IMPROVEMENTS IN FILTER PRESSES
Year: 1877

page_text: 1.
LETTERS PATENT to Carl Pieper, Civil Engineer, of Dresden, Saxony, for the
Invention of "IMPROVEMENTS IN FILTER PRESSES." A communication from
Dr. Drevermann, of Hoerde. Prussia.
Sealed the 28th August 1877, and dated the 2nd March 1877.
PROVISIONAL SPECIFICATION left by the said Carl Pieper at the Office of
the Commissioners of Patents on the 2nd March 1877.
CARL PIEPER, of Dresden, Saxony. "IMPROVEMENTS IN FILTER PRESSES." A
communication from Dr. Drevermann; of Hoerde, Prussia.
Formerly filtering was done by means of the ordinary filtering presses through
bags of coarse canvas.
Without regard to the great expense, in consequence of the everlasting renewals
of the pressing bags, it is another great inconvenience that the first part of the filtered
liquor always runs off dimly, only by degrees a kind of filter bottom forms in the
bag, and after that the clear running liquor mixes with the first unclear and flows
into a common filter basin provided with a cock.
In my new filtering press, two filtering bottoms form together a box or a com-
partment wherein the filtered liquor is gathering, and can be drawn off in a clear
state from the beginning.
This filtering compartiment is composed of two halves of the frame, which can be
tightly bolted together. Within these frames are fixed the filtering slabs, made by
preference of plastic coal, or of porous filtering bason. The material of such filter
bottom, be it plastic coal or other substance, will be provided at the inside of the
compartment with grooves, one slab with horizontal and the other with vertical
grooves, thereby obtaining a good support of the slabs against each other, a great
filtering surface, and free running of the filtered liquor. In the centre the slabs
are connected by a screw joint, forming the supply channel or supply pipe for the
mire, in the same way as in other filtering presses when the frames are put in the
press close together. But differing from the old manner of forming the supply
channel, I introduce into the latter an additional pipe provided with small holes so
that the coarser parts of the mire or sand will be kept back. On both sides the
frames are provided with glass gauges, which by suitable position of the cocks can
be set to communicate with the interior of the compartment. These cocks admit
†Dis 0.71

page_text: besides this a perfect shut off, a connection to outside or to one of the pipes or
channels formed by corresponding holes through the corners of all the filtering
frames and mire frames. These latter are simple frames, having handles in their
lower and top rail for the purpose of easy manipulation in throwing out the
press cake.
Another device of filtering bottoms can be obtained by lining the frames with
sheet metal, the surface of which being perforated with minute holes and the space
between the sheets being filled with oakum or sheep's wool (for neutral liquors),
asbestus, pumice or other natural or artificial porous stones, glass or slag, wool, &c.
When these filtering frames and mire frames are brought into the press alter-
nately the latter will fill itself with the mire entering through the supply chanuel,
and the filtered liquor passing. through the filter bottoms gathers in the compart-
ments, from whence it is drawn off by the corner channels. When the filtering
process is ended the pressure is taken off and the lixiviating medium is introduced
through the corner channels in such a way that it may act in every other com-
partment, and expel all soluble particles by washing them into the interjacent
compartments which have been shut off from the corner channels by a suitable position
of their cocks.
To avoid a mechanical breaking through of the press cakes during the process of
lixiviation, the latter are supported in my filtering press unelastically, so that the
steam or any other medium of lixiviation must pass through the whole mass of the
press cakes in a perfect uniform way, and cannot leave behind any particles still
of use.
While the medium of lixiviation enters the press I can by counterpressure with
compressed air regulate the flow of the liquid in such a way that it passes on very
slowly. These pressures acting on and the difference of pressure and counter-
pressure working through the filter bottoms and cakes contribute too to prevent a
local passage of the liquid.
The said action under counterpressure effectuates a far more solid and dense com-
pactness of the press cakes, and gives to them a firmer consistency than ever could
be obtained by any other press.
This arrangement of the filtering frames with compartments formed of grooved
filtering bottoms admitting by the position of suitable cocks a communication with
the corner channels, or with the glass gauges, or to outside, has the following
advantages =
1. The liquor running clear from the beginning can be excluded from the contact
with the atmospheric air by receiving it in said corner channels and leading it from
there in any convenient manner to other apparatus for further manipulation.
