IMPROVEMENTS IN FILTERING APPARATUS
Year: 1878

page_text: LETTERS PATENT to Henry Edward Newton, of the Office for Patents, 66,
Chancery Lane, in the County of Middlesex, Civil Engineer, for the Invention
of "IMPROVEMENTS IN FILTERING APPARATUS." A communication from abroad
by Albert Louis George Dehne, of Halle on Saal, in the Empire of Germany.
Sealed the 20th December 1878, in pursuance of an Order of the Lord Chancellor,
and dated the 15th May 1878.
PROVISIONAL SPECIFICATION left by the said Henry Edward Newton at
the Office of the Commissioners of Patents on the 15th May 1878.
HENRY EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the
County of Middlesex, Civil Engineer. "IMPROVEMENTS IN FILTERING APPARATUS."
[A communication from abroad by Albert Louis George Dehne, of Halle on Saal,
in the Empire of Germany.]
In filter presses generally filter cloth is used as the filtering material through
which the liquid of the semi fluid which enters under pressure into the chambers
must pass, while the solid matters remain in the chambers in the form of cake.
These cloths are exposed more or less to quick destruction according to the nature
of the liquids to be operated upon, and they must frequently be washed. It will
be evident therefore that they will be very quickly corroded and destroyed by
acidulous liquids.
Instead of using these cloths or other filtering material which is liable to be
quickly destroyed it is proposed to use wooden plates as filtering mediums. These
plates are adapted to the sides of the chambers in which the cakes will be
formed.
By putting these wooden plates on both sides of these chambers they will be
inserted between the chambers and the frames, which latter are either covered with
vertical grooves or with perforated sheets of metal, through which the filtered liquid
In order to avoid warping, the wooden filtering plates are composed of
separate pieces of wood, which are held together by a surrounding wrought-iron
runs.

page_text: frame constructed of separate parts. The parts of the frames are bent at right
angles at their ends, thereby offering facility for screwing these parts of the frames
together by screws, which go through the bent part of the frame.
The wood employed for the wooden plates is cut cross way of the grain, so that
the liquid from the chambers enters and leaves the wood at the grain side.
The same pressure hitherto employed for the filtering process when using cloth
will suffice in filtering through wooden plates. Hitherto the filter cloth on both
sides of the chambers, besides acting as the filter material, was in some construction
of presses used for making the chambers tight externally. In using wooden plates
as filtering medium these plates will also serve for tightening the chambers
externally. For this purpose the wooden plate is of somewhat more thickness (in
horizontal direction) than the surrounding iron frame, and is of larger dimensions
in width and height than the adjusting parts of the press, so that when the press is
screwed together the two wooden plates on the side of the filter chamber will form
the tightening device.
If after using these wooden plates as filtering medium for a certain period the one
side of the plate looking towards the chambers in which the cake is formed, and
which side therefore is in direct contact with the semi-fluid, becomes choked by
reason of the penetrating liquid taking small particles of the mass into the wooden
plate, these wooden plates may be turned in order to clean them by means of the
filtering process itself, so that the side formerly looking towards the cake will now
look towards the grooves or perforated cover of the frame. By this means the
liquid which penetrates the wooden plates from the chamber will clean the plates by
washing out the small particles therefrom in the opposite direction.
It will be obvious that these cross grain wooden filtering plates may be used in
various constructions of filtering apparatus. I do not therefore mean to limit their
use to any particular kind of filtering press. I would also observe that for some
purposes it may be found advantageous to subject the wooden plates to the action
of acid solutions before placing then in the filter press, as the treatment by acid is
found to render the plates more fit for filtering purposes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Henry Edward Newton in the Great Seal Patent Office on the
21st December 1878.
HENRY EDWARD NEWTON, of the Office for Patents, 66, Chancery Lanc, in the
County of Middlesex, Civil Engineer. "IMPROVEMENTS IN FILTERING APPARATUS."
A communication from abroad by Albert Louis George Dehne, of Halle on Saal,
in the Empire of Germany.
This Invention relates to improvements in filter presses in which chambers are
formed for the reception of the liquid to be filtered and for the reception of the
liquid when filtered by placing together frames and plates with interposed filtering
mediums, the same being tightened up by screw or other pressure to close the
joints between the plates and prevent the escape of the fluid under treatment from
any but the proper channels.
In such presses it has been usual to employ filter cloths, but their rapid destruction,
especially when acidulous liquids have to be treated, has rendered it highly desirablo
to provide an efficient substitute therefor. Now the object of the present Invention
is to secure this result, and to this end it is proposed to construct filtering plates by
utilizing the porous character of soft woods in the direction of the grain. To this
end a rectangular metal clamping frame is formed to receive and hold firmly pieces
of wood cut to a uniform length crosswise of the grain, and placed together so as
to form a slab or plate. This plate will somewhat exceed in thickness the depth of
the clamping frame, and the parts of the frame will be connected together by
tightening screws passed through flanges prepared to received them.
A porous filtering plate of this construction is shewn in the accompanying
Drawing at Figure 1, which represent the metal clamping frame surrounding and
binding tightly together closely fitting blocks of porous wood, preferably pine, cut
crosswise of the grain. The slabs may be arranged in the press in various ways
to suit the varying requirements of the materials intended to be filtered under
pressure.
Fig. 2 shews in side elevation partly in section and Fig. 3 in plan view a filtering
press fitted with the improved filtering plates which are indicated at A, A.
As arranged in these Figures two of these plates A will form the chambers to
which the liquor to be filtered is supplied.
Between these plates is inserted a frame of iron B, shewn detached at Fig. 4, and
it is the spaces contained within the frames B which constitute the supply
chambers C of the filtering press. To the opposite sides of the filtering plates A
grooved metal plates D are applied. One of these plates is shewn detached at
Fig. 5. These plates D are cast with parallel grooves on their opposite sides, and
they communicate by channels with a discharge pipe fitted to one of the lower
corners of the plate. These grooved plates, like the open frames B, are interposed
between two filter plates A, and they thus form receptacles for the filtered liquid as
it percolates through the porous wood plates. The supply of the liquid to be
filtered to the chambers C may be effected by means of an external pipe fitted with
branches which lead to the several chambers, but it is preferred to employ the
internal arrangement shewn at Fig. 2. In this case the end plate nearest the pump,
which is a plate D, with grooves on one face only (the inner face), is cast with a
hole corresponding in diameter with the bore of the supply pipe from the pump.
Corresponding with this hole are holes made in the filtering plates, and in all the
plates D of the series except the last, which formins the end plate. Similar holes aro
also formed in the solid part of the frames B. When these plates and frames are
brought together and secured in place by a binding screw or screws in the ordinary
manner, a tubular passage is formed extending from end to end of the press in line
with the supply pipe leading from the pump. Lateral holes are made in the
frames B, as shewn in Figs. 4 and 6, to allow of the liquid in the tubular passages
to enter the central spaces of the frames and fill the chambers C. The pressure put

