South Africa-based Mine Support Products (MSP) last month launched Rocbolt, a hydraulically set anchoring device, with a patented friction ring that enables the device to resist pull loads of up to 12 t.
“Hydraulically set anchors are a proven way to reinforce the surrounding rocks and excavation in underground mining operations. The advantage of this design is that it combines the benefit of a full- length friction anchor with the characteristics of an end anchored bolt,” notes MSP GM Conrad Engelbrecht.
The Rocbolt is a fabricated steel tube that is C-shaped in cross section and sealed at both ends. At one end, a hydraulic filler nipple allows connection to a hydraulic pump and an integral nonreturn valve on the nipple that allows the user to either contain the water under pressure, which improves the pull-out resistance, or release the water, which improves the ability of the anchor to deform with the rock mass.
MSP marketing manager Ivan Jacobs explains that a hole is drilled through overhead rock fractures, which are caused by a combination of blasting and stresses in underground mining operations. The Rocbolt is then placed inside the hole and water is pumped into it at 35 MPa, causing it to expand and hold the rock mass sur- rounding the excavation in place.
Jacobs says the friction bolt locks in the harder rock above the fractures when the Rocbolt expands and is the reason for the device exceeding the industry standard pull load of 8 t.
The Rocbolt varies in length, from 900 mm to 3 m, and has a diameter of 28.9 mm at the friction ring and 26.8 mm elsewhere.
It was developed and manufactured at MSP’s office in Vereeniging, Gauteng. The steel tube used for the unit was supplied by steel, tube and pipe manufacturing company Robor.
The unit has been tested at the operations of China-based nonferrous metals mining, processing and trading company China Nonferrous Metals-owned Luanshya Copper Mines (LCM), in Zambia, and MSP hopes to export the unit to LCM’s mines in the near future.
“Further, MSP is aiming to gain more international exposure by exhibiting the Rocbolt at the Peru-based mining exhibition, Perumin, to be held in Arequipa, Peru, from September 16 to 20,” says Engelbrecht.
“MSP will attend the event as part of the South African Department of Trade and Industry delegation,” he says.
Engelbrecht says the Rocbolt is potentially exportable to countries where hard- rock mining conditions exist, such as in Australia, South America and China.
However, he adds, MSP will focus on the South African market, as the company is familiar with the local market conditions, and expand into copper-rich countries, including the Democratic Republic of Congo, Zambia and Peru.
The development of the Rocbolt began in February 2012, as MSP identified the fractured rock mass support market as a viable option in which to expand its product line.
MSP has also tested the Rocbolt at some of South Africa-based gold mining company Sibanye’s operations, says Jacobs.
Engelbrecht concludes that the company is in discussions to supply the Rocbolt to South Africa-based platinum mining companies Impala Platinum and Anglo Platinum.