Title:
APPARATUS FOR EXTRACTING WITH A LIQUID, PRODUCTS WHICH ARE PART OF SOLIDS
United States Patent 3660042


Abstract:
This invention relates to an apparatus for extracting with a liquid, products which are part of solids, by advancing in countercurrent liquid and solids through a drum which comprises at least one screw conveyor with an upstream end and a downstream end, part at least of the conveyor turns defining compartments which are provided with elements for raising the solids and for separating the solids from the liquid, the solids falling from the raising elements back into the drum bottom each time in a different liquid fraction.



Inventors:
Duchateau, Georges Francois (Tienen, BE)
Vanherwegen, Ferdinand Joseph (Oplinter, BE)
Application Number:
04/801018
Publication Date:
05/02/1972
Filing Date:
02/20/1969
Assignee:
RAFFINERIE TIRLEMONTOISE
Primary Class:
Other Classes:
127/6, 127/45
International Classes:
B01D11/02; C13B10/10; (IPC1-7): B01D11/02
Field of Search:
23/267,269,270,270.5,309,310 127
View Patent Images:



Foreign References:
PK108361A
GB417302A1934-10-02
GB443848A1936-03-09
FR524533A1921-09-06
Primary Examiner:
Yudkoff, Norman
Assistant Examiner:
Emery S. J.
Claims:
We claim

1. An apparatus for extracting material from solids by contacting the solids with a counterflowing liquid comprising:

2. An apparatus as in claim 1 where the solids raising means includes a substantially 90° arc shaped basket positioned in each cell.

3. An apparatus as in claim 1 where the channels of the liquid conveyor means are inclined relative to the axial direction.

4. An apparatus as in claim 1 where the pair of separate solid conveyor means includes a pair of interthreaded helical screws and the liquid conveyor means further provides two separate liquid paths through the drum without intermixing.

5. An apparatus as in claim 4 where the helical screws are formed from stepped discs having pairs of notches and slots.

6. An apparatus as in claim 5 where the discs have inclined walls with respect to the axial direction to form chutes for directing the solids in a forward direction.

7. An apparatus according to claim 6, in which the means for feeding the solids includes a transversally positioned circular wall arranged at a distance from the central partition and from the inlet end of the drum;

8. An apparatus for extracting material from solids by contacting the solids with counterflowing liquid comprising:

Description:
It is known, notably from the Belgian Pat. Nos. 367,630, 371,926 and 475,626, to provide such apparatus in which fractions of said solids having a decreasing content of products to be extracted, are treated by means of fractions of said liquid which also have a decreasing content of products to be extracted, said solid fractions and said liquid fractions having resulting movements along opposite directions, with the feature that the axial feeding of said liquid fractions is insured in the adequate direction together with said solid fractions, said solid fractions then undergoing an axial displacement along the opposite direction out of the liquid phase and which is longer than the movement they made together with said liquid fractions.

These known apparatus comprise a rotating drum the inside of which is divided into compartments by the turns of at least one screw conveyor integral with the drum, means at the conveyor outlet to supply the solids, and means at the conveyor inlet to supply the liquid. In such apparatus, the advancing of the liquid fractions in the feeding direction of the screw conveyor(s), is insured together with the solid fractions by the drum rotation. The solid fractions carried together with the liquid fractions along the feeding direction of the screw conveyor(s) due to the drum rotation, thus undergo a displacement along a direction opposite to the one which is desired for the solids.

To feed the solid fractions in the desired direction therefor, that is the direction opposite to the liquid fraction feeding, use is made of separating elements and slanting chutes.

The separating elements which are located radially between the turns, let the liquid fractions pass through, said liquid fractions still following on the thread of the screw conveyor(s). The solid fractions slide in the slanting chutes which are located in the center part of the drum and are integral therewith. Such slanting chutes lead in the selected compartments in such a way that the solid fractions perform by sliding through said slanting chutes, an axial displacement along the desired feeding direction for the solids, which is longer than the displacement they made along the opposite direction together with the liquid fractions.

Such slanting chutes make the apparatus design intricate, limit the useful solid charge and set contraints regarding the ratio between the compartment width and the drum diameter. Indeed it must be understood that the chutes must have enough slanting to enable the sliding of the solids which are separated from the liquid without such solids falling back in the compartments they come from.

