MXNL04000097A - Thermal treatment for clays pertaining to the montmorillonite family, which is incorporated into the formulation of ceramic products. - Google Patents

Abstract

The present invention consists in a thermal treatment performed at a temperature of from about 500 degree C to about 1000 degree C for clays pertaining to the montmorillonite family (montmorillonites, bentonites and beidellites), which is useful in the formulation of ceramic bodies at concentrations higher than 5% and up to 80% by weight, thereby removing flocculation and plasticity problems. The treatment may be incorporated to the formulation of pieces which are both industrially and handmade processed, thereby allowing high density pieces to be produced using a low power consumption during the grinding process. The invention is further useful for porcelanic ceramic bodies.

Description

THERMAL TREATMENT OF CLAYS OF THE MONTMORILLONITAS FAMILY FOR THEIR INCORPORATION IN THE FORMULATION OF CERAMIC PRODUCTS OBJECT OF THE INVENTION The present invention has for its object the development of a method for the use of the clays of the family of the montmorillonites (montmorillonite, bentonite and beidelite) in the field of the ceramic industry for the manufacture of known ceramic tiles and coatings as extracted or pressed floors: stoneware (group? G), semi-stoneware (Bita group) or porcelain tiles (Bla group), wall and monoporous tiles and coatings (group BIU), according to the classification of the European Standard for ceramic pieces used in floors and walls UNE 67-087-85 EN 87, as well as manufacture of ceramics in general where kaolin, feldspars or any other aluminosilicate are used as raw materials, as well as in the pottery in which plastic clays are used for modeling manual of ceramic pieces, in percentages greater than 10% by weight of montmorillonites, this percentage being higher than currently possible pray.

BACKGROUND Montmorillonites (montmorillonite, bentonite and beidelite) are a family of clay minerals whose name derives from the French town of Montmorillon, where they were identified in 1874. Both its structure and its chemical composition are directly related to those of pyrophyllite. which has the general chemical formula (Al2 (OH) 2 (Si205) 2).

The montmorillonites (montmorillonite, bentonite and beidelite) have the property of adsorbing cations and retaining them, by isomorphic substitution in the structure, generating negative charges in its structure. As a result of these isomorphic substitutions, for example the substitution of Al3 + by Mg2 + or by Fe2 + in octahedral positions and that of Si * by Al3 + in tetrahedral positions of the crystalline structure, generate a deficiency of positive electric charge in the structure that has the form of sheet. It can be considered that the general chemical composition of montmorillonitic minerals is: Being: n = Number of cations in octahedral positions, ranging between 2 and 2.22 so all the montmorillonites: Mintmorillonite, Bentonite and Beidelite, have octahedral character. m = Number of extreme cations that oscillates between 0.30 and 0.33 w = Number of water molecules located between the leaves.

As can be seen, because montmorillonite has different types of isomorphic substitutions, depending on the amount and type of cation that this substitution makes, there is a range of compositions (n) that derive in continuous series of composition, characteristics of the montmorillonite minerals. In general, the average composition of a montmorillonite mineral will be: (All.5-2.oMgo-0.66) (Alo-o.33SÍ3.67-4.0) Olo (OH) 2Na0.33ewH20 There are also different minerals with contents of variable iron (Fe3 +) substituted isomorphically in the structure of montmorillonite , whose mean compositions and denominations are: (Al1.5iMgo.6oFe0.o7) (Alo.28SÍ3.72) Oio (OH) 2Nao.33 wH20 Denominated Montmorillonites as a consequence of its low iron content.

(Al1.53Mgo.33Feo.18) (Alo.13SÍ3.87) Oio (OH) 2Nao.4o, wH20 Called Bentonites.

(Ali.46Mgo.o8Feo.5o) (Alo.36SÍ3.64) Oio (OH) 2Nao.4o wH20 Called Beidelitas.

