IMPROVEMENTS IN FILTER PRESSES
Year: 1885

page_text: We, RICHARD JOHN FRISWELL of 5 Darenth Rd, Stamford Hill, in the county
of Middlesex, consulting chemist, and AMBROSE MYALL of 21 Cockspur Street,
Charing Cross, in the county of Middlesex, Civil Engineer, do hereby declare
the nature of our invention for "IMPROVEMENTS IN FILTER PRESSES
" to be as
follows:-
In the ordinary form of filter press, which is used, as is well known, for the
separation of solids from liquids in which the aforesaid solids are in a state of
suspension or precipitation, it is usual to corrugate the surfaces of the plate
forming the chambers of the press with ridges arranged, some times vertically, but
generally in concentric rings.
In the latter case the rings are placed in communication with each other and
with the cutlet of the plate by means of radial drifts or grooves in the lower
portion of the plate.
When the fluid to be filtered is forced by any of the ordinary means into a filter
press formed in any of the usual modes as described above, the filter cloth is
stretched and forced into the corrugations and drifts so that in a very short time
it is in actual contact with the surfaces of the chambers, almost or quite as perfectly
as though no such corrugations had existed.
This is especially the case when fluids containing fine, soft or pulpy substances
in suspension, (such as many of the aniline and especially the diazo colouring
matters are found to be when precipitated from solution); are submitted to the
action of the press. The fluid separated can then only find its way out by
travelling horizontally along the thickness of the cloth or in a thin film between
the cloth and the plate and the filtration gradually ceases-Increased pressure only
aggravates the evil-If the chambers are more than an inch or two in thickness,
the press cakes are found to be hollow, consisting of a properly filtered portion
in contact with the cloth, enclosing a partially or wholly unfiltered sludge in the
centre.
In order to obviate the above difficulties, it is necessary to afford a free flow to the
fluid passing through the cloth-This can only be done by supporting the same on
some substance that shall afford within its lateral dimensions interstitial spaces
freely communicating with each other, the mass within which they exist being
practically incompressible-Such substances may be found in various porous bodies
such as certain sand-stones, earthenware &c.

page_text: We have however discovered that all the necessary advantages can be secured
by the use of incompressible woven materials placed in contact with the plate
and beneath the filter cloth-Such a material is found in the well known asbestos
cloth.
The best substance however, and that for which we claim protection as a
novelty, is ordinary wire-gauze which may be constructed of any suitable metal
and of any gauge of wire or size of mesh found to be convenient and suitable to
the particular liquid requiring filtration.
In filter presses constructed according to our invention, we recess the entire
surface of the plate, all but a small exterior annular portion sufficient for the
intermediate rings to bed against in the usual way.
Within the said recess a disc of wire-gauze is placed, the depth of the recess
and the thickness of the wire-gauze being such that the surface of the gauze shall
be nearly level with the projecting annular part of the plate. The said disc may
be secured to the surface of the plate, if required, by any suitable device and if
necessary two or more such discs may be superposed, and the aforesaid discs may
have their edges bound by pressing over them fillets of any suitable metal.
The cloths may be fixed in the usual way, and when the pressure is applied, the
wire-gauze provides innumerable apertures for the escape of the liquor and yet
gives such ample and well divided bearing surface, that the cloth can never be
pressed into the apertures of the gauze to such an extent as to touch the surface
of the plate and seal the apertures.
Holes or drains are formed in the plates for the escape of the liquor, and they
may, if desired, be provided with concentric or other grooves in the usual way.
Our invention as will clearly be seen can readily be applied to any existing
filter press by simply recessing the plates to the required depth.
Our invention may be applied to existing filter presses without removal of the
annular or other corrugations provided there is room for the introduction of the
gauze.
The great advantage of our invention is that it enables liquor to be extracted
from any given mixture with a less amount of pressure, and that with certain
mixtures a larger per centage of liquor than can possibly be obtained from the
ordinary press with the greatest pressure employed therein.
In the case of pulpy precipitates, liable to block and become impervious under
heavy pressure, wider chambers can be employed and the labour and consumption
of cloths and the weight of the press can thus be diminished-In cases of air
and steam forced filtrations, the safety of the operation is greatly increased by
reason of the lighter air or steam pressure brought to bear upon the liquor in the
mont-de-jus or pressure vessel.
The filtration generally is effected with a much smaller expenditure of power.
Dated this Seventh day of March 1885