Moreover, in this kind of apparatus the head compartment, that is the one where the solids are supplied, should have a separating capacity which is higher than the one of the other compartments as it receives besides the normal liquid fraction, another liquid fraction which is required for carrying the solids inside the apparatus. There results practically a widening of the compartment and consequently a diameter increase thereof. This design of the first compartment makes the apparatus construction intricate.

The invention has for object to obviate these drawbacks by providing an apparatus which does not require such slanting chutes.

For this purpose, in the apparatus according to the invention, the solid inlet is arranged on the side of the upstream end of the screw conveyor and the liquid inlet lies on the side of the downstream end of the conveyor, in such a way that the solids advance together with said liquid fractions, axially along the conveying direction of the screw conveyor, each raising and separating element being located downstream in the drum rotating direction, of flow surfaces for the liquid from the considered compartment to an upstream compartment, so as to displace the liquid fractions separated from the solids, along a direction opposite to the screw conveyor conveying direction.

According to an advantageous embodiment, the drum is divided inside into compartments by disks with at least one notch, the opposed edges of two corresponding edges of two adjacent disks being connected by slanting surfaces, the sequence of said disks and of said slanting surfaces forming in the peripheral part of said drum at least one distorted screw conveyor, two succeeding disks being connected by at least one flow wall for the liquid towards a liquid channel on the drum circumference which connects the compartment formed by the two considered succeeding disks with an upstream compartment.

According to an embodiment in which the products contained in the solids are extracted by a liquid flow subdivided into two separate partial flows which work in parallel relationship and which advance along a direction opposite to a solid flow divided into two partial flows and with such relative displacements to the partial flows of solids, that said solid flows are met periodically and in succession by each one of the liquid partial flows, each disk has two notches and two slots which are arranged alternately and symmetrically about a geometrical axis of the disk, the succession of the disks and of the slanting surfaces forming in the peripheral part of the drum two distorted screw conveyors which overlap one another, each pair of adjacent disks being connected by an axial partition located between the slots and extended on either side along the slots by a pair of slanting flow walls which bound together with the peripheral drum wall, a liquid flow channel, said axial partitions and said liquid flow walls defining between the pairs of succeeding disks and the peripheral drum wall, two solid cell series, the cells of one series being connected together by the slanting surfaces.

According to another embodiment, the disks are comprised of a succession of circle portions which are located in different cross planes relative to the drum lengthwise axis and which extend alternately from one notch to a collecting wall, connecting walls joining the circle portions of one and the same disk.

Other details and features of the invention will stand out from the description given below by way of non limitative example and with reference to the accompanying drawings in which:

FIG. 1 is an elevation view with the body sheet taken away, of part of an apparatus for extracting with a liquid, products which are part of solids according to the invention, some only of the separating elements being shown.

FIG. 2 is a plan view with the body sheet taken away, of part of the apparatus shown in FIG. 1.

FIG. 3 is an end view along the arrow III of FIG. 1.

FIG. 4 is a section view along line IV-IV of FIG. 1.

FIG. 5 is a section view along line V-V of FIG. 1.

FIGS. 6 to 8 each show a front view of the disks which are part of the apparatus shown in FIG. 1, at the level of the section lines VI-VI, VII-VII and VIII-VIII in FIG. 1.

FIG. 9 shows diagrammatically a development of the inside sheeting of part of the apparatus, showing the intersections with the notched disks, the slanting surfaces, the slanting collecting sheets, the location of the separating elements, the path of the liquid flows and of the solid flows in the apparatus shown in FIG. 1.

FIGS. 10 and 11 show another embodiment of part of the apparatus shown in FIG. 1.

FIG. 12 is an elevation view with the body sheet taken partially away, of another embodiment of an apparatus according to the invention, but four compartments including the solid supply and outlet compartments being shown.

FIG. 13 is a section view along line XIII-XIII of FIG. 12.

FIG. 14 is a front view at the level of the section line XIV-XIV of FIG. 12, of a distorted disk.

FIG. 15 is a side view of the disk of FIG. 14.

FIG. 16 is an elevation view, with the apparatus having a somewhat different angular position relative to FIG. 12, of the inside sheeting of the supply compartment and of the first compartment of the apparatus shown in FIG. 12.

FIG. 17 shows diagrammatically the development of the apparatus shown in FIG. 12, as well as the path of the liquid and solid flows.