In all the mentioned compositions, sodium can be substituted by other alkaline or alkaline cations such as K + and Ca ++, although the nature of these external cations does not modify the crystalline structure of the mineral.

The problems that have been associated with the use of the clays of the family of montmorillonites for the formulation of ceramic pieces on an industrial scale, are the low concentration of solids that can be handled, the problems associated with the drying of the molded pieces and during the decorating processes subsequent to molding, which are usually carried out by means of aqueous suspensions of enamels (slips) on the molded part, since one of the characteristics of dehydrated bentonites is that they increase their volume when hydrated and reduce it when losing the humidity, causing cracks in the decorated pieces.

In a traditional formula of the ceramic body, the content of plastic clay known as Ball Clay (Aluminum silicate derived from the Kaolinite Al2 (Si205) (OH)) and feldspar is of the order of 60% by weight, it being common that the rest is composed by Silica, Kaolin and other aluminosilicates, as well as bleaches derived from Zirconium silicate or Titanium dioxide; fluxes such as talc, Calcium or Sodium carbonate, phosphates and additives (binders, suspending agents, deflocculants, and preservatives), etc.

In these formulations, the clay content of the bentonite type is not higher than 5%, due in large part to the modification of the rheological properties that this type of minerals impart to the aqueous suspensions, observing an increase in the viscosity at concentrations of solids less than 40%, which does not allow its use in the processes of preparation of ceramic fillings by wet milling or in the preparation of extrusion pastes, due to the high cost of eliminating surplus moisture. In high-water extrusion processes, the clays of the montmorillonite family, when they are in an amount greater than 5% by weight, increase the shrinkage during the drying process, causing cracks to appear in the pieces. thus elaborated, even when there is a high availability of this mineral, which involves a lower cost of raw material and due to its chemical composition and physical properties that modify the behavior and properties of aqueous suspensions, as well as dry pieces molded by any available method can replace the feldspar and the Clay Clay when the heat treatment object of this invention is applied.

In industrial processes, the concentration of solids desirable in the aqueous suspensions obtained by grinding or mixing the clays that make up the ceramic body, is equal to or greater than 60% in order to reduce costs in the drying stage and reduce the shrinkage of the molded parts (by pressing, extraction, casting or industrial or artisanal turning) during the drying of the same. For the reasons explained above, the use of clays from the montmorillonite family has always been limited.

On the other hand, when it has been tried to use these clays in the production of artisan pieces in the field of pottery, the paste that is prepared for manual molding, although it has the appropriate plasticity to be molded with the hands, also presents serious problems of cracking during the drying of the pieces or they must be subjected to periods of prolonged drying and humidity control of the dryer atmosphere, as a consequence of the excessive contraction they present.

Due to the above, only the use of bentonites in the formulation of ceramic bodies as stabilizing agents of suspensions has been reported, being used in a maximum of 2-3% (Pat, ES 2,190,728, Vicente Diez). The use of bentonite as an additive for the increase of compaction (bulk density) and the mechanical strength of ceramic bodies has also been reported (MF Abadir, EH Sallaman, IM Baku, "Preparation of Porcelain Tiles from Egyptian Raw Materials". Ceramics International 28 (2002), 303-310.), Or in US Pat. No. 5,763,345 (Ohshima), where a method for making a synthetic clay substitute for use in ceramics is described, where the use of 2-20 is reported. % Sepiolite, Palygorskite and Bentonite, any of these clays or mixtures thereof for the composition of a substitute of natural clays for use in ceramics, differing from the present invention in that no thermal treatment is proposed to control and modify their properties before being part of the composition of synthetic clay.

In the Pat.CN1454941, a method to obtain homoionic sodium bentonites is described, by means of the sprinkling of a reaction liquor., composed of an alcoholic solution plus sodium compound, which is sprinkled on a layer of clay, allowing the exchange of the cations that make up the bentonite by the sodium ion containing the reaction liquor and accelerating this process by heating the mixture by means of microwaves, which is different from the objective and procedure of the treatment of the present invention, since the present invention does not aim to homogenize bentonite clay by thermal treatment, but to modify its physical and chemical properties in order to be used in higher concentrations 20% in ceramic compositions.

