US3811815A - Apparatus for manufacturing of bodies of bulking clay - Google Patents

Abstract

An apparatus for manufacturing of bodies of swelling clay or equivalent material which comprises a burner adapted for heating of gases and a heaped body to be heated by the gases. A passage chamber is arranged for guiding of the gases and for receiving the heaped body. A rollable, molding box is provided which has massive side walls and a sieve-like perforated bottom wall, as well as a massive, perforated cover, selectively usable in the passage chamber or applicable outside of the passage chamber, and the heaped body is received in the rollable molding box and comprises granules of clay.

Description

United States Patent Sundermann et a1.

11] I 3,811,815 1451 May 21, 1974 [5 APPARATUS FOR MANUFACTURING 0F BODIES 0F BULKING CLAY 75] Inventors: Erich Sundermann; Johanna Viedt,

both of Broitzem, Germany [73] Assignee: Waldemar Dolle, Braunschweig,

Germany; by said Sundermann [22] Filed: May 5, 1971 [21] Appl. No.: 140,479

Related US. Application Data [62] Division of S61. No; 20,916, March 19, 1970, Pat.

[30] Foreign Application Priority Data Mar. 21. 1969 Germany... 1914372 Sept. 10,1969 Germany..................... 1945810 Sept. 10, 1969 Germany 1945811 [52] US. Cl 425/446, 425/383, 425/453 I [51] Int. Cl B29b 3/00 [58] Field of Search 264/42, 43, 44, 53;

[56] 7 References Cited UNITED STATES PATENTS 6/1973 Wunning 425/446 FOREIGN PATENTS OR APPLICATIONS 280,567 2/1929 Great Britain 2.64/42 Primary Examiner-Robert D. Baldwin Assistant Examiner-John McQuade .1571 ABSTRACT clay.

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APPARATUS FORMANUFACTURING OF-BODIES OF BULKING CLAY This is a divisional application of the co-pending application Ser. No. 20, 916, filedMar. 19, 1970, now US. Pat. No. 3,745,201.

The present invention relates toan apparatus for the production of. bodies of swelling clays or the like, in

which substantiallyball-shaped granules, formed of light structure elements. In this case the formed, under circumstances pre-dried granules are swelled in rotarytube furnaces and baked and thereafterused asadding material. for concrete or forothers, also as organic binders.

It hasbeenattempted for some time, to drain the granulesswelled in the rotary-tube fumace, and thereafter, in their hot state to cause the formation of ceramic binders by means of a pressure treatment. The

pressure destroys, however, the .swelled structure which is mechanically sensitive in itshot. state. There is alsono assurance for the formation of ceramic binders sincethe granules cool off after the drain from the rotary-tube furnace quickly and are mostly already too cool at the start of the pressure treatment, in order to It isone objectof the present invention: to provide an apparatus for manufacturing of bodies of swelling clay or equivalent material, whichmakes possible the production of ceramically-bound bodies of swellingclay.

The present invention exploits the following; essential recognitions: r

The heaped body of granules ispermeable to gases and can be heated therefore by flowing gases, whereby by means of a control of the temperature in the flow speed nearly anyquantities fofheat can be transmitted within a short time onto the granules. The granules have a low heat conductivity, however, comparably, a'

great specific heat, so that at first large heat quantities are stored in the outer scale of the granules and high temperatures are produced, before the heat can propagate into the inside of the ball-bodies of the granules. The outer surfaces are thus capable ofbinding plastically, when the size growth caused by the swelling process sets in. It is essential that this size growth alone is sufficient to bring intounison'the granule surfaces capable of plastica'lly-binding and to deform the granules in the sense'of a filling of thegap spaces; The granules grow thereby, however, without any pressure from th outside into the free-gap spaces. lndustrially exploitable clayscontain different iro oxides, and in particular mostly Fe O and FeO. Fe O; influences clays in such manner that the .pyroplastic state and the state of being capable of plasticallybinding occurs only within the range of higher temperatures, and in particular about 1,1 and l,l35C., re-

spectively, FeO has the opposite effect and appears to be like a flux.

