IMPROVEMENTS IN APPARATUS FOR EXPRESSING LIQUIDS FROM PRECIPITATES OR OTHER BODIES
Year: 1880

page_text: LETTERS PATENT to Walter Weldon, of Rede Hall, Burstow, in the County of
Surrey, for an Invention of "IMPROVEMENTS IN APPARATUS FOR EXPRESSING
LIQUIDS FROM PRECIPITATES OR OTHER BODIES." A communication., from
abroad by Alfred Rangod Pechiney, Chemical Manufacturer,; of; Salindres, in
the Republic of France.
PROVISIONAL, SPECIFICATION left by the said Walter Weldon at the Office
of the Commissioners of Patents on the 24th May. 1880.
WALTER WELDON, of Rede. Hall, Burstow, in the County of Surrey.
"IMPROVEMENTS IN APPARATUS FOR, EXPRESSING LIQUIDS FROM PRECIPITATES
OR OTHER BODIES." A communication from abroad by Alfred. Rangod, Pechiney,
Chemical Manufacturer,, of Salindres, in the Republic, of, France.
The apparatus which is the subject of this Invention is specially applicable, to
the filtration of the precipitate of bicarbonate of soda which is formed in the course
of the manufacture of soda, by what is known as the ammonia process, and will be
described as applied to the filtration of that, precipitate; but it is also applicable
to the expression of liquids from other bodies of whatever kind.
The essential features of this apparatus are a large hydraulic press,which may be
called A; a smaller hydraulic press which may be called B and two filtering
cylinders which may be called C and D. The two presses A and B are placed one
on one side, and the other on the opposite side of a pillar, which may be called E,
and to this pillar E the filtering cylinders C and D are attached by a collar in such
wise that they can revolve round the pillar. This collar can slide up and down
the pillar E sufficiently to permit of the cylinders C and D being raised or lowered
a few inches. The filtering cylinders are so placed that their centres are in a line
with the centre of the pillar, so that when the centre of the cylinder C is imme-
diately over the centre of the cylinder of the press A, the centre of the cylinder D
is immediately over the centre of -the-cylinder-of-the-press B. A balf-revolution
will then bring the cylinder Cover the cylinder of the press B, and the cylinder D
over that of the press A. The function of the press A is to press out the liquid
from the precipitate which is charged into the cylinders C and D alternately, and
the function of the press B is to discharge from the cylinders the solid residue

page_text: remaining in them after the precipitate with which they have been charged has had
as much liquid as possible expressed from it by the press A. The bottom of each
of the cylinders C and D is moveable, in the manner of a piston, and a little above
the moveable bottom of each cylinder, and attached to the said moveable bottom, is
a plate of iron perforated with many holes, and covered with any suitable kind of
filter-cloth or other filtering material. In the cylinder of the press A are two
pistons disposed concentrically, the one being annular, and the other placed inside
the annular one, being cylindrical. Dispositions which will be well understood
permit either of these pistons to be worked separately from the other. The central
or cylindrical piston is the one which expresses the liquid from the precipitate
charged into the filtering cylinders C and D; the annular piston merely raises and
lowers those cylinders. The press B is smaller than the press A, and has but one
piston, so disposed that water can be admitted either above it or below it.
This apparatus works as follows:-The filtering cylinder C having been charged
with precipitate of bicarbonate of soda (for example), it is swung round till it is
immediately over the cylinder of the press A. Water is now admitted below the
annular piston in that cylinder. This annular piston presses the cylinder C against
the under surface of the head of the press A. Attached to this under surface of
the head of the press A is a perforated iron plate covered with cloth or other
· filtering material in the same way as the similar perforated plates attached to the
moveable bottoms of those cylinders. The upper edge of the cylinder being now
pressed tightly against the under face of the head of the press A, water is admitted
under the inner of the two concentric pistons of that press, and this piston presses
upwards the moveable bottom of the cylinder C. The charge in the cylinder C is
now being pressed between two filtering surfaces, one above it and one below. The
liquid expressed from the charge,passes partly into the space between the perforated
plate below the charge and the moveable bottom of the cylinder, and partly into
the space between the perforated plate above the charge and the under surface of
the head of the press.
