IL168332A - Ceramic roof tiles from mamshit calcareous clay and granite and other powdered fillers and process for their manufacture - Google Patents

Description

0004/10 168332/4 ιιιιιιιιιιιιιιιιιιιιιιιιιιιιιη 168332 j7'Ji I 453569 ΤΑΊΝ ου iranm ]ΤΌ TJIU ΙΏΤ\Ώ onsran D^nii? JM Ί9ΐ οπ^ l^nm ΏΊ_ΙΤΙ Κ D^Tipna νινθΏ pi ϊπυ I N"7T] Ceramic roof tiles from Mamshit calcareous clay and Granite and other powder fillers and process for their manufacture r 0004/10 168332/4 Ceramic roof tiles from Mamshit calcareous clay and Granite and other powder fillers and process for their manufacture Field of the Invention The invention relates to the production of ceramic roof tiles utilizing Israeli natural calcareous clays and Granite Eilat stone mixed with other powder fillers fired between 760°C to 950°C. The fired ceramic roof tiles, manufactured according to the present patent exhibits a unique crystallographic phase structure comprising Gehlenite, Anorthite and Albite which grow during a low temperature firing process. It is this special mixture together with the time-temperature profile which imparts the roof tiles a specially nice uniform red-brown colour with shining golden Mica dots on its surface. The natural Israeli soft Negev Mamshit clay is the main clay used for making said tiles, which mixtures are characterized by containing natural Granite Eilat stone powder mixed with other kaolinite non-plastic clays fillers.

Background of the Invention It is well known that ceramic products are manufactured by add mixing of clay minerals with fillers such as Feldspars or non-hydrous (non-plastic) clays, and firing of the mixture. According to geological dictionaries a clay is a soil matter containing mainly hydro aluminum silicates which by wetting forms a plastic material. The definition of natural clay is given, for example, in the Dictionary of rnining, mineral, and related terms P.W. Thrust - Bureau of Mines, U.S Department of the Interior 1968.

A clay material for industrial purposes is a mixture of clay and a non-clay materials. The non-clay materials is frequently described as an additive filler material to the natural clay. For example, quartz sand, basalt, feldspar or hard non-clay kaolinite, all may serve as fillers. The common properties of all the fillers is that they do not absorb water and do not form a plastic mould. To conclude, by mixing clay and an additive (filler) with the appropriate amount of 0004/10 - 2 - 168332/4 water a workable plastic mould is obtained from which one can form any desired body so called a green body. After drying, the green body should be sintered at temperatures usually above 1050 °C, to become hard stone like (Ceramic) material conserving its initial green body shape.

By definition, a natural clay is always a mixture of three major mineral components: Kaolinite, Illite and Montmorilonite. The mineralogical composition of clays differ markedly from country to country and even from pit to pit. These differences are observed by the different ratios of Kaolinite/Illite/Iron/ Calcite etc.... It is thus completely wrong to claim CLAY without defining its mineralogical and chemical structural composition. The mineralogical structural composition can be derived by X-ray diffraction technique (XRD). However, the chemical composition may be derived by Scanning Electron Microscope (SEM) or by chemical analytical methods.

The X-ray diffraction pattern obtained by XRD is unique to each claimed clay and may serve as a finger- print of the specific clay claimed. One can recognize the pit or geological area from which a clay sample was taken just by comparing their XRD patterns. By comparing the positions and/or the intensity of each reflection peak one can easily identify the differences between clays of different origin.

In recent years quantitative X-ray diffractometry gained progress and a specialist is able to calculate the quantity of each of the clay components just from the relative intensities of the reflection peaks. Based on the ICDD data base there exist commercial programs which are able to identify accurately the mineralogical composition of natural clays as well as the crystallographic composition of fired clays.

Any ceramic specialist who wants to manufacture ceramic bodies must a priory define the final ceramic body he wants to create. If pottery, for example, he should consider a big body or a tiny one. If a sculpture or sanitary ware, a tile or roof tile is the goal, than different clays should be chosen. It is the final ceramic body that will dictate the type of the clay and the type of the fillers needed. The amount and the particle size of the fillers are governing the plasticity and the workability of the materials. However, the temperature profile must be tuned according to type of clay and the fillers used for the manufacturing purposes.