In the various figures, identical reference numerals pertain to similar elements.

The apparatus comprises a cylindrical drum 1 with an horizontal axis, which is rotatable. Inside the drum and engaging the inside surface thereof, are arranged a number of disks 2 in parallel relationship which are at right angle to the lengthwise axis of the drum 1 and which define n compartments. Each disk 2 shown in FIGS. 6 and 7 has two notches 3, 3' with a generally semi-hexagonal shape opening towards the disk circumference, and two slots 4, 4' also with a semi-hexagonal shape but with a markedly smaller area, which are arranged alternately and symmetrically relative to a geometrical axis of the disk. The arcs of circle which lie between the openings 4 and 3, 4' and 3' are larger than the ones lying between the openings 3' and 4, 3 and 4'. It may be considered that each disk 2 is comprised of four circle sectors L, M, L', M' which are defined by the edges of the notches 3, 3' and of the slots 4, 4' and by the diameter portions that join the crowns of the notches and slots. The disks 2 are so arranged inside the drum 1 that the diameter that passes through the crowns of the notches 3, 3' of any disk 2 is displaced angularly along the drum rotating direction relative to the corresponding diameter of the adjacent disk 2 which is located towards the solid supply compartment 31. This displacement is preferably about 180°/n or a multiple thereof so as to balance the drum rotating couple. The group of FIGS. 1, 2, 6, 7 and 8 shows clearly this displacement. Between two adjacent disks 2, a slanting surface 5 engaging the inside surface of the drum 1 and solid sheets 6 and 7, connects two opposite edges of the notches 3 and 3' of both said disks 2. Two adjacent surfaces 5 form in the peripheral part of the drum 1 a channel 32 through which two adjacent compartments communicate. One slanting surface 5' and solid sheets 6' and 7' join in the same way two opposite edges of the notches 3'. Two slanting surfaces 5' form in the peripheral part of the drum 1 a channel 32'. The surfaces 5, 5' and the sectors L, M, L', M' form together in the peripheral part of the drum 1, two distorted screw conveyors which overlap one another. Each compartment defined by two adjacent disks is divided into two cells I, II . . . N, . . . ; I', II', . . . N' by partitions 8 which lie in an axial plane and which are extended on either side up to the drum 1 by solid collecting sheets 9 and 9' which are inclined relative to the partitions 8 and joining the opposite edges of two slots 4 or 4' of two distant disks 2 from two compartments, said sheets 9, 9' passing through the slot 4, 4' of the central disk. The partitions 8 are joined to the collecting sheets 9 and 9' by solid sheets 11 and 11'. Inside one compartment are thus located two solid sheets 9 and two solid sheets 9' which define together with the solid sheets 11 and 11' and the inside wall of the drum 1, liquid channels 10 and 10' which provide the required communication between the opposite cells of the two compartments located on either side of one particular compartment.

In each cell is arranged a perforated basket 12, 12' for the raising of the solids and the separating thereof from the liquid. Each basket 12, 12' is located in that area of the cell which is formed respectively on the one hand between the sectors M of two adjacent disks and the metal sheet 9, and on the other hand between the sectors M' of two adjacent disks and the metal sheet 9' so as to have a larger filtering area. The liquid which flows from a basket enters directly in the liquid channel 10 or 10' located right behind the basket, in other words the one located upstream according to the drum rotating direction as shown by the arrow 34.

The parts of the apparatus used for the supply and the discharge of the solids and of the liquid will now be described.

The drum inlet is bounded by a first disk 13 with the same diameter as the disks 2; this first disk 13 is not provided with notches 3, 3' and 4,4', but it has a central circular supply inlet 14. Slanting surfaces 5 and 5' and solid, that is imperforate sheets 6 and 6' connect the free edges of the notches 3 or 3' of the second disk 2 to the first disk 13. Between the disks 2 and 13, the drum is extended by a perforated metal sheet 30 which allows the flowing of the liquid used for conveying the solids to the apparatus.