The present invention exploits this by means of a further development of the new process, which is characterized by the feature, that the granules at first are preswelled up to a predetermined volume enlargement disposed below the usable total swelling capacity and is heated then in a further working process after formation of the heaped body and is swelled together, whereby the granules are heated up at the end of the preliminary swelling procedure and heated up with oxidizing gas during swellingtogether at least timely partly controlled with. gases which are poor in oxygen or which are reducing, and in particular to a temperature within the range ofabout 900 to l,l00C., preferably of 1,000C. As heating gases are used preferably normal air and for a reducing performance air without oxygen.

The importance of this development of the new method resides in the fact that the swelling process can be influenced in the sense of an exact following of a desired specific-weight of the body to be produced, by determining the space weight of the granules after the preliminary swelling and the energy feed during swelling together is adjusted to the required later volume enlargement during the joint swelling. Beyond that, a predetermined space weight can be maintained, thereby, in spite of the changing swelling ability of the clay, by

. performing during the swelling together, if necessary,

a more or less strong volume enlargement of the granules.

The preliminary swellingby heating can be undesirable or can lead to disadvantages, due to the energy expenditure required therefor, .as well as due to certain temperature behavior of some clays. For this reason, a

further development of the present method resides in the fact that propellants are added to the clay capable of swelling during the treatment and the granules formed of this clay are pre-swelled after their formation from the present propellants in the manner of a foaming process and thereafter heated for the solidification of the foamstructure and in particular to about 950C. to about l,lC. for example 1,050C., and that the granules thus pre-swelled are at first pre-heated and thereafterin the heaped body treated for a short time period up to the melting of the outer-faces with preferably reducing heating gases of increased temperature.

with these gases, whereby the heaped body is received in a rather rollable foam box with massive side walls and 'sieve-like perforated bottom, as well as a selectively usable in the passage chamber, perforated cover or a massive cover usable outside the passage chamber.

With these and other objects in view, which will become apparent in the following detailed description, the present invention, which is disclosed by example only, will be clearly understood in connection with the accompanying drawings, in which:

FIGS. la, b and c disclose the three essential embodiments of the method used in the apparatus of the present invention in a block scheme;

FIGS. 2a, b and c depict volume-temperature diagrams of different clays during swelling and binding;

FIG. 3 is a schematic temperature diagram of a heaped body after multiple blowing through with hot ases; g FIG. 4 is a part-sectional view of the non-yieldingly supported heaped body consisting of granules, prior to the heat treatment;

FIG. 5 is a part-sectional view, similar to that of FIG. 4, of the heaped body after the heat treatment;

FIGS. 6a and b are schematic elevations of the structure of an apparatus for the performance of the method of the present invention;

FIGS. 7a, b and c are schematic elevations of further embodiments of the apparatus indicating details of the after treatment of the swelled and bound bodies;

FIG. 8 is a schematic elevation of still another embodiment of the apparatus designed in accordance with the present invention, indicating the details of the devices, which are required prior to the swelling together of the granules; and

FIG. 9 discloses a sectional view of a possible embodiment of a passage chamber for the heat treatment of the heaped bodies.

Referring now to the drawings, for the production of ceramically-bound bodies of swelling clay, in accordance with FIG. la, suitable starting material, for example, clay capable of swelling, loams, common clay, brick clay, clay slate and slate clay, is prepared and worked to granules l, which are of about ball-shaped. After drying and sifting, the granules l of unitary size are dosed in a molding box 2 as a heaped body 3 and introduced for a heat treatment into a passage chamber 4. Since large gap spaces 5 are present between the granules l, the heaped body 3 is permeable to gases and can be heated by blowing through of highly heated gases.

The blowing through has the advantage, that also thick heaped bodies 3 can be heated quickly and relatively equally up to into the core. Furthermore, during the blowing through large quantities of heat at a temperature range of 900 to l,lC., preferably 1,000C. depending upon the used material, can be transmitted within a short time, if the work is performed with correspondingly high flow speeds and temperatures. Heating procedures, which would extend normally over time periods of the order of one or a plurality of hours, can be shortened by blowing through to the time period of a few minutes and a few seconds, respectively.

During the blowing, the volume of the granules 1 can be increased depending upon the swelling capacity of the clay to a multiple of the starting volume. The nonswelled granules 1 do not fill out therefore the molding box 2, since the latter has the measurements of the body to be produced. For this reason, the granules l are at first pre-swelled, until they fill out without loss of the ballshaped, the molding box (FIG. 4). They are maintained thereby in movement, in order to avoid the blocking, through which the gap spaces can be clogged up between the granules l. Clogged up and closed gap spaces 5, respectively, would render impossible a further blowing through.

