THE ANTHRACITE COAL BREAKER.
In the act of 1885 it is provided that “no inflammable structure other
than a frame to sustain pulleys or sheaves shall be erected over the
entrance of any opening connecting the surface with the underground
workings of any mine, and no breaker or other inflammable structure
for the preparation or storage of coal shall be erected nearer than
two hundred feet to any such opening.” This was for the purpose of
preventing, if possible, such lamentable disasters as those of Avondale
and West Pittston. The results of this legislation in providing greater
security to the employees in mines is invaluable. Formerly it had
been the custom to build not only the shaft-house over the opening
into the mine, but the breaker itself, wherever there was one, was
usually erected over the mouth of the shaft. This was convenient and
economical, since the coal could be hoisted directly from the mine to
the top of the breaker, without the delay of a horizontal transfer at
the surface of the earth. Many of the shaft houses and breakers that
had thus been built at the time of the passage of the act are still
in operation, and will so remain until the time of their utility is
passed. But all new buildings are erected in accordance with the law.
[Illustration: THE SLOAN COAL BREAKER, HYDE PARK, PA.]
At the mouth of the shaft heavy upright timbers are set up, inclosing
the opening. These are united by cross-beams, and the whole structure
is well braced. In this head-frame are set the sheaves, at a distance
from the ground of from thirty to fifty feet, although, when the entire
surface plant was under one cover, they were set much lower. These
sheaves are huge upright wheels sixteen feet in diameter, over which
the ropes pass that connect with the cages. A sheave similar in form to
the bicycle wheel is now coming rapidly into use; it is found to bear a
greater strain in comparison with its weight than does any other form.
The hoisting engine must be in the immediate vicinity of the shaft, and
the rooms for this and the boiler, furnace, and pump are usually all
under one roof. The iron or steel wire ropes extend from the sheaves
in the head frame to the drum in the engine-room, around which they
are coiled in such a manner that as one is being wound up the other is
being unwound. Therefore as one carriage ascends the other descends by
virtue of the same movement of the engine.
Since the breaker may receive coal from two or more openings it must be
so located as to be convenient to both or all of them. If the ground
slopes sufficiently the breaker may be so built that its head will be
on a level with the head of the shaft. This will save breaker hoisting.
When coal is brought out by a slope the track and grade of the slope
are usually continued, by an open trestlework, from the mouth of the
opening to the head of the breaker. Wherever it is possible to do so,
the loaded cars are run by gravity from the mouth of the opening to the
breaker, and the empty ones are drawn back by mules. Sometimes they
are hauled both ways by mules, and sometimes a small steam locomotive
engine is employed to draw them back and forth.
The coal breaker is an institution that is peculiar to the anthracite
coal fields of Pennsylvania. Its need was made manifest early in the
history of anthracite mining, its development was rapid, and it has now
come to be wholly indispensable in the preparation of anthracite coal
for the market. It is very seldom indeed that one sees this coal in the
shape and size in which it was mined. All anthracite coal for domestic
use is now broken, screened, and separated into grades of uniform size
before being placed upon the market, and this work is done in the coal
breakers.
Previous to the year 1844 these breakers were unknown. Several
experiments had been made in the matter of breaking coal by machinery,
but there had been no practical results, and the breaking still
continued to be done by hand. In that year, however, a breaker after
the modern plan was erected at the mines of Gideon Bast, in Schuylkill
County, by J. & S. Battin of Philadelphia. It was started on the 28th
of February, 1844. There were two cast-iron rollers in it, each about
thirty inches long and thirty inches in diameter, and on the surface
of these rollers were set iron teeth or projections about two and one
half inches long and four inches from centre to centre. These rollers
were placed horizontally, side by side, and were so geared that, as
they revolved, their upper surfaces turned toward each other, and the
teeth on one roller were opposite to the spaces on the other. These
rolls were afterward improved by being perforated between the teeth,
thus presenting less of solid surface to the coal, and causing less
crushing. Another set of rollers was afterward added, being placed
above the first set, and having the teeth larger and wider apart,
so that large lumps of coal might first be broken into pieces small
enough to be crushed readily by the lower set. After the perfecting
of the rolls came the perfecting of the screens for the purpose of
separating the broken coal into grades according to size. Before the
introduction of coal breakers a hand screen was used. This screen was
set in a frame, was cylindrical in form, and was slightly inclined from
the horizontal. It was turned by a crank at one end, in the manner of
a grindstone. The screen placed in the breaker was of much the same
pattern, except that instead of being from five to eight feet long the
length was increased to twenty feet, and the diameter correspondingly
enlarged. Mr. Henry Jenkins of Pottsville then invented a method of
weaving thick wire into screen plates about three feet wide, having
the proper curve. These curved plates being joined together formed the
necessary hollow cylinder. These separate plates are called jackets,
and when one of them wears out it may be taken from the cylinder and
replaced, with but little trouble and delay. The screen is set in heavy
framework, and is inclined slightly from the horizontal. The first
segment at the upper end of the screen is made of wire woven into a
mesh so fine that only the smallest particles of coal will pass through
it; the mesh of the next segment is larger, and that of the next larger
still. The screen may contain from two to five segments in its length.
