Based on the unprecedented success of Weir Minerals Africa's new Warman® DWU dewatering pump at the existing Foskor flotation and filtration plant in Palabowra, Foskor has ordered a number of new DWU pumps for its new flotation plant which is currently under construction at the same site. The order, that includes three 125 DWUs, one 150 DWU and three 200 DWUs, will be supplied in 2013.
The first prototype DWU was introduced at Foskor in early 2012 and following its successful performance this new generation dewatering pump has gained popularity within the mining sector. Significantly, Weir Minerals Africa in South Africa has since become the Weir Minerals Division's group's global hub for the manufacture and supply of the DWU pump.
Warren Taylor, product specialist at Weir Minerals Africa, says the Warman® 200RC DWU was installed on site at Foskor's current flotation plant to handle dirty plant water from thickener overflow. The DWU pump was set up for the complex system curve in this particular application and it performed beyond expectation. Taylor says the pump proved itself in the application which is one that can be challenging when not all the thickeners are in operation.
The 200RC-DWU pump provides reliable process water to the entire plant and serves as the high pressure water motor system to drive the plant's many venturi thickener tunnel spillage pumps. "It produces at the same flow rate as the previously installed clear water pumps and Taylor says the unit is performing well. It has been in operation for several months and is outperforming the predecessor pump that had struggled to maintain 10.5 bar pressure."
According to Taylor, Joseph Mathebula, flotation section engineer at Foskor has been impressed with the pump's performance and capabilities.
"Clear water dewatering pumps are frequently used to handle dirty, slurry-like water and this inevitably causes pump failure," Taylor continues. Clear water pumps are best suited to handling clear process water. When they are used to handle dirty process water, they suffer severe corrosion damage to components such as neck rings, stuffing box bushes, impellor vanes and casings. This, in turn, results in poor pump performance and premature pump failure.
"The new DWU is a dewatering pump that is capable of handling slurry-like dirty water, but it has the energy efficiency of a clear water dewatering pump. It's also suited to high pressure applications. We're thrilled to be able to offer the global market a dewatering pump that can handle dirty process water without the compromise on energy efficiency experienced with a normal slurry pump," Taylor emphasises.
In terms of its design, the Warman® DWU dewatering pump offers customers a high head option encompassing the speeds for diesel and electrical driven applications, with heads exceeding 130 metres. This pump was developed to enhance Weir Minerals Africa's existing high lift dewatering pump range.
The DWU pump can handle dirty water of SG 1.05 with RD = 1.05, and a casing pressure rated at 7000 kPa for series pumping, if required. The range comprises four pump frame sizes - DWU 200, 150, 125 and 75.
At maximum operating speed the DWU 200 pump will achieve a head of 115 metres at best efficiency point, with smaller units able to achieve 130 metres. Weir Minerals Africa's R&D engineers have used a double volute casing design and impeller balance holes to reduce the radial and axial hydraulic loads. By making use of the new Warman® WBH® mechanical end design, customers benefit from component interchangeablity, which reduces spares stockholding. WBH® mechanical ends are available in either grease or oil lubricated options.