It is indeed astonishing that in all old and recent published patents on the manufacturing of ceramic bodies the exact definition of the type of the claimed clays and fillers are missing. This 0004/10 - 3 - 168332/4 may cause tremendous difficulty in protecting many patents claiming the use of natural clay. However, the Israeli patents 138826 and 141765 are the only ones in which the clay and fillers are claimed according to their mineralogical and chemical composition together with their XRD finger prints.

The manufacture procedure is crucial to obtain the desired strong ceramic body. Especially, the temperature profile and the maximal firing temperature must be tuned according to the type of the clay and the selected fillers. Generally, it is recommended to fire clay materials to a maximum temperature between 1000 to 1200°C.

For more than 10000 years mankind has manufactured ceramic bodies out of natural clays and fillers. However, one can still invent in this field and recent patents do show invention and progress in the manufactiiring of ceramic bodies. The invention and novelty always combines the special mixture of a certain clay and non-clay materials, modern press techniques and a tuned sintering temperature profile.

During the firing, the clay minerals undergo significant chemical and physical phase structure changes, as evidenced, e.g., by surface reduction, bulk volume reduction and increase in strength, associated with growth of new crystallographic phases. The properties, particularly the physical and mechanical properties, and the appearance, particularly the colour depends on the reactions of the Iron oxides in the used clay components, and the filler additives. Their mixture and in general, the process of the preparation of the raw materials for production and the firing stage profile, impart the roof tile its quality and beauty.

It should be pointed out that the X-ray diffraction pattern of any fired ceramic body differs markedly from one product to another. Indeed, as explained above, the crystallographic structures of the different crystallized phases in the sintered roof tiles depend on the origin of the clay and the origin of fillers, and strongly on the manufacture process, namely, the temperature profile. In the case of ceramic roof tiles, a specialist is able to identify the type of the clay and the type of the filler. In certain cases the firing temperature can also be revealed.

A very special clay called Mamshit clay, was found in considerable quantity in the Israel Negev Mishor Rothem Mamshit area. High quality roof tiles were obtained from mixtures of said Mamshit clay with non-clay materials. The process for their manufacture, are disclosed and claimed in Israeli patents No.138826 and 141765. A unique uniform brown-red colour is achieved by adding small amount of barium carbonate and the appropriate low temperature firing profile. 0004/10 - 4 - 168332/4 It is now been found that equally fine roof tiles can be produced by utilizing the said clays and the process described in IL patents No. 141765, 138826 by using in addition a different filler components. The starting said Mamshit clay material is now mixed with powder of Granite Eilat rock which is different from the Basalt or hard clay described in said patents. By adding Granite powder, which contains Potassium and Mica components mixed with\or without, non-plastic kaolinite (Hadatz), the firing temperature is further reduced where the obtained tiles exhibits good mechanical properties and a pleasant colour with shining golden Mica dots. These new tiles meet the Israeli standards for roof tiles.

As mentioned in the previous US patent No 3,804,644 , 1000°C to 1125°C is in general temperature claimed for firing roof tiles containing Granite powder. However, in order to obtain a denser, more abrasive resistant material the recommended firing temperature range is 1100 °C to l200°C.

In several previous publications on ceramic materials produced from clay and granite the recommended sintering temperature is always above 1000 °C , see for example: (1) " Materials for ceramic tiles baking at 1080 °C etc...." , M.Bacanac et al. 1984. (2) "Utilization of granite-basalt in ceramic floor tiles mixture", F. Osman et.al 2004. (3) "Ceramic tile with granite and Kaolinite clay" , E.T.A. de Souza 2004. (4) "Development of ceramic tiles based on quartzite and granite" P. Torres et al. 2007.

The recommended firing temperatures are much above 1000°C, is a result of the nature of the main clay used, which is different from the Israeli calcareous Negev clay Mamshit. It will be set forth redefined and characterized.

It is the purpose of the present invention to provide ceramic raw materials and a tuned firing profile that drastically reduce the firing temperatures to much below 1000 °C, claimed blow 950 °C. As shown in Fig.5 even a maximum firing temperature of 760°C is sufficient to produce strong ceramic bodies. This sintering temperature is the lowest thus far reported in the ceramic roof tile industry.

It is therefore a purpose of this invention to provide roof tiles of particular mechanical and colour properties with golden dots, and of considerable beauty of practical value. 0004/10 - 5 - 168332/4 It is another purpose of this invention the use of raw material mixtures for sintering roof tiles at temperatures as low as possible, thus saving fuel energy and reduce air pollution.

Thus, the invention has considerable practical value, as the firing temperature is lower than claimed in the US patent No 3,804,644 (1000-1200°C), Korean Patent 92-0005406 (1200°C), Japan Patent 7334410 (1150-1250°C, Patent W094/11321 (1050-1150°C), as well as in Israeli patents No. 141765, 138826 (800-1000°C). This achievement allows to manufacture roof tiles even blow 800°C at a lower energy cost.

Summary of the Invention The invention provides, in the first place, the manufacture of ceramic roof tiles utilizing a mixture of Mamshit clay and Granite\and or Hadatz stones that can be processed and fired below 950°C. Different from the IL patents No. 141765, 138826 the said clays and additive fillers can be sintered even at temperature of 760 °C, utilizing the temperature profile of Fig.5. It further provides a choice of non-clay raw materials mixtures comprising of Granite, Basalt, non-clay kaolinite-Hadatz filler, that permits to achieve the tiles of the invention, and which will be hereinafter characterized by their unique crystallographic phase composition, especially High Albite, Orthoclase and Gehlenite.

The invention further provides a process for mixing and heat-treating the aforesaid clay No 2, redefined in tables IV and V and Fig. 7, mixed with Granite\Hadatz powder to obtain green (unfired) tiles and a firing process between 760 to 950°C for obtaining the final roof tiles from the green tiles, which are essentially the same as those described for obtaining in the aforementioned IL patents 133826,141765. However, they contain GraniteVHadatz powder instead of being mixed with Basalt and\or Chocolate (clay No 1, IL 133826,141765) fillers.

Granite component of the starting mixture of this invention is Granite containing Quartz + Albite+ Orthoclase + Mica+Iron (said four denominations being used as synonyms in this specification and claims) found in Eilat and its surroundings in Israel, as well as 0004/10 - 6 - 168332/4 elsewhere in the nearby regions, which has the chemical composition and the mineralogical structure set forth below in Tables I and II and its X-ray finger print is given in Fig 1.

Table I: Chemical composition of Granit Rock found in the South of Israel Table Π Mineralogical structure of Granite The aforesaid Granit rock is also characterized by the X-ray pattern defined in the 0004/10 - 7 - 168332/4 following Table III as derived from the X-ray finger print Given in Fig.l . As the minarollogical composition of Table II is a model dependent analysis it is always subjected to substantial mistakes, therefore, the X-ray diffraction pattern peaks of Fig.l should serve as the finger print of the raw material used.

Table HI Eilat Granit rock -Main d Values derived from the X-ray pattern finger print Given in Fig.l An=Anorthite, A=Albite 0004/10 - 8 - 168332/4 The raw materials mixtures according to the invention also comprise a main component, called herein "Clay No. 2" - Soft Negev sediment Clay (Yellow-brown stone color called Mamshit clay), and may comprise a third minor component, called herein "Clay No. 3" -Dolomite-rich Mountain Clay (Yellow-green stone color). The chemical composition, mineralogical structure and X-ray diffraction patterns of said clay components are defined in patents 138826 and 141765. Mamshit Clay No 2 was remeasured with the most advanced G670 Guinier X-ray diffractometer. It is now redefined in Fig. 6 and Table IV as below: 0004/10 - 9 - 168332/4 Table IV X-ray diffraction d Values (Angstrom) of clay No. 2 (Mamshit clay) derived from Fig.6, finger print of Mamshit Clay, measured with G670 Guinier Camera. 14.7 M - Montmorillonit 2.34 M-W B broad peak .4 W illite 1.92 W .05 W illite 1.91 S 7.62 VW 1.87 S 7.18 S Kaolinite (K) 1.817 S Quartz 4.98 W 1.92 W 4.49 M (K) 1.91 S 4.35 M (K) 4.27 M Quartz 4.15 M (K) 3.86 M Calcite 3.58 S (K) 3.35 VS Quartz 3.24 W Microcline FS 3.04 VS Calcite Etc.* 2.69 W Hematite 2.56 M K+I * The intensities of the reflections are not subjected to changes due to preferred orientation. 2.49 S Calcite VS - Very Strong; S - Strong; M - Medium; W - 2.38 W (K) Weak; V W - Very Weak; B - Broad Reflection 2.28 S Calcite 2.28 M 2.23 M-W 2.20 VW 2.13 M-W 1.99 M-W 0004/10 - 10 - 168332/4 As the minerallogical composition analysis of the calcareous clay No 2 as defined in patenets 138826 and 141765 is a model dependent result, it is always subjected to substantial mistakes, the X-ray diffraction finger print given in Fig. 6 thus should serve as the finger print of the raw material used. It is thus the X-ray finger prints which counts in order to define accurately the clay materials and fillers used in the present patent.