2. The process of lixiviation after the ending of filtration is made very easy and
effective, as any medium of lixiviation (liquid, or gas, or steam, or hot air) may be
used in the press, passing through the corner channels into every other compartment,
and acting at once all over the whole section of the press, the said medium of lixivia.
tion will wash out all soluble particles of the press cake, and gather them in the
compartments of the interjacent filtering frames.
3. An easy control of the filtering and lixiviating process, by means of the glass
gauges in communication with the interior of the compartment when required.
4. The possibility of retaining in the stone catcher all coarser parts, especially
sand and stones.
5. The extraction of the soluble parts can be effected either by pressure or by
vacuum.
6. Acid or other liquids may be filtered in my new press, which admits conse-
quently a very general adaptability.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Carl Pieper in the Great Seal Patent Office on the 1st September
1877.
CARL PIEPER, of Dresden, Saxony.
"IMPROVEMENTS IN FILTER PRESSES." A.
communication from Dr. Drevermann, at Hoerde, Prussia.
The filtering press with compartments constructed by me, offers, before all others,
the following advantages :-
1. The filtration effected by this apparatus gives from the beginning a clear
filtered liquor of thick or thin, slimy, etc., liquids.
2. All soluble parts of the press cake can be wholly extracted by a suitable and
easy lixiviation.
3. This perfect lixiviation is effected by a minimum of solvent.
4. The filtration and the displacement of the liquid particles by lixiviation can
be obtained either by pressure in vacuo or under exclusion of air by means of any
other gas or steam.
5. The new filtering press admits such a degree of compression of the particles in
suspense as never has been heretofore attained.
6. The apparatus admits a uniform treatment of the press cake with steam or
other gases or liquid solvents at a temperature ranging from the ordinary to
100° C., and above, whereby certain parts of the mass may be dissolved, others
distilled, and whereby the press cake can be dried or decomposed without any loss
of the employed agents.
7. The filter bottoms may be formed of animal, vegetable, or mineral coal, com-
pact or in form of powder; they can be made of natural or artificial porous stones,
of sand, pumice, asbestus, or other minerals, glass or metal, wool, etc., in such a way
that acid or caustic liquors, etc., may be filtered without any injury to the same; a
renewal of the filter bottoms, made of cheap materials and being rarely out of order,
is seldom necessary; and the expensive filtering cloths of the ordinary filter presses
are wholly dispensed with.
8. The working of the apparatus is of a very simple nature, and there is but one
person required for inspecting attendance over one or several presses.
9. The press itself is provided with an arrangement, the so-called stone catcher,
by means of which the coarser parts of the pulp, stones and other impurities are
withheld, and can be returned to the pulp in a easy manner.
10. All parts of the apparatus can easily be reached, and its control is made
possible without any interruption of its functions.
11. The arrangement admits of a combination of several presses into one battery
for the purpose of lixiviating the press cakes and filter bottoms systematically and
continually in such a way that,-1, the solvents on their way through the presses
will gradually become as rich and concentrated as the original medium; 2, the
lixiviation can be carried on to such a point as to exhaust the press cakes
thoroughly; and 3, the lixiviation is continued without any interruption by connecting
or disconnecting newly filled or exhausted.presses with the system, all this by
means of a simple circulation of solvents under convenient pressure, without any
other work as the turning of valves and cocks.
Formerly filtering was done by means of the ordinary filtering presses through
baggings of coarse canvass.
The new filtering press with compartements is represented on the annexed
Drawing with all its essential details.
Fig. 1 is a longitudinal section; Fig. 2, a left-hand side elevation; Fig. 3, a
ground plan.
Fig. 1a a right-hand side elevation of a press with 24 pulp frames B, and with
23 entire and 2 half filtering frames A, and with all complete contrivances for
the combinations of a filtering press battery for the purpose of an exhaustive
lixiviation.

page_text: All filtering frames are supported by two guides h, h, resting on the side frames D, DI,
on which by means of the head plate K they can be moved forward and backward.
The left-hand side frame carries a transmittive motion H with cranks M, M¹, small
bevelled wheels T, T¹, T, and larger bevelled wheels K, K¹, K¹, by way of which
the filtering frames are screwed tightly together.
