Modern Mining September 2021

Karowe Mine

sink shaft equipment. The pre-sink phase also allows the sinking process to commence as soon as possible while the main sink infrastruc- ture is being fabricated and installed. The new underground mine’s production shaft will have an A-frame type headgear, which will hoist 21-tonne payload skips, and will have a single drum auxiliary winder for people movement, and a man/material winder with counterweight and a big cage to service the underground. UMS has refurbished four winders which will be going to the mine for shaft sinking, including two stage winders and two Kibble winders. The company also purchased and refurbished Scotch derrick winder cranes which will be used for the pre-sink. Mobilisation At the rime of writing, UMS was in the process of mobilising up to 170 people to site for the pre-sink, which was expected to commence at the end of August and will take between eight and 12 months to achieve changeover ready for the start of the main sink. The main sink will take another two years after that, ready for mine development to commence in 2024, and full underground operations in 2026. To make sinking safer, Louw says that UMS has adopted different sinking methodologies and equipment to be used at Karowe. “In the past, we used to sink with cactus grabs which needed people in the bottom. We are now using vertical shaft muckers and are buying state-of-the-art jumbo drill rigs to drill at the bottom. We’re doing inline work as opposed to concurrent work with people working at the bottom.” He adds that as part of its safety manage- ment plan, UMS has established a training centre on site at Karowe that facilitates inductions and train- ing of local operators on the various equipment. The company is constructing a mock-up training tower on the surface to train operators on vertical shaft muckers and will have a similar training simulator for excavator operators. With prospects of more open-cast mines tran- sitioning to underground in Botswana, the local community stands to benefit from obtaining special- ised skills related to shaft sinking. Louw says that UMS is fully established in Botswana and has partnered with Botswana Investment and Trade Centre to ensure that the project work permits run smoothly. Furthermore, the UMS design engineers are registered with the

Botswana certification boards and can sign off all engineering designs and drawings for the project. 

Kibble on Karowe ventilation shaft bottom.

Key takeaways  United Mining Services (UMS) is gearing up for the pre-sinking of two shafts at the Karowe Underground Mine Expansion Project in Botswana  UMS was appointed by Lucara Botswana Pty Ltd and JDS Energy & Mining Inc. in October 2019 to engineer and design the shaft sinking of the production shaft and the ventilation shaft, both reaching a depth of approximately 750 m below surface  The company’s wealth of knowledge and expertise in shaft sinking played a key role in securing the contract  Two shafts at Karowe will be blind sunk using conventional drill and blast techniques

September 2021  MODERN MINING  23