EP0046569B1 - Process and apparatus for mixing solids with liquids - Google Patents

Description

The invention relates to a method for mixing solids with liquids, in particular for gluing wood chips according to the preamble of claim 1 and a device for carrying out this method according to the preamble of claim 5.

Such methods and devices are known from DE-PS 2 057 594 and DE-AS 2 113 960 (corresponding to US-PS 3734471). These wood chip glue mixers have revolutionized chip glueing because in them, in an extremely small space, the glue was distributed exceptionally fine on the surface of the chips, resulting in a considerable saving in glue and also in installation costs compared to the previously usual, large-volume ones Thrust or spin and vortex mixers was achieved. The mechanism of action in these so-called ring mixers is such that the mixing material is accelerated by a mixing mechanism that is driven with a high degree of criticality in such a way that it moves in the form of a relatively thin mixing material ring in a helical manner on the inner wall of the mixing container. The glue is introduced directly into this mix ring, specifically in the embodiments according to the publications mentioned by the hollow mixer shaft and liquid feed tubes protruding radially therefrom and immersed in the mix ring or in another embodiment according to DE-PS 2134305 by liquid addition pipes which are stationary are attached in the container wall and are guided through this into the interior of the mixing container and end with their outlet openings in the mixture ring.

In spite of the considerable advantages that the described glueing mixers brought in terms of construction, apparatus and process engineering, they suffered from the disadvantage that the wood chips were damaged to a considerable extent by the extremely high acceleration forces, which led to an undesirable reduction in the quality of the clamping plates produced from the chips . This was especially true when using inferior woods. These mixers can be used in general for mixing solids with liquids.

The invention is therefore based on the object of providing a method of the generic type and a device of the generic type, the damage to the solids largely being avoided and better liquid distribution being achieved.

This object is achieved in a method of the generic type by the characterizing features of patent claim 1 and in a device of the generic type by the characterizing features of patent claim 6. The essence of the invention lies in the fact that the acceleration of the chips extends over a relatively long period of time in comparison with the known ring mixers, that is to say it takes place much more slowly. The acceleration forces, i.e. the forces leading to possible chip damage, significantly reduced. So there is a continuous, temporally stretched acceleration from a shear mixing movement through a centrifugal and vortex mixing movement to a ring mixing movement. The glue is partly added in the shear mixing movement of the chips and then in the centrifugal and whirl mixing movement of the chips, i.e. H. even during the addition of glue no mechanical forces due to imperfections or the like. to be applied to distribute the glue on the chips. On the other hand, after the glue has been added, the advantageous, high-intensity glue distribution takes place on the surface of the chips in a mix ring. The conically widening of the mixing container in the acceleration zone continuously creates the necessary increased volume in which the chips can be distributed from the comparatively dense packing during the push mixing movement into a loosened volume during the spinning and mixing movement. A sufficiently large radius of the mixing container is then again available in the mixing zone, which is necessary so that the tangential accelerations required for the formation of the mixing material ring are generated. The nature of the glue addition in the acceleration zone makes it possible again to use the glue addition known per se through pressure nozzles, which leads to the considerable advantage that the glue can be used with a lower water content than has been customary hitherto. So far, a ratio of glue dry mass to water of 1: 1 has been used. This reduction in the water content means that the water content of the wood chips can be correspondingly higher; The energy-intensive drying of the wood chips can therefore be ended a little earlier than is currently possible. Corresponding advantages apply in general when mixing free-flowing or free-flowing solids with liquids, for example concentrate feed on the one hand and molasses on the other hand.

The measures according to the invention enable a particularly good transition from the thrust movement to the centrifugal and whirling movement to the ring movement.

Due to the further embodiment according to claim 2, the wood chips are whirled extremely strongly by practically the entire cross section of the mixing container at this point due to the air serving as carrier gas for the glue in the area of the glue addition, so that here the glue is distributed very evenly on the chip surfaces . Surprisingly, it has been shown that the specific use of energy, i.e. the energy required to mix a predetermined weight of wood chips with a predetermined weight of glue is significantly reduced.

The measures according to claims 3 and 4 ensure that a large-area nebulization of the glue is achieved, the individual microscopic secondary droplets being applied at extremely high speeds from the outside to the swirling mixture and therefore also penetrating deeply into it, since it is still not as close as in the ring. Since there are to a greater extent coarse chips than fine chips or dust near the mixing container wall, these are glued to an increased extent, which is desirable.

Claims 5 to 13 reflect the constructive possibilities for realizing the method measures according to Claims 1 to 4 in a particularly advantageous manner.

• Fig. 1, einen Mischer gemäss der Erfindung im vertikalen Längsschnitt,
• Fig. 2, einen abgewandelten Mischer gemäss der Erfindung im vertikalen Teil-Längsschnitt,
• Fig. 3, einen Querschnitt durch die Mischer nach den Fig. 1 und 2 gemäss der Schnittlinie 111-111 in den Fig. 1 und 2,
• Fig. 4, einen Querschnitt entsprechend Fig. 2 durch einen abgewandelten Mischer,
• Fig. 5, einen weiteren Mischer gemäss der Erfindung im vertikalen Längsschnitt,
• Fig. 6, einen Querschnitt durch den Mischer gemäss der Schnittlinie VI-VI in Fig. 5 und
• Fig. 7, einen Querschnitt durch eine Leimzugabeeinrichtung des Mischers gemäss der Schnittlinie VII-VII in Fig. 5.

Numerous further advantages and features of the invention emerge from the subclaims and the following description of two exemplary embodiments of the invention with reference to the drawing. It shows:

• 1, a mixer according to the invention in vertical longitudinal section,
• 2, a modified mixer according to the invention in vertical partial longitudinal section,
• 3 shows a cross section through the mixer according to FIGS. 1 and 2 along the section line 111-111 in FIGS. 1 and 2,
• 4, a cross section corresponding to FIG. 2 through a modified mixer,
• 5, another mixer according to the invention in vertical longitudinal section,
• Fig. 6, a cross section through the mixer along the section line VI-VI in Fig. 5 and
• 7, a cross section through a glue addition device of the mixer according to section line VII-VII in FIG. 5.

Since the mixers shown in the drawing differ only in the area on the right in the drawing, the mixer shown in FIG. 1 is shown closed in its area corresponding to FIG. 1. The mixers each have a mixing container 1, which consists of an inner trough 2 forming the inner wall thereof and a cooling jacket 3 surrounding the inner trough and forming the outer wall. The mixing container 1 is closed at its ends by end walls 4. At one end of the mixing container 1, which is on the right in FIGS. 1 and 2, a mixed material feed funnel 6 is provided which opens tangentially from above into the interior 7 of the mixing container 1 enclosed by the inner trough 2 and the end walls 4 and 5. At the other end - on the left in FIGS. 1 and 2 - there is also a tangentially discharging mix outlet funnel 8. The mixing container 1 is divided in half in the horizontal plane, the upper half 9 and the lower half 10 of the mixing container 1 being held together on one long side by hinge joints 11 and on the opposite long side by toggle locks 12 so that they can be swung open and apart.

In the mixing container 1, a mixer shaft 13 is arranged coaxially, which is mounted in bearings 14, 15 and can be driven by an electric motor, not shown, via a V-belt pulley 16 which is non-rotatably mounted on the mixer shaft 13. Balancing disks 17, 18 are also mounted on the mixer shaft 13 outside the mixing container 1, but in the vicinity of the end walls 4, 5. On the mixer shaft 13 threaded bushings 19 are attached, in which hollow mixing tools 20 are screwed. In the mixer shaft 13, a cooling water supply pipe 21 is arranged, with a cooling water pipe 22 branching off into each hollow mixing tool 20, so that the cooling water through the cooling water supply pipe 21 and the branching cooling water pipes 22, through the interior of each mixing tool 20 in between the cooling water supply pipe 21 and the mixer shaft 13 located annular space 23 flows. The cooling water passes through a cooling water connection 24, which is provided on the right in FIGS. 1 and 2, into the mixer shaft 13, the cooling water inflow in direction a into the cooling water supply pipe 21 and the cooling water outflow in direction b from the annular space 23. The bearings 14, 15 are supported on pedestals 25, 26.

The area of the mixing container 1 over which the mixed material feed funnel 6 extends in the longitudinal direction of the mixing container 1 is cylindrical and forms a feed zone A for the mixed material, usually therefore wood chips. In this feed zone A, so-called feed tools are mounted on the mixer shaft 13, which in the embodiment according to FIG. 1 are feed tools 27 designed in the manner of blades and in the embodiment according to FIG. 2 a feed tool 28 designed like a screw. The feed tools 27 or 28 serve to convey material falling into this cylindrical section 29 of the mixing container 1 through the feed hopper 6 in a primarily axially directed pushing movement into the next, conical section of the mixing container. This section 30, which widens conically in the direction of flow 31 of the mixing container 1, that is to say in the shape of a truncated cone, forms an acceleration zone B for the mixture. This conical section 30 is followed by a likewise cylindrical section 32 of the mixing container 1, which forms a mixing zone C which extends as far as the mixture outlet hopper 8 and an ejection zone D which extends over the axial length of the outlet nozzle 8. The conical section 30 widens from the radius r ₂₉ to the radius r32 of the cylindrical section 32. The ratio of the radii r ₂₉ to r ₃₂ is 0.6 to 0.8, preferably about 0.75. The opening angle α of the conical section 30 is approximately 8 to 15 °, preferably approximately 10 °. The axial length ratio of acceleration zone B to mixing zone C is approximately 1: 2. Corresponding to the conical shape of the inner wall of the mixing container 1 in the conical section 30, the mixing tools are designed with a considerably smaller radial extent than in the cylindrical section 32. For this reason, the mixing tools present in this acceleration zone B are provided with the reference number 20 ', the radial length of these mixing tools 20' from the beginning of the acceleration zone B, that is to say from the end of the feed zone A, to the end of the acceleration zone B, that is until the beginning of the mixing zone C, increases steadily, as can be seen from the drawing.

In the acceleration zone B certain liquid addition pipes 33 (FIG. 1) or 34 (FIG. 2) open, in particular for the addition of glue to wood chips. In the embodiment according to FIG. 1, the liquid addition tubes 33 end approximately flush with the inner wall of the conical section 30 of the mixing container 1 formed by the inner trough 2. The liquid can be supplied to them without pressure, as is common practice, for example in DE-OS 2 738,971 (U.S. Patent 4,183,676). The liquid can also be fed to them under pressure. In this case, atomization nozzles 35 are attached to the inner ends of the liquid addition tubes 33, as is known, for example, from DE-PS 1 213 385 (corresponding to US Pat. No. 3 163 403). As can be seen from Fig. 1, the liquid addition pipes 33 are arranged substantially in the front portion of the acceleration zone B as viewed from the input zone A.

In the embodiment according to FIG. 2, the liquid addition tubes 34 protrude to different degrees into the interior 7 of the mixing container 1, the first liquid addition tube 34 ′, seen again from the feed zone A in the direction of passage 31, extending radially farthest from the inner wall into the interior while the In the direction of flow 31 subsequent liquid addition pipes 34 ", 34" 'and 34 "" each extend less deeply from the wall into the interior 7, so that the last liquid addition pipe 34 "" is again approximately flush with the inner wall. The liquid supply can take place in the same way without pressure or under pressure, the liquid emerging in any case at the radially inner end of the respective liquid addition tube 34. In both exemplary embodiments, the liquid addition pipes 33 and 34 lie in the vertical axis plane of the mixing container 1.

In the embodiment according to FIG. 2, the liquid outlet openings 36 are thus arranged on a line which forms an angle β with the longitudinal axis 37 of the mixing container 1, which angle is in any case significantly larger than a. ß is about 20 to 25 °.