Other patents are also available, such as Pat. CN1446845, US 6495511B2, RU2044587C1 and RU2199504 which involve the treatment and activation of bentonites, but which are not within the scope of the present invention, which specifies the heat treatment to modify its physical and chemical properties in order to be used in compositions of ceramic bodies in concentrations greater than 20% by weight.

Other attempts to use montmorillonite or bentonite clays in ceramic compositions have been reported by Bresciani et al. (A. Bresciani, M. Dardi, M. Federic, C. Ricci, "Porcelain Stoneware Large Format Plates." QUALICER 2002, Castellón , Spain), where they used montmorillonite clay to increase the density of the ceramic bodies, and according to their results, a maximum of 15% of this clay was used, although important problems were reported in the Theological properties of the slip (suspensions aqueous for wet milling) elaborated.

The present invention relates to a thermal treatment of montmorillonite or bentonite clays for the modification of their physicochemical properties, which allows them to be incorporated in concentrations greater than 20% in aqueous suspensions, obtained by wet milling, or by dispersing the composition in water for the formulation of ceramic bodies, has the particularity that by means of it, aqueous suspensions of formulations of ceramic bodies are obtained with solids concentrations of 60% w / w with viscosities of 700-800 cps, which have a fluid appearance , which facilitates its use in the subsequent operations of the process of forming ceramic bodies, which can be used in the ceramic processes, by obtaining dry powders to form pieces by pressing, or the direct use of these suspensions for processes of conformation of bodies by casting pieces in plaster molds om Synthetic olives, and that has the advantages of modulating the plasticity of the suspension by changes of time and temperature of thermal treatment of the montmorillonite or bentonite clays, as well as the dry mechanical strength of the compact bodies obtained by any method (pressing, casting , turning etc.), which no other invention claims.

DETAILED DESCRIPTION OF THE INVENTION As described above, the laminar nature structure of the clays of the Montmorillonite family consists of sheets made up of Silicon tetrahedra and Aluminum Octahedrons in a ratio of 2: 1 (Figure 1).

The isomorphic substitutions of Aluminum and Silicon by elements such as Iron or Magnesium among others, induces a decompensation of load in the structure, which is compensated by the integration of hydrophilic groups (OH-), which render the clay highly hydrophilic due to the presence of surface groups with negative charge, which are compensated by the soluble cations present in the aqueous suspension such as H +, Li +, Na +, K +, Mg ++, Ca ++ and others of the same charge and size. The flocculating effect of these ions on the clay suspensions is well known and their effect was described by H. Ardí, being known as the Ardí Schulze Rule (Schulze, H. (1882), J. Prakt. Chem., 25, 431). The surface charges of the material and the amount of soluble cations it contains, induce a high interaction between particles, forming three-dimensional networks, which changes the Theological properties of the suspension such as viscosity and mass or volume flow, presenting a behavior called thixotropy, which is represented by the hysteresis formed by the difference in viscosity between the ascending and descending curves of the velocity gradient vs the shear stress in a given range of velocity gradient for the analysis of the rheological behavior of a suspension or compound . An increase in the area formed by the hysteresis of the gradient velocity curve vs. the shear stress, indicates a flocculated state of the suspension, which is equivalent to saying that the suspension is more prone to form three-dimensional networks of particles that hinder the flow of the same. The montmorillonite, bentonite and beidelite clays, when incorporated in aqueous suspensions without previous treatments, as described in the present invention, tend to increase the state of flocculation of these suspensions, and therefore, have a thixotropic and pseudo plastic behavior , being for this reason that can not be used in the formulation of ceramic bodies in concentrations greater than 5-10%, since the suspensions thus obtained, are not fluid or have a very viscous gel appearance, so it is necessary to reduce the concentration of solids of this suspension at values lower than 60% w / w (w / w) in order to obtain fluid suspensions.

