AU706179B2 - Continuous updraught modular kiln - Google Patents

Description

-JOHuIN SELKIRK and WILLIA j. EMMETT COMMONWEALTH OF AUSTRALIA Patents Act 1990 COMPLETE-AFTER-PROVISIONAL

SPECIFICATION

FOR THE INVENTION ENTITLED "CONTINUOUS UPDRAUGHT MODULAR KILN" This invention is described in the following statement: es* •e ooo *0oo o*ooo 1 17/7/96GS7831.SPE,1 The present invention relates, in general terms, to improvements in kilns and the like equipment for the production of bricks and the like building elements, such as tiles, pavers etc. More particularly, but not exclusively, the invention relates to improvements in what are known as vertical kilns, being apparatus or equipment wherein material is dried and fired, for the creation of bricks or the like building elements, during the course of a vertical movement through appropriate equipment. Throughout the ensuing description reference will be made in particular to an especially preferred embodiment of the present invention, involving a continuous vertical kiln, either with or without furniture, and coupled to a continuous vertical drier. It should be realised, however, that the present invention is under no circumstances to be considered to be restricted to the particularly preferred embodiment or embodiments described hereinafter. In fact, for ease of explanation in the ensuing description reference will be made to an apparatus for the production of bricks. It should be realized, however, that the apparatus in accordance with the present invention is equally well suited for the production of other building, constructional or decorative elements, as for example tiles of all types, pavers and the like. As employed in and throughout this specification, therefore, the expression "brick" is intended to include within its scope all other types of element/article used for building and/or decorative 20 purposes, as for example tiles (for roofs, walls, etc), pavers and the like.

Nowadays, with our burgeoning building industry, there is an everexpanding and on-going demand for bricks and the like building elements.

Traditionally it has been the practice to set up a kiln or brick-making facility on .o or near the site where the principal materials needed for the manufacture of bricks and the like are located. Bricks and the like elements can therefore be manufactured at that site for subsequent transfer to remote sites, meaning sites removed from the actual site of brick manufacture, for use as desired. This need for transport of manufactured bricks and the like elements, sometimes over S substantial distances, has been found to give rise to additional costs in terms of transport, hence making the overall building procedure more expensive.

Again in accordance with the known and in use art, for small outputs, as for example up to 15 million bricks per year, what are known as tunnel kilns are 17/7/96GS7831.SPE,2 not generally employed. Indeed what are termed intermittent kilns predominate in this area, but such intermittent kilns have been found to suffer from a number of disadvantages, in effect resulting from a procedure wherein the product is loaded, kiln-fired, cooled and then subsequently unloaded. Such intermittent kilns have been found, for example, to consume significantly more fuel than a tunnel kiln. Indeed fuel consumption with intermittent kilns is sometimes of the order of from 2 to 3 times greater than that with a tunnel kiln. Furthermore, in intermittent kilns firing of partially dried bricks is not consistent and it has been found to be difficult, if not actually impractical, to take air off for drying. Product recovery with intermittent kilns has been found to be of the order of from to 85%, with generally a high percentage of seconds and rejects. Such intermittent kilns also exhibit high labour requirements and, perhaps most importantly, can only use certain types of fuels. In the result, intermittent kilns have been found to be unsatisfactory in terms of cost of maintenance, cost of operation, efficiency of operation, etc.

Tunnel kilns, again as employed in accordance with the known art, have been found to be more efficient than intermittent kilns, but themselves require air to travel in a substantially horizontal direction along the kiln and drier tunnel.

However, and by virtue of the fact that hot air has a tendency to rise, then cold 20 air enters at the tunnel base and the ensuring of uniformity of firing in any crosssection is a constant problem, with that factor alone having been found to result in cycle times needing to be extended, leading to increased fuel costs. Tunnel kilns also have been found to suffer from high capital cost and maintenance cost.

