Although they won’t attain field readiness in time to help workers trapped by the mine collapse in Chile, a number of new technologies will enter service in the next few years that could drastically increase mine collapse survival rates. These technologies differ in their use, but all use advanced sensors to help miners locate fallen colleagues, alert rescue teams and flee to safety.
The sensors will help navigate drills directly to trapped miners, enable robots and escape vehicles to speed through the darkened labyrinths carved from the living rock and allow rescue teams to find miners in tunnels filled with black smoke and deadly gas.
“After an accident, you’d have a lot of dust and smoke, and right now, we don’t have these robots that can rescue people. We have people who have to use their eyeballs to wander around looking for the dead and wounded. It’s a hellish experience, as you can imagine,” said Sean Dessureault, an associate professor in the Department of Mining and Geological Engineering at the University of Arizona.
“All the technology pieces exist; they just haven’t gotten around to slapping it together,” Dessureault said.
In future mines, the sensors will come in a variety of shapes, sizes and uses, but will primarily fall into two categories: sensors that help guide machinery, and sensors that help locate individual miners.
Finding the Miners
Currently, some companies have done research on marking each miner with a radio-frequency identification (RFID) chip that would record their location inside the mine complex. However, the RFID receivers only give rescuers accuracy between 50 and 500 feet, Dessureault said. For a drill tunneling through hundreds of feet of rock, or for rescuers fighting their way through a pitch black system of caverns, that’s a big margin of error.
To replace relatively inaccurate RFID tags, some companies have begun to develop more portable inertial navigation systems that can track a miner to within nine feet. These devices use gyroscopes lasers to keep track of a wearer’s every step and turn.
Adapted from declassified military technology, recent advances have reduced inertial navigation systems from about the size of a desktop computer to about a single square foot, Dessureault said. Plus, unlike RFID tags, the inertial navigation systems don’t need electronic components whose sparks could set off further explosions in a coal mine.
Similarly, Raytheon, the company that makes Patriot Missiles, has developed a GPS-like navigation system for underground exploration. Since the GPS signal only penetrates about a foot of earth, Raytheon engineers based this system around a series of beacons placed above and within the tunnel systems, said Steve Cotten, director of internal research and development for Raytheon UTD.
Beacons in safe rooms and refuge chambers of the mine would send a signal out to rescue crews in the event of a collapse. The rescuers could then use the signal to guide the drill directly to the area housing survivors, rather than using inaccurate coordinates based on maps of the mine, Cotten said.
Rescuing the Miners
Of course, finding the miners is only half the job, as they still need to get out of the mine. That’s where robots, specially designed escape vehicles and the sensors that guide them come in.
During the Sago Mine disaster in 2006, the Mine Safety and Health Administration used a converted bomb disposal robot named ANDROS to search for survivors amongst the debris. The robot needed to remain tethered to a power source, lacked sophisticated sensor technology and could only explore 5,000 feet of a mine with miles-long sections, all of which limited its usefulness, Dessureault said.
Instead, future robots, like the one under development by the government of Queensland, Australia, would use proximity sensors to navigate through the mine, sensitive microphones and smoke-penetrating cameras to identify fallen miners.
In the latest Sago accident, "they sent people underground, not the robot, and the people walked right by dead and dying miners,” Dessureault told TechNewsDaily. “You can have machines with amazing sensors on it looking for people.”
Potential escape vehicles could have similar proximity sensors to allow miners to drive out of a mine during a collapse or fire, based on a report the National Institute for Occupational Safety and Health (NIOSH) commissioned from Raytheon.
As part of the NIOSH thought experiment, Raytheon researchers envisioned upgrading the Humvee-like personnel carriers that transport miners with enough sensors to allow driving in smoke-obscured tunnels, Cotten said.
However, even if these technologies were available today, they may still not have helped the Chilean mine collapse, Dessureault said. The company operating that mine was a small outfit that didn’t have the devotion to safety that has proved far better at protecting miners than any technology.
“The number one thing about safety is culture,” said Dessureault.
“Sociology gets you more bang for your buck than technology.”