Process description. The material used for the thermal treatments described here was a bentonite clay, which was subjected to thermal treatment. The temperatures corresponding to the treatments were determined from a thermogravimetric and differential thermal analysis (Figure 2). Due to the composition of montmorillonites (montmorillonite, bentonite and beidelite), these can be transformed by thermal means to obtain materials with characteristics similar to Ball Clay and Feldspatos.

The clays of the montmorillonite family, have in their structure hydroxyl groups (OH-), which are lost at temperatures higher than 600 ° C. The loss of these hydroxyl groups, generate a change in the structure of the clay, decreasing the difference of negative charges it contains. Hoffman (Hofmann, U., Endell, K., and Wilm, D (1933), Kristallstxuktur und Quellung von Monmorillonit, Z. Krist., 86, 340-348) observed that montmorillonites possess the property of absorbing cations and retaining them strongly, what is in agreement with the fact that the leaves of this clay have a negative electric charge, as a result of the isomorphic substitution processes; for example: the substitution of Al + for Mg2 + in octahedral positions and that of Si4 + for Al3 + in tetrahedral positions. An effect that is observed with the thermal treatment of the bentonite clay of the present invention, is the loss of swelling ability (interlaminar hydration) of the treated clays, this loss being greater as the temperature and the treatment time increase.

In Figure 2, it is observed that a weight loss occurs in a temperature range of 600-800 ° C, which, as mentioned above, is associated with the loss of hydroxyl groups from the clay structure. According to these results, it was determined that a thermal treatment in this range is adequate so that when preparing clay-water suspensions, the new structure of the clay does not present theological problems (thixotropy or high viscosity) Table 1.

Table 1. Thermal treatments applied to Bentonite.

X-ray diffraction (XRD) Figure 3 shows the X-ray diffractograms of bentonite without treatment and thermally treated at temperatures of 600 ° C, 700 ° C and 800 ° C corresponding to identification 1, 2, 3 and 4 respectively in the aforementioned Figure 3. The structural transformation of bentonite can be observed in the evolution of the 002 plane with the different thermal treatments proposed here, which is observed around a diffraction angle 2T of 10 °. This characteristic peak disappears with the increase of the heat treatment temperature, which indicates a collapse of the foliar structure of the bentonite, and as a result it is observed that the treated clays have less swelling when they are suspended in water and therefore particle-particle interaction is reduced after heat treatment.

Particle size distribution An analysis of the size distribution of the particles (Figure 4) shows that the effect of the different thermal treatments at 600, 700 and 800 ° C, corresponding to identifications 1, 2, 3 and 4 of the figure, it is a tendency to the sintering of the particles, which also corroborates the results observed in the XRD analyzes figure 3.

According to Figure 4, the samples treated at 600 and 700 ° C lines identified as 2 and 3 in the figure, present a concentration of 20% of particles with a size below 1 miera, while the treatment at 800 ° C line identified as 4 in figure 4, does not present particles smaller than 1 miera, and 65% of the particles are between 5 and 10 microns. As the particle size increases with the treatment temperature, it is assumed that a sintering process is being carried out, which can be in the solid state when it is intraparticular, and liquid when different particles are involved in this sintering process. tending to present an agglomerated state, increasing the particle size, detected in the distribution analyzes by particle sizes.