Now the coal, being poured in on top of the revolving rolls, comes out
from under them broken into small pieces, and passes immediately into
the upper or highest end of the hollow cylindrical screen as it would
pass into a barrel. But, as the screen revolves on its axis, the finer
particles of coal fall out through the fine mesh of the first segment,
and are carried away in an inclined trough, while the rest of the coal
slides on to the next segment. Here the next smallest particles fall
through and are carried away, and the process is continued until the
lower end of the screen is reached, out of which end all the coal that
was too large to pass through the mesh of the last segment is now
poured. It will be seen that by this means the different sizes of coal
have been separated from each other and can be carried by separate
shutes to the loading place. This is the principle of the rolls and
screens which are the main features of every coal breaker, though each
breaker usually contains two or more sets of rolls and from eight to
twelve screens. The Woodward breaker recently erected near Kingston,
Pennsylvania, has six pairs of rollers and twenty screens. Some of
these screens are double; that is, they have a larger outside screen
surrounding the smaller one, and the coal that passes through the inner
screen is caught by the outer one and again divided by means of a
smaller mesh.
Before the days of breakers and screens coal was sent to market in
the lump, as it came from the mine, and it was generally broken and
prepared for use by the consumer. But when the separation of coal in
the breaker became reduced to a system, the four smaller sizes than
lump coal were soon graded. They were known as steamboat, egg, stove,
and chestnut. It was thought at the time that no finer grade of coal
than chestnut could be burned to advantage. But it was not long before
a smaller size, known as pea coal, was separated, placed on the market,
and readily sold; and now, within recent years, another still smaller
size called buckwheat has been saved from the refuse and has come into
general use. Everything smaller than this is culm and goes to the waste
pile. The names of the different sizes of marketable coal and the
spaces over and through which they pass in the process of separation
are given in the following table, taken from Saward’s “Coal Trade
Annual,” for 1888:――
───────────────────┬──────────┬──────────
│ OVER. │ THROUGH.
│ Inches. │ Inches.
───────────────────┼──────────┼──────────
Lump coal bars │ 4½ to 9 │
Steamboat “ │ 3½ to 5 │ 7
Broken mesh │ 2⅜ to 2⅞ │ 3¼ to 4½
Egg “ │ 1¾ to 2¼ │ 2⅜ to 2⅞
Large stove “ │ 1¼ to 1⅞ │ 1¾ to 2¼
Small stove “ │ 1 to 1¼ │ 1¼ to 1½
Chestnut “ │ ⅝ to ¾ │ 1 to 1¼
Pea “ │ ⅜ to ⅝ │ ⅝ to ⅞
Buckwheat “ │³∕₁₆ to ⅜ │ ⅜ to ⅝
Dirt “ │ │³∕₁₆ to ⅜
───────────────────┴──────────┴──────────
The necessity which controls the form and construction of the breaker
building is that the unbroken and unscreened coal must first be
taken to a point in the building sufficiently high to allow of its
passage, by gradual descent, with slow movement, through successive
rolls, screens, shutes, and troughs until, thoroughly broken and fully
cleaned and separated, it reaches the railroad cars, standing under
the pockets, and is loaded into them for shipment. It is sometimes
possible, as has already been intimated, to locate a breaker on the
side of a hill so that the coal may be run into the head of it from the
mine by a surface track without the necessity of hoisting. In this case
the building will hug the hill, extending for a long distance down the
slope of it, but without rising at any point to a great height from
the surface of the ground. In these days, however, the breaker is more
frequently erected in the valley. The general results are thought to be
better, and the special convenience to railroad outlets to market is
certainly greater. Besides this, the necessities of the case in shaft
mining seem to demand it.
