A successful shaft sinking project entails the correct installation of various components timeously, in addition to experienced personnel working on the project from the outset and maximising the time spent at shaft bottom, says fastener supplier Swagefast sales manager Neil Koen.

The company’s involvement in projects such as the K4 Shaft at diversified miner Ivanhoe Mines’ Platreef platinum group metals and nickel mine, in Limpopo, underscores the importance of specialised suppliers in ensuring the integrity and success of complex engineering projects, such as shaft sinking, he adds.

Swagefast is a member of South African Capital Equipment Export Council’s South African Shaft Sinking, Equipment and Services supply group.

“Swagefast gets involved in the intricate process of shaft sinking once civil or structural engineers make contact, seeking expertise on the determination of fastener types, fastener sizing, installation specifications and tool access considerations . . .”, explains Koen.

This engagement, he adds, is a critical step in the construction and maintenance of mine shafts, considering that shaft sinking is an essential activity in mining and civil engineering projects, as it provides the primary means of accessing underground orebodies during the development of an underground mine.

The terminology used to describe shaft sinking is based on the starting point of the excavation. When excavation starts at the surface, it is referred to as a “shaft”; however, if the excavation starts underground, it is known as a “winze” or a “subshaft”.

Additionally, small shafts may be excavated upwards from within an existing mine, assuming there is access at the bottom, and these are called “raises”.

The methods differ significantly between shallow shafts, typically sunk for civil engineering projects, and deep mine shafts, usually sunk using conventional drill-and-blast methods or mechanised means. Deep mine shafts can either be developed vertically or at an incline, although Koen says most modern mine shafts are vertical for efficiency and safety reasons.

If access is available at the bottom of the proposed shaft and ground conditions permit, raiseboring may be used to excavate the shaft from the bottom up, resulting in what is known as borehole shafts.

“The design of mine shafts, including their shape, dimensions and depth, varies greatly to meet the specific needs of the mine and the geological conditions,” says Koen.

For example, in North and South America, smaller shafts are designed to be rectangular, with timber supports, while larger shafts are round and concrete-lined.

Following excavation, shafts are usually lined to ensure safety by preventing loose or unstable rock resistance, and to ensure adequate airflow for ventilation.

“Mine shafts are used for various purposes, including the movement of people, materials, auxiliary services, air ventilation and the extraction of ore or waste. They also serve as vital escape routes in case of underground emergencies,” he explains.

Previous mining accidents resulted in local regulations now requiring that all underground mines have a second means of access, often resulting in shafts being constructed in pairs.

Leading shaft sinking contractors are mainly based in Canada, Germany, China and South Africa.

“Shaft sinking is recognised as one of the most challenging and hazardous tasks in mining, with workers and contractors facing numerous obstacles such as restricted space, gravity, groundwater and soil composition,” he concludes.