For manufacturing roof tiles according to the invention, the said components are preferably used in the following proportions by weight: Granite- 15 to 35 wt%, Clays No. 2- 65 to 85 wt% and not more the 20% of clay No 3. However, the present patent comprise the use of Granite filler (filler Nol) with only one of the above clays. In addition, it comprises the mixture of Basalt (filler No2) and/or other non-clay fillers (filler No3) defined in both IL patents 138826, and 141765 as Clay Nol . Clay No 1 in IL patent 138826 basically comprise of pure Kaolinite with or without small amount of quartz, depending on the depth of the pit in Mahtesh (crater) Ramon. For un explained reason Geologists call the pure kaolinite non-clay HADATZ, the finger print of which is now depicted in Fig.7 .

Examples of compositions of mixtures of Granite and other fillers with clays No. 2 and 3 are set forth in Table V. Intermediate proportions can also be adopted within the scope of the invention.

Table V Admixing w% of the Granite/ Basalt and non-hydrous clays with Mamshit Clay Granite Mamshit Clay Basalt Hadatz Mountain Filler No l No.2 Filler No 2 Filler No. 3 Clay No. 3 17 73 10 65 65 10 10 70 15 5 5 0004/10 - Π - 168332/4 It should be understood that the invention comprises the use of clays and fillers that are different from the aforementioned ones to such a degree as not substantially to influence the properties of the roof tiles obtained from them, as will be defined hereinafter.

The operations of the process of the application are essentially the same as those of the aforesaid IL patents No. 138826,141765 with the difference in the low firing temperature, and the filler mixture additives which comprise: A - fine dry grinding and mixing the dry clay No 2 with Granite powder ; B - fine dry grinding and mixing the dry clay minerals No.2 and 3 with Granite/Basal t non- hydrous clays powders mixed with or without natural quartz sand; C -moistening them; D - preferably, allowing the moistened mixture to rest for a time; E - extruding the said mixture; F- cutting the extruded mixtures into plates; G - forming the said plates into green tiles; H - drying the green tiles under gradually rising temperature; I - firing the dried green tiles under a rising temperature up to a maximum from 760 to 1000 °C, for at least one hour.

K - causing the fired tiles to cool to room temperature.

The firing at the maximum (plateau) temperature is preferably carried out for 2 to 8 hours depending on the chosen firing maximal plateau temperature between 760 to 1000°C.

Preferably, the drying is effected up to a final temperature of 60 to 85°C for 20 to 36 hours.

The roof tiles according to the invention are characterized by the crystallographic phase structures are given in table VI and depicted in their X-ray diffractograms of Fig. 2,3and 4. The major peaks are High Albite, Orthoclase and Gehlenite and Augite. The Orthoclase is evidenced by a peak at 3.29 Angstrom in between the very strong Quartz peak at 3.35 and the strong (S) broad peak at 3.21 Angsrom. As albite (Sodium feldspar) and Anorthite (Calcium feldspar) are iso-structural compounds and they mix in nature in all ratios, it is difficult to distinguish between them by X-ray analysis. However, it is possible to verify the existence of Potassium (K), which establishes the Orthoclase phase, according to Figs.2,3 and 4, and the EDAX-SEM electron microscope results given in Table VII . 0004/10 - 12 - 168332/4 Table VI: Main d Values (Angstrom) of fired roof tile containing 25%Granit and fired at temperatures 870 and 800 and 760 °C , derived from the X-ray patterns given in Fig.2,3 and Fig. 4 and both serve as the finger print. d value (Angstrom) Relative intensity * d value A Relative intensity 4.26 V S Quartz 4.21 W Orthoclase 4.04 S Orthoclase 3.82 W 3. 67 W 3.47 W 3.35 VVS Quartz 3.291 S Orthoclase 3.256 S Albite high 3.196 VS Albite high 3.35 VVS Quartz 2.99 M Augite 2.857 S Gehlenite 2.699 MS Hematite 2.55 W *The intensities of the reflections are subjected to changes dependent on the sintering temperature within the claimed range, and due to preferred orientation.

