In the competitive world of pumps, gaining the technological edge is not easy; but ten years ago the South African engineering team at Weir Minerals Africa achieved just this – and the results are being enjoyed worldwide.
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Just over a decade ago in September 2011, the first Warman® DWU (dirty water unit) pump was sold to a mining customer in Phalaborwa in South Africa. “The product was not necessarily a startling breakthrough,” says Weir Minerals Africa head of engineering Christian Stehle, “but was rather an innovative evolution of an existing product – as almost all technical advances are.
“This high-lift dirty water pump was the perfect solution for a gap in the market that had not been fully recognised,” says Stehle. “It really reflected the value of Weir Minerals’ long history in pumps, working closely with customers and understanding their changing needs.”
Developed locally from the design of its Envirotech® pump range, to this day the Warman® DWU pump remains fully manufactured in South Africa. In addition to its enthusiastic customer base in Africa, it has also found regular markets through the Weir Minerals footprint abroad, he says.
“Having joined Weir Minerals Africa in 2004, I became very involved in the development of the Warman DWU pump concept from the time of the initial request around 2007,” he says. “So the range is very close to my heart, and as a team we are extremely proud of its local and global success.”
Filling the gap
Critical modifications allowed the dirty water pump to essentially fill the gap between two well-serviced market segments: the slurry pump – built for high levels of solids suspended in liquid – and clear water pumps. The problem of dirty water arises when the suspended solids in the pumped medium cause excessive component wear rates and premature mechanical failure. “The Warman DWU pump addresses this challenge, accounting in large part for its success. There are many pumps that deal with either slurry or clear water, but few that address those ‘in-between’ applications,” he says. “Our design therefore sets out to combine the wear resistance, robustness and longevity of the slurry pump with the efficiency features of clear water pumps.”
The Weir Minerals Africa design team targeted applications such as emptying mining ponds and dewatering from underground, where the specific gravity (SG) was up to 1.05. At the same time, the units have to achieve relatively high heads, while running reliably over long periods.
“We wanted a high-pressure rating, with the ability to run the pumps in series,” he says. “Pump operators can usually achieve a high head while pumping over long distances and most multi-stage pumps on offer can meet distance and height requirements, but not when pumping dirty liquids. So this became our differentiating factor.”
A satisfied first customer
Such was the need in the market that our first customer needed little convincing about what the pump could do, says Stehle. The performance of the first unit indeed lived up to its promise, and the customer was quick to order further units. Within a few years, the sales numbers rose steadily as the reputation of the Warman® DWU pump spread widely.
“This was quite a new experience for us in the mining sector, where purchasing decisions are usually quite conservative and must be based largely on past performance,” he notes. Awareness of the pump was also disseminated through the Weir Minerals global network, and the Warman® DWU pump found its place in the global product line-up. Today, there are loyal customers in regions as far apart as Australia and Canada.
More choice
With time, customers came to Weir Minerals Africa with particular requirements that could suit the demands of their applications. This led to a wider range of construction materials being introduced in the manufacture of the Warman® DWU pump. For instance, stainless steel was offered as an option, and a whole range is now available in stainless steel and hard-wearing materials for acidic applications.
While it was developed initially with the conventional gland seal arrangement, there were soon requests for mechanical seals, which are now a standard option on all pumps in the range.
“Then we came to consider centrifugal seals or expellers, which required us to implement some design modifications,” Stehle says. “So additional components were added to assist with shaft sealing and we have recently made the whole range available with this centrifugal seal option. This allows our customers to eliminate the use of clean water when operating the pumps, contributing to our sustainability strategy.”
Stehle pays tribute to the expertise of his design team and the power of modern software design tools, allowing the application of Computational Fluid Dynamics (CFD) to improve performance and increase energy efficiency. The 3D modelling of complex shapes, in conjunction with 3D printing technology, now also opens opportunities for intricate manufacturing results. Combined with the company’s advanced material technology, the wear life of the Warman® DWU pump can be continuously improved, and its reliability and sustainability enhanced.