Furthermore, such tunnel kilns suffer in terms of air leakage, poor heat distribution on any given cross-section and the need for expensive hydraulic pushers, transfer cars, kiln roof systems etc. In the result, tunnel kilns in a practical sense are only suitable for larger plants, as for example high output plants as conventionally located at a quarry or the like, where the relevant raw materials are readily available.

In a practical sense, and provided that economic considerations are right, it would be much more appropriate and efficient if it was possible to create, erect or install, at or in the vicinity of the site at which a building is actually to be -3- 17/7/96GS7831.SPE,3 constructed, a kiln or the like means for the manufacture of bricks and the like building elements. Such a situation would also be appropriate when a factory, in other words an intermittent or tunnel kiln, is no longer practical due to the encroachment of housing estates and/or because of environmental constraints.

By way of example only in this day and age, wherein what are termed satellite townships are regularly being constructed, then rather than transporting large quantities of bricks and the like building elements from the site of manufacture to their site of intended use, it would be more efficient and effective, in terms of both cost and practicality, if the bricks and the like elements could be constructed at or in the vicinity of their intended site of use.

Conventional brick manufacturers employ large-scale and accordingly expensive apparatus, as previously described, which occupy large tracts of land and are permanently fixed in that position or site. The present applicants have determined that, in certain contexts at least, and dependent upon market demands and trends, it would be more appropriate and expedient to be able to erect, at or in the vicinity of an actual building site, an apparatus for the manufacture of all bricks and the like building elements required to be used on that site. Once construction has been completed at that site, then the kiln that was used for manufacture of the bricks and the like building elements could be .20 dismantled, for transport to another building site as required.

The applicants have found that a vertical kiln will have better fuel efficiency than the aforementioned tunnel-type kiln, since a vertical kiln does not suffer from the problems associated with the need for reheating kiln cars, not to mention leakage from sand seals and the like. A vertical kiln is also extremely simple in its construction, with the principal components being a drier elevator, a kiln jack raising and lowering device or the like means, a transfer cassette or product carrying device.

An especially preferred apparatus in accordance with the present invention will include, in general terms, at least two vertically extending structures to be erected on a side-by-side or adjacent basis. In an especially preferred embodiment a first vertically-extending structure will be in the form of a tower, preferably constructed from at least four modular sections, the said tower having -4- 17/7/96GS7831.SPE,4 a single shaft extending therethrough and along which pre-formed material to be employed for the creation of bricks and the like elements is to be moved. This vertically-extending tower, preferably of modular construction, is to be employed for purposes of drying the pre-formed material, in a manner to be described hereinafter in more detail.

In accordance with the present invention, therefore, there is provided an improved apparatus for the production of articles for use in building, said articles being in the form of bricks, tiles, pavers and the like, said apparatus being in the form of a continuous updraft kiln including: at least one substantially vertically extending drying tower for receiving a plurality of green articles (as hereinbefore defined) and subjecting such articles to a continuous drying process so as to reduce the moisture content thereof to a predetermined level; at least one substantially vertically extending firing tower interconnected with said at least one drying tower, for receiving said dried articles from said drying tower and for subjecting such articles to further heat treatment; and means allowing for transfer of said articles from said at least one drying tower to said at least one firing tower, the arrangement being such that said plurality of articles is adapted to be passed, successively and continuously, upwardly through said at least one drying tower and then downwardly through said at least one firing tower, thereby to allow said 20 articles to be subjected in turn to respective drying and firing operations.

In order that the invention may be more clearly understood and put into practical effect reference will now be made to a preferred embodiment of an apparatus in accordance with the invention. The ensuing description is given by way of non-limitative example only and is with reference to the accompanying drawings, wherein: FIG. 1 is a schematic, side elevational view of a kiln-drier combination in accordance with the present invention, illustrating thereon the flow of product S° through the overall apparatus; FIG. 2 is a plan view of the combination of FIG. 1; FIG. 3 is a schematic, side-elevational view of a kiln-drier combination in accordance with the present invention, illustrating the path of movement of air/gas therethrough; FIG. 4 is a plan view of the combination of FIG. 3; 5 31/3/99GC7831.SPE,- FIG. 5 is a side elevational view of a further embodiment of apparatus in accordance with the present invention; and FIG. 6 is a sectional view taken along the line A-A of FIG. The drawings illustrate the principal components of the overall apparatus, ft g ft ft ft ft ft.. ft ft ft ft...

