Mining Mirror Artcle
Worldwide there is a drive to develop remote controlled, unmanned, and semi-autonomous vehicles to reduce the number of persons exposed to dangers on the working face. These vehicles can be operated underground or ideally from the surface. The drive to automation is however a double-edged sword. While it reduces the risk of persons being exposed to danger, it also reduces the number of people that need to be employed.
Electronic access and movement monitoring tags have been developed to monitor the movement of workers underground. In the event of an underground incident, the last known checkpoint can then be used to focus the efforts of rescuers and emergency resources.
Proximity detectors are now fitted on the light caps of miners and operators, which indicate their proximity to heavy vehicles underground. The systems use very low frequency (VLF) technology, which alerts both the miner and the machinery or vehicle operator of their proximity to each other, even if they do not have visual contact of each other. It is effective up to a distance of 15m.
Electronic fall-of-ground (FoG) monitoring systems, which monitor forces due to movements in the hanging wall (roof) and pillars in real time, have also been developed. These monitors are fitted directly to the roof bolts. The monitoring equipment communicates directly with the mine control room and rock engineer office in the event of an incident. In parallel, several seismic studies have been undertaken in conjunction between South African mines and universities and the universities in Japan. The aim of these seismic studies is to be able to predict major seismic events induced by mining and natural features associated with deep-level mines.
The ability to communicate in all areas of an underground mine is a key requirement for safety. To cater to the need of areas that are traditionally not covered by the underground communication network, Kutta Radios provides next-generation medium frequency radios to mine operators as a reliable, cost-effective solution to communication and tracking needs, says Yoni Margalit, MD at Advance Komms. Kutta DRUM radios use cables, wires, tracks, and pipes to create survivable, redundant communication paths underground that extend for miles. The DRUM is a wireless medium-frequency radio system that works irrespective of whether mine power is on or off, post-incident, and even through obstructions.
According to Margalit, the radios use parasitic propagation of medium frequency signals to send voice and data communications in an underground environment. These signals magnetically couple to metallic items commonly found in the infrastructure of a mine, and allow for voice and data transfers several kilometres away. When proper conductors are present, signals can travel for kilometres with non-line of sight. These point-to-point communications can be carried by conductors such as leaky feeder cables (powered or unpowered), phone lines, power lines, lifelines, metal pipes, and tracks. Conductors that are even buried beneath the earth can continue to transmit medium-frequency signals in many scenarios, making the DRUM communication system the ideal safety communication system for mine operators.
The mining environment underground is extremely volatile and miners are exposed to many dangers such as rock falls, toxic gases, explosions, and fires. Communication underground is unfortunately unreliable and really only possible in developed areas of the mine. “The miners that are blasting and digging in the undeveloped areas are fully dependent on communication from the shift manager or the likes regarding any danger warnings from surface,” adds Margalit.
Making strides in communication
Advanced Comms paired up with Kutta to design the WARN device, which functions through the same patented medium frequency as the Kutta radios. This device will be locally manufactured in South Africa. It will be assigned to each individual miner and will alert them immediately of any danger known to surface. The WARN receives an emergency medium frequency signal sent from a transmitter on surface, which is sent by magnetic induction. This means that the signal is sent through the existing metallic infrastructure underground and is not dependent on any communication cabling. The WARN device can give audible, visual, and vibration warnings, ensuring the miner has every chance of early notification of imminent danger and has the opportunity to reach a refuge bay as quick as possible.
The WARN device empowers each miner and removes the dependency on others to warn them of danger. It allows for the earliest possible warning, leading to the quickest possible reaction and ultimately saving lives.
Margalit concludes by stating that the company has successfully tested the technology with the mine rescue services (MRS). “We strongly believe that this innovative communication technology, now available on the market, will contribute substantially to achieving zero harm in the mines,” says Margalit.