From these spaces it passes by suitable conduits, as will be
well understood, into any convenient reservoir. When the charge ceases to yield
more liquid, the water is allowed to escape from below the two pistons in the
cylinder of the press A, and the cylinder then descends a little way. The two
cylinders are now made to make a half-revolution round the pillar. E, whereby the
filtering cylinder D, which has in the meantime been charged with precipitate, is
brought over the cylinder of the press A, and the cylinder Cover that of the
press B. The two pistons of the press A are now operated as before, and at the
same time water is admitted under the piston of the press B, until that piston has
raised the moveable bottom of the cylinder C level with the top edge of that
cylinder. A workman now draws away the cake of compressed bicarbonate which
has thus been pushed out of that cylinder. He then. causes the water to escape
from below the piston of the press B, and admits water above that piston, thereby
drawing down the moveable bottom of that cylinder, until it is in the position in
which the cylinder can be re-charged. When the cylinder C has been re-charged,
and the filtration of the charge in D has been completed, the circle of operations
recommences as before.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Walter Weldon in the Great Seal Patent Office on the 22nd
November 1880.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey.
"IMPROVEMENTS IN APPARATUS FOR EXPRESSING LIQUIDS FROM PRECIPITATES
OR OTHER BODIES"
The apparatus which is the subject of this Invention is specially applicable to the
filtration of the precipitate of bicarbonate of soda, which is formed in the course
of the manufacture of soda by what is known as the ammonia process; but it is
also applicable generally to the filtration of similar precipitates, and to the
separation of other solids from liquids holling them in suspension.
A form of apparatus embodying the essential features of this Invention is shown
in the accompanying Drawings. In Figure 1, B is the cylinder of a powerful
hydraulic press, G is the head of the press, and E and F are pillars supporting G,
and binding G either directly to the cylinder B, as shown in Figure 1, or to a
suitable hed, in the centre of which the cylinder B is placed, as is shown in
Figure 2, and will be well understood; D is another hydraulic cylinder, so placed
that its centre is in a straight line with the centre of the cylinder B and the centre
of the pillar F. The piston N working in the cylinder D is double-acting, so that
it can be pressed upwards by sending water in below it, and be pressed downwards
by sending water in above it. Cand Care two filtering cylinders attached to
each other and to the pillar F by the collar H; they are thus supported by the
pillar and can revolve round that pillar. The collar H can slide up and down
the pillar F through a course of a few inches, to which extent the cylinders C
and C can accordingly be raised and lowered. The filtering cylinders C and C
are provided with the pistons P and P. The function of these pistons P and P¹
is, firstly, to express liquid from the mixture of solid and liquid charged into the
cylinders and C', and afterwards to lift out of the said cylinders the residual
cakes of precipitate or other body from which liquid has been so expressed. For
the latter purpose the pistons P and P are operated by the piston N working in
the cylinder D; for the former purpose they are operated by the central part J of
the compound piston 1, A, J, the part I of which works in the cylinder B. It will
be seen from the Drawing that the compound piston I, A, J, is so disposed as to
constitute in effect two pistons, one of these two pistons being annular and the
other placed inside the annular one being cylindrical, the dispositions being such
that when water is forced into the cylinder B under the part I of the compound
piston 1, A, J, the whole system I, A, J, is pressed upwards, while by forcing water
under J through the telescopic tube g, J can be pressed upwards while I and A
remain stationary. A and J are thus in effect two pistons, which can be operated
separately; A, which rests upon and may be regarded as a part of I, since it cannot
move independently of 1, being thus at once an annular piston and a cylinder for
the cylindrical piston J to work in. The upper part of the telescopic tube q' is
fixed to I, as shown, and moves up and down with I.
It was not necessary to
show on the Drawing the method of admitting water into the cylinder B, since
this need not differ from that by which water is ordinarily admitted into the
cylinders of hydraulic presses.
The function of the annular piston A is to press the filtering cylinders C, C,
against the press-head G, and the function of the central cylindrical piston J is to
express liquid from the mixture of liquid and solid charged into the cylinders C
and by pressing upwards the pistons P and P' working in those cylinders.