A throttle valve 38 is arranged on the mixing material discharge funnel 8 in a conventional manner, which is articulated on its upper, axially parallel edge by means of swivel joints 39 on the mixing container 1 and by the pressure of the mixing material from the closed position shown in FIG 40 can be pivoted so that the mixture outlet opening is opened more or less, so that in turn the mixing tools 20 moving in the direction of rotation 41 throw the mixture through the outlet outlet opening that is then more or less open into the outlet nozzle 8. A motor-adjustable counterweight 42 is attached to the outside of the throttle valve 38, as is known in detail from patent application P 2 923 502 (US Ser. No. 154 098). This motor-adjustable counterweight serves to superimpose the existing possibility that the throttle valve opens in accordance with the pressure of the material to be mixed in the mixing container 1, the further possibility of changing the closing pressure present in each open position of the throttle valve 38 by adjusting the counterweight 42.

• Das durch den Mischgutzulauftrichter 6 eingegebene Mischgut wird von den Einzugswerkzeugen 27 oder 28 axial, also in Durchlaufrichtung 31 bei relativ geringer tangentialer Beschleunigung in die Beschleunigungszone B geschoben, die es aufgrund dieses vorgegebenen axialen Schubs weiterhin axial durchläuft. Gleichzeitig wird das Mischgut durch die Mischwerkzeuge 20' zunehmend tangential beschleunigt, so dass aus der reinen Schubmischbewegung eine Schleudermischbewegung entsteht, bei der also das Mischgut, in der Regel also die Holzspäne, über den vollen Querschnitt des Mischbehälters in diesem Bereich geschleudert und gewirbelt werden. In diese Schleuder- und Wirbelbewegung des Mischgutes wird die Flüssigkeit, in der Regel also Leim, eingegeben, und zwar entweder eingesprüht oder drucklos zugegeben. Bei der Zugabe nach Fig. 2 wird mit dem ersten tief in den Mischbehälter hineinragenden Flüssigkeitszugaberohr 34' der Leim noch in die am Übergang von der Schubmischung zur Schleuder- und Wirbelmischung befindlichen Späne eingegeben, während er zunehmend von den nachfolgenden Flüssigkeitszugaberohren 34", 34"', 34"" in die immer stärker aufgewirbelten Späne eingegeben wird. Die Leimzugabe erfolgt also in einem Bereich, in dem die Holzspäne über einen grösseren Zeitraum stetig, also nicht zu abrupt und daher schonend, aus einer langsamen Schubbewegung in eine Schleuder- und Wirbelbewegung überführt werden. Nach der Leimzugabe erfolgt eine weitere Beschleunigung der Späne, so dass sich in der Mischzone C wieder in üblicher Weise ein sogenannter Mischgutring 43 an der Innenwand des Mischbehälters 1 bildet, in dem eine intensive Durchmischung der Holzspäne und des Leims erfolgt.

The mixing of the material to be mixed with liquid, in particular the mixing of wood chips and glue, takes place as follows:

• The mixed material entered by the mixed material feed hopper 6 is pushed axially by the pull-in tools 27 or 28, that is to say in the direction of passage 31 with relatively little tangential acceleration into the acceleration zone B, which it continues to pass axially due to this predetermined axial thrust. At the same time, the mixing material is increasingly accelerated tangentially by the mixing tools 20 ', so that the pure shear mixing movement results in a centrifugal mixing movement, in which the mixture, usually the wood chips, is spun and whirled over the full cross section of the mixing container in this area. The liquid, usually glue, is introduced into this centrifugal and whirling movement of the mix, either sprayed or added without pressure. 2, with the first liquid addition tube 34 'projecting deeply into the mixing container, the glue is still introduced into the chips located at the transition from the pusher mixture to the centrifugal and whirling mixture, while it is increasingly being removed from the subsequent liquid addition tubes 34 ", 34"', 34 "" is entered into the swirling chips. The glue is added in an area in which the wood shavings are transferred over a longer period of time, i.e. not too abruptly and therefore gently, from a slow pushing movement into a centrifugal and whirling movement. After the glue has been added, the chips accelerate further, so that in the mixing zone C a so-called mixture ring 43 is again formed in the usual way on the inner wall of the mixing container 1, in which the wood chips and the glue are thoroughly mixed.

