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20 October 2023

Modernising Water Supply Infrastructure at the Cullinan Diamond Mine

The Cullinan Mine, located in the town of Cullinan, east of Pretoria, South Africa, has a rich history dating back to 1902. Operated by Petra Diamonds, the mine is renowned for producing some of the world’s most famous diamonds, including the largest rough diamond ever found, the Cullinan Diamond. Aside from its historical significance in the diamond industry, the Cullinan Mine has played a crucial role in the community’s water supply.

Historical Water Supply Challenges:

In its early days, the Cullinan Mine didn’t face immediate concerns about water supply. The surrounding area boasted numerous springs, and a stream provided a strong water source. However, the expansion of the open pit mine led to the closure of a nearby garage, Venter Motors. The mine then relied on a dam for water supply, with two boilers powering four steam pumps.

When the mine acquired the Minnaars’ portion of the farm, a dam was built at Danger Bend, potentially increasing water storage capacity. But by 1905, it became evident that the existing water supply was inadequate, necessitating the search for alternative sources.

The Search for a Sustainable Water Source:

The Board of Directors commissioned Mr. D. Gerrand, an engineer, to find a viable water source. Gerrand conducted a thorough survey and determined that the confluence of the Wilge and Bronkhorstspruit Rivers offered a sufficient water supply. The Spitskop and Zuikerboschfontein farms were acquired for this purpose, and the necessary permissions were granted through an ordinance. Mr. Gerrand was tasked with planning, designing, and executing the entire project.

This initiative resulted in the construction of four steam pumps and five boilers. The infrastructure, including the boilers, the No.1 steam pump, and related buildings, has been preserved to this day. These steam pumps continued to supply water to the mine until 1962 when they were replaced by electric pumps.

Steam-Powered Water Pumping System:

Neels Moolman, a fitter and turner at the Petra Diamonds’ pump station near the Wilge River, described the inner workings of the pump station. Steam was drawn from the river through an intake structure and transported through pipelines. The pump station initially featured two three-cylinder steam pumps and five boilers to power the pumps and other equipment. The boilers generated steam by heating water, which was then directed to a steam turbine, converting its energy into rotational power to drive the pistons of the pump, propelling water through the system.

The steam was then condensed back into water, ready for reuse in the boiler. However, operating and maintaining these coal-fired boilers proved to be expensive.

Transition to Electric Pumps:

In 1962, recognizing the cost and maintenance challenges of the steam-powered system, the pump station made the transition to electrical pumps. The initial electric pumps were Mather & Platt centrifugal pumps, which have since become unavailable.

The Modern Pumping Solution:

Today, the Cullinan Mine’s pump station employs a Vega VHM 110kW submersible pump, arranged in rows of five to achieve the desired flow, covering the 43km distance. The pump is installed beneath a pontoon, which floats on the Wilge River’s surface. Michael van Zyl, an external sales representative for AxFlow/AQS, revealed that the VHM 110kW pump operates smoothly at 133 Amps, delivering the required flow of 120 – 140m³/h at a head of 135m, outperforming the previous pump brand.

The remarkable feature of the Vega VHM 110kW pump is its ability to operate while positioned on its side. This modern pump has been running successfully for over a year without any reported issues, highlighting the importance of adapting to more efficient and sustainable water supply solutions in the mining industry.

Do you still have questions? Give our AQS Liquid Transfer team a call on +27 12 548 7204 or fill out our enquiry form, our friendly team will get back to you with first-hand expertise on how to select the right pump for your needs.

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