Modern Mining June 2015

COVER STORY

The scope of work here has been multi-fac- eted and includes the construction of terraces entailing approximately 400 000 m³ of fill mate- rial to create the final 3 ha platform. The mine’s new No 2 decline shaft goes into the mountain at that level. Also included was the upgrading of a 5 km gravel access road, together with the installa- tion of stormwater systems, the building of four pollution control dams, and the construction of a ventilation shaft. Approximately 140 000 m³ of G5 material was sourced from the existing mine waste stockpile, with MK Africa carrying out screen- ing operations on site. Here MK Africa’s Cat 938K has been the primary loading tool. This G5 material was used as overlay for the road reconstruction, as well as for final terrace surfacing. Previous work at the mine has entailed bulk earthworks and civils at Modikwa South 2. The scope here involved 39 706 m³ of earth- works; 1 150 m of precast pipe installation; and 283 413 m³ of terrace layer works. Presently, MK Africa works on a maximum of three to five contracts in parallel in order to retain tight management control. “Our goal is to keep growing to the point that we become the employer of choice in our niche market, as we expand MK Africa’s construction footprint within the Southern African region. “Whilst the industry is generally under pressure at present, we at MK Africa have a reasonable pipeline of work for the near future and are exploring excellent prospects in the medium term with our ‘partners’ in both the mining and industrial sphere,” adds van Schalkwyk. 

provided a safer alternative during the devel- opment of Brakfontein ventilation shafts 2EO and 6W1. One option is to first excavate to the rock level, construct a concrete shaft, which in the case of Shaft 2EO would have been 20 m in height and then back-fill to return to ground level. This is a time consuming and expensive undertaking. Using the precast ring system to form the shaft, MK Africa, was able to back-fill incre- mentally, which halved the time it would have taken using conventional methods. MK Africa’s project scope entailed bulk excavation and stockpiling of 113 000 m³ of material to form the boxcut; and 170 m³ of reinforced concrete for the vent bases. Precast concrete rings of 4,5 m diameter were used for Shaft 2EO; and 6,1 m diameter precast concrete rings to a height of 10 m for Shaft 6W1. The final phase entailed backfilling and compaction of the boxcut to a total of 113 000 m³. MK Africa has used the same technique successfully on other projects, including Brakfontein ventilation shaft 2B4 at Bokoni. This involved the construction of a 38 m deep ventilation shaft. “This is an example of how we think ‘out- side the box’ to add value for our clients. The simplest solutions are frequently the best,” points out Venter. Modikwa No 2 shaft project A current example is an approximately 11-month bulk infrastructure contract, sched- uled for completion in June 2015 at Modikwa platinum mine, which is located some 15 km north-west of Burgersfort.

Approximately 140 000 m³ of G5 material was sourced from the existing waste stockpile at Modikwa dur- ing MK Africa’s recent bulk infrastructure contract at the mine.

June 2015  MODERN MINING  21