Posted on December 10, 2015
PROFILE: The Alan Bauer Explosives Laboratory
Learning the safe and effective use of explosives for mining
Oscar Rielo, Senior Program Coordinator at the Robert M. Buchan Department of Mining.
Oscar Rielo checks weather conditions before squinting upward at gaps in the cloud cover. The neighbours are more likely to be disturbed by the detonations when it’s overcast because shockwaves bounce back at the ground from the underside of the cloud deck.
Rielo is senior program coordinator at the Robert M. Buchan Department of Mining at Queen’s. He oversees operations at the Alan Bauer Explosives Laboratory under the supervision of Mining Engineering Professor Dr. Takis Katsabanis. The site is a 160-hectare patch of land about an hour north of Kingston.
The lab is used for instructing students in blasting technology and instrumentation and for conducting research related to explosives and fragmentation. The site is equipped with blast chambers of different sizes, as well as the instrumentation needed to record detonation properties, post detonation fumes, vibration, air blast, shock wave propagation and the effects of shock waves on materials. There’s even equipment for drilling holes in rock. It’s a rare resource among universities in the world and allows the performance of realistic tests to assist blast optimization.
Today about 15 Queen’s mining engineering students are here to collect data for their third-year drilling and blasting course. They’re clustered in small groups in the building behind Rielo calculating, measuring and mixing recipes to obtain the perfect ratio.
“They’re learning how to mix proportions for a commercial explosive called ANFO,” says Rielo. “It’s used right now for about 80 per cent of blasting in the mining industry.”
As each batch of ANFO is completed, students pack it into short lengths of steel pipe. There will be a total of seven shots, called confined charges, of varying mixtures in pipes of different diameters. Once the charges are packed, students carry them carefully to the blasting area. Each shot is wired in its turn with a velocity-of-detonation sensor, a primer and a detonator. Each is buried in a sandy pit and detonated remotely from a bunker. As far as safety permits, the mood is light and fun. When a big one goes off, it raises a “Woah!” of exhilaration from the students inside the bunker. Rielo collects, saves and refines the data from the sensors as the students wire up the next shots under the supervision of Staff Mining Technician Larry Steele.
Students prepare charges in the third-year blasting and drilling course.
“The sensor contains a wire with a known resistance of 322.5 ohms per metre,” says Rielo. “It’s connected to a high-speed data acquisition, basically an oscilloscope without a screen. The sensor is consumed as the blast goes off, changing the resistance and causing a change in the voltage output. That voltage-change pattern is our raw data.”
Recorded over the course of a blast, the information is used to calculate the velocity of detonation in metres per second. Differing mixtures result in different detonation velocities. Different detonation velocities can be tailored to different real-world mining applications.
Rielo gets excited as he talks about his work. It’s clear that he loves it.
“I love working with the students,” he says. “My passion is instrumentation. Data from blasting experiments can be challenging. They normally have expected patterns but often there are issues of noise, as at detonation a plasma is created that tends to contaminate measurements. Denoising and understanding the data can be a lot of fun.
“This is a discontinuity in the explosive mix, due to poor mixing,” he adds, pointing at a blip in the data graph from the last shot.
To see more of the Alan Bauer Explosives Laboratory, watch this profile of Queen's mining engineer Luka Ledoux: