The present invention relates to a method for providing large sized ceramic slabs.

The need is felt increasingly, in the building sector, to have large panels that combine structural, soundproofing, thermal insulation, surface toughness capacities and at the same time can be decorated on the surface with colors, designs, prints, depending on the visual impact that one wishes to achieve with these panels.

In particularly, methods for the dry assembly and laying of large slabs, adapted to constitute internal or external walls directly, are increasingly widespread.

Products are currently commercially available each of which has, individually, only one or a few of the capacity characteristics listed above, and most have no fire resistance capacity.

The aim of the present invention is to provide a method for providing large sized ceramic slabs which combine the above-cited structural, thermal insulation and soundproofing capacities with characteristics of light weight and fire resistance.

Within the scope of this aim, an object of the invention is to provide a method that allows the provision of large sized ceramic slabs whose surface decoration can be defined easily according to the instructions of the purchaser.

Another object of the invention is to provide a method that uses raw materials that are easily commercially available and is therefore capable of providing large sized ceramic slabs that have competitive costs with respect to similar products that are already present in the building sector.

Another object of the invention is to provide a method for providing large sized ceramic slabs that can be obtained with known systems and technologies.

This aim, as well as these and other objects which will become more apparent hereinafter, are achieved by a method for providing large sized ceramic slabs, characterized in that it comprises the following steps of operation:

- mixing and homogenizing the raw materials;

- milling the mixed and homogenized raw materials to a particle size of less than 100 μιη;

- granulating or atomizing to a particle size between 100 μηι and 600 μη ;

- rolling continuously at low pressure to obtain a ribbon of moist ceramic material;

- cutting from said ribbon unfired slabs of preset dimensions;

- drying said unfired slabs;

- firing said unfired slabs.

Further characteristics and advantages of the invention will become more apparent from the description of a preferred but not exclusive embodiment of the method according to the invention, illustrated by way of non-limiting example in the accompanying drawing, which is a schematic view of a method for providing large sized ceramic slabs according to the invention.

With reference to the figure, a generic system for providing a method according to the invention is generally designated by the reference numeral 10.

Said method for providing large sized ceramic slabs comprises the following steps of operation:

- mixing and homogenizing, in a mixer A, to be understood as being of a known type, the raw materials 1 1 ;

- milling the raw materials mixed and homogenized in the mixer A to a particle size of less than 100 μιη and preferably to a particle size of approximately 75 μπι;

- granulating or atomizing to a particle size between 100 μπι and 600 μηι, by means of an atomization device C;

- rolling continuously at low pressure so as to obtain a ribbon 12 of moist ceramic material, preferably with a humidity of less than 10%; this step of operation is performed with low-pressure continuous rolling machines, designated by the reference letter D, for providing slabs of formats that can vary according to the requirements, up to more than three meters long;

- cutting from said ribbon 12, with cutting equipment E, unfired slabs 13 of preset dimensions;

- drying the unfired slabs 13 by conveying them through a dryer F, from which dried slabs 14 exit;

- firing in an oven G said dried slabs 14.

Fired slabs 15 are provided at the output of the oven G.

The raw materials 11 comprise

- argillaceous plastic material,

- melting materials, such as feldspars,

- any processing waste, such as glass waste, waste from stone working, foundry waste, alone or in combination,

- any other different raw materials.

In particular, the ceramic material used has the following chemical formulation:

Si0 ₂ 58 - 73%

A1 ₂ 0 ₃ 5 - 20%

CaO 0.5 - 8%

MgO 0.3 - 4%

Na ₂ 0+K ₂ 0 3 - 13%

Fe ₂ 0 ₃ + Ti0 ₂ 1 - 2%

PbO + BaO + ZnO 0.1 - 2%

Zr0 ₂ 0.1 - 1.4%

SiC 0.05 - 5% with loss on ignition between 2% and 4%.

The firing operation is performed in an industrial oven G, on refractory slabs or directly on rollers, at temperatures between 900 °C and 1250 °C, with cycles between 30 minutes and 180 minutes.

The method according to the invention can include a further operating step of wet decoration before the firing step.

This step of decoration can be performed by deposition of one or more layers of granulates containing coloring oxides, distributed in order to provide various geometries and esthetic solutions.

Moreover, the method according to the invention can comprise, as an alternative or addition to the above-cited wet decoration step, an additional operating step of decoration by means of ceramic dry decoration methods.

Furthermore, the method according to the invention can comprise an additional operating step of finishing with dry or wet grinding, cutting and polishing methods.

The method according to the invention can furthermore comprise an additional operating step of cold finishing with glazing and decoration with digital machines.

In practice it has been found that the invention achieves the intended aim and objects.

In particular, with the method according to the invention it is possible to provide large sized slabs, up to more than three meters long, sizing them by means of cutting methods as a function of the application requirements.

Moreover, the invention has provided a method that allows the provision of slabs having a density which is defined as a function of the required characteristics, such as: mechanical strength, thermal insulation, soundproofing, sound deadening.

With this method according to the invention, therefore, it is possible to obtain large sized slabs with high fire resistance characteristics and a very low content of volatile organic compounds, with high-level surface characteristics in terms of hardness, abrasion resistance, resistance to chemical agents, and with a wide range of esthetic solutions, with the possibility of customizing the surfaces according to the purchaser's requests.

The method according to the invention allows the provision of large sized ceramic slabs for example for the following applications: covering internal and external walls, ventilated walls, external insulations, false ceilings, floors, raised floors, coverings, reinforced structural panels for partitions or modules of internal or prefabricated walls, sound deadening barriers, thermal and acoustic insulation of ovens and refrigeration cells, fire doors or barriers, and other applications requiring a lightweight material with thermal-acoustic insulation and fire resistance characteristics, and finally applications requiring products with a controlled density as a function of specific requirements.

Last but not least, the invention provides a method for providing large sized ceramic slabs which can be obtained with known systems and technologies.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials used, as well as the contingent shapes and dimensions, may be any according, to the requirements and the state of the art.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.