CA2628638A1

CA2628638A1 - Cassette chamber and shaped brick in a refractory furnace

Info

Publication number: CA2628638A1
Application number: CA002628638A
Authority: CA
Inventors: Wolfgang Tabbert; Klaus Kassau; Kai Beimdiek
Original assignee: Refratechnik Holding Gmbh; Wolfgang Tabbert; Klaus Kassau; Kai Beimdiek
Current assignee: Refratechnik Holding GmbH
Priority date: 2005-10-06
Filing date: 2005-10-06
Publication date: 2007-04-19
Also published as: CN101283230A; DE112005003697A5; CN101283230B; WO2007042056A1

Abstract

The invention relates to a cassette chamber (1) of a refractory furnace, in particular, for firing anode blocks using a cover grit with an essentially rectangular plan each with two vertical opposing chamber longitudinal walls (3, 4) and chamber transverse walls (5, 6) and at least one vertical cassette wall (7) running perpendicular to the chamber transverse walls (5, 6) or chamber longitudinal walls (3, 4) fixed to said chamber walls (3, 4, 5, 6) made up of individual essentially square mineral fire-resistant shaped bricks (11, 11), wherein gas channels (9) are moulded in the shaped bricks (11, 11a) running upwards in the cassette wall (7), said shaped bricks (11, 11a) being made from refractory concrete.

Description

Cassette chamber and shaped brick in a refractory furnace The invention relates to a cassette chamber in a refractory furnace, in particular an annular cassette refractory furnace, preferably for the baking of amorphous carbon bodies, in particular of anodes consisting of high-purity carbon, which serve for the electrolytic reduction of aluminum or for other electrometallurgical processes. The invention relates, moreover, to a shaped brick for refractory furnace walls and to a method for its production.

The generation of pure aluminum from aluminum oxide (A1203) usually takes place by means of what is known as electrolytic smelting. This method is based on decomposing A1203, dissolved in a molten cryolite bath, by means of an electrical current which is supplied to the bath by means of an immersed electrode consisting of high-purity carbon (anode). In this case, the pure aluminum obtained is deposited on walls of a crucible which consists of baked carbon and constitutes the cathode, and the oxygen obtained travels to the anode and is burnt with it. For this reason, the anodes have to be renewed at regular intervals, usually when they are approximately 3026 worn, and therefore there is a constant demand for anodes.

In the production of these anodes, first, a viscous mixture of broken or ground coke or hard coal and of a suitable binder, for example, coaltar pitch, is pressed into what are known as "green" anode blocks, and these [ v-are subsequently baked at a temperature of approximately 1200 C, so that the anode blocks acquire the properties required for aluminum production, such as, for example, electrical conductivity and oxidation resistance.

The baking of the anode blocks usually takes place in special refractory furnaces, preferably in annular cassette refractory furnaces, in the gas-heated chambers of which the "green" anode blocks are introduced in stacks and are embedded in what is known as covering grit or carbon grit, this ensuring that the baking operation takes place without oxygen. The carbon grit used for this purpose, which is usually produced from the residual stocks of incompletely worn anodes, consist essentially of graphite and alkali fluorides and has, for example, a grain size of < 3 mm.

An annular cassette refractory furnace of this type for the baking of anodes is known, for example, from DE 200 21 089 U1 and is described below by way of example with reference to figures 35 and 36. This annular cassette refractory furnace 200 has a multiplicity of cuboidal cassette chambers 201 which are arranged both next to one another and one behind the other in two rows, adjacent cassette chambers 201 being flow-connected to one another via a continuous gas ring line 202, so that the combustion or smoke gases are routed from one cassette chamber 201 to the next (fig. 36). The individual cassette chambers 201 have in each case two vertical, opposite and mutually parallel chamber longitudinal walls 203 and two likewise vertical, opposite and mutually parallel chamber transverse walls 204, the chamber longitudinal walls 203 and chamber transverse walls 204 being arranged perpendicularly to one another and forming a continuous belt wall or chamber wall 205 in which a plurality of vertically extending smoke gas passages 212 are provided. Moreover, each cassette chamber 201 is subdivided into parallelepipedal cassettes 207 by means of likewise vertically oriented cassette walls 206 extending perpendicularly to the chamber longitudinal walls 203 from one chamber longitudinal wall 203 to the opposite one. Each of the cassette walls 206 in this case likewise has a plurality of vertically extending smoke gas passages 212. The cassettes 207 serve for receiving the baking stock 218 embedded in the carbon grit bed 217.

Both the cassette walls 206 and the chamber wall 205 in this case usually consist of relatively small-format individual wall bricks produced in a complicated way and consisting of hydraulically pressed, ceramically bound and essentially gastight fireclay bricks which are bricked in by hand and grouted with fireclay mortar. The fixing of the fireclay bricks with respect to one another takes place via groove/tongue connections known per se. These fireclay bricks normally have an AL203 content of approximately 40% and a length of 200 to 500 mm, a width of 200 to 300 mm and a height of 130 to 180 mm.

Moreover, each cassette chamber 201 is closed by means of a chamber cover 208 in such a way as to form an upper cavity or compensation space 211 between the chamber cover 208 and upper cassette wall surfaces 210 of the cassette walls 206 and the baking stock 218 located in the cassettes 207. A further, lower cavity or compensation space 213 is formed in a chamber region or chamber bottom region 214 of the cassette chambers 201 or of the cassettes 207.

During operation, that is to say during the baking of the anodes, the smoke gases are routed in the line flow direction 215 from one cassette chamber 201 to the adjacent cassette chamber 201 in each case. For this .

purpose, first, fuel is burnt in separate vertical heating or combustion shafts 216 which are provided in that chamber longitudinal wall 203 of each cassette chamber 201 which lies on the entry side with respect to the line flow direction 215, usually in each case one heating shaft 216 being present per cassette 207.
The smoke gas thus generated rises upward in the respective heating shaft 216 and collects in the upper compensation space 211 where pressure and temperature compensation takes place. The smoke gas is routed from there, through the smoke gas passages 212 present in the cassette walls 206 and the chamber wall 205 and, if appropriate, through the carbon grit bed 217 downward into the lower compensation space 213, where pressure and temperature compensation again takes place. The gas flows out of the lower compensation space 213 into the next heating shaft 216 of the cassette chamber 201 which is adjacent in the line flow direction 215, fuel being supplied in countercurrent. The smoke gases thus follow an essentially sinusoidal or meander-shaped profile from cassette chamber 201 to cassette chamber 201.

During operation, a reducing and, because of the carbon grit, an alkali fluoride-containing baking atmosphere is present in the individual cassettes 207, whereas an oxidizing atmosphere prevails in the heating shaft 216.
Usually, when an annular cassette refractory furnace 200 of this type is in operation, always one or two of the cassette chambers 201 are in this case used as combustion chambers, while the cassette chambers 201 arranged upstream of them in the line flow direction 215 are operated as heating chambers, and the cassette chambers 201 lying downstream are operated as cooling chambers, out of which the baked product is extracted and into which new baking stock 218 is subsequently introduced. In this case, a normal baking cycle, .

including the pre-heating and cooling of the anodes, lasts approximately 14 days.

Owing to the constant change in the operating state of the cassette chambers 201, the chamber wall 205 and, above all, the cassette walls 206 are exposed to high thermal loads and fluctuations, and therefore the chamber wall 205 and the cassette walls 206 must possess good thermomechanical properties, such as high refractoriness under load, low softening under load, a low flow behavior under load, a low expansion/contraction behavior and good spalling resistance.

Problems are, in particular, thermally induced, ever alternating expansions and contractions in the cassette walls 206 and the chamber wall 205. The expansions result, inter alia, in undesirable barreling or bulging of the cassette walls 206, since these are connected essentially fixedly to the chamber wall 205 on the end face and cannot shift. Moreover, owing to the constantly changing tensile and compressive load, the joints between the individual fireclay bricks are broken open and destroyed, so that, in time, individual fireclay bricks break out from the cassette walls 206.
This effect is also intensified in that the fireclay bricks are highly susceptible to thermochemical attack by the alkali fluorides contained in the covering grit.
The alkali fluorides penetrate into the pores of the fireclay bricks and contribute to undesirable mineral phase transformations which lead, on the one hand, to an increased expansion behavior of the material and, on the other hand, to premature softening under load.
Moreover, the very fine carbon grit, because of its low grain size, gradually penetrates into the destroyed joints and prevents and blocks the .

expansion/contraction movement of the cassette walls 206 to an even greater extent. This leads to an even higher instability of the cassette walls 206 and, in the end, to the destruction of the cassette walls 206 which then have to be repaired or exchanged completely, which is highly complicated, time-consuming and cost-intensive, inter alia because bricking-in has to be carried out by hand.

In order to counteract this, it is known to mount the cassette walls 206 in grooves of the chamber longitudinal walls 203 and to provide expansion joints which extend vertically in the chamber wall 205 and in the butting region between the cassette walls 206 and the chamber wall 205 and which are filled with Styropor and/or ceramic elastically deformable fiber materials.
In this case, the Styropor serves merely as a spacer during the mounting of the cassette walls 206 and for providing a defined width of the expansion joint, since the Styropor burns away immediately when the annular cassette refractory furnace 200 is in operation. Both the expansion joint provided by the Styropor used and the ceramic elastic fiber material, which is compressed reversibly in the event of the expansion of the cassette walls 206, thus make it possible to have a defined length change of the cassette walls 206 without deformation.

The problem in this case, however, is that the ceramic fiber materials possess only a limited period of use.
This is because, inter alia, for mounting and ensuring freedom of movement of the cassette walls 206, the width of the grooves is generally somewhat greater than the width of the cassette walls 206, so that in each case a gap is present between the cassette outer walls and groove side walls. The very fine carbon grit also gradually penetrates through or into these gaps and into the ceramic fiber material, so that the movement of the cassette walls 206 is blocked again, thus leading once more to the problems described above.
Problems in such annular cassette refractory furnaces known per se are therefore, on the one hand, the thermally induced damage to the refractory furnace walls, such as the barreling of the cassette walls and the breaking open of the joints between the fireclay bricks, this being further intensified due to the susceptibility of the fireclay bricks to thermochemical attack by the alkali fluorides contained in the carbon grit.

Moreover, the production of the refractory furnace walls by the manual bricking-in of the many individual fireclay bricks is highly time-consuming and cost-intensive, and also the repair of the damaged refractory furnace walls is possible only in a highly complicated way.
The CO resistance of the fireclay bricks is also insuf f icient .

The object of the present invention is to provide a cassette chamber for a refractory furnace, in particular an annular cassette refractory furnace or the like, in particular for the baking of amorphous carbon bodies, in which the thermally and chemically induced damage to the refractory furnace walls, such as, for example, barreling and crack formation, is minimized, while the refractory furnace walls can be produced and repaired simply and cost-effectively.
Moreover, the object of the invention is to provide a shaped brick for such refractory furnace walls, which can be produced more simply, has good thermochemical and thermomechanical properties and experiences less thermally and chemically induced damage.

Furthermore, a simple and cost-effective method for production of such a shaped brick for refractory furnace walls is to be specified.
These objects are achieved, with regard to the cassette chamber, by means of the features of claim 1, with regard to the shaped brick by means of the features of claim 59 and, with regard to the method, by means of the features of claim 60. Advantageous developments are characterized in the accompanying subclaims.

The invention is explained in more detail below by way of example with reference to the drawing in which:
fig. 1 shows a diagrammatic perspective view from above of a cassette chamber according to the invention, fig. 2 shows a side view of a shaped brick according to the invention with a longitudinal sectional cutout along a brick longitudinal mid-plane, fig. 3 shows a top view of a shaped brick according to the invention, fig. 4 shows a longitudinal section of the shaped brick according to fig. 3 along the line A-A, fig. 5 shows a side view of a shaped brick according to the invention in a further embodiment, with a longitudinal sectional cutout along the brick longitudinal mid-plane, fig. 6 shows a longitudinal section of the shaped brick according to fig. 5 along the line B-B, fig. 7 shows a view of a detail of the cutout marked in fig. 6 by C, fig. 8 shows a cross-sectional view of a cassette chamber according to the invention in a first embodiment with regard to the connection of cassette walls and chamber wall along a horizontal plane coplanar with a top side of an upper shaped brick, fig. 9 shows a longitudinal section of the cassette chamber according to fig. 8 along the line D-D, fig. 10 shows a view of a detail of the cutout marked in fig. 8 by E, f ig . 11 shows a top view of a connecting shaped brick used in the first embodiment with regard to the connection of cassette walls and chamber wall, fig. 12 shows a view of a detail, corresponding to the view in the form of a detail illustrated in fig. 10, according to a second embodiment of the cassette chamber with regard to the connection of cassette walls and chamber wall, fig. 13 shows a top view of a connecting shaped brick used in the second embodiment with regard to the connection of cassette walls and chamber wall, fig. 14 shows a perspective view from above of the connecting shaped brick according to fig. 13, arranged in a connecting groove of a chamber longitudinal wall illustrated in the form of a cutout, fig. 15 shows a view of a detail, corresponding to the view in the form of a detail illustrated in fig. 10, according to a third embodiment of the cassette chamber with regard to the connection of cassette walls and chamber wall, fig. 16 shows a top view of a connecting shaped brick used in the third embodiment with regard to the connection of cassette walls and chamber wall, fig. 17 shows a perspective view from above of the connecting shaped brick according to fig. 16, arranged in a connecting groove of a chamber longitudinal wall illustrated in the form of a cutout, fig. 18 shows a top view of a connecting shaped brick used in a fourth embodiment with regard to the connection of cassette walls and chamber wall, fig. 19 shows a perspective view from above of the connecting shaped brick according to fig. 18, arranged in a connecting groove of a chamber longitudinal wall illustrated in the form of a cutout, fig. 20 shows an end view of a connecting shaped brick used in a fifth embodiment of the cassette chamber with regard to the connection of cassette walls and chamber wall, fig. 21 shows a side view of the connecting shaped brick according to fig. 20, fig. 22 shows a perspective view from above of two connecting shaped bricks according to fig. 18 arranged one above the other, arranged in a connecting groove of a chamber longitudinal wall illustrated in the form of a cutout, fig. 23 shows a longitudinal section, corresponding to the longitudinal section according to fig. 9, of a cassette chamber according to a sixth embodiment of the cassette chamber with regard to the connection of cassette walls and chamber wall, fig. 24 shows a view in the form of a detail of the cutout marked in fig. 23 by F, fig. 25 shows a perspective view from above of two connecting shaped bricks, arranged one above the other, according to the sixth embodiment of the cassette chamber with regard to the connection of cassette walls and chamber wall, arranged in a connecting groove of a chamber longitudinal wall illustrated in the form of a cutout, fig. 26 shows a side view of a connecting shaped brick according to fig. 25, fig. 27 shows a side view of the connecting shaped brick according to fig. 26, fig. 28 shows a perspective view from above of two connecting shaped bricks arranged one above the other, in each case with a slip-off wedge, according to a seventh embodiment of the cassette chamber with regard to the connection of cassette walls and chamber wall, arranged in a connecting groove of a chamber longitudinal wall illustrated in the form of a cutout, fig. 29 shows a longitudinal section along the brick longitudinal mid-plane of a connecting shaped brick with a slip-off wedge according to fig. 28, arranged in the connecting groove of the chamber longitudinal wall illustrated in the form of a cutout, fig. 30 shows a top view of the connecting shaped brick according to fig. 29, arranged in the connecting groove of the chamber longitudinal wall illustrated in the form of a cutout, with a modified slip-off wedge, fig. 31 shows a perspective view from above of the slip-off wedge according to fig. 30, fig. 32 shows a perspective view from above of a connecting shaped brick according to an eighth embodiment of the cassette chamber with regard to the connection of cassette walls and chamber wall, arranged in a connecting groove of a chamber longitudinal wall illustrated in the form of a cutout, fig. 33 shows a side view of the connecting shaped brick according to fig. 32 with a longitudinal sectional cutout along the brick longitudinal mid-plane, fig. 34 shows a top view of the connecting shaped brick according to fig. 33, fig. 35 shows a diagrammatic perspective view from above of a refractory furnace according to the prior art, fig. 36 shows a section along a vertical plane, parallel to cassette walls, through four cassette chambers of the refractory furnace according to fig. 35.
A refractory furnace has at least one, preferably 10 to 20 cuboidal cassette chambers 1 or cassette chambers 1 of rectangular base area, which are flow-connected to one another (fig. 1, 8, 9, 23). Each of the cassette chambers 1 consists of a continuous belt wall or chamber wall 2 which is formed by two chamber longitudinal walls 3, 4 oriented vertically and parallel to one another and arranged so as to be spaced apart from one another in the horizontal direction and by two chamber transverse walls 5, 6 likewise oriented vertically and parallel to one another and spaced apart from one another in the horizontal direction, but arranged perpendicularly to the chamber longitudinal walls 3, 4.
Moreover, the cassette chamber 1 has at least one, preferably 4 to 8 cassette walls 7 which are oriented parallel to the chamber transverse walls 5, 6 and which extend from one chamber longitudinal wall 3, 4 to the opposite chamber longitudinal wall 3, 4 and subdivide the cassette chamber 1 into a plurality of cuboidal cassette spaces 8.

