IMPROVEMENTS IN APPARATUS FOR SCREENING COAL "
Year: 1883

page_text: LETTERS PATENT to Robert Donald Thomson of Jerviston House, Motherwell
in the County of Lanark for an Invention of "IMPROVEMENTS IN APPARATUS
FOR SCREENING COAL
"
PROVISIONAL SPECIFICATION left by the said Robert Donald Thomson
at the Office of the Commissioners of Patents on the 14th July 1883
ROBERT DONALD THOMSON, of Jerviston House, Motherwell, in the county of
Lanark, "IMPROVEMENTS IN APPARATUS FOR SCREENING COAL,"
This Invention relates to improvements in apparatus for screening coal, the main
object of which is to effect the separation into different grades of size or quality, of
the small coal, or dross removed from coal by the screening apparatus at present in
use.
.
The improved screening apparatus comprises a large open cylinder or barrel
composed of rods or bars of iron or other metal which are fitted longitudinally and
form an open grating extending the entire length of the barrel. This barrel, which
is open at both ends, is carried by a rotating shaft passing centrally through it,
and provided with radial spokes or arms to which the barrel is secured in position.
Outside the barrel or cylindrical grating, and concentrically with it, is fitted a
cylinder of wire-cloth or perforated metal, extending from one end of the barrel' to
about its mid length. The diameter of the outer cylinder is considerably greater
than that of the inner one, so that an annular space is left between them. The
central shaft is supported in an inclined position, and is driven by gearing or
otherwise from a counter-shaft or motive-power engine. At the upper end of the
apparatus is fitted a hopper through which the small coal or dross to be treated is
discharged into the inner barrel or cylindrical grating. Through the open bars of
this barrel the smaller dross falls, while the larger pieces or "nuts" travel the
entire length of the barrel and drop out by a shoot at the end into a heap or into
collecting waggons. The smaller dross falling through the open inner grating
drops within the outer wire-cloth or perforated cylinder or sieve, and the finer
dross or dust in turn passes through and is led off by a shoot, while the medium
size. dross which cannot pass through the outer cylindrical sieve falls out at its

page_text: lower end into a discharging shoot. The coal or dross is thus separated into three
grades of size in which it can be disposed of to advantage.
The apparatus may be for convenience fitted within the usual screening house at
a colliery, and may have combined with it, elevators or similar apparatus, to raise
the small coal or dross as it falls from the ordinary screening apparatus, and
discharge it within the feeding hopper provided at the upper end of the improved
screening apparatus.
.
In a modified construction of the improved screening apparatus, the upper end
of the revolving cylinder is made of wirecloth or perforated metal, and the lower
end of longitudinal. bars, the whole forming a single cylindrical barrel. The small
coal dust passes through the wirecloth or finely perforated metal, while the larger
dross travels down to the open longitudinal bars, through which dross of medium
size falls, and the "nuts" or larger pieces are discharged at the lower end of the
barrel as already described.
"

page_text: SPECIFICATION. in pursuance of the conditions of the Letters Patent filed by
the said Robert Donald Thomson in the Patent Office on the 12th January
1884.
ROBERT DONALD THOMSON, of Jerviston House, Motherwell, in the County of
Lanark "IMPROVEMENTS IN APPARATUS FOR SCREENING COAL."
My said Invention relates to improvements in apparatus, for screening coal, the
main object of which is to effect the separation into different grades of -size or
quality of the small coal or dross removed from coal by the screening apparatus at
present in use.
A modification of the improved coal screening apparatus is illustrated in side
and end elevation in figures 1 and 2 of the accompanying drawings.
The improved screening apparatus comprises a large open cylinder or barrel A
composed of rods or bars a of iron or other metal which are fitted longitudinally
and form an open grating extending the entire length of the barrel. This barrel A
which is open at both ends, is carried by a rotating shaft B passing centrally
through it, and provided with radial spokes or arms b to which the barrel A is
secured in position. Outside the barrel or cylindrical grating A, and concentrically
with it, is fitted a cylinder C of wire cloth or perforated metal extending from one
end of the barrel A. to; or somewhat beyond, its mid length.
The diameter of the outer cylinder C is considerably greater than that of the
inner one A so that an annular space is left between them. The central shaft B
is supported in an inclined position in brackets D secured to any convenient part
of the screening house, and it is driven by gearing E or otherwise from a counter-
shaft or motive power engine. At the upper end of the apparatus is fitted a
hopper F through which the small coal or dross to be treated is discharged into
the inner barrel or cylindrical grating A. Through the open bars of this barrel A
the smaller dross falls while the larger pieces or "nuts" travel the entire length of
the barrel and drop out by a shoot G at the end into a heap or into collecting
waggons below. The smaller dross falling through the open inner grating A drops
within the outer wire cloth or perforated cylinder or sieve C, and the finer dross or
dust in turn passes through the sieve and is led off by an inclined shoot H, while
the medium sized dross which cannot pass through the outer cylindrical sieve C
falls out at its lower end into an oppositely inclined discharging shoot I. The
coal or dross is thus separated into three grades of size in which it can be disposed
of to advantage. To prevent filling up of the interstices of the sieve C, a brush J
of wire or stiff bristles is fitted at the outside of the sieve, and is carried in
adjustable bearings or hung on adjustable rods j so that it bears lightly on the
sieve and is caused to revolve by it.
The apparatus may be for convenience fitted within the usual screening house at :
a colliery, and may have combined with it elevators K, or similar apparatus, to
raise the small coal or dross as it falls from the ordinary screening apparatus, and
discharge it within the feeding hopper F provided at the upper end of the improved
screening apparatus.
In a modified construction of the improved screening apparatus, the upper end
of the revolving cylinder is made of wirecloth or perforated metal, and the lower
end of longitudinal bars, the whole forming a single cylindrical barrel. The small
coal dust passes through the wirecloth or finely perforated metal, while the larger
dross travels down to the open longitudinal bars through which dross of medium
size falls, and the "nuts." or larger pieces are discharged at the lower end of the
barrel as already described.

page_text: Having now particularly described my said Invention, and in what manner the
same is to be performed, I declare that what I claim is,-
The construction or combination of parts forming the improved apparatus
herein described for separating small coal or dross into different grades of size or
quality.
In Witness Whereof, I the said Robert Donald Thomson have hereunto set my
hand and seal this eleventh day of January in the year of our Lord One thousand
eight hundred and eighty four.