Improvements in Apparatus for Washing Sand and Gravel
Year: 1897

page_text: 66
PROVISIONAL SPECIFICATION.
'Improvements in Apparatus for Washing Sand and Gravel."
I, SAMUEL WILLIAM BOYER of No. 1. Amberley Wharves, Paddington, London,
W. Contractor; do hereby declare the nature of this Invention to be as follows:-
This Invention relates to apparatus for washing sand and gravel and
consists essentially of an inclined cylindrical screen revolving partly in water
whereby the sand, loam, and other fine particles are washed out and separatel
from the stones or shingle, the water carying off the loam and other matters in
suspension and allowing the clean sand to settle by gravitation in the water. The
screen is provided with means whereby the stones or shingle retained in the screen
are transferred thence to another revolving screen to be thereby sized or graded,
whilst means are provided of maintaining an upward flow of water through the
settling tank so as to ensure the matters in suspension being carried off from tho
sand. Means are also provided of withdrawing the washed sand without arresting
the operation. The sand or gravel is fed in to the upper end of the washing
screen by a shot or otherwise, and the immersed part of the lower end of said
screen revolves against a fixed face plate to retain the stones and shingle which are
raised by ribs or pallets fixed around the interior of the revolving screen near the
lower end and discharged on to a stationary shoot projecting into the screen
whereby they are delivered to the first of a series of revolving screens forming.
practically a continuation of the washing screen but running in the dry, to be
screened and sized in the usual manner or otherwise as may be required.
The agitation of the water necessary to maintain the fine particles in suspension
is ensured by the rotation of the screen within it and the upward flow for carrying
off the matter in suspension may be obtained by injecting the water continually
at or near the lower part of the washing and settling tank and allowing it to over-
flow at the top, whilst the removal of the washed sand may be effected through a
lock or pair of sluice doors or by means of a bucket dredger.
Deted this 14th ……. of
1007

page_text: the same is to be performed to be particularly described and ascertained in and by
the following statement:-
This Invention relates to apparatus for washing gravel and sand particularly
for the purpose of rendering the gravel suitable for making concrete and the sand
for making mortar, and the apparatus consists essentially of an inclined cylindrical
screen revolving partly in water whereby the sand, loam, and other fine particles
arq washed out and separated from the stones or shingle, the water carrying off
the loam and other matters in suspension and allowing the clean sand to settle
by gravitation. The screen is provided with means whereby the stones or shingle
retained in the screen are transferred thence to another revolving screen to be.
thereby sized or graded, whilst means are provided of maintaining an upward
flow of water through the settling tank so as to ensure the matters in suspension
being carried off from the sand, means being also provided of withdrawing the
washed sand without arresting the operation.
The apparatus is illustrated in the accompanying drawings forming part of
this Specification and will be described in detail with reference thereto, Figure 1
representing a side elevation of the apparatus partly in section and Figure 2 a
cross-section through the water tank, the washing screen being shewn in elevation.
viewed from the feed end. Figures 3 and 4 are enlarged detail views of an
elevator bucket, in two positions.
A is a cylindrical washing screen mounted to revolve about an axis slightly
inclined to the horizontal, the lower part of the screen being immersed in water
in a tank B. The screen is preferably supported upon pairs of rollers ce suitably
mounted in the tank, those situated on one side of the axis being mounted on a
driving shaft C which may be common to all the screens and pass through suitablo
stuffing boxes in the ends of the tank. One of the rollers on shaft C is in one with
a spur pinion ² which gears with a ring of teeth alongside one of the roller
paths on the screen for the purpose of driving the latter, whilst the screen is
prevented from moving longitudinally by its lower end bearing against another
pair of rollers c¹.
The gravel or sand is fed into the upper open end of the washing screen A by
a shoot D and gradually passes down towards the lower end of the screen A which
is also open but revolves against a fixed face-plate E which may be formed by the
adjacent end of the tank, suitably inclined, and which closes the end of the screen
so far as it is immersed. The screen A is provided, towards the lower end, with
pallets F fixed around the interior, as shewn, by which the washed stones and
shingle are raised as the screen revolves and discharged on to a stationary shoot
G which is suitably supported and projects into the screen A as far back as the
pallets extend.
The shoot G also projects into a grading screen H forming
practically a continuation of the washing screen A but running in the dry. This
grading screen may be supported in the same way, and be driven from the same
shaft C, as the washing screen and is clothed with perforated metal or wire work
of various grades as may be required. The washing screen A would be preferably
constructed of annular and longitudinal ribs (as indicated more fully in the case
of the grading screen H) upon the inside of which would be fixed the clothing of
wire gauze or other foraminous material of a grade to allow the passage of the
sand and other fine particles but retain the shingle, the pallets being attached to
the longitudinal ribs a by screws passing through the gauze and being placed not
quite radial but slightly tangential so as to retain the stones and shingle until the
pallets have risen sufficiently above the shoot to discharge the whole of their
contents therconto.
The tank B in which the screen A revolves is provided at top with an overflow
b and a water-inlet 61 preferably towards the lower part (but above the level to
which the sand is allowed to accumulate) so as to cause an upward flow of water
through the tank whereby to carry off the fine particles in suspension in the water,
the rate of flow being so adjusted as to allow of the clean washed sand settling to

page_text: the bottom. The tank B is formed with a sump K to receive the sand and accom-
modate the lower part of an endless bucket elevator L whose buckets have
perforated backs lined with loose covering flaps 1 of canvas, cocoa-nut matting,
or other porous fabric supported by attachment at the top and bottom edges to the
bucket (as shown in the sectional view in Figure 3) so that when the bucket
reaches the point of discharge the loose lining will turn inside out as indicated
(in Figure 4) and permit of the complete discharge of the sand.
The revolution of the screen A and its contents in the water, the passage of the
elevator through the water, and the upwad flow of the water itself, all maintain
an agitation which tends both to promote the separation of the sand and fine
particles from the shingle within the screen, and also to prevent the settlement
of the fine particles along with the sand in the sump K, both shingle and sand
being delivered in a clean washed condition.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I declare that what I
claim is :-
Apparatus for washing gravel and sand, consisting essentially of a continuously-
fed, inclined, cylindrical, revolving screen partly immersed in water so as by
its motion to wash the sand, loam, and dirt out of the gravel; a settling tank for
separating the sand from the loam and dirt by gravitation; a bucket elevator for
removing the sand from the settling tank without interruption of the washing
process; and means of continuously discharging the washed shingle from the
screen; all substantially as specified.
Dated this 14th day of October 1897
A. M. & WM. CLARK
Chartered Patent Agents. 53. Chancery Lane, London.