Each one of the notches 4, 4' of the second disk 2 shown in FIG. 8 has on the disk circumference side, a widening 15, 15' to which is attached on the side of the first compartment formed between the second and the third disk 2, a partition 16 or 16' which together with, on the one hand, a second partition 17 or 17' attached on the side of the supply compartment 31 defined between the disk 13 and the second disk 2 and, on the other hand, three crosswise partitions 18, 19, 20 or 18', 19', 20' attached around the slots 4 and 4', forms a housing 21 or 21' communicating through openings 22, 22' in the drum 1, with a manifold 23 surrounding the drum 1. The manifold 23 is divided into two zones 24, 25 by a ring partition 26, each zone having a liquid discharge duct.

The last compartment, that is the one where the solids leave the apparatus, is only provided with two half-cells which are diametrally symmetrical. Guide partitions 27, 27' located in a plane at right angle to the axial plane 8 and which are inclined relative to the drum axis bound said half-cells in the central part of the drum 1 and guide the solids out of the apparatus.

The extracting liquid is supplied on that side where the solids leave the drum, in one or two compartments, by means of two pipes which pass through the drum or the slanting surfaces 5 and 5'. The intersections of the piping with the drum 1 shown in 28, 28' or with the slanting planes, shown in 29, 29' have only been shown in the penultimate compartment.

With reference to FIGS. 1, 2, 4 and 9, the path followed by both solid flows and by both liquid flows in the above apparatus, will now be described.

The conveying direction of the screw conveyors is shown by the arrow 33 and the drum rotation direction by the arrow 34. Both series of cells are respectively numbered I, II, . . . , VI, . . . , N and I', II', . . . , VI', . . . , N', each compartment comprising two cells is thus represented by the numbers I I', II II', . . . . , VI VI', . . . , N N'. The center lines -.-.- show the path of a fraction of the flow A of the solids, the dot-and-dash lines -..-..- the path of a fraction of the flow B of solids. The dash lines --- show the path of a fraction of the flow a of liquid, the dotted lines ..... the path of a fraction of the flow b of liquid; the dot-and-dash lines with three dots -...- show the fractions of liquid c which enter together with the solids in the apparatus and are taken along therewith up to the first compartment where they are discharged through the openings 22, 22'.

The solids are supplied continuously in admixture with the liquid used for the extraction, through the inlet 14, in the supply compartment 31 where they are separated when passing the lowest point of the sheets 5 and 5' into two equal fractions which supply the flows A and B. The fraction of flow A is taken along by a rotation of the drum over 180° inside a channel 32 and it is collected in the separating basket 12 of the cell I. During the following 180° rotation, the fraction of flow B is taken along inside a channel 32' and it is collected in the separating basket 12' of the cell I'. The same process occurs by each 360° rotation of the drum.

Most of the liquid brought with the solids inside the supply compartment 31 passes through the perforated partition 30 and ends up in the zone 24 of the manifold 23 while the remainder c of this liquid which is carried through a channel 32 or 32' with the solids in the first compartment of the drum, goes through the separating basket 12 or 12' and passes through the slot 4 or 4' into the housing 21 or 21' from which it is discharged through the opening 22 or 22' and therefrom it ends up in the zone 25 of the manifold 23.

There will now be described the path followed by the fraction of solid flow A introduced in cell I. From a position at the bottom of the basket 12 of cell I and during a drum rotation over 180° along the direction of arrow 34, the considered fraction of solid flow A is first raised by the separating basket 12, then it slides down a partition 8 towards the opposite part of the cell I where it comes downstream of a slanting sheet 9'.

During the succeeding 180° rotation, this fraction of solid flow A is carried inside a channel 32 and it passes into the cell II where it will be raised by a separating basket 12 and so on, from one 360° rotation to another up to the half cell N of the last compartment where the fraction of the solid flow A is raised for the last time and discharged on the guide partition 27 along which it slides to come out of the apparatus. It is thus noticed that the fractions of flow A only proceed through the cell series I, II, . . . , VI, . . . , N that comprises one half of the drum and they advance from one compartment to the next along the conveying direction of the screw conveyors to the rate of one compartment by each drum rotation over 360°. Due to the symmetry between both series of drum cells, it is clear that the fraction of solid flow B introduced inside cell I' will proceed in a similar way through all of the cells of the series I', II', . . . , VI', . . . , N' that comprises the other half of the drum.

In the embodiment described, the supply liquid is brought, continuously or not, inside the compartment N-I, N'-I' by means of two pipes that end in 28, 28' or 29, 29' and it is equally divided between both cells of this compartment to supply the liquid flows a and b.

