Formerly called Premier, Cullinan is now named after the 3,106-carat diamond (in its uncut state) found close to the sidewall of the mine’s open-pit, still the largest gemstone ever discovered. Today it is an underground mine, with mining extending to the 763 m level, and about 1,000 employees help produce around 1.3 million carats annually. The Cullinan pipe, with a surface area of 32 ha, contains three types of kimberlite: grey kimberlite, which comprises the bulk of the pipe; brown kimberlite, found on the eastern side, and with a high clay content that swells when exposed to moisture; and black kimberlite, found in the western section. The loading safety problem arises in parts of the mine where water percolates through highly fragmented kimberlite, making mud pushes possible if the water is allowed to build up. The remote control technology allows the loaders to work in such areas while the operator remains in a safe location selected after risk analysis.

The technology installed is the Control Master system from the Australian firm Remote Control Technologies, based in Perth, Western Australia. This is offered in a range comprising line-of-sight remote control systems, teleremote control systems, barrier systems and teleremote communications equipment for surface and underground applications. Each remote package comes with a customized machine logics package, electrical interface and communications system to suit the application. Product skills training is also offered to ensure the customer maximises the safety and productivity benefits from using the new remote control system.

Cullinan has installed the Control Master remote control system from Remote Control Technologies on two of the
mine’s LHDs. Photo shows the Control Master television screens (left), the view behind the R1300G and (right) the
view in front.

The two LHDs running under remote control at Cullinan
average about 300 operational hours per month and
are serviced and repaired at the mine’s underground
shop.

The interface for the remote control of the LHDs incorporates a transmitter and a radio receiver. Effective and safe control by the operator is achieved through proportional control of the accelerator and steering systems. This form of control is comparable to having an operator in the driver’s seat. The system allows the remote operator to load ore by maximizing the breakout force required, without spinning the wheels or stressing the machine. With a full bucket, the operator shifts into reverse, steering the machine under full proportional control, without any shaking, rattling or rolling. As the machine approaches the remote station, the operator slows down the LHD and stops it.

The remote-controlled mining area is designated by electronic “eyes” mounted on the tunnel wall. A laser beam is transmitted between these two eyes. If the beam is broken by other mine personnel or vehicles entering the area, it automatically cuts power to the remote control transmitter, thereby halting the LHD, which is braked and the engine shut down. Remote mining operations can only be continued once the area has been cleared and the system reset.

“We decide on a weekly basis how many loads to remove via remote-controlled LHD for production reasons and in order to manage water build-up in an area in the pipe where it occurs,” said Vic Matthews, projects engineer at Cullinan. The remote control LHDs can also be used where tunnels are not in good condition, or where the hanging wall poses a risk to workers.

“The system has been in operation for about two months, and so far we are very happy with the results. Cullinan has a proud safety record, with a decreasing trend in the number of lost-time injuries year-to-year over the last few years,” said Matthews. The LHDs, which are maintained in underground workshops, average about 300 hours a month— excellent uptime, he added.