The upper surface of each of the pistons P and P is channelled, as shown in
Figure 2. Upon the channelled upper surface of each of these pistons is placed a

page_text: circular iron plate perforated with many holes, and covered on its upper side with
filter-cloth. A similar perforated plate covered with filter-cloth on its under side
is attached to the press-head G. In the centre of each of the pistons P, P', is an
aperture provided with a valve. These valves, S and S¹, are so disposed that they
can be pushed and held open by the projecting, piece'a, fixed to the upper surface
of the cylindrical piston J.
The object for which the two filtering cylinders C. and C are attached to each
other and to the pillar F, as above described, is that of permitting each of them to
be brought alternately, first over the piston N and then over the concentric
pistons A and J. Each is charged with magma of precipitate or other body, from
which liquid is to be expressed when it is in the position in which its centre is
immediately over the centre of the piston N.
.
This apparatus works as follows:-One of the filtering cylinders, say C, having
been charged with magma of precipitate of bicarbonate of soda (for example), it is
swung through a half-revolution round the pillar F, so as to bring its centre
immediately over the common centre of the concentric pistons A and J. Water is
then forced into the cylinder B, whereby I, A and J, and also the cylinder C, by
means of the annular piece K, supported by A, are all pressed upwards until the
upper edge of the cylindor is in tight contact with the press-head G, when the
admission of water into B of course ceases. I and A are now left stationary, and
water is forced under J through the telescopic tube g. As J is thereby pressed
upwards, the valve S is pushed open by the projecting piece a, and the piston P is
then pressed upwards, compressing the charge in C between two filtering-surfaces,
one above it and one below it. The liquid which is forced through the lower
filtering surface flows by the passages c, c, into the annular conduit 1, which
annular conduit is cast in the piece K, and from this annular conduit / it passes
by n into any suitable reservoir. The liquor forced through the upper filtering
surface flows into the annular conduit m, from which it is conducted by the
passage m'.
When the expression of liquid from the charge in the cylinder C has become as
complete as possible, and the forcing in of water under J has accordingly ceased,
the two cocks by which water is discharged from under I and under J are opened,
and the whole system I, A, J, K, P, C, H, C and P', is thereby caused to descend,
until the descent of all but I, A, J, and K, which descend a little further, is arrested
by H coming into contact with the projecting piece of the column F which is shown
in Figure 1 a little below H. The two filtering cylinders are now swung through
another half-revolution round the pillar , whereby C', which has in the meantime
been charged with magma of bicarbonate, is brought over the concentric pistons A
and J, and C over the piston N. While filtration of the charge in (' is now being
effected, the cake of bicarbonate remaining in the cylinder C has to be discharged,
and that cylinder re-charged with magma. To this end, water is forced into the
cylinder under the piston N. That piston then rises, and by means of the
piece R attached to the upper extremity of that piston pushes up P until the bottom
of the cake of bicarbonate resting on the perforated plate on the upper surface of P
is raised to a little above the upper edges of the cylinder C, so that a workman can
readily remove it. The cake having been removed, water is discharged from below
tlie piston N, and that piston made to descend by water being forced in above it.
In its descent, the piston N draws down with it the piston P, which has been seized
during the previous ascending movement by the hooks o, o. These hooks work
with a spring, as is shown in the case of one of them in the Drawing. Toward the
end of the descent, the hooks o, o, are disengaged from the piston P by g, g, being
forced outwards by z, t, as will be well understood. A little before N arrives at
the bottom of its course, P arrives at its lowest position in the cylinder C, and
that cylinder is then re-charged.
.
It will be understood that my correspondent does not confine himself to the
details above described, since some of those details may be varied without departing
from the nature of his Invention. The foregoing Specification however describes

page_text: what he believes to be the best method of carrying his Invention into effect. What
he believes to be novel in what has been described, and what is claimed as the
Invention to be secured by the hereinbefore in part recited Letters Patent is, an
apparatus for expressing liquids from chemical precipitates, or from other mixtures
of liquids with solids, in which that operation is performed by hydraulic pressure
in filtering-cylinders, held in place by an annular piston while the necessary pressure
upon their contents is applied by a central cylindrical piston, and in which the
filtering cylinders are disposed, supported, and operated for charging and discharging,
substantially as is above described.
In witness whereof, I, the said Walter Weldon, have hereunto set my hand
and seal, this Eighteenth day of November, in the year of our Lord One
thousand eight hundred and eighty.
WALTER WELDON. (L.S.)