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ft ft ft ft ft ft ft. ft.

ft ft ft ft ft ft 5a 31 /3/99GC7831.SPE,- as explained in more detail hereinafter.

Throughout this specification the expression "green article" is intended to refer to an article, initially pre-formed into the desired shape (whether for a brick, tile, paver or the like) from the appropriate raw material and then to be subjected to drying and firing treatments thereby to give rise to the desired end product intended for use in building, whether for structural or decorative purposes.

With reference now to FIG. 1 there is illustrated an apparatus including a drier 1, preferably in the form of a vertically-extending tower of any prescribed height or length, having means for preventing, or at least minimising, flow of ambient air thereto, such means preferably being in the form of an airlock 2 (of any known type) disposed at or in the vicinity of the bottom thereof. The airlock 2 serves to allow for loading of "green" product into the drier 1, whilst substantially eliminating the possibility of entry of outside air thereinto. It should be realized that the height of the tower is not of the essence of the invention.

Indeed, that dimension can be varied to suit production demands, spatial requirements, etc.

In accordance with an especially preferred embodiment the drier 1 may be formed from a plurality of discrete sections, adapted in use to be interconnected and disassembled in any known manner. The modular arrangement thus created 20 facilitates transport, an important practical advantage of the present applicants' S. arrangement.

*The "green" product, loaded on to a cassette or the like kiln furniture of any given type, or perhaps drier trays (not shown), is moved into the main tower of the drier 1 for deposition on a lifting device 3 of any given type, as for example a jack or other similar elevator means. Here again the actual means employed for lifting is not of the essence of the invention. Any lifting means currently in use in this context can equally well be employed. The lifting device 3 serves, in use, to control the speed and path of movement of the kiln furniture 4 and associated "green" product in an upward direction along or through the tower of the drier 1. To assist in such control of the direction of movement the drier 1 includes at least one internal wall 4. At the upper end of the drier 1 there is provided a drier cover and seal arrangement 5, intended to assist in thermal -6- 17/7/96GS7831.SPE,6 insulation of the drier tower itself. In that regard it should be realised that the dried tower 1, and the various modular sections making up such tower 1, have suitable thermal insulation associated therewith.

After passage through the drier 1, and retention therein for a prescribed period of time whereby to allow for reduction of moisture content of the "green" product by a predetermined amount or to a predetermined level, the thus dried product will exit from the top end of the tower, via the cover and seal arrangement 5, into a transfer tunnel 6 for subsequent transfer, laterally of the overall apparatus and in a substantially horizontal direction, to a kiln portion of the overall apparatus. To assist in such transfer, in the especially preferred embodiment illustrated the transfer tunnel 6 will be provided with or include a gripper means and runway 7, for the loaded kiln furniture. In practice, however, any suitable means may be employed for achieving movement of the dried product out of the drier 1 into the kiln portion 20 of the apparatus, via the horizontally disposed tunnel 6. The transfer tunnel 6 is enclosed and insulated, whereby to minimise loss of heat. At or in the vicinity of the upper end of the drier 1 the transfer tunnel 6 is provided with exhaust means 8 of any given type, as for example a duct, preferably including a fan or the like draft-inducing **equipment therein.