During the following swelling together, the granules l are heated to about a temperature of l,l35C. such,

that the faces thereof, become capable of plasticallybinding. The simultaneously progressive volume enlargement of the granules 1 cannot cause a volume enlargement of the heaped body 3, because the molding box 2 is filled up and its walls do not yield. Accordingly, the granules l are deformed. They swell into the gap spaces 5 and fill up the latter depending upon the heat fed thereto, or upon the swelling capacity completely or partly. Simultaneously, the surfaces of the granules l grow towards each other. Since they are capable of plastically-binding, they melt. An integral body 6 (FIG. 5) is created, which is rolled out from the passage chamber 4 and is subjected to after treatment.

For the after treatment, a predetermined time period without extreme cooling is provided, which is instituted prior to, or after the deformation, in order to make possible later swelling procedures, etc., and to balance out or the like, temperature caused expansions.

A cooling as well as an after treatment of proper type follows this equalization or the deformation, by which cooling and after treatment, for example, a surface of the body 6 can be mechanically roughened.

The above-described method assumes, that the used clay at about the same temperature range is capable of binding in which also the desired volume increase has taken place (see diagram FIG. 2c). This is in the practice an exceptional case. The clays suitable for industrial application or the desired space weight of the body 6 cause situations, which are shown in the diagrams in FIGS. 2a and 2b. The diagram in FIG. 2a shows the case in which the particular clay becomes capable of binding only at a temperature, at which the swelling has progressed up to the double of the desired volume. The diagram in FIG. 2b shows the opposite case, the clay becomes capable of binding, before the desired volume enlargement takes place.

An essential point of view of the present invention resides in the fact that the blowing through of the heaped body 3 takes place in accordance with requirements controlled with oxygen-poor or even reducing gases or with oxidizing gases. By this arrangement also in the situations disclosed in FIGS. 2a and 2b the desired bodies can be produced.

The more or less large content of iron oxides, present in all industrially usable clays is a presumption therefor. These iron oxides are present normally as Fe O as well as FeO. Fe O displaces the range in which a clay becomes capable of plastically binding in the direction towards higher temperatures. FeO operates, however, as an addition in the sense of a lowering of this temperature range. The quantity ratio, in whichboth iron oxides stand relative to each other, influences the pyroceramic behavior of a clay.

If granules 1 are heated with oxidizing gases, then Fe O surpasses, while with reducing gases FeO dominates, and the similarly as an addition operating Fe O can be found. If in the practice the desired volume enlargement is obtained, the state of capability of binding occurs, however, only at higher temperatures (FIG. 2a), then it is merely necessary to heat with reducing gases, in order to reach the stage, which is shown in FIG. 20. In the example shown in FIG. 2b, the capability of binding has to be at first prevented up to the point of reaching the desired volume enlargement by heating with oxidizing gas.

In the practice, a pre-swelling takes place with an oxidizing gas at least for some time periods. During swelling together by an oxidizing gas at first can be taken, that the gap spaces 5 are maintained long enough, in order to transmit sufficient energy. Only at the end of the blowing together, at least for a short time period, heating takes place with reducing gas, whereby the granules 1 immediately melt.

By the pre-swelling with relatively stable oxidizing gas, pre-swelled granules l are created mechanically, which can be sifted and transported, without causing any damage to the swelling structure. For this reason, the pre-swelling in accordance with FIG. lb can be performed timely, as well as spaciously separate; The heaped body 3 isformed only then, when-the granules 1 are pre-swelled, whereby the dosing takes place in dependency from the space weight of the pre-swelled granules and in dependency of the desired space weight of the body 6. The after treatment body 6 takes place in the samemanner as in the method according to FIG.

If by the application of reducing or oxidizing heating gases alone, in accordance ith the requirements, the state in accordance with FIG. 2c cannot be set, then the granules can be surrounded with, suitable layers. In the situation shown in FIG. 2a, the layer must consist of a clay or the like, which is capable of binding at correspondingly lower temperatures. 1

The swelling of clay, etc. rests mostly on organic particles in the clay', which particlesdeliver during the heating gaseous combustion products or also disintegration products. Clays which cannot swell naturally or only to an insufficient extent, can be made capable of swelling by suitable additions as for example diesel oil.