page_text: We, RICHARD JOHN FRISWELL of 5 Darenth Road, Stamford Hill in the county
of Middlesex, Consulting Chemist, and AMBROSE MYALL of 21 Cockspur Street,
Charing Cross, in the county of Middlesex; Civil Engineer do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :—
In the ordinary form of filter press which is used as is well known for the
separation of solids from liquids in which the aforesaid solids are in a state of
suspension or precipitation, it is usual to corrugate the surfaces of the plates
forming the chambers of the press with ridges arranged sometimes vertically but
generally in concentric rings.
In the latter case the rings are placed in communication with each other and
with the outlet of the plate by means of radial drifts or grooves in the lower
portion of the plate.
When the fluid to be filtered is forced by any of the ordinary means into a filter
press formed in any of the usual modes as described above, the filter cloth is
stretched and forced into the corrugations and drifts so that in a very short time it
is in actual contact with the surfaces of the chambers, almost or quite as perfectly
as though no such corrugations had existed.
This is especially the case when fluids containing fine soft or pulpy substances in
suspension (such as many of the aniline and especially the azo colouring matters
are found to be when precipitated from solution) are submitted to the action of the
press.
The fluid separated can then only find its way out by travelling horizontally
along the thickness of the cloth or in a thin film between the cloth and the plate
and the filtration gradually ceases.
Increased pressure only aggravates the evil. If the chambers are more than an
inch or two in thickness, the press cakes are found to be hollow, consisting of a
properly filtered portion in contact with the cloth enclosing a partially or wholly
unfiltered sludge in the centre.
In order to obviate the above difficulties it is necessary to afford a free flow to
the fluid passing through the cloth. This can only be done by supporting the same
on some substance that shall afford within its lateral dimensions interstitial spaces
freely communicating with each other, the mass within which they exist being
practically incompressible.
Such substances may be found in various porous bodies such as certain sand-
stones, earthenware &c.
We have however discovered that all the necessary advantages can be secured by
the use of incompressible woven materials placed in contact with the plate and
beneath the filter cloth.
Such a material is found in the well known asbestos cloth.
The best substance however and that for which we claim protection as a
novelty, is ordinary wire-gauze which may be constructed of any suitable metal

page_text: and of any gauge of wire or size of mesh found to be convenient and suitable to
the particular liquid requiring filtration.
In filter presses constructed according to our invention, we recess the entire
surface of the plate all but a small exterior annular portion sufficient for the
intermediate rings to bed against in the usual way.
Within the said recess a disc of wire-gauze is placed, the depth of the recess and
the thickness of the wire-gauze being such that the surface of the gauze shall be
nearly level with the projecting annular part of the plate. The said disc may be
secured to the surface of the plate, if required, by any suitable device and if
necessary two or more such discs may be superposed and the aforesaid discs may
have their edges bound by pressing over them fillets or strips of any suitable
metal. The cloths may be fixed in the usual way. When the pressure is applied,
the wire-gauze provides innumerable apertures for the escape of the liquor and yet
gives such ample and well divided bearing surface that the cloth can never be
pressed into the apertures of the gauze to such an extent as to touch the surface of
the plate and seal the apertures.
Holes or drains are formed in the plates for the escape of the liquor and they
may, if desired, be provided with concentric or other grooves in the usual way.
Our invention as will clearly be seen can readily be applied to any existing filter
press by simply recessing the plates to the required depth or our invention may
be applied to existing filter presses without removal of the annular or other
corrugations provided there is room for the introduction of the gauze.
The great advantage of our invention is that it enables liquor to be extracted
from any given mixture with a less amount of pressure, and certain mixtures a
larger per centage of liquor than can possibly be obtained from the ordinary press
with the greatest pressure employed therein.
In the case of pulpy precipitates, liable to block and become impervious under
heavy pressure, wider chambers can be employed and the labour and comsumption
of cloths and the weight of the press can thus be diminished.
In cases of air and steam forced filtrations, the safety of the operation is greatly
increased by reason of the lighter, air or steam pressure brought to bear upon the
liquor in the mont-de-jus or pressure vessel.
The filtration generally is effected with a much smaller expenditure of power.
In order that our invention may he clearly understood we will proceed to further
describe the same by reference to the accompanying sheet of drawings.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a section, through the line X X in Figure 2 of two plates in a filter
press shewing our invention applied thereto.
Figure 2 is an elevation of a plate, with one half of the filtering cloth removed.
Figure 3 is an elevation of a wire gauze disc.
Figure 4 is an alternative method of securing the gauze discs in place.
The same letters refer to the same parts in all the figures.
A A are two of the plates of a filter press and B B B are the intermediate rings
forming the chambers C C C. Only two plates are shewn but it will be understood
that the press may consist of any desired number or series of plates.
The plates are formed with central apertures D by which the chambers
communicate with each other in the usual manner.
The surfaces of the plates are recessed as shewn at E to a sufficient depth to
receive the wire gauze discs F. The shoulder of the recess is slightly undercut as
shewn, so that the gauze disc may be sprung or forced into the recess and securely
retained therein.
The gauze discs are provided with a central aperture D¹, and to prevent them
unravelling, or the ends of the wires cutting or penetrating the filter cloth, we
prefer to bind their edges with fillets H H formed of strips of soft sheet metal or
other suitable material.