S. 20 After passage along the transfer tunnel 6 the kiln furniture, with dried product disposed thereon, is transferred into the kiln 20 via or through a cover and seal arrangement 21. The kiln 20 itself, in the form of a vertical tower, exhibits three distinct zones, namely a pre-heat zone 22, a fire or firing zone 23 S. and a cooling zone 24. In like manner to the drier 1, the kiln is preferably 25 modular in construction, being made up of a plurality of discrete sections, dependent upon production requirements. In other words, the overall height of the kiln 20 is not of the essence of the invention and may be varied to suit practical requirements.

The dried product entering the top of the kiln 20 is passed downwardly through the respective zones 22, 23, 24 to the bottom 25 of the kiln 20. To achieve such lowering a jack or the like lifting and lowering device 26 is included within the kiln 20 itself, to allow for traverse of product to be fired from the top -7- 17/7/96GS7831.SPE,7 to the bottom of the kiln 20. In like manner to the drier 1, the kiln 20 is provided with at least one internal wall 27 to assist in controlling the direction of movement of the product through the kiln 20. At or in the vicinity of the lower section of the kiln 20 there is provided an area 28 for receiving fired product exiting from the kiln 20, such area 28 including an airlock or the like means 29 to prevent unwanted entry of ambient air thereinto, as well as unwanted egress of heated air from the kiln The preferred embodiment illustrated involves a single drying tower 1 and corresponding kiln tower 20 disposed adjacent thereto. It should be realised, however, that the present applicants' arrangement is not to be considered to be limited to the configuration shown. In an alternative embodiment a plurality of drying towers can be arranged in a side-by-side array, with preferably the equivalent number of kiln towers associated therewith and interconnected thereto. In yet another preferred embodiment, two drying towers can be associated with a single kiln tower, the arrangement being such that dried product exiting the towers can be directed, in turn and in sequence, into the kiln for firing. Suitable means will be employed for controlling the speed of movement, and the extent of drying achieved.

The mode or principle of operation of the apparatus in accordance with the S. 20 present invention will now be described in more detail with reference to the drawings. In that regard it should be understood that, whilst FIGS. 1 and 2 illustrate the movement of product throughout the apparatus in accordance with the present invention, FIGS. 3 and 4 illustrate the movement of air or gas through that same apparatus.

25 The apparatus as illustrated includes, in general terms, a drier 1 and a o kiln 20, connected in series whereby to allow for passage of product in sequence therethrough. Green product is fed into the base of the drier 1 through an arrangement of one or more air locks 2 intended to preclude the entry of external ambient air into the drier 1, since the ingress of such air will result in reduced efficiency of the drier.

In an especially preferred embodiment the green product is loaded into or on cassettes or ceramic boxes, constituting what is termed kiln furniture. The -8- 17/7/96GS7 831.SPE,8 use of such kiln furniture serves to simplify the overall kiln and drier design and allows for greater flexibility and control of the firing operation itself. It should be realised, however, that the use of such cassettes or ceramic boxes is not of the essence of the invention. In an alternative arrangement drier trays or pallets can be used, as for example for direct kiln set products.

Once green product has entered into the base of the drier 1, via the air lock 2, the carrier or container therefor will be brought into contact with lifting means 3. In the preferred embodiment illustrated a jack or the like elevator system may be employed for purposes of movement of green product and its associated container in an upward direction through the drier 1. Once again, however, it should be understood that the actual lifting device employed is not of the essence of the invention and that any suitable means for achieving the desired result will be appropriate.

Once the green product has traversed the length of the drier column 1 it can be transferred, in any known manner, to thereafter enter the kiln portion of the apparatus, disposed adjacent to the drier 1. In an especially preferred embodiment a transfer gripping means and runway of any known type may be associated with and extend between the drier 1 and kiln 20 as illustrated. The transfer tunnel 6, which extends between the drier 1 and kiln 20, through which 20 the dried product exiting from the drier 1 travels towards the kiln 20, is enclosed and insulated whereby to minimise heat losses.

