World record-breaking steel headgear extracts gold award
- By Deborah Minors
An engineering alumnus leads the steel company which manufactured the world's tallest steel headgear (the hoisting mechanism a-top a mineshaft) and which won the Mining and Industrials category of the national Southern African Institute of Steel Construction (SAISC) Awards on 15 September 2011.
Managing director of Steel Services & Allied Industries, Lawrence Bartlett (BSc Eng Mech, 1997) oversaw the R100-million steelwork component of the 87m tall, 1900 tonne A-frame structure built at Gold Fields South Deep Twinshaft complex in Westonaria, south of Joburg.
We are proud to be a critical part of the project team that successfully supplied, fabricated and installed the tallest, if not largest, steel headgear in the world, says Bartlett.
The conversion of Gold Fields South Deep existing vent shaft into a production shaft increases the mines rock-hoisting capacity by 195 000 t/m. Combined with the existing main shaft rock winder, the headgear will help the mine reach its gold production target of 750 000 oz/y by late 2014. The headgear will likely extend the life of the mine by more than 50 years.
The Gold Fields headgear won the Excellence in the use of structural steel category at the SAISC Awards. Judges said the project was a flagship in the use of steel and excellently met challenging structural requirements.
Extending the height of the existing concrete headgear was not possible since its foundations were not designed to accommodate the additional mass, Bartlett explains. Since the existing headgear was still operational, destroying it and rebuilding the headgear was also not an option. The only viable option was to construct a new headgear from steel, and erect it over the top of the existing headgear.
Further challenges included the height; erecting headgear on top of an existing shaft (from the west side, which was the only option); rotating the legs off square to increase strength; and working with knuckle connections weighing in excess of 40 tonnes.
The Gold Fields headgear now trumps the worlds former tallest steel headgear structure; the 81m high Konkola Copper Mines Konkola Deep mine in Zambia. South Africa retains the second-highest steel headgear record, with Impala Platinums Shaft 17 headgear, near Rustenburg at the same height as Konkola.
The worlds tallest concrete headgear is at Impala Platinums No. 16 shaft, near Rustenburg, North West Province. It is 132m high.