The deflocculation curves of the bentonite treated at 600, 700 and 800 ° C with the different deflocculants (Sodium Tripolyphosphate, Sodium Hexametaphosphate and Sodium Polyacrylate) tested, are shown in Figures 5, 6 and 7 for each heat treatment respectively, The additives sodium tripolyphosphate, sodium hexametaphosphate and sodium polyacrylate, were identified in each figure as 1, 2 and 3 respectively. As expected, according to the results of particle size distribution (Figure 4), by increasing the heat treatment temperature, suspensions are obtained that can be deflocculated more easily than clay without treatment. The clay treated at 600 ° C is difficult to deflocculate due to the well-known properties of montmorillonites, bentonites and beidelites (high hydrophilic character and high surface charge that favors the inter-particular interaction edge-face, edge-edge and face-face ). Although with the heat treatment at 800 ° C it is possible to have adequate Theological properties for the formulation of the slip with any of the three deflocculants used for these treatments, there is a loss of plasticity in the clay that does not favor the conformation of the ceramic body during the pressing, decreasing the mechanical strength of it. With the treatment at 700 ° C, it is already possible to handle suspensions with solid solids percentages of 60% by weight, using traditional deflocculation systems (Sodium Tripolyphosphate, Sodium Polyacrylate) as presented in the figures mentioned, for dispersions and wet milling. For the cases of preparation of ceramic bodies by grinding in dry way, it can be used with the proposed treatments, since the loss of the hydrophilic character of the clay, allows to avoid the problems of cracking during the drying of the molded parts by pressing, extracted , casting or turning.

A study of rheological properties was carried out on the samples treated at 700 ° C. The results of the analysis are presented in Figure 6, which shows how the curves correspond to the behavior of a plastic fluid (since it is necessary to apply a cutting force greater than zero to set the fluid in motion). The previous thing verifies that this clay, treated thermally, is adapted to replace feldspar and Ball Clay in ceramic formulations, since these generally present / display the same plastic behavior observed in the Figure 8.

Optical microscopy with heating and dilatometric analysis. In the sintering curves obtained by heating microscopy in the sintering curve, the following characteristic points of the thermal behavior of the treated materials can be observed: sintering (1), softening (2), sphere (3), half sphere (4) ) and fusion (5). These results are shown in Figures 9, 10 and 11 for the materials treated at 600, 700 and 800 ° C respectively, as well as in Table 2. These sintering temperatures are similar to those presented by the sodium and sodium feldspars. -potasics that are normally used in the formulation of ceramic bodies. In Table 3, the values obtained from the dilatometric analysis of the samples are shown, and as can be seen, the value of the thermally treated clays is higher than that of the Clay Clay, which suggests that, if necessary, a agent regulator of the total contraction of the pieces as it is the Silica.

Table 2. Sintering temperatures according to the microscopy analysis with heating.

Table 3. Results of the measurement of the coefficient of expansion of clays. Material Clay Ball dilatation 1.576 x 10-5 Bentonite if treated 2.520 x 10-5 Bentonite treated at 600 ° C 2.394 x 10-5 Bentonite treated at 700 ° C 2.361 x 10-5 Bentonite treated at 800 ° C 2.652 x 10 -5 To make clear the way to carry out the process we will cite the following examples: Example 1: The formulation indicated in Table 4 was used for the preparation of a porcelain ceramic tile. The preparation of the suspensions of examples 1 and 2, were carried out by wet milling (planetary mills with alumina jars and alumina bead grinding media), adding the necessary water to the ceramic materials to obtain aqueous suspensions with a density of 1.6 gr / ml, viscosities between 400 and 700 cps, depending on the grinding residue (from 100 gr of suspension the retentate is determined in a sieve of 0.74 μ (microns).) After grinding, the aqueous suspensions were dried and the The dry material was disintegrated until it passed through a 500 μ sieve, after which it was moistened at 6.5% w / w, the moisture required for the pressing and compaction of these powders For the evaluation of the formulations of examples 1 and 2, they prepared test pieces by unidirectional pressing of 5 x 10 x 0.8 cm (width, length and thickness respectively) at a pressing pressure of 350 kg / cm2 The evaluation of the pieces of example 1 during cooking was carried out with the graph of its sintering curve (gresification: Temperature vs% contraction and Temperature vs% water absorption), and as can be seen in Figure 12, above 1180 ° C the pieces have a contraction of 7-8 % and water absorption < 1%, which are within the required values for tile and ceramic tile.

