Precast concrete sleepers saved time and money for the client in the construction of a new 4 765m overland ore conveyor at Bafokeng Rasimone Platinum Mine JV. The conveyor runs from Styldrift’s No.1 Shaft storage silos to the mine’s concentrator.
A total of 227 sleepers in combination with percussion-drilled imported fill were installed in place of concrete plinths in areas of poor founding and over three animal crossings. As they were manufactured and fully cured off site, the use of the sleepers enabled works in progress to continue undisturbed.
Each weighing 690kg, the sleepers were manufactured according to specified drawings at a rate of 20 per day using custom-made moulds. They included cast-in U-bolts which were installed at a Class 1 degree of accuracy and which facilitated bolting the conveyor framework onto the sleepers. In addition, cast-in eye bolt holders enabled the sleepers to be installed by crane at a rate of 15 per day.
The total combined length covered by the sleepers was approximately 850m. The conveyor is 1.2m wide and has a 45˚ trough. It feeds 1 000 tonnes of Merensky reef ore (2.8 to 3.15 tonne/m³) per hour. The nominal particle size transported is 350mm at a load factor of 55%.
No non-conformances were issued during the various quality inspections performed during the manufacturing process.