VS - Very Strong; S - Strong; M - Medium; W - Weak; VW - Very Weak; B - Broad Reflection VS= High Albite S= Gehlinite For the full pattern finger print see Fig. 1 0004/10 - 13 - 168332/4 The structure of the roof tile fired at 760 °C contains in addition a small amount of the mineral Illite evidenced by two reflection peaks at 10.00 and 4.50 Angstrom . The Augite is evidenced by a peak at a "d" value of 2.99 (Angstrom).

Table VII The chemical composition of roof tiles manufactured with 25% Granite Eilat and Negev clay No 2, derived by Electron Scanning Microscope (ED AX).

Element Wt % At % O 30.38 46.40 Na 0.84 0.89 Mg 3.13 3.14 Al 10.94 9.91 Si 29.34 25.53 S 0.61 0.46 K 3.32 2.07 Ca 12.49 7.62 Ti 0.82 0.42 Fe 8.13 3.56 Total : 100.00 100.00 Having the aforementioned crystallographic structures the roof tiles gains a unique color, the Rosa color with shining golden dots, as well as desirable strength and water absorption properties. All tiles having such a structure and colour are comprised in the invention. 0004/10 - 14 - 168332/4 Brief Description of the Drawings In the drawings: Fig.l: X-ray Diffraction pattern (in 2 Theta scale) finger print of Granite Eilat stone. The calculated X-ray d value analysis of the mineralogical-structural composition of Granite stone is pointed.

Fig 2: X-ray Diffraction pattern (in 2 Theta scale) finger print pattern, of roof tile manufactured from Clay No. 2 and Granite Eilat powder No. 1, sintered at 870°C. The line positions of albite high (Albite, A, Anorthite, An) and Gehlenite (Geh) and Orthoclase (Or) are indicated. The line positions and their calculated d values are indicated and are also given Table VI.

Fig. 3: X-ray Diffraction pattern (in 2 Theta scale) finger prints patterns, of roof tiles manufactured from Clay No 2 and Granite Eilat powder and fired at 800°C . The line positions of albite high (Albite+ Anorthite) and Gehlenite and Orthoclase are pointed and are also given Table VI. Measured by Guinier type Huber G670 diffractometer.

Fig. 4 X-ray Diffraction pattern (in 2 Theta scale) finger prints patterns, of roof tiles manufactured from Clay No 2 and Granite Eilat powder and fired at 760°C . The line positions of Illite, albite high (Albite+ Anorthite) and Gehlenite and Orthoclase are pointed and are partially given Table VI. Measured by Guinier type Huber G670 diffractometer.

Fig. 5: Temperature profile example for sintering roof tiles manufactured from Negev clay and Granite filler. The recommended maximum temperature plateau is 760 to 780°C depending on the sintering time preferably for a longer time if firing at low temperature and depending on the clays and fillers admixturesTime-temperature diagram of the firing of tiles according to an embodiment of the invention. It is the thermal firing profile of claim 61 and 6K.

Fig. 6 : X-ray diffraction pattern (in 2 Theta scale) finger print of Mamshit clay No 2 as defined in table V and in IL Patents 138826 and 141765.

Fig. 7 : X-ray pattern (in 2 Theta scale) finger print of Iron rich Negev hard Non-clay Kaolinite of type 1A found in Crater (Mahtesh) Ramon. It is identical to clay No 1 of patent 138826 but does not contain Quartz. Equally, it serves as non-clay filler. Israeli Geologists named this geological layer HADATZ.

