Sensors Mag

Cries, and More Crying

May 24, 2006 By: Stephanie vL Henkel, Sensors

E-mail Stephanie vL Henkel

A couple of weeks ago, cries of joy arose across Australia. Last Saturday, another kind of crying arose across Kentucky. Miners in the news again, some saved by sensors and others lost for the lack of them.

A Two-Thirds Happy Outcome

The first story got more news coverage than the second has thus far because the Australian event was a cliffhanger and it had a two-thirds happy ending. What happened at the 100-year-old Beaconsfield Gold Mine in the southern Australian state of Tasmania was that an earthquake set off an underground rockslide that killed one miner and trapped another two in a cage for 14 days. All three were quickly found; the survivors, identified as such by a thermal imaging camera, were fed and comforted while the rescuers worked. Mining union official Bill Shorten was quoted as saying the operation was like "throwing Kleenex at rock." But they got those two out.

A One-Sixth Happy Outcome

At the Darby Mine No. 1 near Holmes Mill in Harlan County, Kentucky, it didn't go so well. All the reports I've read tell a similar story. Six miners were doing weekend maintenance work. There was an explosion. One made it out alive. Four were found together and another in a separate part of the mine. All dead.

Not to Sound Suspicious, But . . .

The first set of news flashes that came in said those miners had been doing some welding. That detail has now been replaced by official mystification over what could have caused that explosion. Hmm. Welding is a common activity in underground mines. Methane is present in every one of those mines. Oxygen too. Now, what could have set off that blast?

Where were the methane sensors? Every miner ought to be wear one with an audible or vibratory alarm. What about instrumenting welding equipment (or, for that matter, anything else that could spark an explosion or conflagration) with sensors that could shut off the machinery before the lower explosive limit is reached? Even better might be to use structural supports made of composites that don't need welding to hold them together.

The Oxygen Tanks That Failed

The Kentucky miners had been assigned the same one-hour air packs that didn't save the 11 miners who died of carbon monoxide poisoning (CO displaces oxygen in the lungs) in West Virginia's Sago Mine this past January. Randal McCloy, Jr, the only survivor of that disaster, said that at least four of his crewmates' self-contained self-rescuers (SCSRs) didn't work. Autopsies on those lost in Darby Mine No. 1 are saying the same thing: death by carbon monoxide.

We're also hearing that all these SCSRs have been tested and pronounced functional. I would like to know where those units were tested. Equipment may be on its best behavior in a lab, but in the field it's a different story. The chill and dank of a coal mine can be a valve-sticking environment.

Here Comes Mr. Bill

So far this year U.S. coal miners have lost 31 of their own, all in the eastern region. They were our own too, unless you'd like to forego electricity or, in some cases, heat. Last year's total was 22. In 2001 it was 42. I don't see an encouraging trend. A bill has been introduced in Congress with several potentially life-saving provisions: SCSRs with two (instead of one) hours of oxygen; extra oxygen stored along escape routes; each mine to have two trained rescue crews with a one-hour response time; and "two-way wireless communications and tracking systems . . . within three years." That bill now goes to the Senate. Anyone want to start a pool on whether or when this bill will be signed into law?

A Higher Standard

Canadian mining operations have been punctuated by some terrible disasters with great loss of life. That country has learned from them and is now setting an example, as is Australia, by having adopted some safety procedures and practices that should be imported into the U.S. The mining safety records of those two countries are now, if not exemplary, at least a great deal better than ours. For instance, in 2005 the First International Workshop on Wireless Communication in Underground and Confined Area attracted a paper, "Advanced Wireless Networks for Underground Mine Communications," presented by the National Research Council, Canada, and Cape Breton University. You might want to take a look. If they can do it, why can't we? A great part of saving trapped miners lies in simply finding them.

Of course, none of these sensing and location technologies is trivial, nor is it cheap. Neither are our miners' lives.

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