The fraction of liquid flow b brought inside the cell N-I during a drum rotation over 180°, is led in the cell N through the channel 32. From the cell N, this liquid fraction flows through a liquid duct 10 in the cell N'-II. During the next 180° rotation, this same liquid fraction is carried inside a channel 32' and led in the cell N'-I, from which it flows through a liquid duct 10' in the cell N-III and so on, from one 180° rotation to the next. It is thus noticed that the fraction of flow b introduced in N-I passes by a rotation over 180°, in N and it ends up in N'-II with a displacement corresponding to one compartment along a direction opposite to the conveying direction of the solids and while passing from one cell series to the other. During the next 180° rotation, that same liquid fraction passes from the cell N'-II to the cell N'-I and therefrom in the cell N-III. By a rotation over 360°, the fraction of flow b has advanced over two compartments along a direction opposite to the solid conveying direction and the path of flow b thus passes through the following cells: N'-I, N', N-II, N-I, N'-III, N'-II, N-IV, N-III, . . . . Both flows thus pass through all of the cells without ever mixing however and they only go through the liquid/solid separating surfaces of every other cell. In the compartment II, II', the flows a and b will thus come out separately, one through the liquid duct 10 and the other through the liquid duct 10' to reach the housing 21 or 21' from which they will be discharged through the opening 22 or 22' in the zone 25 of the manifold 23.

To sum up, it is clear on the one hand that each fraction of each liquid flow passes alternately from the cells of one series to the cells of another series, while meeting thus alternately and in succession the fractions of the solid flows A and B with which the liquid fractions proceed through the channels 32 and 32' during the axial advance of the solids and, on the other hand, that the liquid flows advance during a 360° rotation of the drum, over two compartments along a direction opposite to the solid conveying direction and twice as fast as such solids.

The advantages of the above-described invention are numerous and they result mainly from the fact, as the axial advance of the solids occurs along the feeding direction of the screw conveyors, with a guiding in the lower peripheral part of the drum due to the slanting surfaces which are part of the conveyor turns and with the solids contacting during such displacement the liquid, that it is no more required as in the known apparatus, to provide slanting chutes in the central area of the drum for the axial feeding of the solids.

The removal of the slanting chutes allows an increase of the useful solid charge capacity of the compartments as a crumbling of said solids out of said slanting chutes is no more to be feared. Moreover, after raising, the solids crumble down in that part of the cell opposite to the one they originate from, which has substantially the same capacity as the partition which divides the compartment into two cells is located axially while in the known apparatus, the slanting chutes discharge the solids over a screen the plane of which lies to the initial screen at an angle of 180° less twice the angular displacement which is normally used for the balancing of the drum. A further increase of the solid capacity of the cells may still be reached by means of the inequality of the arcs of circle lying between the openings 4 and 3, 4' and 3' and the arcs lying between the openings 3' and 4, 3 and 4' of a disk 2, which allows to compensate the volume lost by the arrangement of the separating basket 12 or 12' inside a half-cell. With respect to the known apparatus, the drum capacity is further increased due to the movement made by the solids out of the liquid being a conveying without axial displacement from one cell end to the other by raising and crumbling down inside the same cell; the width of the passage section over the partitions being of course larger than inside the slanting chutes, and consequently the height of the passage section for the solids below the notches 3, 3' may be lower than the height of the slanting chutes, which allows a larger volume for the liquid-solid mixing in the lower position of the cell, such volume being limited by the overflow level over the slanting surfaces 5, 5'.

As the crumbling down of the solids occurs earlier than in the known apparatus, the torque may be reduced.

As the solids advance continuously by one compartment for each revolution without undergoing any backwards movement, the solids are discharged from the last compartment as opposed to the known apparatus where they are discharged from the penultimate compartment; the solid outlet may thus lie higher, the slanting guide partitions 27 and 27' being shorter than the slanting chutes in the known apparatus.

In the apparatus according to the invention, during the contacting phase between the solids and the liquid, the mixture is subjected to a substantial change of direction by the guiding by means of the slanting surfaces. Thereby, the extraction of the products which are part of the solids is made faster. The removal of the chutes allows to increase the area of the liquid-solid separating elements and to have by each revolution, a decrease of the liquid amount carried away by the solids and/or this allows to increase the drum rotating speed.