1. The filtration is effected principally by the filtering frames A, the pulp being
introduced under certain pressure into the interior pulp supply channel c where
the filtered liquid separates from the compact parts of the pulp, the former oozes
through the porous partitions of the filtering frames (represented in Fig. 7, 8, 9),
whilst the compact parts remain in the pulp frames as a hard cake.
The filtering frames are made in two different forms,-
a. As represented in Fig. 4, 5, 6, the filtering plates b, b, consist of solid porous
slabs which can either be made of two equal halves b, b, joined firmly together by
means of the external frame and nuts and screws a, a, as well as by the hollow
screw forming the interior supply channel, or they may be moulded from plastic
material and by calcinating formed into solid and porous plates which are firmly
fixed into the frame and securely fastened by means of fused metal or metal alloy.
b. As represented in Fig. 4, 5, 6a, this design is also shown in Fig. 18, 19, 20,
and consists of 2 cases b, b, the flat sides of which are made of perforated sheet
metal;
the opening on the higher edge provided with a sliding cover admits the
introduction of all kind of coarsely powdered filtering material. These two cases
forming one set may also be combined to one case with an interior filtering
chamber, and firmly fixed into the frame by fusing round metal alloy.
2. In the interior of the filtering plates or cases (filtering bottoms) is a hollow
chamber or a number of communicating channels y, Fig. 4, 6, 4, 6ª, 20, and 21, in
which the filtered liquid oozing through the interior surface of the filtering bottoms
freely collects to be drawn off.
3. The filtering bottoms in the two above-described forms may be made,-
a. In the form of filtering plates, of plates of mineral, vegetable or animal coal,
of artificial stone made of sand, clay, clay and sand, pumice stone, or other unorganic
material, or of naturally porous stone, or of compact plates of wood, wood fibres,
paper machee, and any other fibres, etc.
b. In the form of filtering cases, of cases densely filled with powdered or coarsely
powdered filtering material, as for inst., powdered animal, vegetable or mineral coal,
asbestus, pumice stone, sand, or other minerals, wood, or any other vegetable fibre,
or animal fibre, waste of all kinds, as tow, etc., etc.
4. If amongst the above-named filtering material such are selected which are not
effected by acids or alcalic liquids it is evident that the described filtering and pulp
frames may also be prepared in such a way, for inst., by a coating of vulcanized
india-rubber, or lead, tin, or any other suitable metal composition, as to admit
without any injury the filtration of strong acid or alcalic pulps.
5. The drawing off of the filtered liquid from the filtering chambers is generally
done by four corner channels f, f¹, Fig. 5, 5ª, 8. These channels are formed by
congruent grooves in each of the frames when the latter are screwed together.
The corner channels communicate with the filtering chambers in a peculiar way
as follows: a. Supposing the filtering chambers carry running numbers, the odd
numbered chambers will either communicate with the two channels of the higher
left-hand and lower right corner, as represents in the higher right-hand and lower
left-hand side corner communicates with the even numbered chambers as shown in
Fig. 5. Or, b. The two channels in the left-hand higher and left-hand lower corner
communicate with the odd numbered filtering chambers, whilst the higher right-
hand and lower right-hand corner channels communicate with the even numbered
filtering chambers.
6. The filtering chambers also communicate with special glass gauges, Fig. 4, 5,
6, 4, 5, 6a, which allow the necessary observation and examination of the filtration
whilst the press is closed, and process is going on.
7. The regulation of the manifold communications of the filtering chambers with

page_text: the corner channels, with the glass gauges, and with the outside of the press is
effected by peculiarly constructed cocks, which serve at the same time as brackets
for the glass gauges. These combinations, unavoidable for the working of the
filtering press, demand four different positions of the cocks.
1st. position. Communication of the filtering chamber with the interior of the
cock, and of the latter with the corner channel and the glass gauge, whilst the
opening towards the outside of the press is closed; this is represented in Fig. 13ª,
140, 150, and the position of the cock handler.
2d. position. Communication of the filtering chamber with the interior of the
cock, and of the latter with the glass gauge, whilst the corner channels and the
communication with the outside are cut off; this is shown in Fig. 15b, 14b, 13b, and
position of cock handle rb.
