth RD8 would be used in the construction of two ventilation shafts at Palaborwa, in Limpopo, with each shaft 6.1 m in diameter and 1.2 km deep.

The RD8 uses the latest operational technology, which is also fitted to other Master Drilling machines, and enables full diagnostics, as well as automated and remote operation.

Master Drilling’s remotely operated shaft support unit and inspection device will be used to line parts of the shafts, either during or after the raiseboring process.

The inspection device can scan the geometry of the execution and identify the lithology; this is important to determine the stability of the shaft during or after construction.

“Once completed, the project will qualify as the largest scope of raiseboring work per cubic metre ever embarked on worldwide,” he said.

The RD8 was designed with an extended height of 11 m, a total rig weight of 120 t and 1 600 kVA installed power.

“Compared with conventional methods, the RD8 is a lower-cost alternative and faster method that ensures shorter operational schedules, which, in turn, offers economical and sustainable benefits to the client,” said Jordaan, adding that the equipment and technology used reduced the number of personnel required to operate the machinery and, subsequently, safety-related issues.

Larger raiseboring rig types such as the RD8 are unique, as these machines are the only ones to use 3-m-long drill pipes. These longer drill pipes reduce the number of connections within the drill string, which significantly reduces the risks involved when drilling larger-diameter shafts.

Jordaan added that the RD8’s root size and ability to further expand its capacity from its current design make it unique.