page_text: J J are the filter cloths made in the usual manner, no means are shewn of
suspending them but any of the methods now in use for that purpose may be
employed.
In Figure 1, in order more clearly to shew the construction, the cloths are not
represented in close contact with the gauze discs, as they would be during the
process of filtration.
KK Figure 2 are the horizontal bars supporting the plates and rings.
LL are drainage holes communicating by cross passages at their upper ends with
both surfaces of the plates A A. Drifts M M shewn in Figure 2 may be formed
in the surface of the plates, if desired, to communicate with the said cross passages.
In the plates shewn in the drawings, the outer surfaces of the discs are not in
the same plane as the turned edges N N of the plates A A, and plates so formed
could be used without intermediate rings to form shallow chambers, but in cases
where such intermediate rings are always employed we prefer to place the surface
of the discs in the same plane with the edges N N.
In plates formed as in the drawings, instead of recessing the surface as shewn
at E, two, three or more small projecting lugs may be provided upon or affixed to
the plate to catch the edges of the gauze disc and retain it in position. Such lugs
are indicated by dotted lines O O in Figure 2.
Or as shewn in Figure 4 two flanged tubular sockets P P¹ may be provided to
fit tightly one within the other in the central aperture of the plate, so that their
flanges hold the gauze discs tightly against the plate.
Although the plates are shewn with flat surfaces, plates having vertical or
concentric corrugations in the usual manner, may be employed if preferred.
The wire-gauze discs may be made of any suitable metal or size of mesh required
and we may when found necessary, employ two or more discs superposed.
Although we find in practice, that the best results are obtained by using discs of
wire-gauze, we do not necessarily confine ourselves to the use of wire gauze, as we
may employ any other suitable incompressible woven material in their construction.
Nor do we confine ourselves to the exact details of construction herein before
described and shewn, as for example the gauze discs may be made square instead
of round to suit presses made with square chambers.
It is obvious that our invention can very readily be applied to any existing
filter press by recessing the surface of the plates, if necessary, and providing any
suitable device for retaining the gauze discs in position.
In making use of the words "incompressible woven material," we wish it to be
understood that we mean, not compressible under the conditions of filtration,
i.e. heavy fluid pressure.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is
(1.) The construction of a Filter Press having discs or sheets of wire gauze or
other suitable incompressible woven material interposed between the filter cloths
and the surfaces of the plates, substantially as and for the purposes hereinbefore
described and shewn.
(2.) In a filter press the combination therewith of discs or sheets of wire gauze
or other suitable incompressible woven material interposed between the filter cloths
and the surfaces of the plates, substantially as and for the purposes hereinbefore
described and shewn.
(3.) Discs or sheets of wire gauze or other suitable incompressible. woven
material having their edges bound with fillets or strips of sheet metal or other
suitable material, substantially as and for the purposes herein before described and
shewn.
(4.)-Forming the plates of a filter press with recesses to receive discs or sheets
of wire gauze or other suitable incompressible woven material, substantially as and
for the purposes herein before described and shewn.

page_text: (5.) Forming the plates of a filter press with under cut recesses to receive and
retain discs or sheets of wire gauze or other suitable incompressible woven material,
substantially as and for the purposes herein before described and shewn.
(6.) Providing upon or affixing to the plates of filter presses, lugs or projections
to retain in position thereon discs or sheets of wire gauze or other suitable incom-
pressible woven material, substantially as and for the purposes herein before described
and shewn.
(7.) The combination of flanged tubular sockets with the plates of a filter press
and with discs or sheets of wire gauze or other incompressible woven material,
substantially as and for the purposes hereinbefore described and shewn.
Dated this Ninth day of Decembe 100%
RICHARD JOHN FRIS WELL.
AMBROSE MYALL.