3d. position. Communication of the filtering chamber with the interior of the
cock, of the latter with the glass gauge, and with the opening towards the outside,
whilst the corner channels are cut off; this is shown Fig. 15, 140, 13d, position of
cock handle d
4th. position.--Communication of filtering chambers with the corner channels,
and the opening towards the outside, whilst the glass gauge is cutt off;
this is
shown Fig. 150, 14d, 13, position of cock handle 1°C.
It is obvious that for this peculiar cock a combination of valves or cocks, or both
together, may be substituted, and that for deviating positions of the corner channels
towards the filtering chambers the cocks must be suitably adapted to attain the
same end.
8. A peculiar contrivance combined with the cog gear H, and shown in Fig. 1, 2,
3, for the purpose of removing the hard deposits from the supply channel, and
serving at the same time as stone catcher. In the interior of the pulp supply.
channel there is a tube o, open on one end, and closed at the other by a movable
piston, as shown in Fig. 16 and 17. The tube o, as far as it penetrates through the
pulp frame, is perforated on its circumference, so as to retain the coarse parts of the
pulp, as well as all foreign matter. In the process of filtration this tube will fill
with more compact deposits of the pulp; the filtration being finished the two
slides g and 8, and the screw nut t are opened, and the crank M of the cog gear is
turned. This crank after being disconnected from the pressing spindle by the
apparatus L acts in a peculiar way on a square rod u inside the hollow spindle 1,
moving the same backward and forward by means of a disk being pushed over the
same. This rod presses the lose piston p through the tube o, and in this way cleans
the tube from all deposits; the square rod is now turned back, a wedge is placed in
two slids of the tube o, and the same may now be entirely removed.
9. It has been shown how the lixiviation of the cakes in the press may be
carried on until the same are completely exhausted; but in a single press such
complete exhaustion can only have a material value in case an entirely clean cake
is the purposed end, as with continued lixiviation the solvent becomes too much
diluted.
If it is intended to obtain complete exhaustion of the cake, and at the same time
highly concentrated solvents, it is necessary to combine several presses in form of a
battery for the purpose of a systematical lixiviation by way of countreacting
currents. A similar combination of several filtering presses has hitherto presented
such difficulties that with the old presses it never has been tried, and in fact it
requires all the new constructions and their systematic working together to attain
this purpose. Unavoidable conditions to carry this object are,-
a. That the access of the solvent takes place under uniform pressure on the
entire interior surfaces of the filtering chambers; this can only be obtained by
introducing the solvent through two corner channels, as far apart as possible, one of
which for other reasons must be on the upper side.
b. That the tube and valve communication of the combined presses be so disposed
that the connecting or disconnecting of any single press with the whole system may.

page_text: be effected through simply turning off valves or cocks without disturbing the process.
of filtration.
A similar combination of five presses to one battery, allowing the most compli-
cated operation which ever may occur in practice, viz., the successive treatment of
the cakes, or at least the successive introduction into the press of five different
agents; 1, compressed air; 2, steam at high pressure; 3, water; 4, vacuum pressure;
5, the pulp, is represented in Drawing, Fig. 1, 1a, 3, and 1b. In this representation
the diametrical opposite corner channels on each of the higher left-hand sides and
lower right-hand sides of the filtering frames, and the respective higher right-hand
side and lower left-hand side corner channels communicate with the odd numbered
respectively, the even numbered filtering chambers as described under 5% and 5b.
In the construction described under 5b this system of valves and tubes is much
simplified, which is also the case when less then the above-named agents are
required to operate successively on the pulp cakes.
The operation of this systematical combination of 5 presses for one lixiviation
battery is exemplified further on. Here it will suffice to mention, 1, .that in Fig. 1
the systematical combination of tubes and valves connected to the right-hand side
frame is represented in vertical section, and for the detail representation of valves
and cocks a larger scale is taken; 2, that Fig. 1 is a front elevation; and 3, that
Fig. 3 is a upper view of the lower portion of the pipes and valves; and 4, that
Fig. 1b is a systematical representation of the whole system of the five combined
presses.
From the above mentioned purpose of the construction and of the combination
of the tubes, valves, or cocks, shown in detailed Drawings, as well as from the exemple
mentioned below, the expert will readely understand the whole somewhat complicated
disposition of the new press.
The faculties of the press, how the same can be emptied easily and quickly after
use, and can be put in action again, will be clearly understood by examination of
Fig. 1, 2, and 3.
