Unplanned power outages, which have affected business across South Africa in recent years, has prompted a major platinum miner in the Thabazimbi district to invest R6-million on the installation of stand-by diesel-driven underground dewatering pumps to prevent flooding in the event of serious or sustained power outages.

The order for the pumps, placed on Weir Minerals Africa, is believed to be the first of many from South African mines, which pump water on a 24-hour basis to keep their operations dry. Weir Minerals Africa's deep mines dewatering division sales manager Rui Moreiras says an order has been placed on the company for two MSG 12 pumps fitted with 1050-kW caterpillar diesel engines.

Each 12-stage pump will deliver clear water at a rate of about 60 l a second at a head of 1050 m.

"Hundreds of MSG pumps have been installed in South Africa's deep mines for dewatering purposes, but this is the first time that we have been asked to supply such a pump fitted with a diesel engine. Our client said they were not in a position to take chances with Eskom's uncertain power supply as a sustained cut would result in flooding," Moreira said.

South African industrial group Barloworld will supply the two Caterillar 3516 16-cylinder V four-stroke turbo-charged engines and the units will be manufactured and assembled at the Weir Minerals Africa site in Isando.

Moreiras comments that Weir Minerals is known for dependability, efficiency and ease of maintenance, and is the largest supplier of pumps and process related engineering equipment in Africa. The policy of the company's dewatering division is to ensure that its products outperform the competition and exceed expectations.

"While electricity supply concerns have centered on Eskom's failure to develop adequate generating capacity to keep pace with growing demand, a recent report compiled by the National Energy Regulator of South Africa (Narsa) has also thrown the spotlight on South Africa's neglected distribution systems and the regulator warned of a spiraling power crisis," concludes Moreiras.

New submersible dewatering pump a success
Meanwhile, the market's response to a new range of premium submersible dewatering pumps, capable of handling water containing solids with SGs of up to 1,1 and heads of up to 80 m, was to snap up the first consignment within three weeks of entering the South African market.

The instant popularity of the pumps surprised and satisfied members of the Weir Minerals dewatering team at its Isando plant in Johannesburg. "The audience had reacted very positively at road shows held at major coal, platinum, gold mining and stone quarrying centres during June and July. What we did not predict predicted was how ready the market was for a pump of this type," says dewatering manager Ian Farquhar.

The first order for two of the Envirotech SJ submersible pumps was placed by a tunneling contractor in northern KwaZulu-Natal, followed by an order for an additional six from a gold mining operation in Mali, West Africa. "The orders kept coming in and we have had to bring in our second consignment of pumps ahead of schedule," Farquhar said.

The Envirotech SJ range is manufactured in Europe using Weir Minerals wear and materials technology. "A submersible dewatering pump, using standard materials, has a life of about six weeks. We reached a conclusion that there was a need for a longer-life submersible dewatering pump, made from exotic materials, which would be capable of handling fluids containing abrasives," adds Farquhar.

The SJ series of five pumps have a working life of about one year, and can handle flows of between 10 and 1 000 cu m a hour at heads of between 14 m and 80 m. A high chrome iron impeller, nitrile covered motor plate and diffuser and polyurethane wear plate represent the optimum combination of materials technology for dirty water conditions. The pumps can run dry or under snore conditions. All wear parts are replaceable.

"The pumps can be operated vertically or horizontally, while the weight of the pumps is its advantage over similar dewatering pumps. An example is the 8 kW SJ pump that weighs 85kg compared to the 8 kW SHW slurry pump, which weighs in at 385 kg," Farquhar says.

GEHO autoclave pumps for Madagascar project
The company has also been awarded a contract of about R200-million to supply GEHO autoclave feed pumps, which will be installed in the processing plant at Madagascar's new Ambatovy nickel and cobalt mine.

The mine, which will produce 60 000 t of nickel and 5 600 t of cobalt a year, is located in the east-central region of Madagascar, about 130 km east of the capital, Antananarivo. Weir Minerals GEHO pumps product manager Henk Lombard says that according to the developers of the $2, 25-billion project, the Ambatovy mine will be one of the world's lowest-cost nickel producers.

Previous test work has indicated that the resource is amenable to pressure acid leach (PAL) processing and GEHO piston diaphragm pumps will be ideally suited to the role of high temperature autoclave feed pumps in the concentrator, Lombard said.

The pumps will be built at Weir Minerals' GEHO pump plant in the Netherlands and shipped to Madagascar towards the third quarter of 2008.

"Weir Minerals are recognised leaders in piston diaphragm heat barrier pump applications. The pumps will be installed in the concentrator at Ambatovy, owing to the extremely harsh slurry characteristics and high temperatures encountered in the PAL process," Lombard said.

The order was placed on Weir Minerals by global provider of engineering, procurement, construction and management services to the mining industry SNC-Lavelin based in Canada. SNC-Lavelin is a shareholder in the Ambatovy project.

Closer to home, Weir Minerals is in the process of supplying four similar GEHO piston diaphragm heat barrier pumps to uranium producer SXR Uranium One's Dominion Reefs uranium mine near Klerksdorp.

The pressure leach circuit uses the first autoclave is currently being prepared for commissioning, and will enable the Dominion mill to achieve higher extraction recoveries at a throughput of up to 100 000 t/m. The first ADU slurry, which contains uranium, was recently produced at the mine using another process, known as calcining.