Alternatively to this, the cassette walls 7 are oriented parallel to the chamber longitudinal walls 3, 4 and extend from one chamber transverse wall 5, 6 to the opposite chamber transverse wall 5, 6 (not illustrated).

A plurality of vertically extending heating shafts 101 of rectangular cross section are formed in the chamber longitudinal wall 3, usually one heating shaft 101 being present per cassette space 8.

According to the invention, the cassette walls 7 in this case consist of individual large-format inner shaped bricks 11 and of the connecting shaped bricks lla which, arranged so as to be offset one above the other and lined up in a row next to one another, in each case form a cassette wall 7 (fig. 1-34). These shaped bricks 11, lla in each case have two planar and mutually parallel wide sides 12, 13, an underside 14, a top side 15 and two opposite end faces 16, 17.

Furthermore, vertically extending continuous smoke gas ducts 9 of essentially rectangular cross section are introduced into the shaped bricks 11, lla. In this case, the shaped bricks 11, lla of the assembled cassette chamber 1 are arranged in such a way that the smoke gas ducts 9 lie vertically in alignment with one another. Preferably, the smoke gas ducts 9 are in this case symmetrical with respect to a brick longitudinal mid-plane 10.

The length of the shaped bricks 11, lla according to the invention, that is to say the distance between the opposite end faces 16, 17, is in this case preferably 600 to 2000 mm, preferably 1000 to 1900 mm, and the width, that is to say the distance between the opposite wide sides 12, 13, is preferably 190 to 350 mm, preferably 200 to 300 mm, the height, that is to say the distance of the underside 14 from the top side 15, preferably being 500 to 1000 mm, preferably 600 to 800 mm. Consequently, the shaped bricks 11, lla according to the invention are markedly larger than the building bricks conventionally used and therefore, inter alia, much simpler to handle.
According to the invention, the shaped bricks 11, lia consist of a refractory concrete which consists essentially of a refractory granulated product as aggregate, in particular A1203 granulates, such as, for example, mullite-rich materials and/or fireclay and/or andalusite, of a refractory flour-like product as additive, such as, for example, aluminum oxide and/or clay and/or mullite-containing components and/or non-oxidic materials, of mineral binders, such as, for example, aluminum oxide cements and/or microsilica and/or reactive aluminum oxides, and also of additions, such as, for example, liquefiers and/or binding regulators and/or organic and/or inorganic fibers.

The use of a refractory concrete of type ULCC (Ultra Low Cement Castables), with a CaO content of 0.2 to 1.0% by weight, has proved to be particularly advantageous within the scope of the invention.

By such a refractory concrete of type ULCC being used for the shaped bricks according to the invention, in particular, a synergistic effect is achieved. On the one hand, the shaped brick 11, lla according to the invention has a low softening under load and low flow under load which are characteristic of ultra low cement refractory concrete. On the other hand, because of the low water requirement of the refractory concrete during production, the shaped bricks have very low open porosity, so that the shaped bricks 11, lla possess low gas permeability and are thereby resistant to the absorption and attack of the alkali fluorides contained in the carbon grit.
In order to achieve the Co resistance required for use in the refractory furnace, moreover, the refractory concrete has only an Fez03 content < 2% by weight, preferably < 1% by weight.
In particular, preferably, a refractory concrete with the following thermomechanical, thermochemical and physical properties is used as a material for the shaped bricks 11, lla according to the invention:

Physical In particular properties Open porosity 12-20 13-17 [%]
after 400 C
combustion Reversible 0.4 - 1.0 0.5 - 0.7 [%]
expansion up to 1000 C after 1300 C combustion Irreversible -0.5 - +0.2 -0.2 - +0.2 [~]
expansion after 1200 C combustion Strength after > 50 > 90 [MPa]
1300 C combustion Thermomechanical properties Softening under > 1400 > 1500 [ C]
load T05 after 1300 C combustion Refractoriness > 1500 > 1600 [ C]
under load ta after 1300 C
combustion Flow under load < 0.01 < 0.005 [o/h]
at 1280 C between 14 and 24 h Spalling > 50 > 100 []
resistance Thermochemical properties Alkali/fluorine Alkali- and fluorine- []
resistance resistant according to CO resistance A-B - []
according to ASTM C 288, 500 C, 200 h The production of the shaped bricks 11, lla in this case takes place preferably by the customary concrete technology, that is to say, for example, by the introduction or casting of a previously produced fresh refractory concrete into a mold, preferably subsequent shaking or vibration, hardening of the fresh refractory concrete and removal of the hardened shaped bricks 11, lla from the mold. By means of this production method, in principle, any desired three-dimensional shape of the shaped bricks 11, lla can be produced, and there can be a simple, rapid and flexible reaction to changed requirements with regard to the three-dimensional shape. Moreover, this production is highly cost-effective, since the casting molds or formwork required can be produced likewise cost-effectively from wood or plastic.

In the installed state, the shaped bricks 11, lla arranged one above the other are fixed with respect to one another by means of groove/tongue connections, a fixing groove 18 being provided in the top side 15 and a fixing tongue 19 matching this being provided in the underside 14. Both the fixing groove 18 and the fixing tongue 19 are in this case arranged preferably symmetrically with respect to the brick longitudinal mid-plane 10 and are therefore interrupted by the smoke gas passages 9. In this case, fixing groove side faces 20 or fixing tongue side faces 21 are expediently not perpendicular to a fixing groove bottom 22 or fixing tongue bottom 23, but, instead, form an obtuse angle with the respective bottom 22; 23, so that the fixing groove 18 and the fixing tongue 19 have a trapezoidal cross section.

