Mineral Facts and Problems: 1960 Edition Page: 50
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MINERAL FACTS AND PROBLEMS, ANNIVERSARY EDITION
ods and because of the low cost of recovery,
culm banks became important as a source of
anthracite to meet the demand for the small
sizes. Recovery methods comprise loading the
culm material from the bank by power shovel
into trucks and hauling to the preparation
plant. Over the past several decades, a sub-
stantial output of clean coal originated from
culm banks. Fourteen percent of total produc-
tion in 1958 came from culm material.
RIVER OR DREDGE COAL
Wasting of the unmarketable smaller sizes
of coal in the early days of the industry was
either to culm banks from which much material
subsequently was washed into the streams or
by direct discharge into the streams. Even-
tually the beds and banks of the Susquehanna,
Schuylkill, and Lehigh Rivers and many of
their tributaries were covered with considerable
quantities of small-sized anthracite. Owing to
its weathering-resistant characteristics, the an-
thracite in the rivers showed virtually no de-
terioration. With the improving demand for
the small sizes, recovery of the coal from river-
beds was started in the late 1800's with simple
suction dredges mounted on barges. Peak re-
covery of river coal was in 1941 when more
than 1.5 million tons were obtained by dredg-
ing. In the 1954-58 period, the annual output
of river coal averaged about 700,000 tons.
Raw feed to the preparation plants contains
excessive impurities, such as bone coal, slate,
etc., and ranges in size from fines to very large
pieces. It is the function of the preparation or
cleaning plant to break the large pieces, remove
the impurities, and classify the coal into the
The first anthracite breaker, capable of sizing
as much as 200 tons of coal a day, was erected
in the Southern field in 1844. Modern breakers
are far removed from this first plant and one of
the largest, constructed not too many years
ago, has a capacity of about 2,000 tons of clean
coal per hour. In recent years there has been
a rapid trend away from the construction of
large central breakers or preparation plants.
With only a few exceptions, all new plants
have been of small to moderate size utilizing
modern equipment with good instrumentation
and low manpower requirements.
Jigs which clean coal with moving pulses or
rapid currents of water were widely used in the
past but now play only a minor role in anthra-
cite preparation. Cones, introduced in 1921,
are still used in the larger plants for cleaning
a wide range of sizes. Sand and water mix-
tures had been used universally in cones in the
past but currently some plants are employing
mixtures of magnetite and water. Dense-
medium equipment employing mixtures of
magnetite and water has found ready accept-
ance in current practices for cleaning the
large and intermediate sizes. Hydro-separators
or hydro-classifiers, using the principle of slow
currents of water and hindered settling, also
have been widely accepted for cleaning the
small sizes. Concentrating tables have been
and continue to be used widely for cleaning the
small sizes, and launder screens, since their in-
troduction, have been adapted for preparing
small sizes in a number of plants. Humphrey
spirals, for cleaning the small sizes, were intro-
duced about 1945 but have never been widely
adopted. Flotation equipment first was used
about 1940 for cleaning the smallest sizes of
anthracite, and there now are several plants
with this type of equipment. The most recent
addition to anthracite preparation has been the
use of cyclones with or without dense media
for cleaning the small sizes.
Currently there is only limited forced drying
of the small sizes of anthracite by filtering or
heating. Dewatering is accomplished usually
on vibrating or other types of active screens.
The uses of anthracite generally fall into
two broad categories: (1) As a fuel; and (2)
as a source of carbon.
For over 100 years the space-heating market
has provided the largest outlet for anthracite.
Until the advent of fuel oil and, later, natural
gas, anthracite occupied a dominant position in
the space-heating markets of the New England
and Middle Atlantic States and in the eastern
Provinces of Canada. Although much of this
market has been lost to competitive fuels, it is
expected that domestic and commercial space-
heating installations in these consuming areas
will absorb large quantities for many years.
Several public utilities with plants in or
close to the anthracite producing region pro-
vide the next largest outlet-consuming be-
tween 2 and 3 million tons of small-sized an-
thracite annually to generate electric power.
While the source of utility coal is largely un-
known, a large part-perhaps as much as one-
third-is high-ash fine material obtained at low
cost from old silt or culm banks and from
creeks and rivers draining the anthracite fields.
The iron and steel industry is undoubtedly
anthracite's third largest consumer, using more
than 1.5 million tons of all sizes in 1958 for
coke making, sintering iron-ore fines, pel-
letizing beneficiated low-grade domestic ores,
lining pots and molds, heating, and as a substi-
tute for coke in foundries. Class I railroads
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United States. Bureau of Mines. Mineral Facts and Problems: 1960 Edition, report, 1960; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc38790/m1/58/: accessed January 19, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.