Charging system keeps underground miners clear from danger

Robotics allow mining companies to remove operators from high-exposure danger zones.

There are fewer easily available ore deposits than there once were, forcing mining companies to go deeper underground. But with depth comes increased potential for accidents such as rock falls and rock burst incidents. So how can companies improve the safety of operators in these high exposure danger zones? One answer is to remove the operator from the unsupported tunnels and replace them with robotic technology.

Technology company Normet has recently launched a charging system that does this. Called Charmec Revo, the tool comprises a remote-controlled robotic arm that places the initiating system into the borehole and, together with the emulsion kit, dispenses emulsion, allowing the operator to remain in a supported tunnel area.

“During tests, the Charmec Revo technology demonstrated its ability to improve operational safety while retaining similar productivity,” says Anssi Mykkänen, product line director of Explosives Charging at Normet. “Ease of use and low learning curve ensure effortless implementation of this technology.”

Designed with intention

The remote charging system is designed for tunnel sizes from 4x4m to 6x6m which covers most mining tunnels. Meanwhile, the charging manipulator includes an in-house developed, agile servo-robotic arm, specifically built for underground mining.

Normet also designed its manipulator arm to ‘pick-and-deliver’ the priming unit (detonator-booster package) from the ground level’s reduced exposure area or, alternatively, the priming magazine and deliver it to the face wall. The path between the borehole and the position is also automated, according to the company.

The company drew inspiration from inverse kinematics, the process of obtaining joint angles from known coordinates of end effector, to develop the charging arm’s control system. Only the tip of the boom is controlled, enabling fully autonomous movements, similarly to the path between the borehole and the home position.

MACHINE VISION AND CONNECTIVITY

Operators can upload maps of the drilled boreholes from the drill rigs to help locate them in the face wall. Normet’s machine vision system also helps operators find the drilled boreholes, shortening cycle time.

“The machine vision system helps the operator finds drilled boreholes by identifying and marking them in the control screen of Chamec Revo,” Mykkänen tells IME. “Revo’s boom arm has automatic movements, from priming unit picking point to face wall. And the machine vision system means operators can find new boreholes quickly.”

If the information is not available, the machine vision serves as the main operator support for locating the boreholes. And once found, the charging hose delivery system will take care of the priming unit and explosive delivery. The system also recognises plastic lifter pipes and helps with their use, Normet adds.

Furthermore, Charmec Revo’s collision avoidance system slows down and stops the arm before contact with the tunnel wall or other obstacles, and the close contact prevention feature of the system uses ultrasound sensors. Additional safety sensors also stop boom movement if the operator enters the working area.

The Revo system is also compatible with wired, semi-wireless or wireless initiating systems and the priming unit can be managed manually or by using magazines provided by explosives suppliers. The initiating system magazine is placed at a platform next to the charging arm, enabling the priming unit’s unique pick-and-deliver method. As with initiating systems, operators can use the Revo with all commercial bulk emulsion systems.

MAXIMISING PAYLOAD CAPACITY

The Revo boasts a load capacity of 6,000kg and allows for matrix payloads of up to 4,000kg to be mounted safely on the rear platform, away from all hot surfaces. A large bulk capacity reduces the need for driving between the charging sites and the explosive warehouse and, therefore, both significantly increases productivity and helps keep the charging machine in excellent working condition.

“At Normet, we believe that the Charmec Revo, with its servo-robotic remote arm and ability to use any commercially available initiating and bulk systems, will help create safer more efficient explosives charging operations,” says Mykkänen.