Carl Hamm

Having introduced an innovative open pit dewatering concept at the Electra Mining Africa exhibition in 2018, turnkey dewatering specialist Carl Hamm Pipes, Pumps and Solutions (PPS) and its “key” industry partners has spent the last six months perfecting and expanding the solution optionality’s to ensure this ground-breaking initiative delivers quick and effective results, CEO CHRIS MUNNICK tells LAURA CORNISH.

This article first appeared in Mining Review Africa Issue 4, 2019
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Having established himself as an expert in dewatering solutions (including acid mine drainage) over the span of his career, Munnick is now injecting his time and energy into the delivery of new dewatering innovations that will completely change the way open pit mines are dewatered.

Speaking to Munnick at the Electra Mining Africa exhibition last year, he emphasised the mining industry’s conventional approach to dewatering:

“Most open pit mines traditionally invest heavily into extensive in-pit dewatering infrastructure that is costly, requires on-going maintenance and invariably becomes a costly exercise to manage as the pit becomes progressively deeper.”

On the back of his most recent success – implementing a heavy-duty pump and pipe solution for the Department of Water Affairs’ three AMD plants – Munnick has turned his expertise to achieving similar dewatering results for surface mines.

(Today, the three AMD plants ensure underground AMD from historic gold mining does not infiltrate the surface across a widespread area stretching from the far East Rand to the West Rand).

“Through this new concept I am looking to offer the mining sector an opportunity to not only eliminate their existing dewatering infrastructure challenges but to further provide significant benefits and opportunities that will enhance their dewatering performance and operating costs,” Munnick highlights.

How does it work?

The dewatering solution, which can effectively remove 90% of existing in-pit dewatering infrastructure, is completely non-invasive to existing operations because it requires access to the pit via a non-active sidewall.

The process requires the establishment of an approximately 100 m long horizontal tunnel (approximately 9 m wide by 5 m high) situated inwards from the dead sidewall.

“This tunnel will provide access to underground storage dams and pumping facility.

“The storage dams will then be used to hold/buffer water pumped from the pit while a pump station with a capacity of up to 2 000 m³/hour will pump the water to surface through a 2.5 m raise bore hole. All electrical infrastructure (VSDs, etc.) will be situated on surface and not inside the pit,” Munnick explains.

The next step will see Carl Hamm PPS develop a decline at about 3 to 4° from the tunnel to below the pit bottom from which another raise bore shaft to surface will be equipped with additional submersible pumps to capture additional water as the pit becomes deeper. Equipment can be designed to pump up to 12 000 m³/hour if needed.

The success of such a project will rely heavily on the correct hydro-geological characterisation to ensure it is designed and implemented with this information at hand, Munnick highlights.

“Not only will our system increase operational efficiency and effectiveness; it will significantly reduce life-of-mine dewatering costs as well. But the advantages this system offers extends further,” Munnick highlights.

The Carl Hamm PPS solution is not impeded by the finite life of boreholes, for example.

“We can sink additional shafts and declines as the pit extends. And should the pumping requirements increase, the addition of variable speed drives to the pump will increase the speed at which our pumps can operate,” Munnick explains.

The installation of the system itself is another benefit. The Carl Hamm pipeline can easily be extended, and additional pipe links fitted at surface to extend the pipeline length using its ZSM system whose benefits are outlined below.

The next step

While the mining industry is largely resistant to untried and untested innovations, Munnick says a similar concept has already been implemented successfully at a mine in Zambia which enabled the company to perfect its design.

Mining companies can also take comfort in knowing that Munnick has combined his dewatering experience with a number of experienced suppliers who will partner with the company to deliver the solution.

Carl Hamm PPS has partnered with shaft sinking and decline development specialist Solrock Mining Services & MCP Consultingto deliver all sinking requirements.

This company will deploy Small controlled sensitive explosive sinking techniques. This enhances both safety and environmental sensitivity – two critical components in the mining sector.”

Once successfully executed, Carl Hamm PPS will be able to reduce the number of boreholes and pumps inside the pit by more than half which in turn reduces supporting pumping infrastructure as well.

Carl-Hamm PPS will be implementing their own ZSM piping coupling solution. ZSM is an axial non-positive and detachable pipe connection.

The patent-protected tight sleeve system is a unique alternative to other conventional connection systems due to its quick and easy assembly/disassembly and space-saving design – making the establishment of pipeline infrastructure a seamless job.

Other supply partners will include the Germany-derived Düchting HPX pumps (Carl-Hamm PPS is the local distributor for this product).

With the directive to supply effective and efficient equipment the well-known German Pump Company, KSB, are involved to assist with the design and supply of submersible borehole pumps.

Various features (e.g. double-entry impellers, wear-resistant parts etc.) form part of the KSB UPZ Pumps, ensuring low cost of ownership and reliable operation.

Rockwell Automation has been selected as the company’s automation and VSD partner while Efficient Power will deliver on the system’s power requirements and Woodrow Engineering on the electrical installation, control system design and system integration.

Moving forward, the concept and design is fully market-ready and Munnick is confident will be well received by industry for its extensive benefits. Any and all Open cast mines are key target regions for the company – Southern Africa has a wide variety of large-scale open pit mines which must contend with frequent high rainfall.

Even though SADC is a key market the technology is not limited to Africa or to mining as it can be adapted to Potable water abstraction replacing well fields and as such it is a truly Global solution.

“The system does require a close working relationship with the client and access to their geological and hydrological information which will enable us to seamlessly deliver a system that performs optimally,” Munnick concludes.

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