The method in accordance with FIG. 1c is characterized by thefact, that additions are provided during the preparation. Suitable additions are calcium carbide, calcium hydride, sulphate of aluminum, as well as hydrogen peroxide-solution which produce jointly with water gases, by which the clay foams after formation of the granules without heat treatment. The point-dotted line in FIG. indicates, thatthe addition takes place i in dosages, whereby the results of space weight measurements are usedas reference values.

The mechanically sensitive foam structure of the granules l pre-swelled by additions is solidified, by drying and burning the granules. The solidified granules 1 are subjected to dosaging either prior to or after the pre-heating within a time period of to 'minutes, which takes place under circumstances in the rotarytube furnace, after a space weight measuring to the heaped body 3. The pre-heating takes place, without producing an extensive inner pressure of the additions contained in the pores of the foam structure, which could tear up the pore walls and could destroy the foam structure. An oxidizing gas feed supports this procedure. Upon termination of the preheating, heating takes place within the shortest possible time suddenly, under circumstances with reducing gases, up to the setting of the state of the capacity of plastically-binding. Thereby, simultaneously a thermally caused swelling of the granules 1 occurs which makes possible the swelling together to the body 6.

FIG. 3 shows a heaped body 3 with indicated temperature profiles 7a 7h. At the start of the blowing through of highly heated gases, a unitary temperature 7a prevails at all points of the heaped body 3. After a first blowing through which occurs observing FIG. 3

from the bottom to the top, the temperature profile 7b is obtained. The temperature profile 7c results, if then the blowing occurs from the top to the bottom. By continuous change of direction of the heating gases, the temperature profiles 7b, 7c 7g flattened out slowly always more, until they approach the profile 7h. This procedure occurs with very thick heaped bodies 3 or then, when between the temperature curve and the curve 711, a comparatively large temperature distance is present. If this is not the case, also exclusively from one side can be blown through.

The method of the present invention can be performed continuously or stepwise. Thus, in accordance with FIG. 6a, molding boxes 2 can be continuously filled from a dosing device. For this purpose, either dried, preferably, however, pre-swelled granules I are used. Before the molding boxes 2 with the heaped bodies reach the passage chamber 4, a planning device 9 takes care, that-the heaped body 3 has a plain smooth surface.

The molding boxes have massive side walls 10 (FIGS. 4 and 5), however, a gas permeable, for example, a grate-like bottom 11. The molding box 2 can be closed in upper direction either with a permeable, grate-like cover 12a, or amassive cover 12b. The cover 12a is required, if the covering is performed prior to rolling in to the passage chamber 4 or in the latter. In case of short tact time periods, the heat inertia of the granules is exploited and the cover 12b is applied after emerging from the passage chamber 4 (FIG. 6b).

FIGS. 6a and 6b show only a singlepassage chamber 4. Practically, however, a plurality of passage chambers 4 is used, which depending upon the requirements, for

example, is disposed parallel relative to each other and for the reception of very large molding boxes 2 can be combined or can perform exclusively special functions, as the pre-heating, the blowing together, etc. For the pre-heating, solidification or thermal pre-swelling, rotary-tube furnaces 13 can be used instead of the passage chambers 4 (FIG. 8).

FIGS. 7a to 70 show examples for the after treatment of the bodies 6 after the deformation. From a feeding device 14, it is possible to apply a layer 15, for example, a glazing layer and the layer-can be burned either by the heat of the body 6, which heat is still present, or under the effect of burners 16. For the cooling serves a cooling tunnel 17 (FIG. 7a).

The body 6 can be smoothed between rollers 18 or also equipped with a design (FIG. 7c). The smoothing or designing of the surfaces of the bodies 6 can also be performed by presses 19. By this arrangement, the bodies 6 can obtain particular front faces on one side.

FIG. 8 shows a scheme of the apparatus for the method of the present invention. The previously mentioned rotary-tube furnace 13 serves either for the solidification or for the thermal pre-swelling of the granules l. The filling of the molding boxes 2 with preswelled granules 1 takes place by means of the dosage device already indicated in connection with FIG. 6a, which dosage device, however, has coordinated thereto a measuring device 20 for the determination of the space weight.

FIG. 8 shows a molding box 2 with movable bottom 11. By such arrangement, bodies 6 can be produced with unitary molding boxes, which bodies 6 have different thicknesses or a different space weight.