The filter frames A, A, A, and pulp frames B, B, B, which are set into the press
alternately, rest by means of braces g, g, Fig. 5, 5, and 8, serving also as handles
on two girders h, being threaded on one side, whereon the nuts i connected to the
moveable head plate k, Fig. 1 and 3, can be easily moved to and fro by a toothed
gear opening the press or shutting it, according to the direction in which the hollow
shaft revolves. The braces of the last filtering frames can be provided with pulleys,
Fig. 5, that the thread of the girders may not be injured.
On the sides of the pulp frame styles project pins m, Fig. 5, 5, 8, carrying hooks n,
Fig. 10 and 11, which in opening the press by screwing back the head plate, latchi
over the tappets on the filtering frames, and over the pins of the next pulp frame,
separating all the frames from each other, and leading them from the closed position,
Fig. 11, to the open one (Fig. 10). Now the pulp frames can be removed to throw
out the press cakes.
It is obvious that the frames can be of any desired form (other than the here
represented) if it is required that the cakes should be of a circular or any other shape,
even on surface. The supply channel becomes filled with a compact mass, connecting
the cakes, and making their removal more difficult. The steam cannot master
this substance to drive it out, as some manufacturers have tried to do. In my new
filtering press the supply channel will be cleared before the opening of the press,
and the parts of pulp that fill it, and are not yet wholly lixiviated, will be pushed
back into the material still to be pressed. This will be effected in the following
manner Fig 1, 2, 3, 16, and 17, show that the supply channel is formed by a
pipe o open on the end near the fixed head plate, and closed at the other end by
a moveable tubular piston p. The pipe is perforated with many small openings at
all the parts, being in direct communication with the inside of the pulp frames
when the press is closed (Fig. 16 and 17). The coarser parts, especially stones
and foreign matters, will of course be kept back in the pipe, and do not pass into the
cakes.
:-

page_text: When filtration has finished the front slide q is closed, and lixiviation begins by
steam, etc.
The cocks r of the filtering frames A, A; are turned into such position that the
steam passes through the corresponding corner channels f₁, f, f, f¹, into the
alternate odd or even filtering chambers, that is, either into the 1st, 2d, 5th, 7th, or
into to 2, 4th, 6th, 8th. The steam or any other solvent must consequently on its
passage from the odd numbers of filtering compartments to the even ones filter
through the two filter bottoms b, b, of two adjoining filter frames, and through the
press cake that has been formed between them. As the lixiviating solvent can act
at once all over the whole section of the press, finding every where the like
resistance, it is evident that a perfect and expeditious lixiviation must be obtained;
which can be regulated at will by counter pressure with compressed air, etc.
Hereafter both slides q and s (Fig. 1 and 3) are opened, the head screw t is taken
off, and the contents of the pipe o (the stone catcher) is pushed out by means of a
square rod u, the head of which being provided with steep thread fitting into the
thread of the hollow shaft moves the rod slowly forward. Then the pipe o itself
is pushed out in the same way so far that it can be taken hold of with the hands,
whereupon it can easily be removed. Now the press is opened by screwing back the.
moveable head plate k, whereby the looks n, n, act in the herein-before indicated
way, and the pulp frames are emptied out. For very large filtering presses extra
girders may be applied under the frames, which will be lifted after the closure of
the press by screws, and then give to the filled press an additional support.
For the control of the pressure acting in the different channels of the new filtering
press, three pressure gauges (one shown in Fig. 1) are connected to the upper two
channels ff, and to the supply channel o. Much more important for the control
of filtration, and especially for lixiviation, are the glass gauges d, d, Fig. 4, 5, 4ª, 5ª,
fixed to the sides of each filtering frame in a very protected position. The com-
munication of these glass gauges with the corner channels can according to the
above described four positions of the cocks be established & interrupted. If in
the corner channels clear solvents are introduced under pressure for the purpose of
lixiviating, the respective filtering chambers, say, for inst., the odd numbered
oves, are immediately filled. The solvent penetrates through the partition into the
pulp in the pulp frame, and from there through the partition of the next filter
bottom into the opposite even numbered filtering chamber. Here it may always be
examined by means of the glass gauges communicating with the filtering chambers
by a thermo-aeriometer, and the lixiviating process interrupted when the cakes
appear sufficiently exhausted. The examination and the control of the lixiviation
of all the filter plates collectively is effected in the described manner by a glass
gauge near the head plate, which may at will be connected or disconnected with
the corner channels.