A peculiar and characteristic feature of a breaker so built is the
great vertical height to which one portion of the building is run
up. This is the portion that contains the shaft up which the coal is
hoisted, and from the top of which it starts on its long descending
route to the surface again. From one hundred to one hundred and fifty
feet is not an unusual height for this portion of the building. From
this topmost part of the structure the roof slopes down by stages, on
one or two sides, widening out, running off at an angle to cover a
wing, spreading by a projection here and there until, by the time the
last ten feet in height are reached, the ground space covered by the
building has come to be very great. Under the last or lowest portion
of the structure are the railroad sidings on which the cars stand to
be loaded from the many pockets in which the shutes have terminated.
Two engines are necessary at the breaker, one a winding engine to
hoist coal from the surface to the top of the breaker, and the other a
breaker engine to move the rolls, screens, and other breaker machinery.
The winding engine is usually put on the opposite side of the shaft
tower from the rolls and screens, and the ropes from it, either exposed
or under cover of a long sloping roof, reach up to the sheaves in the
head frame. The breaker engine is usually housed in a wing at one
side of the main building, while the several nests of boilers, under
a separate cover, are required by the act of 1885 to be at least one
hundred feet away from the breaker.
No one, having once seen and examined an anthracite coal breaker, could
ever mistake one for a building erected for any other purpose. These
breakers have a character peculiarly their own. They are the most
prominent features in the landscape of every anthracite coal region,
where they tower up black, majestic, many-winged, and many-windowed, in
the range of almost every outlook.
When the mine car full of coal is hoisted to the head of the breaker it
is run by two headmen from the carriage across the scale platform to
the dump shute bars on to which it is dumped. These are long, sloping,
parallel iron bars, set two and one half inches apart. The dirt and all
the coal that is small enough falls through these bars into a hopper,
from which it is fed into a pair of screens, one on each side. These
separate the dirt in the manner already described, and divide the clean
coal into sizes smaller than, and including, egg. Each size as it falls
through the segment of, or out at the end of, the screen, is caught in
a separate shute and carried to a second set of revolving screens where
it is again cleaned and separated, passing from these screens into the
picking shutes. All the shutes or troughs in which the coal is carried
have a sufficient inclination to make the material move by gravity,
and, to decrease the amount of friction, the bottom and sides of each
shute are lined with sheet iron. The large coals which passed over the
dump shute bars now slide down to a second set of bars, set four and
one half inches apart, called steamboat bars; all coal falling through
these being separated by still a third set of bars into steamboat and
egg, and eventually finding its way to the picking shutes or to the
rolls which break the prepared coal. All coal which passed over the
steamboat bars is lump coal, and, after having the slate and bony coal
removed from it by hand as it passes, is carried into the lump-coal
shute and sent down to the loading place; or else it is carried, by
another shute, into the heavy rolls and crushed. As it emerges,
broken, from these rolls, it passes into revolving screens, and the
same process of screening and separating goes on that has been already
described in the case of coal falling through the first or dump-shute
bars. But all this broken, screened, and separated coal finds its way
eventually into the picking shutes. These are narrow troughs down which
the separate grades of coal pass slowly in shallow streams. Across the
top of each trough, at two or more points in its route through the
picking-room, narrow seats are placed on which boys sit facing up the
shute. These boys are called slate pickers. It is their duty to pick
out the pieces of slate, stone, or bone, from the stream of coal which
passes under them, and throw this refuse into a trough at the side of
the shute, from which point it slides rapidly away. The coal as it
comes from the mine is full of waste material, so that the boy who
sits first or highest on the shute has no trouble in finding plenty to
do, and, work as hard as he may, much of the unfit material must still
escape him. The boy who sits below him on the shute is able to give the
passing stream a closer inspection and more careful treatment, and,
should there be one still below, he must have sharp eyes and skillful
fingers to detect worthless pieces that have been left by his comrades.
The boys often put their feet in the shute and dam the coal back for
a moment to give them time to throw out the abundance of slate that
they may see, but no matter how careful they are, nor how many hands
the coal may pass through in the picking process, a certain percentage
of slate and bone is sure to remain. The slate pickers are not all
stationed in one room, though the picking-room usually holds the
greater number of them. They are put at the shutes in any part of the
breaker where their services may be useful or necessary. Indeed, there
are pickers who sit at the refuse shutes to pick out the pieces of good
coal which have been inadvertently thrown in by the other pickers. In
some breakers the coal passes from the shute across a gently sloping
platform, by the side of which the boy sits to pick out the waste.
[Illustration: SCREEN-ROOM IN BREAKER, SHOWING SCREEN AND SHUTES.]
But the time is undoubtedly coming when the occupation of the picker
boy will be gone. The inventive genius of the age has already devised
machinery which does its work faster, better, and with greater
certainty than the most conscientious breaker boy could hope to do it.
