With far superior safety standards in the industry irrespective of the length of an exploration drilling contract, Murray & Roberts Cementation is known to deliver even under the harshest and most difficult geological conditions.

Pete Ferreira, general manager mining services at Murray & Roberts Cementation, says that good core recovery is as important as achieving a consistently good production rate on surface exploration contracts.

"Use of appropriate machines for a given application coupled with competent skilled operators is an important factor as is the use of technologically advanced directional drilling techniques," Ferreira says.

The Rotary Vertical Drilling System (RVDS), originally pioneered by RUC and MICON, offers levels of accuracy substantially higher than other pilot hole directional drilling systems. Ferreira explains that it is possible with the use of the RVDS to improve pilot hole accuracy to a tolerance of 0.1%.

Gyro-based technology is incorporated into the controlled drill head tooling and this facilitates drilling of inclined holes to a just as high a degree of accuracy.

Murray & Roberts Cementation is currently undertaking a number of surface drilling contracts on the Africa continent.

Surface exploration drilling is being done at Konkola Copper Mine in Zambia where approximately 20 000 metres will be drilled between the contract start in June 2005 and March 2006. Exploratory drilling is being done to improve the size of the ore reserve for both near surface and deep ore bodies. One Boart Longyear LF90 and three Smith 620 drill rigs are being used on this contract.

Ferreira says the LF90 is a new machine which was purchased to cater for the increased demand as it is capable of achieving higher efficiencies. The machines have been mobilised because of the anticipated increased surface exploration requirement in Zambia.

Further north in Ghana, two Sullivan 50 drill rigs are being used for surface exploration at Obuasi Deep. The contract duration is three years at this gold mine, and drilling will be done to depths of 3800 metres with multiple deflections. A total of 28 000 metres will be drilled.

"This is a technically challenging contract as we need to ensure a high level of accuracy in the top section of the hole which is not simple due to the geological conditions in this region. The geology is very steep and the drill string tends to follow the geology seeking softer ground," Ferreira says.

"High levels of accuracy are being achieved through the use of directional drilling techniques as well as regular surveying of the holes and wedging."

Exploration drilling to delineate and confirm the platinum ore reserves at Afplats’ Leeukop project is nearing completion. Drilling being done with the Boart Longyear LF230, purchased specifically for this contract, will be completed in February 2006.

Another contract nearing completion is the drilling of multiple holes to varying depths at Modikwa using one Boart Longyear LF90 and two Smith 620 drill rigs. This contract reaches completion at the end of the year.

Exploration drilling is ongoing at Moab Khotsong where two Sullivan 50 rigs have been doing deep hole drilling to a depth 3000 metres for the past year.

A Sullivan 50 is being employed at Red Bush in Groblersdal for the purpose of delineating and confirming ore reserves for Ridge Mining.