They tasked CEMI with developing a rigorous and objective business case for VOD, asked what steps would have to be taken to ventilate based on quality as opposed to quantity of air called for and sought help with better understanding the role of the different sensors on which a VOD system relies.
“The future is very bright for ventilation-on-demand,” said CEMI R&D program director Glenn Lyle. “The ability for a mine to be able to effectively and efficiently move air from one area of a mine to another will be a tremendous benefit in terms of energy savings because you don’t have to ventilate to the same levels all the time.”
Another equally important benefit is the ability to increase production by putting the air where it’s needed.
“Most mines tend to be more ventilation constrained than production constrained,” said Lyle. “If you had ventilation available, you could likely achieve higher production rates.”
In the final analysis, he said, VOD decreases the energy intensity of mining, allowing mining companies “to get more tonnes out of the ground for a lower energy investment.”
Optimizing the benefits of VOD involves both technical and cultural challenges.
“There are a lot of technologies that need to fit together, and as we have seen during the course of the last year, they don’t always come out of the box and immediately connect up,” said Lyle. “There has been a lot of success in getting all the pieces to work together, but it doesn’t happen automatically.”
The CEMI team is particularly excited about new tool developed by Objectivity, a Sudbury-based decision support company contracted to manage the demonstration projects at the two mines.
The box sits between a simulator and a ventilation solver and calculates the demand for ventilation based on the number and location of equipment in a mine at a given time, explained Lyle. This information is then fed into the ventilation solver to determine the airflows required on the various mine levels.
“We think this is going to be a very useful tool that will give mining companies a much better idea of how and where to spend their money if they’re looking to upgrade their ventilation systems. We’re very excited about it and see it as something we intend to build on in the future.
“Most of the justification for ventilation-on-demand to date has been done on the basis of Excel spreadsheets. Instead of tweaking your Excel spreadsheet 100 times, you can run through a multitude of simulations, put them through the rules engine that Objectivity developed and come up with a suite of (best case options).”
The tool will give mining companies the confidence they require to ensure they are investing in the right place and that the VOD system they are acquiring will meet their objectives.
The tool will help mining companies make decisions about moving forward with VOD systems, said Andrew Dasys, president of Objectivity.
“We don’t have anything to gain by telling a company the numbers are better or worse, and we can tie it back to the production plan, which I think is incredibly important. We can give a mining company ranges of what is achievable and what types of technologies are required to get to those levels of achievement.”
Quality vs. quantity
Ventilating to quality criteria, one area of study undertaken by CEMI, will first require legislative changes in Ontario, where mining regulations currently prescribe a minimum ventilation rate of 100 cubic feet per minute of air per brake horsepower of operating diesel equipment.
Other jurisdictions are moving toward ventilation requirements based on quality in recognition of the cleaner burning diesel engines in increasingly greater use and it’s inevitable that Ontario will move in the same direction, but the challenge, said Dasys, is “how you measure quality correctly.”
That, in turn, raises a series of issues about sensors.
“If you’re going to have VOD, you need to have a good, reliable sensor network because as you’re moving quantities of air throughout a mine, you want to know that what you expect to happen is actually happening,” said Lyle.
“VOD relies heavily on feedback from sensors installed underground, so there has been a fair number of learnings about making sure the sensors are in the right location, that they’re properly calibrated and properly maintained.”
Centre of expertise
The VOD work being done in Sudbury can be leveraged for the benefit of the global mining industry, said Lyle.
“We see a nucleus of expertise developing here and we believe this expertise can be marketed to the rest of the world.”
Detailed findings from CEMI’s research were to be shared at a workshop attended by representatives of several mining companies in May. The plan for the balance of 2011 is to continue collecting data from the two Sudbury mine sites and begin scoping a follow-up study to probe VOD issues requiring further research.
“We want to get other partners involved because everyone in the mining industry recognizes that whether you’re at Vale, Xstrata, Barrick or Goldcorp, a lot of the issues are the same,” said Lyle. “If we can work together and solve these issues in a collaborative effort, it will be a lot more cost effective and we’ll end up with a better product.”
The $8.5 million study was made possible by a $4.25 million contribution from the federal government’s Community Adjustment Fund and a matching amount funded by Vale and Xstrata Nickel.