May 17, 1918.

THE COLLIERY GUARDIAN

995

jig-filler trough. This arrangement consists of a
trough running back of the jigs with a 3 in. cast
iron connecting pipe from the bottom of the trough
to each jig. A connection will be made from the
distributing main to the trough, with an automatic
float valve on the end arranged to maintain a constant
level of water in the trough. The trough will be
filled with water up to a height to balance the water
in the jigs through the connecting pipe. If the height
of water in any jig falls below the proper level, water
in the trough will flow into the jig and the automatic
float valve will open, and the water fill the trough
until the balance is reached, when the automatic float
valve will close. This arrangement maintains a con-
stant water level in the jigs, and results in better
jigging due to the uniform conditions. It should also
result in a saving in the quantity of water used by
the jigs, as compared to the amount used when ineffi-
ciently controlled by hand.

Machinery.—The shakers are made of 3 by 6 in.
wood sides with 3J by 3J by f in. cross-frame angles,
suspended by 1 by 6 in. hanger boards. They are
driven by 3 in. throw eccentrics at 150 revolutions per
minute, connected to the shaker by 3 by 6 in. Parrish
flexible wood arms. The shakers are 4 ft. and
4 ft. 6 in. wide by 15 ft. to 24 ft. long.

Rolls are of the slow-speed type, 36 by 36 in.,
compound geared with cast iron chilled teeth built
up in segments. The peripheral speed is 300 ft. per
minute, and they have a capacity of about 300 tons
an hour.

The jigs are the Simplex pan type, running at 137
revolutions per minute, with automatic slate gate
and automatic starter. There are 20 jigs placed back
to back in two rows of 10 each, facing opposite sides
of the breaker, affording excellent light for refuse and
coal inspection. At present there are five jigs for
egg, four for stove, four for nut, three for pea,
and two for buckwheat.

All the conveyors have 6 by 18 in. flights with
9 in. pitch Keystone chain. The elevators have 22

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Fig. 6.—Scheme of Preparation, Drifton Breaker.

by 25 by 12 in. buckets at 18 in. centres, with two
strands of 9 in. pitch heavy pattern Keystone chain.
The elevators travel 90 ft. per minute, and have a
capacity of 200 tons an hour.

The moving picking tables, 4 ft. 6 in. wide, are of
the overlapping pan type, and run at about 30 ft. a
minute. Each table is equipped with a friction clutch
for starting and stopping, and a moving apron
discharge chute.

The breaker engine is an 18 by 36 in. double
reversible Corliss valve type, non-condensing, running
at 100 revolutions per minute, belted to the main
line shaft by a 24 in., 10 ply rubber belt. The average
indicated horse-power is 272 loaded, and 165 when
running light.

Several of the drives from the main line shaft
are equipped with friction clutches. These drives are
arranged so that combinations of machines may be
operated while other combinations are momentarily
stopped for attention or repairs. Generally speaking,
all rope sheaves are 60 in. in diameter for 1| in.
manilla rope, and belt pulleys are 48 in. diameter.
The feeder is built like the shakers, but is fitted with
blank plates, and is driven by adjustable-throw
eccentrics in order to vary the feed.

The loading belt conveyor is a 36 in. by 6 ply | in.
rubber covered belt, running on Robins troughing and
return idlers. The speed ranges from 300 to 500 ft.
per minute, according to the size of the coal handled,
and is adjusted by hand control of the 8 by 10 in.
driving engine; the larger the size of coal, the slower
the speed.

Steam Heat.—A gravity return system is used, the
returned condensed steam being wasted. The pipe
radiator coils consist of 15,300 lin. ft. of 2 in. pipe,
or 155 cu. ft. of breaker contents per foot of 2 in.
pipe. Exhaust steam from the breaker engine is used
when operating; live steam at other times.

Coal prices in Alexandria are about £17 per ton for
Cardiff qualities, and £15 5s. for north country qualities.

French Coal for Switzerland.—The announcement that
the French Government, in agreement with its Allies, is
prepared to let Switzerland have about 85,000 tons of coal
a month, at 150 fr. (£6) a ton, has given great satisfaction.
The chief difficulty still to be solved is that of transport.
France asks for Swiss trucks for the conveyance of the
coal, and the question is whether sufficient Swiss trucks
are available. The Bund learns that no conditions are
attached by the Allies to the use of this coal, except that
Switzerland shall make with Germany no hampering con-
ditions in addition to those already existing.

MANCHESTER GEOLOGICAL AND
MINING SOCIETY.

A meeting of the Manchester Geological and Mining
Society was held on Tuesday last, with Mr. W.
Pickup, president, in the chair.

Stone Dusting in Mines.

Mr. A. Rushton read a paper on “ Stone Dusting
in Mines” (see p. 996).

DISCUSSION.

In opening the discussion, the Chairman said that
the advantage of the method described was that by
mechanical means Mr. Rushton obtained a better
distribution of stone dust in the travelling air current,
thus securing a wider deposit and better mixing with
the coal dust at a less cost than by many methods now
in use. He moved a vote of thanks to Mr. Rushton.

Mr. C. Fletcher seconded the motion, which was
carried unanimously.

