Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr
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UNDERGROUND COMMUNICATIONS Guiding Miners to Safety Many mining accidents are caused by fire, rockfall or gas explosions. With any of these events, the probability is high that a network cable will be damaged and the logic link lost. Conversely, because there also is high probability that active devices in proximity to these events would be damaged, the system's indication of a suddenly missing link can be interpreted by miners as "this route may be blocked." This emergency localization feature of the MICs results from the combination of downloaded static information and real time sensor data available in the network. It is the basis for a number of safety support functions such as guiding trapped miners to emergency exits, shelters or other safe areas as well as providing information for rescue teams to quickly access the site. In a regular network, communication is not possible when the network's connection with central systems on the surface is lost; the underground network is "dead." However, in such cases the active hardware underground, equipped with battery backup power supplies, often is still functional, and MICs can switch to an independent "emergency mode" when connections to surface-located central systems are lost. In this mode, all MICs in the disconnected island automatically negotiate among themselves as to which unit will "replace" the central services that have been lost and assign IP addresses or coordinate digital voice communications, for example. In emergency mode, all network traffic is limited to services that are essential for mine safety, such as voice communication, environmental sensor information, and tracking. Other services may be blocked by the MICs. In any emergency it is important to safely evacuate all workers from the mine and to ensure that no one is left behind. The first step in this phase should be a muster at a dynamically assigned assembly point. The entire procedure is illustrated in Figure 3. 46 E&MJ; • MARCH 2013 Figure 3ÑUsing network intelligence to guide miners to safety. For this example it is assumed that: to an emergency event the cable in position 1 was taken out of service due to maintenance. However the associated tunnel is passable for people and suitable as an emergency escape route. 2.The network is cut or interrupted by an event at positions 2 and 3. Because the tunnel at Position 1 is passable for people and suitable as an emergency escape route, it makes the area close to this exit a suitable meeting point. This information is available in the MIC devices and becomes part of the evaluation of the current situation by the miners, based on information available from the network. When the decision about a meeting point is made, either a related button on a network node is pressed or the location is presented on the displays of wireless devices. The network thus knows where to guide the miners, and MICs will begin transmitting mes1. Prior www.e-mj.com