Impala Platinum has in place plans to maintain production levels at a minimum of 1.1 Moz of platinum for the next 30 years. A cost-effective R5.3 billion capital programme to extend the lives of the existing shaft systems and to develop new shafts to enable access to reserves was initiated in 1993. Of this, R4.6 billion had been spent by the end of the 2005 financial year. The first phase of this included the development of a series of five decline shaft systems below the current third generation vertical shafts and a vertical shaft link with No 12 shaft. At present, three decline shafts are in full production with development of the remaining two decline projects (11 shaft decline and 14 shaft decline) nearing completion. Capital expenditure of R6.6 billion for two new shaft systems (Shafts 16 and 20) was approved by the Implats board in September 2004. At full production, these two shafts, the first of the fourth generation shafts, will together produce 355,000 oz/y of platinum. No. 20 shaft is scheduled to come into production in 2009 and No. 16 in 2012. The No. 20 Shaft project is located north of No 12 Shaft on the north-west corner of the Impala mining lease area.

The scope of Murray & Roberts Cementation's project covers the sinking and equipping of a main downcast shaft, an upcast ventilation shaft, service infrastructure on surface and all ancillary excavations and access development necessary to establish the footprint for 185,000 t/month of Merensky and UG2 reef production.

Safety is the primary focus on the project, and the teams sinking the two shafts have excellent track records. The team on the main shaft recently completed the sinking, equipping and commissioning of the deepest single hoist shaft in the world (South Deep), while the team for the ventilation shaft completed sinking a shaft at Black Mountain, fatality free. Freddie Geldenhuys, business manager responsible for this sinking contract says Murray & Roberts Cementation has been on site for the past year, and three Lost Time Injuries (LTI) have been recorded. The commitment is to finish the project without any further accidents. The shaft system comprises an 8.5 m diameter downcast shaft to a depth of 1,051 m, and a 6.5 m diameter man, material and rock shaft together with an upcast ventilation shaft to a depth of 977 m. Pre-sink was completed to a depth of 99 m on the ventilation shaft and 80 m on the main shaft. This work was completed with a single sinking crew, completing the one shaft and then moving to the other shaft. A Scotch Derrick headgear was used for both pre-sinks. A single deck stage was used and cleaning of the shaft bottom was done with 630 loaders. For the pre-sink, 4.5 and 6 t capacity kibbles were used and all drilling of the bottom shotholes and support of the sidewalls was done with hand-held rock drills.

Sidewalls are supported by cladding and SplitSet rockbolts on an overlapping system. The shaft concrete lining is placed from the sinking stage concurrently with sinking operations, with the exception of the breaking and lowering of the curb ring, during which time there are no activities at the shaft bottom. During the pre-sink, the permanent sinking kibble and stage winders were installed. The main shaft headgear and kibble winder was supplied and installed by the client. All other winders and ventilation shaft headgear were supplied, installed and commissioned by Murray & Roberts Cementation.

The main-sink for the shafts is using multi-boom shaft drill rigs for the main and ventilation shafts. The shaft bottom advances at a rate of 3 m/blast with concrete lining concurrent, at a distance of 18 to 24 m from the shaft bottom. Both the ventilation and main shafts are cleaned by cactus grabs loading into 10 t and 12 t kibbles, respectively.

Site establishment started in November 2004. The main sink on the ventilation shaft commenced in July 2005 and on the main shaft in August 2005. The ventilation shaft is currently 400 m below collar while the main shaft is 260 m below collar. Both shafts are beating planned cycles. In the production month of October, both achieved more than 100 m for the month.

The shaft bottom in the ventilation shaft will be reached in May 2007 and the main shaft bottom in August 2007. On completion of the sinking, the main shaft equipping will commence and shaft bottom loading arrangements will be installed in the ventilation shaft. After this, Phase 1 access development will begin from the ventilation shaft, with concurrent equipping of the main shaft.

On completion of the development, the permanent loading arrangements for the main shaft system will be commissioned. Handover of the 20 Shaft project is planned for October 2008.