Leak Hunting

Ifyou walk past a really noisy spot in an underground mine, far away from the active faces, the racket is probably caused by a leaking compressed air line. That’s the sound of energy, and tens of thousands of dollars, vanishing into thin air. With compressed air typically accounting for 15-30% of the electrical energy consumed at a mine, it is worthwhile investigating if you’re getting your money’s worth.

To address this issue, the Ontario Mining Association has undertaken the Compressed Air Leak Management project at a cost of $532,000, funded by the Ontario Power Authority (OPA)’s Conservation Bureau ($218,000) and the participating mines (in cash and in-kind efforts).

The project, begun in summer 2006, is a comprehensive audit of electricity use and savings opportunities in compressed air systems at different types of underground mines, co-ordinated by Ivor da Cunha of Mississauga, Ont.-based LeapFrog Energy Technologies Inc. Three Ontario mines are participating–FNX Mining’s McCreedy West nickel mine and CVRD Inco’s Copper Cliff South nickel mine, both near Sudbury, as well as Teck Cominco / Barrick Gold’s Williams gold mine near Marathon–representing a cross-section of size, consumption and instrumentation.

The goal is to develop best practices and guidelines for energy-efficient compressed air systems; the final report will be made available to OMA members in spring 2007. Da Cunha outlined the progress of the project for CMJ in late December.

The main culprit of energy loss is leaks in the compressed air distribution system. A good place for a mine to start, according to da Cunha, is to install instrumentation to measure flow and pressure, to find out how much air is going into each level. Air “leak tags” can also be used by anyone in the mine, to help the maintenance department locate leaks and prioritize their repair. A next step would be a sophisticated onscreen system for managers to determine the extent of compressed air and energy losses.

Tracking the leaks can help determine which types of valves and clamps are more effective (helpful for future procurement), and the best methods of installing valves and clamps to prevent air leaks from occurring. In some cases pipes that are being bumped by vehicles (causing leaks) should be moved to a safer place.

The study has already resulted in improvements. For example, a sprinkler system that uses a mix of air and water to suppress dust was being left on all the time at one mine. To reduce the loss, it now operates on a timer, using just the amount of air that is needed.

“The foremen are the key people for detailed training in best practices; they can increase awareness across the site through employee meetings,” says da Cunha. Another important person is the mine manager: “Having the top management on board makes energy efficiency projects more sustainable.” Other audiences for the report will be maintenance managers and chief engineers. At the planning stage now is an information workshop that will teach the best practices and lessons learned from this study.

“The results won’t be one-size-fits-all but a portfolio approach,” he says. “What each mine has will determine which tools it will pull from the report.” But because compressed air systems are much the same throughout the world, the results will be useful well beyond Ontario’s borders, and not just in mining.

“The OPA wants to develop a sustainable energy conservation culture,” says da Cunha. “Since compressed air is common to virtually all underground mines and has identifiable losses, it’s the ‘low-hanging fruit’ for energy conservation. We want this eventually to lead into other types of energy savings.” For more information contact da Cunha at ivor.dacunha@sympatico.ca, or Cheryl Brownlee of the Ontario Mining Association at cbrownlee@oma.on.ca.