In accordance with FIG. 8, clay 21 is fed into a preparation device 22 and with the provision of additions prepared by means of a dosing device 23. An extruder 24 works the prepared clay into granules l, which foam under the influence of the additions, that means they are pre-swelled and are fed to the rotary-tube furnace 13 for solidification. 1f the material is thermally preswelled, the dosing device 23 can be omitted. Instead of an extruder 24 other granulating devices are used which release the granules produced therein, either directly, or after passage of a drying device in the rotarytube furnaces.

Referring now again to the drawings, and in particular to FIG. 9, another embodiment of the present invention is disclosed in a sectional view, as stated before, in which a passage chamber 4 receives the mold 2 and the latter is arranged such in the passage chamber that a uniform treatment of the content of the mold by the heating gases by means of a symmetric structure of the mold 2 relative to the passage chamber 4 is assured. For the proper feeding of the heating gases through the mold 2 a flow circuit defining feeding channels 28 and 28, respectively, which feeding channels have incorporated therein blowers 27 which by means of controlled dampers 26 which cause alternately the flow of the heated gases from one group of channels into the other group of channels in order to reverse the flow from one direction into the opposite direction.

Deviating from this presentation, burners can also be structurally connected directly with passage chambers or can also be built in. Devices can be used thereby in order to drive the heating gases pulse-like or explosionlike through the heaped body 3. During the blowing through, by gas feeding and by the structure of the passage chamber and of the burner, respectively, care must be taken than an equalized heating takes place.

In order to prevent, that the highly heated clay adheres to the walls of the molding boxes 2, suitable layers can be used of the molding box surfaces. By cooling of the molding box walls, such that they remain closely below the critical temperature, the adherence can also be prevented.

While we have disclosed several embodiments of the present invention, it is to be understood that these embodiments are given by example only and not in a limiting sense.

We claim:

1. An apparatus for manufacturing of bodies of swelling clay material, comprising a rollable, molding box having massive side walls and a sieve-like perforated bottom wall, as well as a massive, perforated cover, the perforations being distributed grate-like throughout in said bottom wall and said cover, in order to permit a flow of heated fases through said molding box,

a passage chamber surrounding and receiving said molding box for guiding said heated gases through said molding box containing a heaped body of swelling clay granules,

feeding channels disposed at opposite ends of and connected'with said passage chamber for flow of said heating gases through said molding box alternately in opposite directions,

said passage chamber being symmetrically disposed in relation to said molding box and to the flow of said heating gases, in order to uniformly heat said heaped body during flow of said heating gases in opposite directions, and

blower means and controlled dampers determining the direction of the flow of said heated gases.

2. The apparatus, as set forth in claim 1, wherein said molding box has inner metallic faces and a separating mass is applied to said metallic faces engaging all said bodies of swelling clay forming granules, in order to prevent an adherence of said granules on said metallic faces.

3. The apparatus, as set forth in claim 1, which includes a dosing device for filling said molding box with preswelled granules, and

a measuring device in operative connection with and for controlling said dosing device, said measuring device determining the space weight of said preswelled granules.

Claims (3)

1. An apparatus for manufacturing of bodies of swelling clay material, comprising a rollable, molding box having massive side walls and a sievelike perforated bottom wall, as well as a massive, perforated cover, the perforations being distributed grate-like throughout in said bottom wall and said cover, in order to permit a flow of heated fases through said molding box, a passage chamber surrounding and receiving said molding box for guiding said heated gases through said molding box containing a heaped body of swelling clay granules, feeding channels disposed at opposite ends of and connected with said passage chamber for flow of said heating gases through said molding box alternately in opposite directions, said passage chamber being symmetrically disposed in relation to said molding box and to the flow of said heating gases, in order to uniformly heat said heaped body during flow of said heating gases in opposite directions, and blower means and controlled dampers determining the direction of the flow of said heated gases.

2. The apparatus, as set forth in claim 1, wherein said molding box has inner metallic faces and a separating mass is applied to said metallic faces engaging all said bodies of swelling clay forming granules, in order to prevent an adherence of said granules on said metallic faces.

3. The apparatus, as set forth in claim 1, which includes a dosing device for filling said molding box with pre-swelled granules, and a measuring device in operative connection with and for controlling said dosing device, said measuring device determining the space weight of said pre-swelled granules.

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