The tables and diagrams included in this description illustrative and are not intended to limit the invention, the scope of which is defined by the claims. 0004/10 -15- 168332/4

Claims (13)

1. Ceramic roof tiles of red-brown colour with shining golden Mica dots on their surface manufactured by dry mixing of powdered Soft Negev Mamshit clay No. 2 with powdered Granite Eilat stone filler Nol (as described in Tables II and III and Fig.1), sintered at the temperature range from 760°C to 950°C and characterized by the fact that they contain the crystallographic Gehlenite, Augite, Anorthite, Albite and orthoclase phases, the said Gehlenite being evidenced by the X-ray reflection peak at d value of 2.859 Angstrom, Orthoclase is evidenced by reflection peaks at d values of 4.05, 3.28, 2.23 Angstrom, and a strong broad reflection peak being of Anorthite + Albite + orthoclase, centred at about d value of 3.21 Angstrom.

2. Process for production of ceramic roof tiles as claimed in claim 1 comprising providing a mixture of clay No 2 with powdered Granite filler No 1 , optionally mixed in all ratios with hard non-plastic clays Iron- Rich Negev Kaolinite (Hatdatz) filler No 3, and/or mixtures of Granite with Basalt Feldspar filler No 2, and firing the said mixtures.

3. Process according to claim 2 comprising providing a mixture of Mamshit Clay (Clay No. 2), optionally mixed with Dolomite-rich Mountain hydrous clay, as minor clay (10-20w%), and firing of said mixtures.

4. Process according to claim 1 or 2, comprising the following steps: A - fine dry grinding and mixing the dry clay No 2 with Granite powder ; B - fine dry grinding and mixing the dry clay No.2 with Granite/Basalt/non-hydrous clay powders fillers No 1,2 and 3, fine mixed with or without natural quartz sand; C -moistening them; D - preferably, allowing the moistened mixture to rest for a time; E - extruding the said mixture; F cutting the extruded mixtures into plates; G - forming the said plates into green tiles; 0004/10 - 16 - 168332/4 H - drying the green tiles under gradually rising temperature; I - firing the dried green tiles under a rising temperature up to a maximum of from 760 to 950 °C, for at least one hour. K - causing the fired tiles to cool to room temperature.

5. Process according to claim 4 wherein the firing temperature raises from 40 to a maximum of 760 °C according to the temperature profile of Figure 5., and sintered for at least lhour in the maximal plateau temperature zone.

6. Process of manufacturing the roof tiles according to claim 1 comprising mixing powder materials according to claim 2 and 3, using as fillers a mixture of Granite (filler No 1) and/or Basalt rocks (filler No 2) and/or non-hydrous Kaolinite clay (filler No 3) with the clay No. 2 - Soft Negev Mamshit clay as major ingredient, and optionally clay No. 3 - Dolomite-rich Mountain clay as minor clay, sintering between 760 to 950 °C, the ceramic roof tiles, having the X-ray d values set forth in Table VI , substantially as described and illustrated.

7. Ceramic roof tiles according to claim 1 processed according to claim 4 , using clay mixtures - containing clay No 2 as a major clay, with Granite and/or mixed fillers according to claims 2,3,4 and 6, processed sintered at temperatures between 760 to 800°C, substantially as described and illustrated. 0004/10 - 17 - 168332/4

8. Ceramic roof tiles according to claim 1, manufactured according to the process of claim 2,3,4 or 5, whenever fired at maximum plateau temperature of 760°C , having substantially the following X-ray diffractogram d values finger print: 2 T h e ta

9. Ceramic roof tiles of claim 1, manufactured according to the process of claim 2,3,4 or 6 whenever fired at maximum plateau temperature of 800°C , having substantially the following X-ray diffractogram d values finger print: 2 Theta 0004/10 - 18 - 168332/4

10. Ceramic roof tiles according to claim 1, manufactured according to the process of claims 2,3,4 or 6 whenever fired at maximum plateau temperature of 870°C , having substantially the following X-ray diffractogram d values finger print: G e h -G e h le n ite e 2 T h eta

11. Ceramic roof tiles according to claim 1 having the Chemical composition analysed by Scanning Electron Microscope SEM-EDAX set forth in Table VII .

12. Production of ceramic roof tiles according to claiml, substantially as described and illustrated.

13. Use of mixtures of clay No 2 as the main clay with Granite and/or other mixed fillers for the manufacture of ceramic roof tiles, as claimed in any of the claims 1, 8-10 and substantially as described and illustrated.