The pieces thus obtained at temperatures > 1800 ° C (% shrinkage 7-8, Water absorption < 1%), were evaluated in terms of their mechanical strength, being found a resistance superior to 350 kg / cm2, being free of visual defects. Table 4. Formulation used for the preparation of ceramic bodies according to example 1.

Example 2: The formulation indicated in Table 5 was used for the preparation of a ceramic tile with a higher content of bentonite (55%). The preparation of the aqueous suspension was carried out by wet milling at a density of 1.6 g / ml, obtaining viscosities between 400 and 700 cps depending on the dry residue of milling retained in a 74μ sieve. After grinding, the aqueous suspensions were dried and the material was disintegrated until passing through a 500 μ sieve, after which it was wetted at 6.5% w / w to prepare these powders for pressing. For the evaluation of the formulations, test pieces were formed by unidirectional pressing of 5 x 10 x 0.8 cm (width, length and thickness respectively) at a pressing pressure of 350 kg / cm2.

Table 5. Formulation used for the preparation of ceramic bodies according to example 2.

The pieces thus obtained were evaluated in terms of their mechanical resistance, with a resistance greater than 350 kg / cm2. With respect to the contraction, this was less than 10% and the pieces were free of visual defects. In order to control and / or improve the characteristics of mechanical strength in green (wet and dry mechanical strength of pressed or cast pieces) it is common to use additives in the formulations of ceramic bodies such as lignins, polyvinyl pyrrolidone (PVP) , Polyvinyl Alcohol (PVA) and humic acids.

Applications of the invention.

This invention is applied in the manufacture of ceramic pieces by means of industrial or craft processes. The use of bentonite or montmorillonite clays treated by means of the process described here is applied to all types of ceramic coatings known as coatings for floor or wall and depending on their mechanical resistance, porosity (water absorption) and composition as: stoneware, semi stoneware, extracted pieces with water absorption > to 10% or wall covering, as well as to the formulation of porcelain ceramic pieces, extracted, pressed, turned or molded by hand in traditional pottery processes or industrial processes.

BRIEF DESCRIPTION OF THE FIGURES Figure 1.- Structure of a unit cell of the Montmorillonite family (structure 2: 1) consisting of two tetrahedral silicon layers and an octahedral layer of alumina.

Figure 2.- Graph of thermogravimetric analysis and differential thermal analysis of the bentonite clay, before being thermally treated. It is observed that at 800 ° C the free water has been lost, as well as the interlaminar water of the clay.

Figure 3.- X-ray diffraction analysis results of the untreated clay (1), and the clay treated at 600 (2), 700 (3) and 800 ° C (4), where the structure is observed It conserves, appreciating the definition of the signal due to the plane (001) as a result of the decrease in the interlaminar separation of the clay.

Figure 4.- Sedigraph analysis of the particle size distribution of the treated bentonite clays and the untreated clay clay, which is added as a reference. Bentonite clay treated at 600 ° C (1), at 700 ° C (2), at 800 ° C (3), Ball Clay (4).

Figure 5.- Deoculation curves with Sodium Tripolyphosphate (TPF) (1), Sodium Metasilicate (2) and Sodium Polyacrylate (3), commonly used in the ceramics industry, for clay calcined at 600 ° C. The test conditions correspond to those used in the industry to adjust the conditions of preparation of the slip that is used in the production of ceramic pieces.

Figure 6 Defolation curves TPF of Sodium (1), Sodium Metesilicate (2) and Sodium Polyacrylate (3), commonly used in the ceramics industry, of clay calcined at 700 ° C. The test conditions correspond to those used in the industry to adjust the conditions of preparation of the slip that is used in the production of ceramic pieces.