In general terms the kiln 20 exhibits three distinct zones, namely a preheat zone 22, a firing zone 23 and a cooling zone 24. The passage of product to be fired through the various zones is controlled in any suitable manner, as for 25 example by computer means or the like (not shown). It should be noted, however, that the means for controlling such passage is not of the essence of the invention. In any case, the retention time of product in any given zone can be "controlled to suit practical requirements for the end product. In the cooling zone 24 means 30 (of any suitable type) may be provided allowing for rapid injection of cooling air, whereby to assist in cooling. The cooling zone 24 also includes means 31 allowing for hot air disposed therewithin to be removed therefrom and directed to the drier 1 for re-use, thereby to improve the overall -9- 17/17/96GS7831. SPE,9 efficiency of the drier. Preferably at the top end of the kiln 20 there is provided an exhaust means 32 of any given type. In an especially preferred embodiment heated air exhausted from kiln 20 can be re-cycled back to drier 1.

In accordance with the present apparatus hot dry air from the kiln cooling zone 24 is directed so as to enter the drier 1 from the top thereof. Such air, once resident within the drier 1, is prevented from escaping therefrom by means of the drier cover and seal 5. In accordance with the method the subject of the present invention, at the prescribed moment the drier cover 5 will be withdrawn, with a new series of kiln furniture, such as for example cassettes or the like, being elevated up the drier tower or column 1. This in turn results in the cassettes or kiln furniture disposed uppermost in the tower, which are now loaded with product which is to all intents and purposes dry, to exit from the top of the drier into the tunnel 6. The thus dried product exiting from the drier 1 is then passed along the transfer tunnel 6 to the top of the kiln 20, whilst at the same time the drier seal and cover 5 closes.

Again at the prescribed time (as controlled by any suitable means and in any suitable manner) the kiln cover and seal 21 opens, allowing a suitable "transfer device to lower the kiln furniture, with dried product resident thereon, into the kiln column 20. The product is then lowered, via the jack or the like 20 lifting and lowering means 26, and the kiln cover and seal 21 closes.

In the preferred embodiment illustrated, prior to lowering of dried product into the kiln 20, column support rods 40 enter a slot (not shown) created or provided above the cassette of kiln furniture and associated product. As the lowering device acts to lower the product, the second bottom cassette will come 25 to rest on the support rods 40, thereby supporting the entire product column within the tower or kiln 20. The bottom cassette is then free of the column and resting on the lowering device 26. A horizontal conveyor or the like means of any given type then functions to move cassettes resident in the bottom of the column 20 from the kiln via air seals. From there burnt product is unloaded from the cassette or the like kiln furniture, with that kiln furniture then being recycled in any known manner whereby to be again loaded with green product for passage through the drier 1.

17/7/96GS7831.SPE, Green product entering the apparatus has thus been dried to the desired extent during movement in an upward direction through the drier tower 1. At the same time drying air, by becoming moist and hence "heavy", moves vertically downwardly through the drier tower, hence improving the overall efficiency of the apparatus. This same improved efficiency is utilised in the vertical kiln wherein the product moves downwardly whilst hot air naturally rises from the cooling section 24 whereby to pre-heat incoming product.

Hot air for the drier 1 comes from the rapid cool and primary cooling air at the kiln cooling zone 24. Air flow through the drier 1 and kiln 20 may be closely controlled, hence maximising the overall efficiency of operation.

The vertical kiln, preferably of modular construction, in accordance with the present invention acts like a chimney, as the air is heated in the fire zone 23 imparting heat to the product and, since its natural tendency is to rise, the hot air then heats up new product entering the kiln. As the product moves in a downward direction through the fire zone and into the cooling zone, it heats up primary air entering the kiln at the base thereof. Some of this air transfers heat up the kiln and provides oxygen for firing fuel. Most of the air recovered from the cooling zone is ducted off for re-use in the drier 1.