The shaped bricks 11, lla arranged next to one another are likewise connected to one another by means of groove/tongue connections, in each case a connecting groove 24 being provided on one end face 16 and a matching connecting tongue 25 being provided on the opposite end face 17 in each case. Here, again, connecting groove side faces 26 or connecting tongue side faces 27 are expediently not perpendicular to a connecting groove bottom 28 or connecting tongue bottom 29, so that the connecting groove 24 and the connecting tongue 25 also have a trapezoidal cross section.
According to a further embodiment illustrated by way of example in fig. 6, 7, 20, 21, 26, 27 and 33, the shaped brick 11, ila has no centrally arranged fixing tongue 19 described above, but, instead, two semi-cylindrical adaptor tongues 30 running in each case next to the smoke gas ducts 9 and parallel to the brick longitudinal mid-plane 10. These adaptor tongues 30 correspond in their shape and dimensions to tongues conventionally used, so that these shaped bricks 11, lla can be used as adaptor bricks, for example in the lower row in a known refractory furnace.
As already explained above, the smoke gas ducts 9 provided in the cassette wall 7 and consequently in the shaped bricks 11, lla have an essentially rectangular cross section symmetrical with respect to the brick longitudinal mid-plane 10 and having rounded duct edges 31. In particular, the smoke gas ducts 9 have a cross-sectional length L in the direction of the brick longitudinal mid-plane 10 of 80 to 250 mm, preferably of 100 to 200 mm, and a cross-sectional width B
perpendicularly to the brick longitudinal mid-plane 10 of 80 to 250 mm, preferably of 100 to 200 mm.

In a cassette wall 7, the shaped bricks 11, lla are in this case dimensioned and arranged in such a way that vertical wall joints 33 of a horizontal shaped brick row 34, which are present between the individual shaped bricks 11, lla, are arranged so as to be offset with respect to the wall joints 33 of a shaped brick row 34 arranged above or below it. A good strength and stability of the cassette wall 7 are thereby achieved, without the shaped bricks 11, lla being bricked in with one another, thus affording, during assembly, an enormous benefit in terms of cost and time, as compared with the bricks conventionally used which are bricked in by hand.

In order to prevent the barrelings occurring in the prior art, according to the invention the cassette walls 7 consisting of a plurality of shaped bricks 11, lla are connected on the end face, displacably in the horizontal cassette longitudinal direction 35, to the chamber longitudinal walls 3, 4, in each case by means of connecting devices. In order to ensure that this displacably is not blocked in the long term, even during operation, and remains operable for as long as possible, a plurality of variants are provided according to the invention.
On the inside of the chamber, vertically oriented and continuous connecting grooves 36 of the connecting device, in each case with a connecting groove bottom 37 and with two mutually parallel connecting groove side faces 38, 39, are provided in the chamber longitudinal walls 3, 4. The depth of the connecting grooves 36 in this case is preferably 30 to 200 mm, preferably 60 to 150 mm, the distance between two connecting groove bottoms 37 opposite one another in the horizontal direction being greater than the length of the cassette wall 7 arranged between them, that is to say the distance between their cassette wall end faces 40 in the horizontal direction, so that in each case a free space or an expansion joint 41 is formed as a further element of the connecting device between the cassette wall end faces 40 and the connecting groove bottoms 37, and the cassette wall 7 is connected to the chamber longitudinal walls 3, 4 displacably by a limited amount in the cassette longitudinal direction 35.
The distance between the two connecting groove side faces 38, 39 is in this case likewise somewhat greater than the width of the cassette walls 7, that is to say than the distance between cassette wall sides 42, 43 or than the width of the shaped bricks 11, lla, so that there is in each case a small gap 44 or slot 45 between the cassette wall sides 42, 43 and the connecting groove side faces 38, 39. In this case, the gaps 44 preferably have a width of 2 to 5 mm, preferably 1.8 to 2.4 mm, and the slots 45 preferably have a width of 5 to 25 mm, preferably 9 to 13 mm. The gaps 44 and slots 45 are expedient, in order to ensure as low-friction a mounting as possible of the cassette walls 7 in the connecting grooves 36 and as low-friction a movement as possible of the cassette walls 7 in the cassette longitudinal direction 35, even in the event of a thermally induced width expansion of the cassette walls 7, and in order to compensate manufacture-related inaccuracies. Gaps 44 and slots 45 are likewise in each case an integral part of the connecting devices.

In order to provide an expansion joint 41 of defined depth, for example, in each case a Styropor strip 46 bearing against the connecting groove bottoms 37 is provided for mounting the cassette walls 7, is burnt completely when the cassette chamber 1 is put into operation and leaves behind the expansion joint 41 with a depth of preferably 5 to 50 mm, preferably 15 to 40 mm.

According to the invention, in each case one of the two end faces 16, 17 of the connecting shaped bricks lla have no connecting groove 24 or connecting tongue 25, but, instead, elements for the connection of the connecting shaped bricks lla to the chamber walls 3, 4.
This end face 16 or 17 is designated below as a connecting end face 100 and is a further integral part of the connecting device.

According to a preferred embodiment of the invention with regard to the connection of cassette walls 7 and chamber longitudinal walls 3, 4, the connecting device has a sealing device which prevents carbon grit from penetrating into the expansion joint 41.

For this purpose, in each case, a vertically extending sealing groove 47 is provided in the wide side 12 as an element of the sealing device in the region of the connecting end face 100 (fig. 8-11).

This sealing groove 47 has a rectangular cross section, a sealing groove bottom 48 running parallel to the wide sides 12, 13. The depth of the sealing groove 47 is preferably 15 to 120 mm, preferably 30 to 80 mm, and the width of the sealing groove 47, that is to say the distance between sealing groove side faces 49, 50, is preferably 60 to 200 mm, preferably 100 to 150 mm.

In the assembled cassette chamber 1 (fig. 8, 9), the connecting shaped bricks lla are arranged in the cassette walls 7 in such a way that the sealing grooves 47 are arranged vertically in alignment one above the other. Moreover, the sealing grooves 47 lie, at least in part regions, within the connecting grooves 36 and, with respect to the connecting groove side faces 38, 39, on the side of the slot 45 delimited by the connecting groove side face 38 and the wide side 12.
This overlapping of the connecting grooves 36 and of the sealing grooves in part regions is dimensioned in such a way that it is maintained even in the event of the thermally induced contraction of the cassette walls.

Provided as a further element of the sealing device in the sealing grooves 47 is, for example, in each case a vertically extending strip-shaped, elastically flexible or resilient ceramic fiber mat 51 which bears with its fiber mat underside 52 against the respective sealing groove bottom 48 and preferably extends over the entire sealing groove width. The thickness of the fiber mats 51 is in this case preferably 2 to 40 mm, preferably 5 to 20 mm.

Moreover, in=each case a sealing element, in particular a cuboid vertically extending sealing cuboid 53, is seated as a further element of the sealing device, preferably with an interlock or a slight interference fit, in the sealing grooves 47 and bears slidably and sealingly over a large area with its sealing cuboid rear side 54 against a fiber mat surface 55 and with its sealing cuboid sliding face 56 lying opposite the sealing cuboid rear side 54, at least in part regions, against the respective connecting groove side face 39.
In this case, the width of the sealing cuboids 53 corresponds essentially to the width of the sealing grooves 47 and the thickness of the sealing cuboids 53 is preferably 20 to 100 mm, preferably 30 to 80 mm. The length of the sealing cuboids 53 is preferably 500 to 1000 mm, preferably 600 to 800 mm, so that a plurality of sealing cuboids 53 are expediently provided one above the other in a sealing groove 47 of a connecting shaped brick lla (fig. 9).
Moreover, the sealing cuboids 53 preferably consist of lightweight refractory bricks and/or fireclay bricks and/or aluminum oxide bricks and are produced by pressing and/or casting.
Since the sealing cuboids 53 bear slidably and sealingly over a large area with their sealing cuboid sliding faces 56 at least partially against the respective connecting groove side face 39, the carbon grit used for the baking of anodes does not penetrate through the slots 45 into the expansion joints 41, and the movement of the cassette walls 7 in the cassette wall longitudinal direction 35 under the thermally induced expansions and contractions is not impeded by penetrating carbon grit. In this case, a long-term uniform pressure force of the sealing cuboids 53 against the connecting groove side faces 39 is achieved by the use of the elastic flexible fiber mats 51.