The great collieries are, one by one, adopting the new methods, and the
army of breaker boys is gradually but surely decreasing.
Nearly all the slate-picking machines are based on the fact that the
specific gravity of coal is lighter than that of slate or stone. One
method brings the principle of friction into play. A section, a few
feet in length, of the floor of the shute down which the coal passes
is made of stone. At the end of this stone section is a narrow slot
cut in the floor, crosswise of the shute, and beyond the slot the iron
bottom is continued as before. Now when the shallow stream of broken
coal strikes the stone bottom the friction between that bottom and
the pieces of slate and stone is so great that these particles are
impeded in their progress, and by the time they reach the slot they
have not impetus enough to cross it and must therefore drop into it and
be carried away. But the friction between coal and stone is slight in
comparison, and the pieces of coal retain enough of their impetus to
carry them safely across the slot and on down the shute. This is not a
perfect separation, and the coal and slate which it divides has usually
to be looked over again, to insure satisfactory results. The best and
most practicable invention thus far brought into use is that of Mr.
Charles W. Ziegler, picker boss at the Von Storch colliery, Scranton.
This machine acts somewhat upon the method last described, though by
a system of rollers, levers, and screens in connection with it and
attached to it, it is able to make quite perfect separation of the coal
and slate. Two or three of these machines placed on a single shute
should do the work required of them very thoroughly.
The experience of domestic buyers of coal would seem to indicate,
either that the picker boys do not do their whole duty or that the
picking machines have not yet been made perfect. But it must be
remembered that the separation of slate and bony coal from good
material is made only in a rough and general way in the mine, and that
a very large percentage of the output, as it reaches the breaker,
is unfit for use. To clean and separate this material thoroughly,
therefore, requires much labor, and extreme care and skill.
After these separate streams of coal have passed the scrutiny of the
picker boys or the test of the picking machine, the shutes in which
they run are narrowed into pockets or bins, closed at the end by a
gate. The pocket projects over the car track high enough from it for a
railroad coal car to stand beneath, and the coal is then fed from the
pocket into the car at will.
There is also a loading place for the rock and slate which have been
separated from the coal on its way through the breaker; and there are
two or three points where the coal dirt is gathered from its pockets
to be taken away. All this refuse is run out by separate tracks to a
convenient distance from the breaker and there dumped.
It is estimated that sixteen per cent. of the material which goes
into the breaker to be prepared comes out as waste, and is sent to
the refuse dump. It can readily be supposed, therefore, that in the
course of a few years these waste heaps will grow to an enormous size;
and as a matter of fact they do. The dirt or culm, which includes all
material finer than buckwheat coal, is usually dumped on a separate
pile from the rock, slate, and bony coal, since it is not wholly
without at least prospective value. It has been used frequently in
the coal regions to fill in beneath railroad tracks supported by
trestle-work, and it is valuable as a foundation on which to lay
stone flagging for footwalks, since it does not yield readily to
the action of frost. Culm has also been utilized by adding to it a
certain percentage of mucilaginous or pitchy material and compressing
it into bricks for fuel. In some European countries a large amount of
waste is burned in this way, but in America the cost of preparation
is still too great to permit of competition with prepared anthracite.
The most characteristic feature of scenery in the anthracite coal
regions, aside from the breakers themselves, is the presence of these
great, bare, black hills of culm, shining in the sunlight, smoothly
white under the snows of winter. Sometimes these culm banks take fire,
either spontaneously or as the result of carelessness or accident. If
the pile is near enough to the breaker to menace it, or near enough
to an outcrop to carry combustion into the coal of the mine, the fire
must be extinguished, and this is sometimes done with much labor and
at great expense. If no danger is apprehended, the fire is allowed to
smoulder until it burns out, a process which may take months or even
years, during which time little blue flames flicker on the surface of
the bank, the sky above it is tinged with red at night, and the whole
black hillside is finally covered with great blotches of white ash. To
the poor people who live in the vicinity of the breakers these heaps
of refuse coal are an unmixed blessing. Pieces of good coal are always
being thrown out inadvertently with the waste, and the bony coal that
is discarded is not by any means without value as a fuel; indeed it
makes a very respectable fire. So, too, one can obtain, with a screen,
from the culm heap quite a little percentage of material that will
burn. Thus it comes about that every day women and children and old
men go to these black hills with hammer and screen and gather fuel for
their fires, and carry it home in bags, or wheelbarrows, or little
handcarts. It is the old story over again of the gleaners in the field.