Strictly speaking a cover and seal 21 is not required for the kiln 20. In a S. 20 practical sense, however, the very existence of such a cover and seal 21 ensures minimal air passing into the transfer enclosure tunnel 6, at the same time ensuing that waste air is ducted outside via a kiln exhaust duct which could be connected to other kilns. Such an arrangement also allows gas to be fed to an exhaust scrubber (not shown) if required.

25 The arrangement in accordance with the present invention, comprising in series at least one vertical drier and at least one vertical kiln, preferably both of modular construction, is responsible for a number of important advantages when compared with the prior art arrangements. One such advantage results in or resides in utilisation of natural movement of drier air and kiln air.

The continuous nature of the method of production of product utilising the present applicant's apparatus serves to minimise the fuel requirements. The utilisation of vertically-disposed modular configurations serves to minimise 11 17/7/96GS7831.SPE,11 maintenance costs, power costs and the ground area covered by or required for any given plant for a prescribed output. The overall efficiency resulting from the present applicant's arrangement in the long run minimises capital requirements.

The utilisation of kiln furniture of any known type, and in particular socalled cassettes, allows the kiln/drier apparatus in accordance with the present invention to exhibit improved flexibility in the type of product resulting therefrom.

Indeed the present applicant's arrangement is equally suited for the production of bricks, pavers, split tiles, roof tiles and other ceramic products.

The present applicant's arrangement may be fired with any given type of fuel, be it gaseous, liquid or solid.

Furthermore, and in a practical sense, existing vertical kiln technology only allows for the firing of bricks to a temperature of the order of 800'C. By modern standards, and when compared with more conventional kilns, products manufactured by such kilns are underfired and, accordingly, structurally weak, with a relatively high water absorption. Such products are, generally speaking, only suitable for use on internal work, or alternatively require some form of facing to be applied thereto to allow for external use. By virtue of such low firing temperatures, the original concept kilns cannot be used for the production of external face brickwork, paving and/or roofing tiles. This lack of flexibility is of 20 obvious practical and economic significance. In contrast thereto, the arrangement in accordance with the present invention allows firing to temperatures approaching vitrification 1050 0 C to 11500C) thereby 99o producing better, more versatile bricks, pavers and roofing tiles.

In closing it should be understood that the aforegoing description refers merely to preferred embodiments of the method and apparatus in accordance with the present invention and that variations and modifications will be possible thereto without departing from the spirit and scope of the invention, the ambit of which is to be determined from the ensuing claims.

-12- 1717/96GS7831.SPF,12

Claims (13)

1. An improved apparatus for the production of articles for use in building, said articles being in the form of bricks, tiles, pavers and the like, said apparatus being in the form of a continuous updraft kiln including: at least one substantially vertically extending drying tower for receiving a plurality of green articles (as hereinbefore defined) and subjecting such articles to a continuous drying process so as to reduce the moisture content thereof to a predetermined level; at least one substantially vertically extending firing tower interconnected with said at least one drying tower, for receiving said dried articles from said drying tower and for subjecting such articles to further heat treatment; and means allowing for transfer of said articles from said at least one drying tower to said at least one firing tower, the arrangement being such that said plurality of articles is adapted to be passed, successively and continuously, upwardly through said at least one drying tower and then downwardly through said at least one firing tower, thereby to allow said articles to be subjected in turn to respective drying and firing operations.

2. The apparatus as claimed in Claim 1, including a plurality of drying towers arranged in a substantial side-by-side array, and an equivalent number of firing towers, each said firing tower being in flow connection with an associated Z0 drying tower. S3. The apparatus as claimed in Claim 1 or Claim 2, wherein the or each said drying tower is adapted to receive, at or in the vicinity of the bottom thereof, °o.o L ,r i rldin m ea ns for a.. a a a a. a a, C a plurality of said green articles, the or each said drying Lvv I nu t moving said articles upwardly through the height dimension thereof at a %5 predetermined speed or rate of travel whereby to subject said plurality of articles to a continuous drying process, the or each said drying tower including, at or in the vicinity of both the bottom and the top thereof, means allowing for ingress and egress of said plurality of articles in a substantially air-tight manner.

