Underground wireless remote blasting systems are here at last.
A pyrotechnic initiation company has developed what is said to be the first underground wireless remote blasting system in a big boost for underground safety.
“The technology is important for safety in the underground mine environment, so that no people are underground conducting blasts,” Davey Bickford Sales and Business Development Vice President Kim Greenock told Australian Mining.
Conventional blast initiation involves underground blasting crews retiring a safe distance from the blast zone.
“Retreating to a safe distance achieves the safety objective, but it is a complicated and time consuming process with the amount of equipment being relocated,” Greenock said.
“Operators with a wireless system can simply take an initiation box to wherever they like,” he said.
Davey Bickford Australia and Becker NCS have developed the blasting system in Perth.
The system features a bi-directional communications protocol, said to confirm the status of each protocol before a blast is initiated.
“Other products only receive data from a source, but the remote system can receive and transmit data from both the remote and the master unit,” Greenock said.
“One of things that you want to ensure in an underground blast is that all the detonations fire as planned. This way there is no ore or precious metals remaining after the blast.
“The remote system allows the operator to check each detonation before the blast is fired.”
Leaky feeder system
The remote blasting system uses a two-way communications device called the leaky feeder system to relay messages back and forth between blasting devices underground and a safe initiation location above ground.
The system is no more than a conduit as it takes an encoded signal and transmits it between primary and secondary computers.
“A signal from a two-way radio at the bottom of the mine jumps from a radio to the leaky feeder and travels up to a control device on the surface,” Greenock said.
“The control system on the surface then returns the signal back through the leaky feeder to be picked up by a receiver at the other end.”
The remote blasting system effectively piggy backs off the leaky feeder system, between blasting machines on the surface and underground.
A feature of the technology is the return messages that are sent via the leaky feeder system to authenticate messages that are sent using the technology.
“Not only does the signal have to go to an underground receiver to our blasting machine, our blasting machine actually returns a signal back to the surface to make sure that it is the correct signal,” Greenock said.
“The system will authenticate in both directions before a blast can be initiated,” he said.
The leaky feeder system is named after cable designed to leak radio frequency signals out and allow signals in from remote transceivers within 30 m to 40 m (VHF), or up to 200 m (UHF).
The cable is different from coaxial cable that is designed to retain radio signals within the cable, and block foreign signals from penetrating.
The technology is due to be released in late 2007 and will be available to all mines using the Davey Bickford leaky feeder system.
Greenock said the accuracy required for reliable underground blasting technology has not been developed by the mining sector, but mines have wanted more accuracy to improve underground blast performance for a long time.
The reliability and speed of airbag release technology has been harnessed from the automotive sector for mining applications, according to Greenock.
Davey Bickford Australia