According to a further embodiment of the sealing device, the connecting shaped bricks lla have in the connecting end faces 100 in each case a vertically extending U-shaped sealing cylinder groove 57 with a semi-cylindrical cylinder groove bottom 58 and two mutually parallel cylinder groove side faces 59, 60 in the wide side 12 which adjoin these tangentially and are perpendicular to the wide sides 12, 13.
In the assembled cassette chamber 1, the sealing cylinder grooves 57, too, are arranged vertically in alignment one above the other and lie on the side of the slot 45. Moreover, the sealing cylinder grooves 57 are arranged in such a way that, even in the event of the contraction of the cassette walls 7, they lie at least half within the connecting grooves 36.

A cylindrical sealing rod 61 as a sealing element is arranged in the sealing cylinder grooves 57 in each case, for example, with a form fit or with a slight press fit. A form fit means that the radius of the sealing rods 61 corresponds to the radius of the sealing cylinder grooves 57. In this case, the depth of the sealing cylinder grooves 57 is less than the diameter of the sealing rods 61, so that the sealing rods 61 bear linearly against the respective connecting groove side face 39 (linear contact) and seal off, so that the carbon grit does not penetrate through the slots 45 into the expansion joints 41. In the event of a movement of the cassette wall 7 in the cassette wall longitudinal direction 35 on account of the thermally induced expansions and contractions, the sealing rods 61 slide along on the connecting groove side faces 39 or roll on these, so that the sealing action is maintained even during the movement of the cassette walls 7.
The length of a sealing rod 61 in this case is preferably 500 to 1000 mm, preferably 600 to 800 mm, so that 1 to 10 sealing rods 61 are expediently likewise provided one above the other in a sealing cylinder groove 57 of a connecting shaped brick lla. The radius of the sealing rods 61 is preferably 10 to 60 mm, preferably 15 to 30 mm.

Moreover, the sealing rods 61 preferably consist of fireclay and/or aluminum oxide and/or high alumina and/or corundum and/or magnesium oxide and are produced by casting and/or vibration.

Of course, it is in this case also within the scope of the invention to provide a further sealing device which seals off the gap 44 delimited by the wide side 13 and the connecting groove side face 39, the gap 44 then preferably having the same width as the slot 45 (not illustrated).
Moreover, it is perfectly expedient to provide the sealing grooves (47, 57) in the connecting groove side faces (38, 39) instead of in the wide sides (12, 13), so that the respective sealing element (53, 61) sealingly bears against or slides along the wide sides (12, 13) (not illustrated).

A further idea of the invention is likewise to provide for the carbon grit, as an integral part of the connecting device, a storage device which has, for example, a repository or storage volume or oversize volume or a storage free space which is provided as a consequence of production or by virtue of assembly and in which a large quantity of carbon grit can collect before it results in the blockage of the movement of the cassettes wall 7. As a result, necessary repair work is postponed and the useful life of the cassette chamber 1 according to the invention is increased.

According to a third preferred embodiment of the invention with regard to the connection of cassette walls 7 and chamber longitudinal walls 3, 4, (fig. 15-17), this is achieved, for example, in that the connecting end faces 100 of the connecting shaped bricks lla have in each case a vertically oriented storage volume, in particular a vertically oriented repository groove 62 with, for example, a trapezoidal cross section and a depth of preferably 15 to 100 mm, preferably 25 to 50 mm.

During operation, the carbon grit gradually penetrates through the gaps 44 and slots 45 into the repository groove 62, collects there and falls downward on account of gravity in the repository grooves 62, so that the carbon grit level in the repository grooves 62 rises slowly from the bottom. In this case, the volume of the repository grooves 62 always remains essentially identical independently of the thermally induced contractions and expansions of the cassette walls 7, whereas the volume of the expansion joints 41 varies with the constantly changing contractions and expansions of the cassette walls 7. The volume of the expansion joint is in this case defined or fixed in each case by the connecting groove bottom 37, the connecting groove side faces 38, 39 and the depth of the expansion joint 41, that is to say the shortest distance between the connecting groove end face 100 and the connecting groove bottom 37.

Preferably, the ratio of storage volume to expansion joint volume in the repository grooves 62 is 30 to 80%, preferably 40 to 60%, at room temperature.

In order to keep the amount of carbon grit penetrating into the repository groove 62 per unit time as low as possible, in each case a vertically extending ceramic fiber mat strip 63 is provided in the slots 45.

According to a fourth preferred embodiment of the invention (fig. 18, 19) with regard to the connection of cassette walls 7 and chamber longitudinal walls 3, 4, the connecting shaped bricks lla are chamfered laterally on the connecting end faces 100 in such a way that in each case two oblique vertically extending planar end edges 64, 65 which connect the end faces 16, 17 to the wide sides 12, 13 are formed.

In the assembled cassette chamber 1, the connecting end faces 100 project into the connecting grooves 36 to an extent such that a vertically extending storage volume of essentially triangular cross section, a triangular repository 66, 67, is formed on both sides of the connecting shaped bricks lla in each case between one of the two connecting groove side faces 38, 39, one of the two end edges 64, 65 and the expansion joint 41. In this case, the triangular repositories 66, 67 of the connecting shaped bricks lia lie in each case one above the other in alignment in the cassette walls 7.
The volume of the triangular repositories 66, 67 also always remains essentially identical independently of the thermally induced contractions and expansions of the cassette walls 7.
Preferably, the ratio of storage volume to expansion joint volume in the triangular repositories 66, 67 is in each case 30 to 80%, preferably 40 to 60%, at room temperature.

In this embodiment of the invention, too, in each case a ceramic fiber mat strip 63 is expediently provided for sealing off in the slot 45 (not illustrated).

Alternatively to this, the end edges 64, 65 are, for example, curved inwardly or designed concavely, so that the storage volume is further increased (not illustrated).

In order further to assist the lowering of the carbon grit in the repository grooves 62, according to a fifth embodiment of the invention with regard to the connection of cassette walls 7 and chamber longitudinal walls 3, 4, there is provision for configuring the connecting end faces 100 in such a way that the slipping off of the carbon grit in the repository grooves 62 is promoted.

In order to achieve this, end faces 68, 69 laterally delimiting the repository grooves 62 have a trapezoidal profile, as seen from the side (fig. 20 - 22). The two end faces 68, 69 in each case adjoin the top side 15 level with or on the same plane as a repository groove bottom 70 and initially have in each case a planar oblique sloping end face 71, 72 which forms with the top side 15 an angle a of preferably 100 to 130 , preferably 105 to 120 . The sloping end face 71, 72 has adjoining it in each case a likewise planar vertical end face 73, 74 which has adjoining it in each case a planar oblique overhang end face 75, 76 which runs out on the underside 14, level with the repository groove bottom 70, and forms with the underside 14 an angle of preferably 100 to 130 , preferably 105 to 120 .

Preferably, in this case, the sloping end faces 71, 72 and the overhang end faces 75, 76 have the same gradients, that is to say the angles a and 0 are expediently identical.
The vertical length of the vertical end faces 73, 74 is preferably 200 to 600 mm, preferably 300 to 500 mm.

By means of the sloping end faces 71, 72, on the one hand, the. reception volume for the carbon grit is further increased and, on the other hand, the slipping off of the carbon grit is assisted. The undercut arising due to the overhang end faces 75, 76 also brings about an increase in volume and, in accompaniment with this, a higher storage capacity.

So that the carbon grit which has accumulated in the repository grooves 62 can be removed between the baking cycles, according to a sixth preferred embodiment of the invention with regard to the connection of cassette walls 7 and chamber longitudinal walls 3, 4 the cassette chamber 1 according to the invention has one or more suction extraction orifices 77 per cassette wall 7 which connect the storage volumes, in particular the repository grooves 62 or the expansion joints 41 (not illustrated), to the cassette space 8, so that the carbon grit can be sucked away from the repository grooves 62 in a simple way by means of the suction extraction orifices 77 between the 14-day baking cycles.