Another advantage of the removal of the slanting chutes is the easing of the limits regarding the ratio between the compartment width and the drum diameter. It is thus possible to consider giving different widths to the compartments in one and the same apparatus, that is it is possible to vary the pitch of the screw conveyor(s). It has indeed been noticed that the volume of the solid fractions becomes smaller in the course of the extraction, in such a way that it is advantageous to reduce the capacity of the last compartments.

In the apparatus according to the invention, the head compartment has the same diameter as the drum body which reduces the overall space occupied by the apparatus is smaller. The width of the supply compartment is also smaller than the head compartment width of the known apparatus, which results from the possibility of easily discharging the liquid from the drum before the supply compartment and thus of reducing the liquid-solid separating area of the supply compartment. Moreover, in the supply head, there no more occurs a raising of the solids as they are conveyed in the first compartment by the screw conveyor movement while it was impossible in the known apparatus to balance such raising of the solids in the head compartment by displacing the screens. Finally, this head compartment being less wide and already supported by the slanting surfaces 5, 5', it is possible to do away with the special armature which had to be provided for in the known apparatus.

There results from the above that the design of the apparatus is made substantially easier due to the removal of the slanting chutes, due to the supply compartment being integral with the drum remainder, due to the removal of the armature of said head compartment and due to the possible increase of the compartment width without varying the drum diameter.

The apparatus described may notably be used for extracting saccharose from sugar beets or canes, as well as for extracting any other product contained in solids, such as for instance the tannins from nut-galls.

In the modified embodiment shown in FIGS. 10 and 11, the collecting metal sheets 37, 37' are located at right angle to the disks and they end up at a small distance away from the drum, the solid curved sheets 35, 35' and the solid helix-shaped sheets 36, 36' forming together with the wall of the drum 1, liquid channels 38, 38' which connect the opposite cells of two compartments spaced by at least one compartment.

The apparatus shown in FIGS. 12 to 17 has for difference relative to the one shown in FIGS. 1 to 9 that the disks 50 are not flat but distorted and consequently they have two sectors of circle 51, 51' of about 90° which correspond to the sectors M, M' of the disk shown in FIG. 6, which sectors lie in the same plane which is at right angle to the drum lengthwise axis, while the two sectors L, L' are each formed by a portion of circle 52, 52', lying in the same plane at right angle to the drum axis but with an axial displacement along the solid feeding direction inside the drum with respect to the plane of sectors 51, 51', the portions of circle 52, 52' being joined to the sectors 51, 51' and to the edges of the notches 66, 66' and of the slots 67, 67' which correspond respectively to the notches 3, 3' and to the slots 4, 4' of the disks 2, by means of slanting metal sheets 53, 53', 54, 54' and of portions of axial partitions 65, 65'. The notches 66, 66' are formed by a cut-out 68, 68' similar to the one of the notches 3, 3' in the portion L, L' and by the corresponding free edge 69, 69' of the sector M, M'; consequently, the length of the disk arc they cover is reduced in each case by half to the advantage of the sector M, M'. Finally, as in the apparatus of FIGS. 1 to 9, the distorted disks are arranged inside the drum with a steady angular displacement.

The axial displacement between the sectors of circle 51, 51' and the portions of circle 52, 52' is preferably such that a portion of circle 52, 52' will be equidistant from the two adjacent sectors 51, 51 or 51', 51'.

As in the apparatus shown in FIGS. 1 to 9, the opposite edges 68, 69, 68', 69' of the notches of two adjacent distorted disks 50 are joined by slanting surfaces 5, 5' which form between them the channels 32, 32' through which two adjacent compartments communicate. It is clear that the drum also comprises two overlapping screw conveyors which are each formed by the succession of the following surfaces: 51', 65', 54', 53', 52', 5', 51, 65, 54, 53, 52, 5 . . . .

As in the embodiment shown in FIGS. 1 to 9, each compartment defined between two adjacent distorted disks 50 is divided into two cells by axial partitions 8, the portions 65, 65' of which are extensions and by the sheets 9, 9' and 11, 11'; these sheets form the liquid ducts 10, 10'. In front of the sheet 9, 9' of each cell and inside the part comprised of the sectors 51, 51' is arranged a perforated basket for raising the solids and for the separation thereof from the liquid.