The mixer shaft 13 is driven at high speed, so that there is a far supercritical speed, at least in the mixing zone C. The critical speed is defined in that when it reaches the radially outer ends of the mixing tools 20, an acceleration corresponding to the acceleration due to gravity acts. The mixing ends so that corresponding acceleration forces can be exerted Tools 20 and 20 'in the vicinity of the inner wall of the mixing container 1. This applies in particular to the mixing tools 20 arranged in the mixing zone C, since here the mixing material ring 43 is relatively thin and the mixing tools 20 must protrude into this mixing material ring 43 in order to be able to operate again To exert acceleration forces on the wood chips forming the mix ring 43.

When the liquid, that is to say in particular the glue, is added through the liquid addition pipes, pressurized gas can of course be used as an additional atomization aid.

In the acceleration zone B, there are in particular liquid addition nozzles 44 intended for the addition of glue to wood chips, which are flush with the inside of the inner trough 2 of the mixing container 1, ie do not protrude into the interior 7 of the mixing container 1. How out

4 shows, these liquid addition nozzles 44 open predominantly tangentially into the interior 7. These nozzles are so-called two-component nozzles, through which liquid glue, which is supplied through a glue supply line 45, and compressed air, which is supplied through a compressed air line 46, are sprayed into the interior 7 in a finely divided manner.

The centrifugal and whirling movement of the chips is significantly supported by the air sprayed in through the liquid addition nozzles 44, which not only serves as a carrier for the glue, that is to say for the glue division, but also substantially loosens the chips.

The compressed air is supplied to the liquid addition nozzles 44 at a pressure in the range from 2 to 6 bar, preferably at a pressure from 2.5 to 4 bar.

With an average specific weight of the wood chips of 100 kg / m ³ , compressed air is supplied to the liquid addition nozzles 44 in a ratio of 2 to 5 standard m ³ / m ³ chips, preferably 2.5 to 3.5 standard m ³ air per m ³ Chips.

Since the mixer shown in FIGS. 5 to 7 is identical in its basic structure to that of FIG. 2, a renewed description can be dispensed with; Comparable parts are identified by the same reference numerals with a "'".

In this exemplary embodiment, the conical section 30 'widens from the radius r ₂₉ to the radius r _{32 of} the cylindrical section 32'. The ratio of the radii r ₂₉ to r ₃₂ is 0.55 to 0.7, preferably about 0.6 to 0.65. The opening angle a 'of the conical section 30 is approximately 12 to 20 °, preferably approximately 18 °. The axial length ratio of acceleration zone B to mixing zone C is approximately 1: 2. Corresponding to the conical shape of the inner wall of the mixing container 1 'in the conical section 30', the mixing tools are also designed there with a considerably smaller radial extension than in the cylindrical section 32 '. For this reason, the mixing tools present in this acceleration zone B 'are provided with the reference number 20 ", the radial length of these mixing tools 20" being from the beginning of the acceleration zone B', that is to say from the end of the feed zone A ', to the end of the acceleration zone B'. , ie up to the beginning of the mixing zone C ', increases approximately continuously, as can be seen from FIG. 5.

In the discharge zone D ', the mixing tools are designed in a blade-like manner to produce tangential movements of the material to be mixed and are therefore designated by the reference number 20 "'.

In the acceleration zone B ', in the exemplary embodiment shown at the transition from the conical section 30' to the cylindrical section 32 ', a glue addition device 47 is provided which works according to the centrifugal principle. It has two centrifugal disks which are connected to one another in a rotationally fixed manner, namely an inner centrifugal plate 48 and an outer centrifugal plate 49, which between them delimit a gap 51 which is largely radial to the central longitudinal axis 50 of the glue addition device 47. The outer, that is, the centrifugal plate 49 facing the inner wall of the mixing container 1 merges into a tubular section 52 in which a likewise tubular centering section 53 is fixedly arranged by means of some radial webs 54. The inner centrifugal disc 48 has a centering collar 55, by means of which it is held radially and axially in the tubular centering section 53. The width c of the largely annular disk-shaped gap 51 can be changed by a corresponding length of the tubular centering section 53 - or by inserting washers at the separation point between the centering collar 55 and the centering section 53.

