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20 COALANDTIMBER February, 1905
plosion of coal dust without gas being
present.
In flour mill dust explosions you
have
might
illuminating gas or something of that
kind mixed with the dust, though I do not
think it is necessary to assume this to be
the case.
I believe, though I have no data
upon the subject, that the more bituminous
or volatile a dust is, the more dangerous
it will be. Anthracite dust is certainly not
so dangerous as bituminous.
It is certainly true that the flame from a
blown out shot will be carried much further
in a dust laden atmosphere.
I believe there is something in the
physical condition of the coal which affects
its explosibility. A number of years ago
I carried on a number of tests on Nova
Scotia coals. First I made chemical analyses,
but I do not remember just what the
analyses were. I rigged up an ordinary
stove pipe into the top of which I could
drop the dust, and by means of a gas jet
below, test each of the samples. Sometimes
1 would get an explosion and sometimes
I would not with the same sample. Sometimes
_ one sample would explode and
another of about the same composition
would not. As far as I could see, the condition
of the samples seemed to be about
the same.
M. LeChattellier has shown that gases
are given off by a coal face for a very long
time. He showed that gas was being given
off no matter how long the faces were allowed
to stand.
When we say there is no gas present we
speak comparatively, but wherever you
have coal you are bound to have a certain
amount of fire damp being given off.
In tbe case of a blown out shot incomplete
combustion takes place and explosive
gases remain, such as C. O. These
gases, mixed with the dust undoubtedly
produce a very explosive mixture, so that
even in a mine, which is. free from fire damp
and other explosive gases under ordinary
conditions, a blown out shot may generate
sufficient explosive gas to render the dust
which it stirs up explosive, even if this
dust was not explosive without being
mixed with the gas.
By Mr. Phillips.
I understand from Mr. Duncan that there
will be more gases in new coal and that it
will disintegrate much quicker. The fact
is that some of the worst explosions which
have been attributed to coal dust, have occurred
in old main roads of mines.
By Mr. Evans.
I believe that dust which is found tramped
along main haulage roads for several reasons
has no danger in it. Following Mr.
Duncan's theory, it has left off its gases
and becomes dead, but I will admit that
grefMt explosions have occurred on main
roads, but not from the dust, but from new
dust which
had gathered around the top.
It must have heat, and that will occur with
a room that is turned and driven up 40 or
50 feet; there is more danger there, because
there is more heat, and especially
with this strong current passing through,
all the dust is kept in there, and there is
a certain amount of heat there more than
anywhere else. I think it essential that
each mine should have an analysis made of
its COM.l.
I believe I once said that the volatile niMitter
in the Harwick mine was 37%, but I
heard today that it was only 33 or 34. I
have an analysis that runs to 38.
In my region I don't think that we have
any coal that runs much above 27 and 1
don't think we have very much danger of
dust explosions for the reason that the
volatile matter is very low. When it becomes
30, it becomes very dangerous and
one should find out the amount of volatile
matter in the coal and extra precautions
should be taken. I do not believe the
dust itself is dangerous. I know in my
district when I get into a dry road, 1 talk
wetting it immediately. I want to be on
the safe side; I want it sprinkled. I think
the greater danger lies in the volatile matter.
By
Mr. Fole.
I would like to ask the Institute whether
(here is any record of a dust explosior
in the Pittsburg seam of coal, or in the
Connellsville seam of coal? I have seen
lots of mines in the Pittsburg seam which
seem to me to be ripe for an explosion.
By the Chairman.
I think the physical structure of the coal
has something to do with it aside from the
volatile matter of it. A man told me last
night that they had a flint coal in which
the volatile matter was 47%. He also said
that in their operation, the whole waste
was less than 100 pounds to the ton, so it
shows there is a physical factor as well as
a chemical factor there.
By Mr. William Clifford.
The fineness of division is the gauge of
explosions, but there is dust from mines
that won't explode, while there is some
dust from other mines that will explode,
and it has puzzled the best scientists to
account for this. The fineness of division
in some dust is such that when coal is
rubbed between the fingers like granules
it will explode, but, of course, the greater
the surface to apply that action to, the
quicker the explosion takes place.
By the Chairman.
I think the fact, and it is a fact, that
of two coals that analyze almost exactly
alike in volatile matter, carbon, ash, sulphur
and phosphorous, one will coke and
the other will not coke, and you cannot
make it coke. There is something lacking
and it must be in its physical make-up,
and if that applies to the coke process, it
certainly would apply to the volition of
gases or whatever you may term it.
By Mr. Mollison.
In answer to Mr. Fole's question about
explosions in Pittsburg seam, I know of a
slight explosior. which I think was a dust
explosion.
About ten years ago there was a
slight explosion in the Galitzin mine by
which one man was killed, and I have arrived
at the conclusion that we can have a
dust explosion without the presence of
fire. All that is necessary is sufficient heat
to distill gas out of the dust, and
I believe
that dust is lower in volatile matter
than coal, but it requires more heat to
start it.
In the Connellsville region
in 1901, an
explosion occurred in Southwest No. 4
mine, and I would say that explosive gas
has never been detected in that mine. The
place where the explosion occurred was
very dusty and there was ice a very short
distance from where it ignited. I do not
think there was any gas present.
In Margaret mine, two men had fired
a shot in a heading which was comparatively
damp, tne bottom being damp all
around. It was about 6:30 in the morning.
before they had mined very much and they
had built a well about five feet deep, and
fired, and men, who claimed to be 150
feet away, were burned. This occurred on
Saturday and on Monday I was unable to
find the slightest trace of gas with a Wolf
lamp, notwithstanding some of the men
said I could find it out on the hill, and I
believe all that prevented a greater explosion
in the Margaret mine that day was the
fact of its dampness. I believe there was
very little dust, except what was pulverized
by that shot. After investigating this
matter, I came to the conclusion that with
a blown-out shot we can very easily get
a dust explosion in any mine.
By Mr. Fole.
I will have to object to an argument about
the theory that the highly volatile coals
are the most explosive, because as far as
it has been brought out here, it is merely
a theory.
By Mr. Clifford.
I agree with Mr. Fole. We have a mine
at Crcightou a very few miles from the
Harwick mine, working the same -roil, with
the same chemical composition, and we
have never had any explosion of dust.
Creighton runs 38% of chemical, but the
cover there is not so heavy and I think it
is purely a physical matter and not a chemical
one.
A paper on "Coal Dust Considered
Physically and Chemically" will be one of
the features of the next meeting of the Institute.
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