Mr. Harrison said he had recently had an oppor-
tunity of seeing how the apparatus worked. The
test was made with dust of three colours. The first
was black coal dust; a cloud of that went off, and
he saw how it deposited on all kinds of surfaces,
whether vertical or flat. Then grey shale dust was
discharged in the same way as the coal dust, and
stuck anywhere on the top of the latter. Looking
through the electric lamp glasses, one could see the

black cloud of the coal dust and how the shale dust
cloud got on top of it. Then Mr. Rushton took a
bucket of white ground lime dust. When that had
been distributed with the apparatus everything was
white; it got into the interstices of the packs and
into every crevice, whether vertical or horizontal.
Then he took a dozen iron rail nails and ejected them
in the same way as the dust. The first one was found
five yards away from the sprayer, the last ones to
be picked up were 14 or 15 yards away. That showed
the force of the current. He (Mr. Harrison) was
quite satisfied that there was no cheaper way. The
weight of the stone dust was about 80 lb., and the
operation occupied 30 to 35 seconds by the watch. If a
man had to carry pipes and a bucket and do it by
hand it would take a long time and cost considerably
more in wages, so that if it was at all convenient to
do it by this method it was much the cheapest, and
certainly the distribution was far more effective.

Mr. C. Fletcher agreed with Mr. Harrison. If com-
pressed air was available there was no more simple or
more effective method.

Mr. Siddell said he had witnessed Mr. Rushton’s
experiments, and was much impressed by them. The
surprising thing to him was the enormous distance
that the dust travelled. It came back into the return.

Mr. Harrison said if the members desired to see
some experiments carried out at the pit, no doubt
Mr. Rushton would try to meet their wishes.

Mr. Stephenson said he had used not quite the
same thing but something similar, and it acted very
well indeed, making the atmosphere just like a foggy
day.

Mr. Rushton stated that he was willing to arrange
an exhibition of the apparatus at *the colliery on some
day to be fixed.

The Chairman said so far as they were able to judge
that afternoon the method was very effective. The
proposed visit would come before the council.

Outburst of Coal and Gas.

Mr. F. N. Siddall read a paper on an “Instan-
taneous Outburst of Coal and Gas at Bedford Col-
lieries, Leigh” (see p. 997).

DISCUSSION.

The Chairman, in moving a vote of thanks to Mr.
Siddall, said these outbursts were somewhat alarming,
but, fortunately, were not of frequent occurrence.
If a careful record of the circumstances surrounding
each was made, the way might be indicated along

which protection against them in a greater or less
degree might ultimately be obtained.

Mr. Atherton seconded the vote of thanks, which
was carried unanimously.

Mr. H. Speakman said that when he was in the
pit the day before he noticed that there was a small
trickle of water coming from the orifice, but the place
was practically clear and they were able to get right
up to the face with the safety lamps. They had
electric lamps with them. There was rather more than
a slight show of gas on the higher side of the level,
and he did not think it was coming from the orifice
itself, but from cracks in the coal on the higher side
of the level. In this particular mine they were obliged
to drive the levels and brows in the manner adopted
because they were in the nature of test places. They
were proving some coal which was beyond the extent
of their ordinary take; it had been surrendered by a
neighbour, and they had certain work to do in a
specified time. They had to prove it by levels and
brows, and that was the reason this method of working
had been adopted.

Mr. Miller said he was for ten years the manager
at one of the collieries Mr. Siddall had mentioned.
It was specially liable to outbursts of coal and gas, and
the deductions which Mr. Siddall made agreed with
the views which he himself formed as to the prevention
of these sudden outbursts. His experience was that
the best remedy was to work longwall. If that could
not be done he was certainly in favour of bore holes;
it had been proved that bore holes were of great

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Fig. 7.—Longitudinal Section, New Drifton Breaker.



service where strait work was being done. After
crossing a fault they could open out, and they simply
seemed to riddle the place with bore holes in every
direction. At the same time one was never sure
whether sufficient bore holes were being put in or
whether he was going far enough ahead.

Mr. Drummond Paton asked whether any investi-
gation had been made with regard to the reddish,
salty-tasted deposit on the specimens of coal exhibited.
In the oil region they never got a big blower of gas
with oil unless it was accompanied by marine deposit,
and very often salty water came out at first. Mr.
Siddall should wash off some of this material, remove
the red deposit, and then examine the microstructure
of the coal. It might be material which produced
petrol and oil. He did not knew whether the water
had been tested or what had been done with the
material, but he suggested an investigation along
those lines.

Mr. Lomax said some of the coal had been put into
his hands, and he had made a microscopic examination
of it. He had prepared a number of slides, including
specimens of the coal dust, each particle of which
was tinged with red. That indicated resinous material
of certain kinds. He had not been able to determine
the nature of some of the crystals, but they were
well defined, the angles being quite perfect. Another
slide taken from the block of coal showed that it was
porous and full of cavities. In the case of such porous
coal heating to a certain extent would drive off gas
very quickly, but where the coal was not porous there
was practically no occluded gas, and the coal was of
a more resinous nature. It was worthy of notice that
all these cavities seemed to be coupled together. One
slide showed vegetable tissues, which were quite open,
and there was a decayed stem in the centre. A stem
of that kind might be in the coal for a distance of
a yard or two and connect hundreds or thousands of
cavities of that sort. When the end of that stem was
broken off it acted as a conduit to the others, and a
lot of gas escaped. The hard coal, which was charac-
teristic of the Trencherbone, was dull-looking, and was
made up of more or less laminated tissue, layers of
leaves, and other matters, and they would see from
the slide how that lay in the coal. Below that was
another kind, which constituted the bright portion of
the coal. The bright portion of all seams of coal
contained more resinous matter than the other por-
tion. The place where most of the gas would occur
was where there was broken up turfy matter, as seen
in the slide. The jumbled aggregation of the various
kinds of tissue would make that coal more soft and