Additional shaft-sinking work was awarded early this year to international shaft-sinking and underground construction group Shaft Sinkers by platinum producer Lonmin for work at its existing Karee 3 upper group two (UG2) project, in Marikana, Rustenburg, in the North West.
The Karee No 3 shaft UG2 decline will enable Lonmin workers to mine the UG2 reef on four levels, between levels 21 and 25. The subdecline will balance the depletion of the Karee No 3 shaft from a production and mining efficiency point of view and will ensure continued availability of stope faces at the shaft.
The work at the Karee 3 UG2 project consists of two separate contracts covering the extension of the UG2 decline and the ongoing operation and maintenance of the decline shaft. The additional work, which is currently under way, is scheduled for completion in October 2015 and has a total value of £11.4-million.
The initial Karee 3 UG2 contract, valued at £8.6-million, involves the development and associated civils work for the extension of the Karee 3 UG2 decline from Level 25 to Level 26, including all associated bulk infrastructure. The extension of the UG2 decline will enable Lonmin to access further ore reserves to 900 m below the surface, helping to maintain production levels at Karee 3. The UG2 contract was signed on an agreed target cost basis.
Meanwhile, the mine shaft contract, valued at £2.8 million, is a cost-plus contract to maintain and equip the shaft.
“I’m delighted that we have secured these additional contracts with Lonmin. They represent a strong endorsement of the quality of our work by a valued and long-standing client. I would like to congratulate the Shaft Sinkers team working on Karee 3 for their diligence and hard work,” says Shaft Sinkers CEO Alon Davidov.
He highlights that Shaft Sinkers specialises in the sinking of particularly deep and wide vertical and decline shafts and the development of underground infrastructure, used primarily in mining and hydropower applications.
“Shaft Sinkers has the capability to sink shafts through all types of rock strata, including running sands and clay,” says Davidov, adding that Shaft Sinkers works principally for established mining and infrastructure companies.
Historically, the group has completed projects in more than 20 countries across Africa, Europe, South America, the Middle East, Asia and Australia.
Shaft Sinkers was responsible for sinking one of the deepest ever man-and-materials South African shafts, a secondary shaft at gold mining major AngloGold Ashanti’s TauTona gold mine, west of Johannesburg, to a depth of 3 131 m below bank.
Meanwhile, Shaft Sinkers has been awarded additional work by platinum miner Afplats, which is owned by Implats, on its existing Leeuwkop project.
The scope of the work includes the continuation of sinking activities on the main shaft at Leeuwkop to a depth of 984 m from the current level of around 700 m. The contract, which is currently under way and was signed on a rates basis, is scheduled for completion in June and has a total value of £2.2-million.
This follows a previous contract extension at Leeuwkop in August 2013 under which the group introduced revised working practices that have resulted in cost savings for the client, while also gaining significant time on the project schedule.
“The recent introduction of an innovative new shift system by the Shaft Sinkers team at Leeuwkop has saved Afplats time and money. This is a clear example of the strong technical skills and commitment to operational excellence of the group’s employees. We look forward to continuing to work with Afplats on the successful delivery of this project,” says Davidov.
The development of the Leeuwkop project represents the first phase in the turning to account of the Afplats acquisition. The project involves the development of a 1 350 m twin-shaft system to access the orebody.
Mining operations will initially begin at around 1 100 m below surface and extend to a depth of about 1 500 m. Other major infrastructural developments to be undertaken include the construction of a concentrator facility with a capacity of 250 000 t/month and a tailings dam. Both of these will be constructed to allow for possible increases in capacity should future expansions to the mining operation become viable.
While the mine design and production profile is still to be finalised, the most likely mining method will be mechanised bord-and-pillar mining. Ore will be accessed through a four-barrel on-reef decline system, which will enable a rapid and cost-effective ramp-up to production from development.
“The UG2 orebody is well developed relatively wide and, in comparison with other areas, relatively undisturbed by major faulting,” says Davidov.
Shaft Sinkers says that a key advantage for Implats is the project’s location on the well-developed western limb of the Bushveld Complex, with its proximity to the extensive management, services, technical and processing infrastructure at Impala Rustenburg, some 55 km away.
“Further, the sourcing of scarce mining skills is expected to be less challenging than on the eastern limb of the Bushveld Complex as this is a long-standing mining region with an available, skilled human capital base,” says Davidov.
The mine will exploit the UG2 reef in the Leeuwkop area. Yearly capacity at full production will be three-million tons a year (250 000 t/ month), yielding 140 000/oz to 160 000 oz of platinum from ore averaging 3.75g/t. Capital expenditure is estimated to be R3-billion over the first five years. There is a 22-year life expectancy for the project.