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Mining accidents are no joke. Every year, explosions and fires in underground
mines take the lives of scores of people all over the world.
According to the Pennsylvania Department of Environment's Bureau of Mine
Safety, during the period from January 1, 1995 to June 7, 1999, fatalities
in underground coal mines in the United States alone totaled 96.
The task of reducing numbers like those to zero is never-ending, but
clearly the goal is worth pursuing. One jurisdiction with considerable
mining activity, the state of Queensland in Australia, has found a way
to apply the latest Agilent gas chromatography technology to the challenge.
The SIMTARS facility in Queensland, Australia Although not the world's leading coal producer, Australia is, surprisingly,
the world's leading coal exporter. Much of its coal production is centered
in Queensland in the northeastern corner of the country, spread over an
area about the size of Texas. While Queensland is famous for such tourist
attractions as the Great Barrier Reef, the folks who make steel in Japan
are more inclined to focus on the quality of its coking coal, which is
some of the best in the world.
As in every other mining jurisdiction, Queensland continually wrestles
with the problem of accidents in its underground mines. Over the last
20 years the state has experienced four major mine explosions, killing
some 50 people in all. To deal with the problem, Queensland established
SIMTARS, the Safety in Mine Testing and Research Station.
"Queensland has never been immune to major coal mine disasters related
to gas explosions and spontaneous combustion," says SIMTARS' Colin Hester.
"Indeed our coal appears to be more prone to it than many others."
So the focus of SIMTARS from day one has been to minimize the incidence
of these events.
In the old days, the task of monitoring underground mine gas was assigned
to a canary. (In some countries, they're still doing it that way.) If
the canary fell off its perch, that was the signal to evacuate. For those
who need to know such things, the response time of a canary to 100 parts
per million of carbon monoxide in the atmosphere is less than one minute.
Trouble is, somebody has to monitor the canary at all times. And the
problem is really explosions and fires, not asphyxiation. "Given that
we haven't for some years now dropped anyone for lack of oxygen, we have
switched to focusing more on the prevention of spontaneous combustion,"
says Hester.
Most mining accidents, in fact, are directly related to the incidence
of spontaneous combustion, a self-initiated coal fire. Often spontaneous
combustion occurs as a natural result of exposing coal to the oxygen-containing
atmosphere. "If you have a dead space in the mine, areas where the ventilation
is poor, places where lots of coal is lying around in areas that have
been mined out, that's the sort of coal that can heat up and catch fire,"
notes SIMTARS' Darren Brady.
This is a serious problem if the section where "a heating" or smoldering
fire is located also contains combustible levels of gas, since the combustible
mixture and ignition source may cause an explosion. "Such a sorry situation
has resulted in most of Queensland's worst mining disasters," Brady adds.
So SIMTARS requires each mine operator to monitor the gas coming out
of the mines and make sure spontaneous combustion ("sponcom" in the jargon
of the industry) isn't under way, and fire isn't taking hold in the mine. Until
recently this meant applying conventional gas chromatography to analyze
air samples being taken from the mines. Only a gas chromatograph (GC)
is capable of detecting all the indicators of spontaneous combustion –
hydrogen, ethylene, ethane, carbon monoxide and other gases – simultaneously
across the wide range of values required. So GCs were installed at the
minesites, with SIMTARS monitoring them by remote control via modem.
"Customarily, the people operating the GCs aren't chemists," Hester points
out. "They're normal mine operators that we've trained to do the basic
operation on the GC. And the SIMTARS chemists provide the necessary expertise
to keep it all going.
"But the fragility of ordinary GCs make them less than ideal for rugged
applications like minesites. So SIMTARS has been delighted with the development
of Agilent's micro GC, and the agency has now deployed them in five of
the 13 existing minesites in their jurisdiction. New mines are equipped
with them as they come on-stream. And in an emergency response situation,
SIMTARS people routinely transport one to the site in question.
"Because they're designed to be portable, they have a number of features
that are attractive to us," says Brady. "They have low power requirements,
the instrument itself is rugged. We can run them pretty much off a standard
computer. We don't have to spend a lot of time setting them up. The gas
supplies are generally a bit easier for us to get. It's an all-round better
instrument for an emergency response."
SIMTARS has written a program to complement Agilent's EZ CHROM application
which is provided with the chromatograph. Called EZ GAS, it guides the
relatively unskilled operator step by step through the process of doing
a run. It also requires them to name and save the datafile in a format
called SEGAS which is the standard throughout Australia's mining industry.
"We don't necessarily prevent spontaneous combustion by monitoring,"
says Darren Brady. "What we do is pick up on it earlier if we do effective
monitoring. Then once the situation is happening, we have to undertake
some mitigation of the heating of spontaneous combustion and we need to
know whether we're actually winning or losing control."
"Since we've been using the micro GCs, we've quite routinely just hooked
up and been running within 15-20 minutes" says Hester. "Mind you that's
a fairly tense 15 or 20 minutes while they're waiting for the first analytical
results from a pit that might be about to catch fire or explode."
Concludes Brady, "When a mine's on fire or when a critical situation
arises, time is of the essence. So the 5-minute setup and analysis time
on the Agilent high-speed GC is much better than the times we could achieve
on the older GCs, which ran to about 25 minutes."
In other words, if sponcom's your problem, you should probably be looking
at the Agilent micro GC as the beginning of a solution.
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