The Nkomati mine in South Africa has tapped the knowledge of wireless pump monitoring and control specialists Omniflex to boost efficiencies at the nickel operation.

Located near Machadodorp in Mpumalanga, Nkomati hosts one of the largest nickel reserves in South Africa. Having an estimated 408.6 Mt of ore grading 0.33% Ni, it requires large amounts of water to be moved around for ore processing and pit dewatering operations.

These processes rely on water pumps and, crucially, pump monitoring systems, according to Ian Loudon, International Sales and Marketing Manager at Omniflex.

“Furthermore, because mines are in difficult-to-access and often unsafe locations, monitoring pumping systems isn’t always easy,” he said. “It’s an expensive task installing control cables through a whole site, so plant managers are increasingly adopting wireless systems.”

Plant managers have been using radio telemetry systems, in licence band radio frequencies, to monitor and control pumps for some time. Usually, this uses controllers and separate radio units with a data interface. However, administration costs to maintain annual licences mount up and much of the equipment becomes obsolete, according to Loudon. The OEMs often no longer support the products because they have either gone out of business, were sold to other companies, or simply don’t make the products anymore.

“With failing and expensive instrumentation, plant managers have no way of monitoring water conditions and switching the pumps on and off,” Loudon said. “If water can’t be managed within the plant from the reservoirs, or waste can’t be pumped out, the mine’s ability to wash and concentrate more efficiently is put at risk.

“It is time plant managers looked at upgrading their wireless solutions to leverage productivity gains and run plant assets cost-effectively and reliably.”

Choosing a reliable solution

By exploring wireless products that blend radio and controllers into a single DIN rail mounted package, it is possible to control pumps remotely over a large distance, according to Loudon. Products like these use licence-free band frequencies to avoid unnecessary engineering and administration.

One solution is a system comprising multiple radio remote terminal units (RTUs), interfaced into a SCADA system using an on-board ethernet port. This plug-and-play system has one RTU housed at the local control end, with all the inputs and outputs dedicated to control and feedback status, and another located remotely near the pump. The only necessary wiring is for the power supply — battery or solar— and any required control circuits.

Unlike the traditional systems, simple configuration templates on each unit is edited to share the input/output status between each RTU. For example, if a switch on one side is triggered, it will promote an output on the other side to turn the pump on or off. This makes programming a line of code unnecessary.

“Given running cable from one area of a plant to another is costly, a simple wireless solution that needs no programming will reduce expenditure and save time,” Loudon said.

For applications requiring some control decisions to be made, RTUs can be programmed into any universal PLC branded IEC 61131 language. The RTUs are also robust, housed in weatherproof casing with power supply charger units and backup batteries.

The system ensures mines can monitor the conditions of their pumps wirelessly over distances of up 20 km.

Nkomati’s settling dams and wash plants are separated by several kilometres, so this solution suits its needs. What’s more, the low power consumption of the system makes it suitable for solar power-out stations at remote reservoirs.

Easy-to-use remote monitoring

“With any remote monitoring system, ease of use is imperative to ensure efficient and productive operations,” Loudon said. “Therefore, wireless distributed RTUs with data acquisition capability are an attractive option over cable-based systems. The units can be interfaced to an existing SCADA or DCS system via on-board ethernet ports. This makes installation quick and simple, and plant managers also save on additional hardware and engineering time.”

Once collected, all data can be viewed on fully customisable HMIs. Operators can program their pump and view statuses and alarm conditions on an LED touch screen and supervisory systems. Adding Omniflex’s cloud-based Data2Desktop service allows plant managers to reap the benefits of monitoring their site using a tablet or phone, rather than having to use a fixed desktop in the plants control room, according to Loudon.

“Mining is a productivity driven operation, and downtime is lost revenue that can’t be recovered,” Loudon said. “When plant assets are spread over a large geographical area, wireless remote monitoring technology makes control and management more simple, efficient and cost-effective.”