page_text: on this fluid will cause it to seck an exit from the chambers C through the filtering
plates A, and the result will be the discharge of a clear liquid into the grooves of the
plates D, whence it will pass off, as already explained, out of the press into a suit-
able receptacle. The solid portions of the filtrant will however be retained into the
chambers C, and form eventually solid cakes therein, which are to be removed from
time to time by slackening the binding screws and removing the frames B,
which are provided with handles at their sides for this purpose.
To facilitate the putting the press together the frames B, and also the plates A
and D, are provided with lateral projections, which rest upon longitudinal bars fitted
to the press to support the frames and plates in position prior to the tightening up
of the press. By this tightening up of the several parts constituting the filter the
contact surfaces of the frames and plates will constitute close joints, and to insure
this result without introducing any special packing at the joints the filter plates are
.not only extended transversely beyond the faces of their respective clamping frames,
but they are also made of larger dimensions in width and height than the adjoining
parts of the filter. Thus when the press is tightened up the wooden plates of which
the sides of the several filter chambers C are formed will constitute an elastic
packing medium between the rigid plates D and frames B. This will be best
understood by reference to the enlarged sectional view, Fig. 6.
When the filter plates have been used for some time, and the pores of the wood
have become to some extent choked, it will be only necessary in order to clear the
pores to reverse their position in the press by turning them round, so that the face
which was presented to the frame B is now presented to the plate D. The act of
filtration under pressure will cause the particles which choke the pores to be driven
out, and thus the filtering plates will be restored to their original efficiency.
In preparing the filtering plates it has been found desirable in some cases to steep
the wood in a dilute solution of muriatic or other mineral acid, in order to clear the
pores by dissolving out any gummy matter that may be contained therein.
Having now set forth the nature of the Invention of "Improvements in Filtering
Apparatus," as communicated to me from abroad, and explained the manner of
carrying the manner of carrying the same into effect, I wish it to be understood that
under the above in part recited Letters Patent I claim the use in filtering presses
of filter plates constructed and operating as above described with reference to the
Drawing.
In witness whereof, I, the said Henry Edward Newton, have hereunto set
my hand and seal, the Twenty-first day of December, in the year of our
Lord One thousand eight hundred and seventy-eight.