Recent years indicate a rapid growth in the African mining industry that is likely to continue well into the future as more markets open up and new resource companies enter the market, says South African project management and engineering company DRA Mineral Projects.

The company reports that it has placed itself squarely at the centre of the current mining boom, building a strong reputation on some of the continent’s largest mining projects. The company has provided expertise in mine engineering, development and project management through complete end-to-end solutions, as well as in contract operations and maintenance for mineral processing plants through its sister company, Minopex.

While the company maintains an extensive international footprint that extends from Canada to China, India and Australia, it remains a strongly South African company capable of handling a broad spectrum of projects in the coal, copper, diamond, platinum, gold, nickel and iron-ore sectors. The company is also focusing particular attention on uranium as a resource.

African Footprint

The company is aggressively expanding its African operations, having established regional offices in Zimbabwe, Mozambique, Tanzania and the Democratic Republic of Congo (DRC). It has also undertaken new projects in countries such as Botswana, Namibia and Zambia. It is involved on a turnkey basis in mining house Perseus Mining’s Central Ashanti Gold project, in Ghana, and other recent projects.

DRA states that it recently featured strongly in the platinum sector with projects such as platinum producer Platmin’s Pilanesberg platinum mine, in the North West province, miner Anglo American Platinum’s (Amplats’) Unki platinum mine and the Ngezi phase one and two projects in Zimbabwe for mining house Zimplats. Other projects include Amplats’ 600 ktpm Potgietersrust platinum plant, the largest of its kind in the southern hemisphere, and the Booysendal platinum concentrator for miner Northam Platinum.

Minopex currently operates a total of nine platinum concentrators in Africa, processing a total of 18-million tons of ore a year and producing 1,2-million ounces of platinum-group metals.

DRA is also entrenched in the coal sector with projects stretching back as far as 1986. Since then, the company has built plants for multiple national mining companies.

It recently designed and built the coal washing plant at Hakhano Colliery, coal company Keaton Energy’s No 5 Seam plant and a 14-million-ton-a-year coal preparation plant for miner BHP Billiton Energy Coal South Africa.

Other work includes a 16-million-ton-a-year washing facility, a run-of-mine storage and materials handling system for Phola Coal and a 50:50 joint venture between BHP Billiton and Anglo Coal. Minopex operates six coal plants on a contract basis.

Renewed interest in the copper belt north of Limpopo has seen DRA complete work such as the copper preconcentrator project at the Etoile mine, in the DRC, as well as new projects in Zambia.

DRA also recently completed phase 2B of platinum producer African Rainbow Minerals Platinum and Russian nickel miner Norilsk Nickel’s Nkomati nickel concentrator. The system will enable the client not only to process nickel, but also to exploit the chrome content of the local ore.

The second phase of DRA’s largest iron-ore project, Khumani, is under way and will see an expansion of the mine’s output from 10- million tons a year to 16-million tons a year.

Bridging the Olifants River

DRA reports that the Dorstfontein project, in Kriel, South Africa, is its turnkey division’s largest project to date and includes a 10,5 km overland conveyor traversing a 160 m bridge over the Klein Olifants river.

The requirement for an overland conveyor, which necessitated a river crossing, is due to a change of scope after what was thought to be the final conceptual plant design acceptance.

The change of scope resulted in a full tender enquiry procedure being implemented by diversified energy company Total Coal. DRA’s proposal to launch prefabricated sections across the Klein Olifants river resulted in the company securing the con- tract for project.

DRA’s civil and structural division, Holley & Associates, which was tasked with designing the bridge in its installed form, supplied the structural integrity.

“Preparation was key to a successful ope- ration and, although upfront planning and innovative design were essential, ground- level input was also critical. A full launch-pad area was set up on the south side of the river, where the incremental launch was to take place,” the DRA states.

Bridge sections weighing 14,4 t each were supplied as 18-m-long fabricated latticed girder sections measuring 1,5 m in depth and 5,2 m in width. Each section was delivered to site as an abnormal load and bolted together to the correct torque specifications. Further, calculations were completed to prevent the cantilever section from giving in to an excess of weight on the launch pad.

Two 32 t hydraulic jacks were positioned on either side of the bolted girder sections, which incrementally jacked the composite unit onto the permanent concrete pillars. Temporary steel support structures were connected on either side of the support pillars to reduce the cantilever distance for the erection period.

A temporary nosepiece, designed to catch the temporary supports and allow for a calculated deflection of 430 mm, was bolted to the front section. The nosepiece and the temporary supports were removed once the bridge was locked into its final position and the four masts and stays installed. At this stage, the maximum unsupported span was 57 m.

Although the full launch of the bridge sections brings the ‘bridge launch’ to a close, only half of the overland conveyor construction process is currently complete.

DRA also reports that 22 t of suspension steelwork will now be installed and the bridge platform dressed with the idler support frames and completely covered with a sheeted housing. This complies with all of the required environmental specifications when launching a bridge across a river.