IMPROVEMENTS IN APPARATUS FOR WASHING SMALL COAL AND OTHER MINERAL SUBSTANCES
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the Office
of the Commissioners of Patents on the 2nd November 1876. A communication.
from abroad by Antoine Barbary, of Paris, France.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of Middle-
sex, Patent Agent. "IMPROVEMENTS IN APPARATUS FOR WASHING SMALL COAL
AND OTHER MINERAL SUBSTANCES."
This Invention relates to improved apparatus for washing small coal and slime.
In order to effect this object it is necessary, 1st, to carefully sort the coal in dif-
ferent grades of fineness; and 2nd, to avoid the use of all mechanical apparatus, and
to separate the shale from the coal according to its density by means of a weak
current of water; this separation can only be properly effected on the condition
that the particles are previously sorted according to grade, as above mentioned, since
the current of water must be different for each grade; 3rd, to inject a current of
compressed air for agitating the matters.
The washing apparatus of this Invention is designed to fulfil all the above con-
ditions, and combines both the sorting by volume and the sorting by density.
The apparatus, which may be modified as regards its form and construction, is in
all cases so arranged that in the portion in which the classification by density is
effected, the upward current of water, which by its ascensional movement carries
with it the lighter particles, is aided in its action by a jet of compressed air.
The apparatus are further arranged in such manner that the shale or residue of
the washing may be readily removed without interrupting the operation.
In order that the Invention may be more readily understood I have illustrated it
in the accompanying Drawings, Figure 1 of which shows the arrangement of
the washing apparatus a, revolving cylindrical seive or trommel turning in bear-
ings b. The sides of this sieve are formed of a number of rings or sections of wire
gauze of progressively increasing coarseness; c, archimedian screw fixed within the.
sieve a, and turning therewith; d water pipe, traversing centrally the whole length
of the screw. This pipe is either perforated or provided with a longitudinal slit
from which water is distributed or discharged under pressure along the whole length
of the sieve; e, band pulley by which rotary motion is imparted to sieve a; f, hopper
and spout at which the small coal is introduced into the sieve; g, hoppers placed im-
mediately beneath the sieve a, and each corresponding to a section of a particular
size of mesh. The tubes h extend downwards vertically from said hoppers each into
a vertical cylinder or trunk i; each trunk is provided with a valve j at bottom,
a casing enclosing an annular space k, through which air may be supplied at holes
5 Uvies 037

page_text: or water at holes m, or both together with a chamber n, forming a prolongation of
the trunk ȧ, with a door or sluice o closing the chamber n, and with an overflow
basin p provided with a discharge orifice r; w, the pipe through which the dirt
passes away.
The whole being arranged as described the following is the action of the washing
apparatus. The cylindrical sieve a being set in motion the small coal is introduced
into the sieve through spout f; the dirt passes away through pipe w, and the coal
is conveyed by the screw c along the sieve and is forced by the water discharged
from pipe d to pass through one or other of the rings of wire gauze, according to
size, whence it falls sorted into sizes into the several hoppers g.
The water and coal in suspension therein pass together down through the tubes h,
and the coal rises in the trunk i, while the shale and other foreign matters fall to
the bottom of the chamber n, the valves j having been previously opened. By in-
troducing a jet of compressed air at apertures 7 the lighter particles of coal will be
carried by the air bubbles to the top of the cylinders i, and pass with the overflowing
water into the basins p, and out at the discharge orifices 7, into one or more other
receptacles of similar construction if it is required to be skimmed, or into a launder
if to be washed simply; in this manner the washed coal may be sorted according to
its purity. The heavier molecules fall into chambers n, which are emptied with-
out stopping the apparatus by closing valves j and opening doors o. Instead
of injecting compressed air into cylinders ia current of water may be introduced
for the same purpose at openings m.
It will be understood that the apparatus shown is only given as an example
of the method of carrying out the Invention, the distinctive features of which
consist,―
1st. In a thorough classification according to size.
2nd. Washing in a vertical apparatus by means of a current of water without
the use of tables or gratings.
3rd. In the use of compressed air as described for raising the matters while in
suspension in water.
4th. In the facility of classifying the washed coal.
The above described apparatus is also applicable for washing small of all kinds,
such as ores, sand, and earthy matters.