A conventional electric motor 56 is used to drive the centrifugal disc 48, 49, which is screwed to a short support frame 57, which in turn is screwed onto a pipe socket 58 which penetrates the inner trough 2 'and the cooling jacket 3' of the mixing container 1 ', the latter of which The inside diameter is somewhat larger than the outside diameter of the tubular section 52. This support frame 57 consists of a few webs 59 extending parallel to the axis 50 and ring flanges 60, 61, which are respectively attached at the ends and which are connected to a corresponding flange 62 of the pipe socket 58 or the connecting flange 63 of the electric motor 56 are detachably screwed by means of screws 64.

The centrifugal plates 48, 49 are screwed non-rotatably to the shaft journal 66 of the motor 56 by means of a threaded screw passing through the centering collar 55 coaxially to the axis 50, a filler piece 67 being provided, which is axially supported on the one hand against the shaft journal 66, and this in turn in the centering section 53 engages, which is supported axially via a collar 68 against the filler 67, so that when the threaded screw 65 is tightened, the inner centrifugal plate 48 with its centering section 53 of the outer centrifugal plate 49 and thus the latter are firmly clamped to the shaft journal 66. So that the centrifugal plate is axially fixed while defining the width c of the gap 51 and non-rotatably connected to the shaft journal 66.

On the webs 59, in the vicinity of the ring flange 61 facing the electric motor 56, an annular disk 69 is fastened, to which a cylindrical ring channel 70, which is closed toward it, is screwed, which into the glue space 71 between the tubular section 52 and the centering section 53 flows openly. A threaded connection piece 72 opens into the side of the annular channel 70, to which a glue supply line (not shown) can be connected.

As can be seen from FIG. 7, the gap 51 does not run exactly radially, but in the form of a truncated cone with a very large opening angle or very small base angle β of approximately 5 to 10 °, which corresponds to an opening angle of 170 to 160 °. The angle β can, for example, be selected such that it is equal to a '/ 2 if the glue addition device 47 is arranged at the transition from the conical section 30' to the cylindrical section 32 '. In this case, based on the longitudinal section of the mixer shown in FIG. 5, the glue addition device 47 is arranged such that its longitudinal axis 50 is inclined at an angle of a / 2.

The glue is added to zone B 'in such a way that glue is metered into a ring channel 70 from a pump, not shown, via a glue supply line, also not shown, from where it runs down into the glue space 71, as indicated by flow arrows 73 . In particular on the upper side of the inner centrifugal disc 48, the glue is accelerated radially strongly and expelled through the gap 51 and leaves the latter in the form of a mist at a very high tangential speed. The rotational speed of the centrifugal plate is usually 2800 rpm, which corresponds to a circumferential speed of the centrifugal plate at the outlet of the gap 51 of slightly more than 20 m / sec with a diameter of the centrifugal plate 48, 49 of 140 mm. The glue is therefore distributed extremely finely and introduced into the material, in particular the chips, from the outside at a very high speed. In particular in the conical section 30 ', part of the glue is deposited on the inner wall of the inner trough 2'. Since the interior wall has a relatively low temperature due to the good cooling of the mixer, condensate water condenses here, which leads to a thinning of the deposited glue, so that it can be particularly easily absorbed by passing wood chips. Since there are coarse chips rather than fine chips or dust in the wall area, these coarse chips are glued relatively more strongly, which is desirable.

At the beginning of the mixing zone C ', a mixture ring 74 is formed on the inner wall of the mixing container 1', in which the wood chips and the glue are thoroughly mixed.

As can be seen from FIG. 7, the mixing tools 20 ″ or 20 ′ run past the inner centrifugal plate 48 in the area of the glue addition device 47. If the mixing material ring 74 was also formed in this area of the mixing container 1 in its initial stage, it would Swipe past the inside of the inner centrifugal plate 48. Due to the fact that the outer centrifugal plate 49 is also driven at high speed, no chips can get into the space, which is only a few millimeters wide, between the inner wall of the inner trough 2 'and the centrifugal plate 49. If such a If the ring is already partially formed, the glue mist is applied to this mixture ring from the outside.