4. The apparatus as claimed in Claim 3, including one or more airlocks at or in the vicinity of both the bottom and the top respectively of the or each drying tower. The apparatus as claimed in any one of the preceding claims, including tunnel means extending between the tops of adjacent and associated

13- 31/3/99GC7831 .SPE,- 13 respective drying and firing towers, said tunnel means allowing for controlled passage of dried articles exiting said drying tower to said firing tower for subsequent further heat treatment. 6. The apparatus as claimed in Claim 5, wherein the or each said firing tower is adapted to receive, at or in the vicinity of the top thereof, a plurality of dried articles exiting from said drying tower, the or each said firing tower including means for moving said articles downwardly through the height dimension thereof at a predetermined speed or rate of travel, whereby to subject said articles to said further heat treatment. 7. The apparatus as claimed in Claim 6, wherein said means for moving said articles respectively upwardly and downwardly within said towers is an elevator or the like disposed internally of the or each said tower. 8. The apparatus as claimed in Claim 6, wherein said means for moving said articles respectively upwardly and downwardly within said towers is a jack or the like, disposed internally of the or each said tower. 9. The apparatus as claimed in any one of Claims 1 to 8, including at least one wall disposed internally of the or each said tower and extending from the top to the bottom thereof, said at least one wall serving to constrain said plurality of articles against lateral movement within the or each said tower during vertical ~0 movement therethrough. 10. The apparatus as claimed in any one of the preceding claims, wherein said drying is achieved by the continuous passage of gas at an elevated temperature upwardly through the or each said drying tower, from bottom to top thereof. 11. The apparatus as claimed in any one of Claims 1 to 10, wherein the or each said tower is of a modular construction, formed from a plurality of discrete sections adapted, in use, to be interconnected in a substantially air-tight manner. 12. The apparatus as claimed in any one of the preceding claims, wherein said plurality of articles are disposed on kiln furniture or the like, such as cassettes, for movement continuously through said apparatus. 13. The apparatus as claimed in any one of Claims 1 to 12, including means associated with the or each said tower for inducing a forced draught therein, thereby to improve drying and firing as required. -14- 31/3/99GC7831.SPE,- 14

14. The apparatus as claimed in Claim 13, including one or more fan means for inducing said forced draught. The apparatus as claimed in any one of Claims 1 to 14, including exhaust means for extracting spent gas from the or each said tower.

16. The apparatus as claimed in Claim 15, wherein said extracted spent gas is returned to said towers for re-cycling.

17. The apparatus as claimed in any one of the preceding claims, wherein said drying and further heat treatment is achieved using heated air.

18. The apparatus as claimed in any one of Claims 1 to 17, wherein the or each said firing tower includes at least three distinct zones for further treatment, including a pre-heat zone, a firing zone and a cooling zone.

19. The apparatus as claimed in Claim 18, wherein said firing of said articles in said firing zone is achieved using air/gas at a temperature of between 10500 and 11500.

20. The apparatus as claimed in Claim 18 or Claim 19, including means for introducing cooling air into the or each said firing tower into said cooling zone, thereby to allow for cooling of said articles exiting said firing zone.

21. The apparatus as claimed in Claim 20, wherein said cooling air as S used for cooling said fired articles, now at an elevated temperature, is directed into *4 :*ZO said drying tower at or in the vicinity of the bottom thereof.

22. The apparatus as claimed in any one of the preceding claims, wherein said articles all constituted from clay ceramic or the like cementitious material. S23. An improved apparatus for the production of articles for use in building, substantially as described herein with reference to the accompanying drawings. S DATED this 31st day of March

1999. a JAGAR DESIGN DEVELOPMENT PTY LTD and LAUNCH INVESTMENTS PTY LTD By their Patent Attorneys: CALLINAN LAWRIE 15 31/3/99GC7831.SPE,-