Figure 2 represents a front view; Figure 3 an end view of another arrangement
of washing apparatus; and Figure 4, a central vertical section on a larger scale of the
apparatus for classifying according to density.
The same letters of reference indicate like parts in the several Figures.
The matters are first carefully sized in the apparatus marked A, the finest par-
ticles fall on to shaking tables a, which are arranged in the following manner:-These
tables or screens which receive the fine matters that have passed through the wire
gauze of classifier A are provided with wire gauze bottoms of a finer quality
than that of the classifier in order to allow the impure water to run off from the
sorted matters. These screens are made to continually vibrate in the direction of
their length by the wheels x, carrying friction rollers acting on jointed levers b, c ;
the shaking motion facilitating the operation by causing the continual displacement
of the matters on the gauze. The classified matters fall into a tank or distributor to
be sorted according to the density. The greater part of the washing water and the
finer portion of the pyrites passing through the meshes of tables a, fall into the
openings d, leading to the outflow e; a preliminary purification is thus obtained
which greatly facilitates the subsequent washing. The matters classified in size
and deprived of their impurities are raised by buckets y or by other means into
the density sorting apparatus B, which is shown separately in Figure 4. In order
to render the action of the apparatus continuous a pan f is placed in each apparatus
so as to divide it into two parts at a height which may vary to suit the kind of
matters under treatment. The diameter of this pan is slightly less than that of the
trunk B, so as to leave an annular space between the two, for the passage of the
heavier particles while the lighter matters are carried off by the current of water,
•

page_text: The following is the method of classification by density in this improved
apparatus:-The matters previously carefully sorted as described are raised by
buckets, archimedian screws, or other means to point g, whence they fall directly
into the pan f. The water is supplied by pipe h to the annular space i, and falls
equally into the pan f, where it mixes with the matters to be sorted. The cylinder
or apparatus being filled with water holds the whole of the matters in suspension
therein. By regulating the flow of water by means of a cock j, Figure 3, the
lighter matters are caused to rise to the surface, while the heavier particles descend
to the bottom and are discharged by the valve K into a cistern at 7. The heavier
matters may either be thus removed as fast as they collect or allowed to accumulate
as desired. The classification of the fine particles is greatly facilitated by the
employment of a current of air bubbling through the water. The air should be
introduced near the circumference, and for this purpose the pan f, Figure 4, is
provided at its circumference with a small pipe m having perforations or slits.
The air supplied to each apparatus by the pumps n, Figure 2, is conveyed by the
pipe o, Figure 4, into the central chamber p of the classifier; in this chamber is
provided another pipe g, from which branches extend from its lower part for obtaining
an equal distribution of the air around the circular pipe m. In order to render the
action of the apparatus continuous it is necessary to remove the heavier matters
without interrupting the current of water. This result is obtained with the aid of
the rotary discharge valve or drum k, provided with cavities in its periphery and
fitted to rotate in a casing above reservoir l, which is made of a size to require
emptying only every 5 hours, viz., during the usual intervals of labor.
The valve receives continuous rotary motion, and may be règualted according to
the amount of material to be removed. The lighter particles raised flow over the
top of the apparatus into the circular trough s, whence they pass by a pipe t,
Figure 3, to be at once collected; or they may be led on to a shaking table and
then into the hopper of a classifier by density of similar construction, as shown in
Figure 3.
Figure 5 shows in vertical section another arrangement of washer or classifier
by density.
a, inlets for coal; b, exit; c, discharge valve; d, pipe for the water by which the
classification is effected; e, outlet leading into a cistern f filled with water; g, second
discharge outlet for the finer particles; h to slide for regulating the discharge of the
lighter particles. The novelty in this rectangular arrangement of apparatus is the
upward current of water and continuous washing action; and also the inclined
part k, up which the whole of the matters may be raised with the aid of even the
slowest current of water. The apparatus is also of simple construction and easily
repaired.
The form of the apparatus may moreover be varied, and either two or four may
be combined, the coal being in each case fed in at the centre.
It will be understood that I reserve the right, 1st, of using compressed air in all
the apparatus, and more especially in that shown in Figure 5, both for dividing
the matters of the kind mentioned and for separating tin ores from feldspar; 2nd, of
using a chain of buckets or box for removing the heavier matters.