This phase entails the commissioning of the main and service shafts. In addition, the commissioning of the ore-handling system marks a major milestone in the project’s timeline.
WorleyParsons RSA, which has designed more deep mine shafts than any other company in the world, was responsible for the delivery of this phase.
“The most important phase in developing a deep underground mine with vertical shafts is equipping and commissioning the shafts to hoist – and we have successfully achieved that within the required timeframe,” says Ryan Illingworth, WorleyParsons RSA’s Project Director for the Bakubung platinum mine project.
He adds that with shaft steelwork, rock skips and man cages installed, and the production and service shaft complete, the vital work has been done and the second phase of developing underground infrastructure can continue.
The downcast production shaft, to be used for man and materials, has a hoisting capacity of 250 000 t of ore and 15 000 t of waste per month. A refrigeration system will provide bulk air cooling at a later stage. The layout of the 8.5 m diameter lined production shaft accommodates two 20 t skips, a two-deck cage with 12 t/150-man payload, a counterweight and 20-man service cage.
The 7.5 m diameter lined service shaft currently consists of a stage winder and kibble winder originally utilised for the sinking of this shaft but currently being used as auxiliary hoisting of rock and materials.
Other major milestones that WorleyParsons has achieved on this project include the construction of the main shaft terrace, main stores, workshops, temporary offices, sewage treatment plant, main access road and the production shaft headgear.
This 83 m tall headgear – for which WorleyParsons RSA received a South African Institute of Steel Construction Award in 2014 in the mining and industrial category – was erected in just 18 days and will be used to service all the conveyances. The three winders are ground mounted and include a Koepe winder for rock hoisting, a double drum cage/counterweight winder for men and material hoisting.
A significant optimisation effort that WorleyParsons RSA achieved during the first phase of the project was the local development and implementation of a cost-effective and highly efficient roping-up system instead of importing a more expensive system.
Illingworth explains that by working in conjunction with the Tech Edge group, WorleyParsons developed the first locally built Koepe roping-up equipment, suitable for four ropes simultaneously.
This tailor-made equipment included deflection sheaves, compression beam, rope reelers and friction winch all controlled from a central desk supplied by Schneider. This was specifically designed for Bakubung platinum mine and is expected to pass significant savings in both time and cost to the client over the life time of the shaft.
Wesizwe officially launched its flagship Bakubung platinum mine development project (previously the Frischgewaagd-Ledig project) on 4 July 2011 and WorleyParsons RSA has been involved in the project for almost a decade, from pre-feasibility and feasibility stages to being appointed as the engineering, procurement, construction management (EPCM) contractor in 2012.
The mine is located in the North Western Province of South Africa in the western limb of the Bushveld Complex and is expected to have a lifespan of 35 years and employ over 3 100 people when full production is reached.
The mine will produce 255 000 tpm at steady state for 24 years. Four mining levels are planned ranging from 690 m to 810 m below collar. Merensky and the UG2 reefs will be mined.
Merensky reef around the shaft area is intersected at about 730.9 m below collar and UG2 reef is 769.4 m below collar. A concentrator plant will also be built on the mine.
Feature image credit: WorleyParsons RSA