The inlet of the drum is defined by a flat disk 13 with a central opening 14 for the supply of the solids. The disk 13 is connected by slanting surfaces 5, 5' to the free edges of the notches 66, 66' of the first distorted disk 50. Between the first distorted disk 50 and the disk 13, the drum is extended by a perforated sheet 30. A solid sector 60 or 60' attached to the slanting solid sheet 9 or 9', in front of the opening of the last liquid duct 10 or 10', on the supply side, forms together with part of a portion of circle 52 or 52', part of the solid sheets 53 and 54 or 53' and 54' and solid sheets 64 or 64', a channel 63, 63' which is used for discharging the liquid from the drum, said channel forming an opening 61 or 61' in the drum wall and ending in the zone 25 of the manifold 23. That drum wall located between the sectors 51 or 51' of the first and second distorted disks 50 is provided with openings 62, 62' which let the liquid from the supply compartment flow in the zone 24 of the manifold 23.

The last compartment of the drum has the same design as the one described for the embodiment according to FIGS. 1 to 9 and the extracting liquid is supplied to the apparatus in the same way as in this embodiment.

In the drum body and at the outlet for the solids, the path followed by the two solid flows and by the two liquid flows, as it is clear from the FIG. 17, is similar to the one described for the first example. However, due to the peculiar design of the disks 2, during the sliding of the solids over partition 8, in other words during the conveying thereof from the cell portion formed between the two sectors 51 -- 51 or 51' -- 51' of adjacent circles to the cell portion formed between the two adjacent portions of circles 52 -- 52 or 52' -- 52', said solids advance axially, along the direction of the general feeding thereof inside the drum, by a length which corresponds to the axial displacement length between the sectors of circle 52, 52' and the sectors of circle 51, 51'. By the advance of the solids together with the liquid from a cell N--I or N--I' to a cell N or N' of the next compartment, through a channel 32 or 32', the solids thus do only advance axially by a length corresponding to the width of one compartment less said axial displacement length. It is thus clear that as in the first embodiment, the solids advance during a complete revolution of the drum over a length equal to the width of one compartment but, as opposed to what occurs in the first embodiment, part of the axial feeding of the solids is made outside of the liquid.

Due to said axial displacement, the liquid carried along with the solids through a channel 32 or 32' from one compartment N-I or N'-I' to a compartment N or N', moves back axially with respect to the liquid feeding direction, by a length corresponding to the width of one cell less the axial displacement length and when passing through a duct 10 or 10' from one compartment N or N' to a compartment N'-II or N-II, the liquid advances axially over a length corresponding to the width of two compartments less the axial displacement length. On the whole, as in the first embodiment, the liquid thus advances over a length corresponding to the width of one compartment during a half revolution of the drum, that is by a length equal to the width of two compartments during a complete revolution of the drum.

In the supply compartment 31 and the first cell, the path followed by the solids remains the same, but the one followed by the liquid is slightly different. The main part of the liquid carried together with the solids in the supply compartment goes through the perforated partition 30 and ends up in the zone 24 of the manifold 23, while the remainder of the liquid which is carried along in a channel 32 or 32' reaches together with the solids the first cell I or I' of the drum, goes through the separating basket 12 or 12' and through the openings 62 or 62', it reaches the zone 24 of the manifold 23.

In the cell II or II', the flows a and b are discharged separately, the one through a liquid channel 10, the other through the liquid channel 10', to end up in the duct 63 or 63', from which they reach through the opening 61 or 61' the zone 25 of the manifold 23.

The design described with reference to FIGS. 12 to 17 is provided mainly for very large apparatus, with such a cell width that the design as shown in FIGS. 1 to 11 would cause a lack of balance between the length of the slanting surfaces 5 and the length of the arcs of circle of the disks 2 which define the cell zones in one of which the solid raising and filtering occurs (in which zone is located the basket 12) and in the other one the solids fall in a new liquid portion.

The design as shown in FIGS. 12 to 17 makes it possible relative to the embodiment according to FIGS. 1 to 9, to decrease for the same compartment width, the length of the slanting surfaces and to increase the basket area and consequently the filtering surface.

It must be understood that the invention is not limited to the embodiments described above and that many changes may be brought therein without departing from the scope of the invention as defined by the appended claims.

It is for instance possible to have an apparatus with but one screw conveyor or with three screw conveyors, with one or with three liquid flow sheet in each compartment, etc.