A great advantage of the filtering process in the new press over the old systems
is realised by the fact that the filtered liquor need not run from the filtering com-
partment through the cock into the grooves forined outside (though this may be
done for special purposes), but that the liquor of all the filtering frames or their
compartments gathers in the corner channels and flows together into a common
external pipe, whereby not only the air can be excluded from the filtered liquor, but
by which arrangement the filtering process may be effected under a certain counter-
pressure, so as to obtain more equally and more densely bedded press cakes. It will
frequently be found of advantage to effect the filtering process by simultaneously
applying pressure to the supply channel and producing vacuum in the corner
channels in this way the press cakes are formed free of any air bubbles. The
process of filtering will generally proceed in such a way that the flow of filtered
liquor passes through all four corner channels at the same time. In this case
the counterpressure will be regulated by a valve fixed externally on the common
pipe outside of the press connected with the corner channels, the filtering goes on
while the compartments are all filled, and the pressure and counterpressure will be

page_text: hydraulic. After ending filtration the odd or even numbers of the filtering com-
partments are put under pneumatic pressure; this effects the emptying of the
filtering chambers, being in direct communication with the corresponding corner
channels, and then supplants the liquor in the respective filter bottoms, as well as
that of the adjacent press cakes, and finally the liquor of the filter bottom of the
neighbouring frame.
I shall now describe a certain arrangement by which several of the above-specified
filter presses can be combined, in order, 1, to produce a systematical and continual
lixivication of the press cakes and filter bottoms, while a constant and very con-
centrated solvent is obtained; 2, to admit during the process of lixiviation the
connection and disconnection of newly filled and exhausted presses; all this by
means of simple circulation of solvents under convenient pressure, without any other
manipulation than the turning of valves and cocks.
Fig. 1, 1, 1b, represents a combination of pipes with the necessary valves, by the
position of which the different presses can be connected, for inst., with the conduits
a for compressed air; b, for fresh steam; c, for water under convenient pressure; d,
for communication with a vacuum pump; e, for the pulp to be filtered in such
a way that f, i, one press is fed anew, while in the next or in several presses the
backward filtration or lixiviation is at work, so that the solvent of one press is
used to lixiviate the press cakes in the next press, etc., and therefore becomes more
and more concentrated.
The different operations in a combination of five presses in one battery take the
following order-Supposing that the 5th press is out of action, the first press on
the left-hand side will have to be pressed together by the cog wheels tightly enough
to stand against a pressure of 120 to 150 lbs., without leaking in the joints between
the frames; the slide q is shut, and after having opened the communication between
the four corner channels and the conduit for the filtered liquor a the pulp is admitted
into the press, while simultaneously in the other conduit for the filtered liquor ẞ by
compression of air a counterpressure of f, i, 90 to 100 lbs. is set in action. As soon
as the filtration begins to relax, i.e., when the settlings forming the press cake offer
a certain resistance to the flow of the liquor, the counterpressure must be stopped
and the vacuum pump is put in action instead. The filtration becomes again very
lively, as the pressure of 120 to 150 lbs. being increased to 135 to 165 lbs. by the
vacuum, works without counterpressure, and the settlings now being firmly pressed
against the filter bottoms and all air bubbles removed will form press cakes that fill
out all the frames perfectly and tightly. The termination of the filtering is indicated
by the difference shown in the pressure gauges fixed upon the press in communication
with the supply channel. Now the feeding of the press with pulp is interrupted, the
slide q is closed, the pulp in the external supply channel is driven back by steam of
high pressure into the reservoir, and the filtered liquor remaining in the corner
channels and the filter chambers is removed by compressed air.