For this purpose, the connecting end face 100 is chamfered or undercut in the lower region in such a way as to form a planar incline 78 which extends from the connecting end face 100 to the underside 14. In this case, the incline 78 forms with the underside 14 an angle y of preferably 30 to 60 , preferably 40 to 50 (fig. 26).

In the assembled cassette chamber 1, the inclines 78 project partially beyond the connecting groove side faces 38, 39, so that the suction extraction orifices 77 are delimited in each case essentially by the incline 78, the top side 14 of the connecting shaped brick lia arranged below it and a connecting groove outer edge 79.

In order to promote the slipping off of the carbon grit in the direction of the suction extraction orifices 77, according to a seventh embodiment, illustrated in fig. 28 - 30, of the invention with regard to the connection of cassette walls 7 and chamber longitudinal walls 3, 4, a slip-off wedge 80, preferably likewise consisting of refractory concrete, is arranged below the respective incline 78. This slip-off wedge 80 has a planar wedge bottom 81, two wedge side faces 82, 83 perpendicular to this and a wedge rear wall 84, likewise perpendicular to the wedge bottom 81 and to the wedge side faces 82, 83, and a wedge front wall 85 parallel to said wedge rear wall. Moreover, the slip-off wedge 80 has two slip-off faces 86, 87 which adjoin the wedge side walls 82, 83 and which taper toward one another in a roof-shaped or gable-shaped manner with respect to the wedge bottom wall 81 and intersect one another at an angle S of preferably 30 to 600, preferably 40 to 50 . Moreover, the slip-off wedge 80 has two wedge ceiling walls 88, 89 which adjoin the wedge rear wall 84 at right angles and likewise taper toward one another in a roof-shaped or gable-shaped manner.

Preferably, in this case, the slip-off wedge 80 is fastened with its wedge rear wall 84 to the connecting groove bottom 37 by means of adhesive bonding and/or bricking-in and lies with its wedge bottom wall 81 on the top side 15 of the connecting shaped brick lla arranged below it. Moreover, the slip-off wedge 80 is dimensioned in such a way that its wedge side walls 82, 83 terminate flush with the connecting groove side faces 38, 39 in the horizontal direction. The distance between the two wedge side walls 82, 83 preferably corresponds to the connecting groove width.
Alternatively to the embodiment described above, the slip-off wedge 80 has a single planar slip-off face 90, the gradient of which expediently corresponds in amount to the gradient of the incline 78, so that both are parallel to one another (fig. 28, 29).

According to an eighth embodiment of the invention, with regard to the connection of cassette walls 7 and chamber longitudinal walls 3, 4, the cassette chamber 1 according to the invention has in the cassette walls 7 draw-off ducts 91 which extend away from the connecting end faces 100 through the connecting shaped brick lla obliquely downward and issue in each case into the first smoke gas duct 9, as seen from the connecting end faces 100. The blow-out ducts to that extent flow-connect the storage volumes, in the case illustrated the triangular repositories 66, 67 and/or the expansion joints 41, to the first smoke gas duct 9. In this case, the cross section of the draw-off ducts 91 widens in a funnel-shaped manner in the direction of the respective smoke gas duct 9, so that the draw-off ducts 91 have a conical profile. Preferably, a draw-off duct axis 92 forms with the vertical an angle E of 30 to 60 , preferably of 40 to 500, the draw-off duct axis 92 expediently running in the brick longitudinal mid-plane 10.

Moreover, a draw-off duct cone angle cp is preferably 10 to 30 , preferably 15 to 200.

In this case, preferably 2 to 6, preferably 2 to 4 draw-off ducts 91 are present per connecting shaped brick lla.

The reason for these draw-off ducts 91 is that the smoke gases flowing from the top downward through the smoke gas ducts 9 of the cassette walls 7 when the refractory furnace is in operation generate in the draw-off ducts 91 a vacuum such that the carbon grit accumulated in the triangular repositories 66, 67 and/or in the expansion joints 41 is properly sucked out or drawn off from the triangular repositories 66, 67 and/or the expansion joints 41 and blown out together with the smoke gas.
In order to obtain this suction effect in the case of an opposite direction of flow of the smoke gases from the bottom upward through the smoke gas ducts 9, in this case the draw-off ducts 91 are correspondingly arranged so as to be mirror-inverted with respect to a horizontal plane (not illustrated).

The draw-off ducts 91 thus in a particularly simple and advantageous way have the effect that, while the refractory furnace is in operation, the carbon grit is sucked away continuously from the triangular repositories 66, 67 or from the expansion joints 41, so that a blockage of the movement of the cassette walls 7 is prevented.
It is, of course, also within the scope of the invention to combine the various sealing devices and/or the various storage devices and/or the suction extraction orifices 77 and/or the draw-off ducts 91 with one another, for example to combine the draw-off ducts 91 with the trapezoidal repository grooves 62 or to provide both repository grooves 62 and triangular repositories 66, 67.

= CA 02628638 2008-04-02 .

Moreover, the shaped bricks according to the invention are pre-eminently suitable as building bricks for the remaining refractory furnace walls, in particular the chamber walls, smoke gas ducts then expediently likewise being present in the chamber walls.

Finally, it must be pointed out that, by the cassette chamber being configured according to the invention, the barreling and destruction of the cassette walls, presenting problems in the prior art, are prevented in a particularly advantageous way.

This is achieved in terms of the configuration of the cassette walls, on the one hand, by the use of refractory concrete, in particular refractory concrete of type ULCC, as material for the shaped bricks of the cassette walls and, on the other hand, by the use of large-format shaped bricks. The shaped bricks consisting of refractory concrete possess outstanding thermochemical, thermomechanical and physical properties in both a reducing and an oxidizing atmosphere, have, above all because of the low porosity of refractory concrete, a very low gas permeability and excellent resistance to the alkali fluorides contained in the covering grit or in the "furnace atmosphere", and can be produced very simply and cost-effectively and with any desired three-dimensional shapes by means of casting methods known per se. In particular, the incorporation of the smoke gas ducts and of the conically running draw-off ducts is possible very much more simply in the large-format shaped bricks according to the invention than in the small-format hydraulically pressed fireclay bricks used according to the prior art, since the respective ducts would extend over a plurality of individual bricks and therefore, inter alia, many different individual bricks would have to be manufactured.

=

However, the large format of the shaped bricks according to the invention also contributes, in addition to the better handling and the accompanying quicker and easier mounting and repair without bricking in, also to a minimization of the barreling and destruction of the cassette walls. Owing to the smaller number of wall joints, as seen over the entire cassette wall, a relatively smaller amount of carbon grit penetrates into the cassette wall, and temperature is distributed more uniformly over the entire cassette wall, since each joint forms a heat bridge. Thermally induced stresses in the cassette wall are also avoided as a result. Moreover, the connection of the shaped bricks arranged one above the other by means of the groove/tongue connection is also configured in such a way that the connection is maintained reliably and in a gastight manner in spite of thermally induced expansions and contractions. Crack formation in the joints cannot occur, as it does in the prior art.

Moreover, the cassette wall consisting of the large-format shaped bricks according to the invention possesses a better moment of inertia and, in accompaniment with this, higher stability.

With regard to the tie-up of the cassette walls to the chamber walls, the barreling and the accompanying destruction of the cassette walls are likewise prevented in various ways.

