First-class fabrication
As mines get deeper in search of ore, so is the contest for the coveted prize in the category in the mining and industrial category. However, in spite of stiff competition from equally compelling entries, the Bakubung Platinum Mine notched the first prize.
The 2014 Mining and Industry winner, the Bakubung Platinum Mine, under Wesizwe Platinum Limited, is an underground mine with a twin vertical shaft system- a main shaft and a ventilation shaft which also functions as the second escape route – and a process plant.
The first priority
From the engineering perspective, the headgears have been designed to satisfy the sinking requirements for the shaft, the equipping stage, over and above permanent mining use with all the skip unloading facilities and safety equipment for emergencies.
The headgear’s core constituents
The structure consists of a frame designed to resist horizontal and vertical wind loads, three sheave levels with the upper level at 72 metres above the bank, a 14 metre centre tower between the bank and the underside of the sheave levels, six floors to the tower, a 30 ton capacity electric overhead travelling (EOT) crane and support structure tops out the structure. A full height staircase and elevator to the 72 metre level complete the structure.
What’s the fuss about the headgear?
The designs of the headgear and its associated loads are in accordance with the SANS10208 series of specifications. These specifications were drawn up by a committee under the auspices of the SAISC.
The dominant loads are gravity, wind and the forces associated with the loads on the ropes and snapping of the steel wire ropes and the catapult-like effect it would have on the headgear. Skip tipping loads are considered for the permanent use. There are other impact loads from emergency situations such as overwind of conveyances that have been taken into account.
Specifically, the steelwork needs to be fabricated to the highest standards with many full NDT tested penetration welds, considering that the heat input from all the welding can lead to distortion. And so, ensuring that the structural elements are dimensionally correct after all the welding is a top priority.
Implementation key
For all its inspiration, the Bakubung Platinum Mine’s design would have no substance without meticulous execution. For this reason, the critical step to kick-start operations was to get the headgears and shafts built so that mining operations could commence.
In terms of steel works, the most important elements included prime painting done to the steel and flooring, hot dipped galvanising of permanent small steel components, and full painting specifications to plate girder components.
In his analysis of the project, Spencer Erling, the 2014 Steel Awards convenor, was very precise. He had this to say:“This a structure where there are literally thousands of bolts, all fitting without modification and tightened to specification, which is testimony to the 3D detailing using Tekla and the accuracy of fabrication. What a pleasure to see and experience and the exceptional quality and final presentation of the steel work. Louwill Engineering has certainly produced excellence in the use of steel.” And nobody can dispute this assessment.
Project Team
Developer/ Owner: Wesizwe Platinum Limited – Bakubung Platinum Mine
Structural Engineer: WorleyParsons
Quantity Surveyor: WorleyParsons
Project Manager: WorleyParsons
Main Contractor: Louwill Bakgoni JV
Steelwork Contractor/s: Louwill Engineering
Detailers/ Detailing Company: PCSA Structural Steel Detailers
Cladding Contractor: Pierrecon Staal
Cladding Supplier: Global Roofing Solutions
Corrosion Protection: BLM Corrosion Protection
Crane Hire: Sarens SA
