MechChem Africa January-February 2024

⎪ Water, wastewater and pumping solutions ⎪

200 mm discharge ANZE submersible slurry pump. “Each of these units weighs in at about 2.3 t and they each transported between 720 to 780 m 3 of slurry every hour: for 24 hours a day over a four-year period. Being able to do this made the operation exceptionally cost effective, with a return on investment on each pump of about five weeks per unit,” Rui Gomes tells MechChem Africa. At the project’s peak, he adds, the operation, which ran from 2017 to 2021, had four Goodwin submersible units operating simultaneously. In terms of service support, Goodwin Submersible Pumps Africa was also re sponsible for regular refurbishments as the wet-end components wore down. “Similar to centrifugal slurry pumps, the impellers, wear plate and casings of Goodwin submersibles must be replaced at regular intervals to re store performance as the pumps wear. The longest running time for one of our pumps on this project was nine months, but in general, we had to replace the impeller and the wear plate at four-to-five-month intervals, while changing the casing on every second service,” he says. Gomes highlights some of the standout features of the Goodwin submersible pump design: “One of the key reasons for the ex ceptional reliability of these pumps, particu larly of the bearings, is the electrical design. The electric motor and the bearings are in a completely sealed unit in the pump-motor housing, which is fully submerged in hydraulic oil to lubricate and cool the drive components. A double mechanical seal at the pressure end of the pump and a ceramic sealing layer around the electrical cable gland at the top fully isolates this motor unit, so we seldom see electrical, seal or bearing failures,” he notes. “This also makes it possible to replace the whole of the wet end, in-situ, without af fecting or compromising the electrical-end, bearings, or the sealing arrangement. This is not normal for a submersible slurry pump,” Gomes asserts. The sealed electrical unit sits symmetri cally in the split pump volute, which reduces vibration and allows the process flow to continuously cool the hydraulic oil inside. “Even during dry-running, air is kept circulat ing around the motor unit to prevent rapid overheating. From real dry running test of our units, we can comfortably claim that these pumps can be run dry for extended periods of time without consequence,” he says. In addition, on the inlet on the bottom of the pump, an inducer has been incorporated onto an extended impeller shaft as a standard on all pumps. This is designed to send hydro dynamic shockwaves into the dense slurry, which re-suspends settled solids on the pond floor to improve pumping efficiency. The open vane impellers used also ensure that large

particles can be accommodated, typically 25 mm ‘stones’ on the smallest 100 mm, 22 kW NZE submersible slurry pump and small rocks of up to 76 mm on the 200 mm 112 kW ANZE. “The 30 kW 100 mm Goodwin submers ible, our smallest, is an ideal substitute for vertical spindle pumps in typical sump ap plications. Traditional vertical spindle pumps are often dotted all over minerals processing plants, to remove accumulated waste slurry from bunded areas beneath the likes of flota tion plants or thickeners for example,” he says. “While the key reason our submersibles are becoming a preferred option is their den sity handling capability, which is far superior to vertical spindle pumps, the reliability of the Goodwin ANZE is a significant second. If the sump is deeper than a metre or so, then a ver tical spindle pump will require a longer shaft. This increases the risk of excessive vibration, which can negatively affect bearing reliability. Vertical spindle pumps are typically pulley driven and pulley drives fail often, which obvi ously results in time consuming maintenance and replacement costs. A Goodwin submers ible has none of these inherent problems and will overshoot vertical spindle maintenance intervals by a long way,” Gomes says. “And if for any reason there is no slurry being pumped and this is not noticed immedi ately by an operator, a vertical spindle’s bear

ings will typically fail within minutes, while our submersibles will grant at least a few hours of safe running before any consequences are likely to occur. Goodwin Submersible Pumps Africa’s South African head office in Edenvale has an extensive workshop for supporting, repairing, and refurbishing its pump range. “We carry spares to enable us to support our installed base for at least four to six months, and that changes as our success grows. We also market the Goodwin Pumps brand across the whole of the African continent, so we tend to make special logistics provisions for customers in countries such a Senegal, Guinea, or Mali to make sure we can get support for the pumps they are using. “Within South Africa, we have got seven sales engineers that are strategically placed in key mining areas, and in Zambia we have a small workshop that carries spares, re placement units and service support staff. In September this year, we opened a similar workshop in Tema, Ghana, which is a port town just outside the capital, Accra. “We only established Goodwin Submersible Pumps Africa in 2016, so we have not really caught up with whole of the market. But we are waving the Goodwin flag to make sure everyone knows we are on their doorstep,” Gomes concludes. www.goodwininternationalpumps.com

Goodwin Submersible Pumps Africa’s South African head office in Edenvale has an extensive workshop for supporting, repairing, and refurbishing its pump range.

Goodwin Submersible Pumps Africa also has a rental fleet to meet the project and short-term needs of plants across Africa.

January-February 2024 • MechChem Africa ¦ 13