Be it supposed, for instance, that 3 presses are connected in such a manner that
the solvent driven through the filter bottoms and press cakes of the first press in the
above-described way is led into the conduit 2, Fig. 1b, descending through the
pipe. The solvent will follow the conduity in the direction to the right towards
the second filter press (the valve behind the joint of the pipes and y being closed),.
and rise in the pipe as the valve y is closed. The solvent can only descent into
y again through the pipe y after having passed the second press from the even
chambers to the odd ones & vice versa, thereby lixiviating the filter bottoms and
cakes; then the solvent is led in the same manner into the third press, etc.,
taking up more and more the soluble particles, and getting more and more concen-
trated, and is finally drawn off into a reservoir by the conduit ẞ. The pipes y and
6 are connected in such a way that they allow an uninterrupted circulation of the
liquids, in order to admit an easy disconnection of any of the presses. Having thus
in the first 3 presses put the systematical lixiviation in action the filtration in the
4th press is made to begin, and afterwards prepared, to be connected with the

page_text: battery as it has been described with reference to the first press. As already
inentioned the solvent on its way from the first press through the next presses into
the reservoir will grow richer; and it is obvious that according to the above
arrangement the lixiviation will be ended first in the first press. As soon as
this has been shown by the different means of control indicated above, the first
press will be disconnected from the circulation of solvents, and the fourth press
inserted instead, while now the fresh solvent enters the second press first. After
its disconnection the first press is emptied in the above specified way, etc.
It is evident that these operations can be carried on in a different order, and
that the 5th press being a reserve press may be used as substitute for any of the
others.
Having now particularly described and ascertained the nature and object of my
said Invention, and in what manner the same may be performed or put in practice,
I hereby declare that I claim of the herein described "New Filtering Press with
Compartments of a very General Adaptability," as my Invention, the following im-
portant points or features:-
1. A contrivance for filtering in filtering presses consisting of solid partitions
(filter bottoms) of various forms fixed in the filter frames, namely,-a, solid filter
bottoms in the form of slabs; b, filter bottoms consisting of perforated cases filled
with coarsly powdered material, all as herebefore specified.
2. The construction of a chamber in the interior of the aforesaid filter bottom for
the reception, distribution, perpetrating from, and leading off of the filtered liquid
in the adjacent pulp frames, and especially for the purpose of admitting a so-called
backward filtration, that is, a complete exhausting of the cakes of all soluble matter
and a uniform and complete lixiviation of the same without their position in the
press being changed. Allowing, further, a continual and uniform treatment of the
cakes in the press with any gas, steam, or any liquid in temperature ranging up to
100 centidegrees and more for the purpose of a gradual solution of certain particles
or for the absorption of certain contents or for desiccation or decomposition of the
cakes without any loss of the agents used, all as herebefore described.
3. The arrangement of 4 corner channels, two and two combined, for leading off
the filtered liquid, under exclusion of air or under exposure to any other gas or
steam, or for the introduction and uniform distribution of solvents, steam, air, or
other gases in combination with a vacuum or pressure pump, as herebefore
described.
4. The arrangement of a combination and the communication or interruption by
peculiarly constructed cocks of each of the alternate filtering frames or filtering
chambers, with the diametrical opposite corner channels, as herebefore described.
5. The communication of the 2 combined corner channels, the filtering frames or
filtering chambers, with glass gauges, as herebefore described.
6. The application in my new filtering press of the following filtering material in
the two above-described forms: a, for the solid filtering slabs, mineral, vegetable,
or animal coal, natural or artificially prepared porous stone, compact plates of
mineral fibres, as asbestus, glas, metal, wool, etc., or vegetable fibre, as plates of wood,
paper machee, etc., or animal fibre, as felt or leather, etc.; b, for the filtering cases,
all kind of coarsely powdered filtering material.
7. The combination of the apparatus for pressing together the frames with a
peculiar contrivance for the removal of the more compact pulp deposited in the
supply channel, as herebefore described.
8. The peculiar contrivances collectively which allow a uniform lixiviation of the
cakes in the press or an operating on the same with steam or any fiuid; and the
peculiar combination of several presses in form of a battery for the purpose of
attaining a systematical, gradual, and continual lixiviation, and thereby the most
concentrated solvents; this. allowing the continuation of the process until the
cakes are completely exhausted whilst the filtered liquid is led off."
9. The arrangement admitting the single presses forming the battery to be de-
tached at will for the purpose of being emptied, filled, or repaired without inter-

page_text: rupting the various circulations of fluid between the remaining presses and
disturbing the process of filtration, all as here before described.
°
In witness whereof, I, the said Carl Pieper, have hereunto set my hand and
seal, this Fifteenth day of August, in the year of our Lord One thousand
eight hundred and seventy-seven.
CARL PIEPER
(1.5.)