“Until now, sensors have been used for monitoring conditions underground, but we see moving to a system where they are going to be used to control airflow,” said Lyle. “That’s going to demand that our sensors are a lot more reliable and robust.
“There’s going to have to be a lot more time and attention spent on sensors in terms of their calibration, installation and maintenance because there can be a lot of challenges with them. They can be affected by depth and pressure and cross contamination from other airborne contaminants.”
To operate a VOD system in the future, mines will need to have access to accurate data from airflow, temperature and gas sensors, said Lyle.
Current legislation in Ontario and other jurisdictions dictates ventilation requirements based on the horsepower of diesel engines regardless of how clean burning they are. At some point, however, government is expected to move toward ventilation requirements based on air quality.
“We don’t believe this will happen in the short term, but given some of the questions we have raised regarding sensor reliability and accuracy, I’m not sure you’d want to run a quality-based system today anyway,” said Lyle.
Quality-based VOD systems in the future will require sensors on mining equipment and in working areas of mines to measure contaminants and control airflow.
As part of the study, CEMI installed tailpipe sensors and SymBot data collection devices from Sudbury-based Symboticware Inc. on underground mining equipment and found the results correlate closely with the data collected by the Canadian government’s CANMET lab in Ottawa.
“That gives us a lot of additional flexibility in that we can now look at doing tests in the lab much easier than we could do them in the field,” said Lyle.
One of the objectives of the study was to try to determine the economics of a VOD system, said Andrew Dasys, president of Objectivity, a Sudbury decision support company.
To do this, Objectivity developed a software tool called VREX.
“VREX is a ventilation rules engine that takes a simulated production model, looks at the air demands for the vehicles required and tries to come up with a reasonable expectation of what the cost will be to meet those requirements,” said Dasys.
“It tells you, if you are going to put VOD into your mine, where you should put it to get the biggest payback. Is it in your auxiliary system or your primary system? It helps mines make better investment decisions.”
CEMI is now proposing a follow-up study and looking to put together a bigger consortium.
“The issues we have identified at the two mines in Sudbury are the same issues that other mining companies around the world will encounter when they start to do VOD,” said Lyle.
The proposed follow-up study will take two or three years to complete and will cost upwards of $6 million.
CEMI is the only research organization in the world currently focusing on ventilation-on-demand at this level of complexity, according to Lyle.
“When we started this project, we brought in two well-known experts in the field of ventilation – one from the United States and one from Australia – to critique our work plan and at that point in time they were not able to identify anywhere in the world where that level of integration was being proposed in any sort of test environment.
“When we start this next phase, our plan is to bring back these same individuals because our goal is not to repeat other work that’s being done. If there is information we can learn from others, we want to learn it before we start our testing, but to our knowledge, there are no other experiments or testing that is being undertaken to this level of detail.
“I believe there’s a lot of interest in what we’re doing and how you can apply the results. We’re certainly seeing that from Vale and Xstrata Nickel, and we believe there’s going to be interest in it from other parts of the world.”
The CEMI VOD study was funded by Industry Canada’s Community Adjustment Fund. Collaborators included Vale, Xstrata Nickel, VOD vendors Bestech and Simsmart, as well as CANMET Natural Resources Canada, Objectivity, Symboticware and Toromont CAT.