IMPROVEMENTS IN SCREENS FOR SEPARATING COAL OR OTHER MINERALS OR SUBSTANCES
Year: 1885

page_text: I, THOMAS HEPPELL of Birtley in the County of Durham, Mining Engineer, do
hereby declare the nature of said invention of "IMPROVEMENTS IN SCREENS FOR
SEPARATING COAL OR OTHER MINERALS OR SUBSTANCES to be particularly described
and ascertained in and by the following statement :-
"
My invention relates to improvements in the construction and operation of
ordinary inclined flat screens (having special reference to coal screens) with a view
to more efficient separation of the various sizes of coal and facility in cleaning
from stones or other foreign substances before leaving the screen with saving of
labour in so cleaning the coal.
.The screens themselves are of the ordinary construction with bars, perforated plates
or wire meshes, which I prefer, and are inclined at an angle suitable for the coal to
be dealt with, but instead of being fixed in the framework, one end, preferably the
top end, has a rapid vertical shaking action given to it by cranks driven by a
steam engine or other power and this shaking action can be varied by the throw
of the cranks and speed of engine.
The opposite end of the screen is fitted in bearings in which it has a motion to
suit the throw of the cranks.
Where a series of screens are used, as in cases where separation into a number of
sizes is required the vertical shaking action may be given to each screen or to any
of the series as may be required, but the first screen which receives the coal from
the tubs will always be so fitted. The vertical shaking action causes a very perfect
separation of the large coal with continuous screening the coal having a constant
and uniform movement down the screen till it is arrested or partially arrested on
the landing tray at foot of screen where it is easily cleaned of stones and other
foreign substances the coal can be better separated and cleaned with a great saving
of manual labour at foot of screen.
In order to provide for cases where a tub may contain an undue quantity of
stones or other foreign substances the ordinary shutter or trap is fitted to retain
the contents of the following tub on "dead-plate at top of screen until the
previous delivery has been checked and cleaned. During this or at any other time
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page_text: when necessary, the screens or any of them, may be thrown out of gear with the
shaking action by shifting the driving belt on to a loose pulley when so driven.
An important auxiliary to this process of screening, especially in the first stage
is an appliance which I call the revolving rake or "distributor" consisting of a
revolving shaft armed with a number, of horns extending across the screen about
midway in its length and worked by suitable mechanism in the opposite direction
to the descending coal. The effect of this distributor is to stir up and spread the
coal allowing the small coal more readily to separate from the larger pieces and to
pass through the bars or meshes instead of being carried down to bottom of
This appliance is equally applicable to ordinary stationary screens and
will greatly increase their efficiency at a trifling cost in fitting and driving it.
screen,
will greatly increase their efficiency at a trifling cost in fitting and driving it.
DESCRIPTION OF DRAWINGS.
Sheet 1 of the accompanying drawings shews a side elevation of a pair of screens
constructed according to my invention and Sheet 2 a plan of same. In this
application the coal is required to be separated into three sizes vizt: 'large coal,
which is delivered to wagon on left hand, small coal delivered into wagon on right
hand & very small or "duff" delivered into centre wagon.
No 1 is the first screen the lower end of which works on a hinge A and the
upper end is attached by rods B to cranks C on a shaft D driven by a belt to
engine shaft on a fast sheave E by which the screen N° 1 has a rapid vertical
shaking motion given to it, the weight of the screen being counterbalanced by a
weight F on a lever G.
No 2 is the second screen which is arranged and operated in precisely the same
manner, a belt H being taken from a sheave on upper shaft to one on lower shaft.
The coal is tipped from tub to dead-plate of No 1 screen and the shutter J being
opened by the rod K the coal is moved on to the open part of screen where it
meets the horns L of the revolving rake or "distributor" (which may be fitted with
springs allowing them to yield to any accidental obstruction) and which are slowly
revolved by the ratchet gear M worked by the vertical motion of the screen and
these stir up and spread the coal facilitating the passage through the meshes of
the small coal and of the very small which are conveyed by the hopper N on to
dead-plate of No 2 screen the large coal passing on to the landing tray O where
stones or foreign substances are picked out, the good coal being delivered into
wagon.
When the contents of a tub are found to be unduly mixed with stones the
shaking is stopped, by throwing the belt on to a loose sheave, until the coal has
been examined and the tub checked and the landing tray O can be raised to
prevent delivery to wagon at these times.
The small coal and the very small now pass on to the open part of No 2 screen
where the very small falls through the meshes and by the hopper P into centre
wagon the rest being delivered over the landing tray 01 into wagon on right
hand.
When separation is to be carried still further other screens are added to the
series and may or may not be fitted with shaking action.
The revolving rake or distributing appliance may be applied to No 2 screen in
some cases, but I do not anticipate the necessity of this.
Having now particularly described and ascertained the nature of said invention
and in what manner the same is to be performed I declare that what I claim is
First Screens for separating coal or other minerals or substances so constructed
and operated that a vertical shaking motion upon a hinged fulcrum is given to the
screen substantially as shewn and described.
Second-In screens for separating coal or other mineral or substances, either
having a vertical shaking motion or of any of the ordinary descriptions, the

page_text: application of a revolving rake or distributor arranged and operating substantially
as shewn and described.
Third The general arrangement of screens having a vertical shaking motion
with means for operating same in combination with a revolving rake or distributor
with means for operating same whether consisting of one screen or of two or more
screens substantially as shewn and described.
THOMAS
HEPPELL
W. Lloyd Wise,
Per C. E. Brougham,
Applicant's Agent.