By means of the sealing devices illustrated, the situation is prevented in a particularly simple and advantageous way where the carbon grit penetrates via the slots and gaps into the expansion joints, and therefore the expansion joint is not filled over the course of time with the carbon grit during baking. The function of the expansion joint is thus maintained permanently, so that the thermally induced expansions and contractions of the cassette walls are compensated by the expansion joint and barreling of the cassette walls no longer occurs.
The storage devices provided as a consequence of production perform a type of buffer function, in that they receive a large quantity of carbon grit which penetrates through the slots and gaps before the expansion joint is clogged and blocked with carbon grit. If the storage devices are combined with the suction extraction devices (suction extraction orifice, draw-off ducts) according to the invention, by means of which the accumulated carbon grit is sucked away from the repositories, for example, in a simple way during the regular cleaning of the cassette chamber between the 14-day baking cycles, or is blown out continuously and automatically with the smoke gases during baking, the clogging of the expansion joints is likewise prevented permanently in a particularly simple way.

Consequently, by means of the cassette chamber according to the invention, by suitable choice of material and size of the shaped bricks and owing to the improved tie-up of the cassette walls to the chamber walls, the useful life of a refractory furnace is markedly increased, and markedly less repair work which is merely simpler occurs, with the result that production stoppages fall drastically and therefore the production costs are markedly reduced.

Claims

1. A cassette chamber (1) in a refractory furnace, in particular for the baking of anode blocks, using covering grit, which has an essentially rectangular base area and has in each case two vertical opposite chamber longitudinal walls (3, 4) and chamber transverse walls (5, 6) and at least one vertical cassette wall (7) which extends perpendicularly to the chamber transverse walls (5, 6) or chamber longitudinal walls (3, 4) and is connected to the respective chamber walls (3, 4, 5, 6) and which is constructed from individual mineral, essentially cuboidal refractory shaped bricks (11, 11a), there being provided in the cassette wall (7) gas ducts (9) which are continuous from the bottom upward and are incorporated into the shaped bricks (11, 11a), characterized in that the shaped bricks (11, 11a) consist of refractory concrete.

2. The cassette chamber as claimed in claim 1, characterized in that the refractory concrete has at least one refractory granulated product as aggregate, in particular Al2O3 granulates, such as, for example, mullite-rich materials and/or fireclay and/or andalusite, at least one refractory flour-like product as additive, such as, for example, aluminum oxide and/or clay and/or mullite-containing components and/or non-oxidic materials, at least one consolidated mineral binder, such as, for example, aluminum oxide cement and/or microsilica and/or reactive aluminum oxide, and, if appropriate, at least one addition, such as, for example, a liquefier and/or binding regulator and/or organic and/or inorganic fibers.

3. The cassette chamber as claimed in claim 1 and/or 2, characterized in that the refractory concrete is a refractory concrete of type ULCC (Ultra Low Cement Castables) with a CaO content of at most 0.2 to 1.0% by weight.

4. The cassette chamber as claimed in one or more of claims 1 to 3, characterized in that the refractory concrete has an Fe2O3 content < 2% by weight, preferably < 1% by weight.

5. The cassette chamber as claimed in one or more of claims 1 to 4, characterized in that the refractory concrete has the following thermomechanical, thermochemical and physical properties:

6. The cassette chamber as claimed in one or more of claims 1 to 5, characterized in that the shaped bricks (11, 11a) have two wide sides (12, 13), two end faces (16, 17) and an underside (14) and a top side (15) and the following dimensions:
width: 190 to 350 mm, in particular 200 to 300 mm height: 500 to 1000 mm, in particular 600 to 800 mm length: 600 to 2000 mm, in particular 1000 to 1900 mm.

7. The cassette chamber as claimed in one or more of claims 1 to 6, characterized in that shaped bricks (11, 11a) arranged one above the other are connected to one another by means of groove/tongue connections, preferably without bricking-in.

8. The cassette chamber as claimed in claim 7, characterized in that the shaped bricks (11, 11a) have in their top side (15) in each case a fixing groove (18) with an expediently trapezoidal cross section.

9. The cassette chamber as claimed in claim 8, characterized in that the shaped bricks (11, 11a) have in their underside (14) in each case a fixing tongue (18) matching the fixing groove (18).

10. The cassette chamber as claimed in one or more of claims 1 to 9, characterized in that shaped bricks (11, 11a) arranged so as to be lined up in a row next to one another are connected to one another by means of groove/tongue connections, preferably without bricking-in.

11. The cassette chamber as claimed in claim 10, characterized in that the shaped bricks (11, 11a) have on at least one end face (16, 17) in each case a connecting groove (24) or a connecting tongue (25) with an expediently trapezoidal cross section.

12. The cassette chamber as claimed in claim 10 and/or 11, characterized in that the shaped bricks (11, 11a) have on the end face (16) in each case the connecting groove (24) with an expediently trapezoidal cross section.

13. The cassette chamber as claimed in claim 11 and/or 12, characterized in that the shaped bricks (11, 11a) have on the end face (17) in each case the connecting tongue (25) matching the connecting groove (24).

14. The cassette chamber as claimed in one or more of claims 1 to 13, characterized in that the shaped bricks (11,11a) have 3 to 10, in particular 6 to 8 gas ducts (9) extending continuously from the underside (14) to the top side (15).

15. The cassette chamber as claimed in one or more of claims 1 to 14, characterized in that the gas ducts (9) have an essentially rectangular cross section with rounded duct edges (31).

16. The cassette chamber as claimed in one or more of claims 1 to 15, characterized in that the cassette wall (7) is connected to the chamber walls (3, 4, 5, 6), at least on one cassette wall end face (40), by means of at least one connecting device, the connecting device having a connecting groove (36) extending vertically in the chamber walls (3, 4, 5, 6), a connecting end face (100) of a connecting shaped brick (11a), an expansion joint (41) delimited by the connecting groove (36) and the connecting end face (100), a slot (45) delimited by the wide side (12) of the connecting shaped brick (11a) and the connecting groove (36) and preferably a gap (44) delimited by the wide side (13) and the connecting groove (36).

17. The cassette chamber as claimed in claim 16, characterized in that the connecting device has a sealing device sealing off the slot (45).

18. The cassette chamber as claimed in claim 16 and/or 17, characterized in that the connecting device has a sealing device sealing off the gap (44).

19. The cassette chamber as claimed in claim 17 and/or 18, characterized in that the sealing device has, in the region of the connecting groove end face (100), a vertically extending sealing groove (47, 57) and a vertically extending sealing element (53, 61) arranged in the sealing groove (47, 57).

20. The cassette chamber as claimed in claim 19, characterized in that the sealing groove (47, 57) is provided in the respective wide side (12, 13) of the connecting shaped brick (11a).

21. The cassette chamber as claimed in claim 19 and/or 20, characterized in that the sealing groove (47, 57) is provided in the respective connecting groove side face (38, 39).

22. The cassette chamber as claimed in one or more of claims 19 to 21, characterized in that the sealing groove (47) has a rectangular cross section.

23. The cassette chamber as claimed in one or more of claims 19 to 22, characterized in that the sealing groove (47) is arranged, at least in part regions, within the connecting groove (36).

24. The cassette chamber as claimed in one or more of claims 19 to 23, characterized in that the sealing element (53) is a sealing cuboid (53).

25. The cassette chamber as claimed in claim 24, characterized in that the sealing cuboid (53) is arranged in the sealing groove (47) with an interlock or with a slight interference fit.

26. The cassette chamber as claimed in one or more of claims 19 to 25, characterized in that the sealing device in the sealing groove (47) has a vertically extending strip-shaped elastic, preferably ceramic fiber mat (51) which expediently bears with a fiber mat underside (52) against a sealing groove bottom (48) and with a fiber mat surface (55) against a sealing cuboid rear side (54) and which preferably extends over the entire width of the sealing groove (47).

27. The cassette chamber as claimed in one or more of claims 24 to 26, characterized in that the sealing cuboid (53) bears slidably and sealingly over a large area with a sealing cuboid sliding face (56) lying opposite the sealing cuboid rear side (54), at least in part regions, against the respective connecting groove side face (38, 39).