The glue addition device 47 can be supplied with the glue without pressure, which enables particularly precise metering in a known manner.

7 that the centrifuge plates 48, 49 are tapered in their outer circumference towards the exit of the gap, so that the centrifugal plates 48, 49 as a whole do not have a cylindrical ring edge on which mixed material, that is to say chips, could be stowed. The chips can therefore run smoothly past the inside of the inner spin plate 48.

As can be seen from FIG. 7, at least one web-like fan blade 75 can be arranged on the outer centrifugal plate 49, which improves the cleaning effect of the rotating centrifugal plate 49 towards the inner wall of the inner trough 2 '.

Claims (13)

1. Method of mixing pourable solid materials with liquids, particularly for glueing wood chips or the like, the solid materials being moved intensively during the addition of liquid and the liquid and solid materials being subsequently mixed thoroughly in a ring of mixed material, characterised in that the solid materials are continuously accelerated out of a translatory motion via a spinning and whirling motion, the solid materials being pulled conically apart from one another during acceleration, and the addition of liquid taking place during this acceleration, and that acceleration to the velocity of the ring of mixed material takes place only subsequent to the addition of the liquid.

2. Method according to Claim 1, characterised in that the liquid is sprayed under pressure into the solid materials with air acting as the carrier medium.

3. Method according to Claim 1, characterised in that the liquid is fed to the solid materials from outside in the form of a mist sprayed in an approximately discoid shape.

4. Method according to Claim 3, characterised in that the liquid is accelerated in an approximately ring-shaped gap which rotates at high speed.

5. Apparatus for carrying out the method according to Claim 1, comprising a mixing vessel in which there is a coaxially arranged mixing shaft which is equipped with mixing implements and which can be driven at high speed and one end of which is provided with a mixed product feeding hopper in the region of a feed-in zone for the solid materials and the other end of which is provided with a mixed product discharge hopper, and which is provided with a liquid adding device in an area subordinate to the feed-in zone, and which, in another subordinate area, has a mixing zone in which the moistened solid materials are mixed in the form of a ring of mixed material, characterised in that between the feed-in zone (A, A') and the mixing zone (C, C') there is arranged an accelerating zone (B, B') which is formed by a section (30, 30') of the mixing vessel (1, 1') tapering outwards in the throughfeed direction (31, 31') and in which the radial length of the mixing implements (20', 20", 20′′′) increases continuously.

6. Apparatus according to Claim 5, characterised in that the ratio of the radius (r_z9, r_9q,) of the cylindrical section (29, 29') forming the feed-in zone (A, A') of the mixing vessel (1, 1') to the radius (r32, r 32) of the cylindrical section (32, 32') forming the mixing zone (C, C') of the mixing vessel is 0.55 to 0.8.

7. Apparatus according to Claim 5, characterised in that the conical section (30, 30') of the mixing vessel (1, 1') has an opening angle (a,a') of 8 to 20°.

8. Apparatus according to Claim 5, characterised in that the liquid adding devices (44) are in the form of dual material jets.

9. Apparatus according to Claim 5, characterised in that the liquid adding device (47) has an approximately ring-shaped gap (51) which is defined by two rotatable spinner discs (48, 49) and which is open on its outer circumference, the outer spinner disc (49) being arranged at an immediate distance from the inner wall of the mixing vessel (1').

10. Apparatus according to Claim 9, characterised in that the distance (c) between the spinner discs (48, 49) is variable.

11. Apparatus according to Claim 9, characterised in that an electric motor (56) is flange- mounted on to the outside of the mixing vessel (1), the spinner discs (48, 49) being connected directly to the shaft extension (66) of this electric motor.

12. Apparatus according to Claim 9, characterised in that a fixed annular channel (70) leading to the liquid supply runs into a liquid chamber (71) which is formed on the spinner discs (48, 49) and which leads into the gap (51).

13. Apparatus according to Claim 9, characterised in that the outer spinner disc (49) has at least one farnblade (75) extending as far as the vicinity of the wall.

Images