Figure 7.- Demodulation curves TPF of Sodium (1), Sodium Metesilicate (2) and Sodium Polyacrylate (3), commonly used in the ceramics industry, on the viscosity of the suspension of the clays when they are calcined at 800 ° C. The test conditions correspond to those used in the industry to adjust the conditions of preparation of the slip that is used in the production of ceramic pieces.

Figure 8.- Theological properties of the bentonite clay treated at 700 ° C in which a suitable behavior is observed for the processing of a slip based on this clay.

Figure 9 - The sintering curve of the calcined bentonite clay at 600 ° C, obtained by microscopy with heating, is shown. From these graphs, the firing characteristics of the clays are obtained for the selection of process conditions.

Figure 10 - The sintering curve of calcined bentonite clay at 700 ° C, microscopy with heating is shown. From these graphs, the firing characteristics of the clays are obtained for the selection of process conditions.

Figure 11.- The sintering curve of the calcined bentonite clay at 800 ° C, microscopy with heating is shown. From these graphs, the firing characteristics of the clays are obtained for the selection of process conditions.

Figure 12.- Sintering curve of example 1.

Claims (10)

1. A process for the elaboration of ceramic bodies for the manufacture of floor tiles or coatings for the construction, extraction, molding and industrial or artisanal turning, characterized by: a) Submitting to clays from the montmorillonite family (montmorillonite, bentonite and beidelite) or clays containing them, to a calcination from room temperature to a temperature range between 500 to 1000 ° C, in a cycle of 10 to 60 minutes. b) Mix the clay resulting from step a) with ceramic materials or bodies for powder or granular construction. c) Add water to the mixture of step b).
2. A process for clays of the montmorillonite family (montmorillonite, bentonite and beidelite) or clays containing them, according to claim 1, characterized in that the calcination temperature is preferably 600 and 800 ° C.
3. A process for clays of the family of bentonites, or clays containing bentonites, according to claim 1, characterized in that the percentage of the bentonite clays that are added to the ceramic bodies must be between 5 and 80% by weight.
4. A process for clays of the montmorillonite family (montmorillonite, bentonite and beidelite) or clays containing them, according to claim 1, characterized in that the ceramic bodies used in said process are preferably Ball Clay, feldspars or other aluminosolicates.
5. A process for clays of the family of montmorillonites (montmorillonite, bentonite and beidelite) or clays containing them, according to claim 1, characterized in that the mixture of step c) is prepared by wet milling (in aqueous suspensions known as slips ), in dry way or by redispersion of powders.
6. A process for clays of the montmorillonite family (montmorillonite, bentonite and beidelite) or clays containing them, according to claim 1, characterized in that the percentage of water used in step c) is 6.5 to 40% if the final mixture It is used for the manufacture of floor tiles and coatings for walls known as stoneware and monoporosa, castings, extruded and turned by hand and industrial.
7. A process for clays of the family of montmorillonites (montmorillonite, bentonite and beidelite) or clays containing them, according to claim 1, characterized in that there may be an additional step consisting in adding plasticizing additives usually used in the ceramic industry such as lignins, Polyvinyl Pyrrolidone (PVP), Polyvinyl Alcohol (PVA) and humic acids.
8. 8. A clay of the family of monmorillonites (montmorillonite, bentonite and beidelite) with clays containing them, according to claim 1, characterized by the following general formula: Xn (AlySi4-y) O10 (OH) 2Zm.wH2O
9. 9. A clay of the family of monmorillonites (montmorillonite, bentonite and beidelite) with clays containing them, according to claim 1, characterized in that it has a particle size of 50 to 100 microns.
10. 10. A clay from the family of montmorillonites or clays contains them, according to claims 8 and 9, characterized by its use in formulations of ceramic bodies for the manufacture of floor tiles and coatings for walls known as stoneware and monoporosa, cast, extracted and artisanal and industrial turning.