28. The cassette chamber as claimed in one or more of claims 19 to 21, characterized in that the sealing groove (57) is a U-shaped sealing cylinder groove (57).

29. The cassette chamber as claimed in claim 28, characterized in that the sealing element (61) is a cylindrical sealing rod (61).

30. The cassette chamber as claimed in claim 29, characterized in that the sealing rod (61) is arranged with a form fit or with a slight press fit in the sealing cylinder groove (57).

31. The cassette chamber as claimed in one or more of claims 29 to 30, characterized in that the depth of the sealing cylinder groove (57) is less than the diameter of the sealing rod (61), so that the sealing rod (61) preferably bears linearly against the respective connecting groove side face (39) and seals off.

32. The cassette chamber as claimed in one or more of claims 16 to 31, characterized in that the connecting device has a storage device for the covering grit.

33. The cassette chamber as claimed in claim 32, characterized in that the storage device has at least one preferably vertically oriented storage volume or oversize volume which is provided as a consequence of production and/or by virtue of assembly.

34. The cassette chamber as claimed in claim 33, characterized in that the storage device has a vertically oriented repository groove (62) as a storage volume.

35. The cassette chamber as claimed in claim 34, characterized in that the repository groove (62) is provided on the connecting end face (100) of the connecting shaped bricks (11a) and has a, for example, trapezoidal cross section.

36. The cassette chamber as claimed in claim 34 and/or 35, characterized in that the ratio of storage volume to expansion joint volume in the repository groove (62) is 30 to 80%, preferably 40 to 60%, at room temperature.

37. The cassette chamber as claimed in one or more of claims 16 to 36, characterized in that the connecting device has at least one oblique vertically extending preferably planar end edge (64, 65) which connects the connecting end face (100) to the respective wide side (12, 13) and which in each case delimits a storage volume together with the respective connecting groove side face (38, 39) and the expansion joint (41).

38. The cassette chamber as claimed in claim 37, characterized in that the storage volume is a triangular repository (66, 67) of essentially triangular cross section.

39. The cassette chamber as claimed in claim 38, characterized in that the ratio of storage volume to expansion joint volume in the triangular repositories (66, 67) is in each case 30 to 80%, preferably 40 to 60%, at room temperature.

40. The cassette chamber as claimed in one or more of claims 32 to 39, characterized in that a ceramic fiber mat strip (63) is provided in the slot (45).

41. The cassette chamber as claimed in one or more of claims 34 to 36, characterized in that end faces (68, 69) laterally delimiting the repository groove (62) have a trapezoidal profile, as seen from the side.

42. The cassette chamber as claimed in claim 41, characterized in that the end faces (68, 69) have in each case a preferably planar oblique sloping end face (71, 72) adjoining the top side (15), a preferably planar vertical end face (73, 74) adjoining said sloping end face and a preferably planar oblique overhang end face (75, 76) which adjoins said vertical end face and which the underside (14) adjoins.

43. The cassette chamber as claimed in claim 42, characterized in that the sloping end faces (71, 72) form with the top side (15) an angle a of preferably 100 to 130°, preferably 105 to 120°.

44. The cassette chamber as claimed in claim 42 and/or 43, characterized in that the overhang end faces (75, 76) form with the underside (14) an angle .beta. of preferably 100 to 130°, preferably 105 to 120°.

45. The cassette chamber as claimed in one or more of claims 1 to 44, characterized in that the cassette wall (7) has at least one suction extraction orifice (77) which connects the expansion joint (41) and/or the storage volume or storage volumes to a cassette space (8) .

46. The cassette chamber as claimed in claim 45, characterized in that at least one connecting shaped brick (11a) has in the lower region a preferably planar incline (78) extending from the connecting end face (100) to the underside (14).

47. The cassette chamber as claimed in claim 46, characterized in that the incline (78) projects partially beyond the connecting groove side faces (38, 39), so that the suction extraction orifice (77) is delimited in each case essentially by the incline (78) of one connecting shaped brick (11a), the top side (14) of a connecting shaped brick (11a) arranged below it and a connecting groove outer edge (79).

48. The cassette chamber as claimed in claim 46 and/or 47, characterized in that a slip-off wedge (80), in particular likewise consisting of refractory concrete, is arranged below the incline (78) and, in particular, within the connecting groove (36).

49. The cassette chamber as claimed in claim 48, characterized in that the slip-off wedge (80) has a planar wedge bottom (81), two wedge side faces (82, 83) perpendicular to this, a wedge rear wall (84) likewise perpendicular to the wedge bottom (81) and to the wedge side walls (82, 83), a wedge front wall (85) parallel to said wedge rear wall and preferably two slip-off faces (86, 87) which adjoin the wedge side walls (82, 83) and which taper toward one another in a roof-shaped or gable-shaped manner with respect to the wedge bottom wall (81), and also two wedge ceiling walls (88, 89) which adjoin the wedge rear wall (84) at right angles and likewise taper toward one another in a roof-shaped or gable-shaped manner.

50. The cassette chamber as claimed in claim 49, characterized in that the slip-off wedge (80) is fastened with the wedge rear wall (84) to the connecting groove bottom (37) by means of adhesive bonding and/or bricking-in and expediently lies with its wedge bottom wall (81) on the top side (15) of the connecting shaped brick (11a) arranged below it.

51. The cassette chamber as claimed in claim 49 and/or 50, characterized in that the slip-off wedge (80) is dimensioned in such a way that its wedge side walls (82, 83) terminate flush with the connecting groove side faces (38, 39) in the horizontal direction, and the distance between the two wedge side walls (82, 83) expediently corresponds to the width of the connecting groove (36).

52. The cassette chamber as claimed in claim 48, characterized in that the slip-off wedge (80) has a single planar slip-off face (90), the gradient of which preferably corresponds in amount to the gradient of the incline (78).

53. The cassette chamber as claimed in one or more of claims 1 to 52, characterized in that the cassette wall (7) has at least one draw-off duct (91) for the covering grit.

54. The cassette chamber as claimed in claim 53, characterized in that the draw-off duct (91) extends away from the connecting end face (100) through the connecting shaped brick (11a) and issues in each case into the first smoke gas duct (9), as seen from the connecting end face (100).

55. The cassette chamber as claimed in claim 54, characterized in that the draw-off duct (91), in particular, flow-connects the storage volume or storage volumes and/or the expansion joint (41) to the first smoke gas duct (9).

56. The cassette chamber as claimed in claim 54 and/or 55, characterized in that the draw-off duct (91) extends away from the connecting end face (100) obliquely downward, preferably a draw-off duct axis (92) forming with the vertical an angle .epsilon. of 30 to 60°, preferably of 40 to 50°, and the draw-off duct axis (92) expediently running in a brick longitudinal mid-plane (10).

57. The cassette chamber as claimed in one or more of claims 54 to 56, characterized in that the draw-off duct (91) has a conical profile, the cross section of the draw-off duct (91) preferably widening in the direction of the smoke gas duct (9).

58. The cassette chamber as claimed in claim 57, characterized in that a draw-off duct cone angle .phi. is preferably 10 to 30°, preferably 15 to 20°.

59. A shaped brick for refractory furnace walls, in particular for cassette walls and/or cassette chamber walls, characterized by the features of one or more of claims 1-6, 8, 9, 11-15, 20, 22, 28, 35, 42-44, 46, 54, 56-58.

60. A method for production of a shaped brick for refractory furnace walls, in particular of a shaped brick as claimed in claim 59, characterized by the following method steps:
a) production of an, in particular, castable fresh refractory concrete, b) introduction, in particular casting, of the fresh refractory concrete into a mold, c) preferably shaking and/or vibration of the fresh refractory concrete in the mold, d) hardening of the fresh refractory concrete in the mold, e) removal of the hardened refractory concrete shaped brick from the mold.