EP1009722B1 - Method for making fitting tiles - Google Patents

Abstract

The invention concerns a method consisting in disintegrating clay in the form of particles of not more than 70 mu m wide in diameter, in preparing a slip by adding water and a deflocculant, in spray drying the slip to obtain spherical granules with wetness ranging between 0,5 and 10 %, and in pressing the granules inside a mould under pressure higher than 300 kg/cm<2> (1 kg/cm<2> = 101 300 Pa).

Description

The subject of the present invention is a method of manufacturing interlocking tiles.

Currently, the manufacture of tiles is carried out by preparation of a clay-based paste with a humidity level of the order 20%. This dough is spun, then pressed into plastic dough, allowing obtaining a tile which is firstly dried before cooking.

A first drawback of this traditional technique is in the importance of the installations to be implemented, especially for drying the tiles before they are cooked and for cost of energy to achieve such drying. Other problems significant encountered on current installations result from variations humidity, dry inclusions, poor positioning of the wafer during pressing and / or irregular flushing of the clay during pressing, defects caused by the molds and especially a non-shrinking homogeneous and stresses during drying which cause cracks or deformation of the product. These different problems lead to a relatively high rate of waste, which lowers the operating profitability.

It is known to produce tiling elements, articles crockery, or refractory elements, by pressing a powder relatively dry, allowing items to be cooked without drying prior. However, these products do not have the characteristics essential to the tiles which are, among other things, waterproofing and ingenuity, without additional surface treatment.

The object of the invention is to provide a method for manufacturing interlocking tiles that do not require a drying phase, while allowing obtaining a tile which has the characteristics essentials, including good waterproofing and good ingenuity, without specific further treatment.

• à broyer l'argile sous forme de particules d'un diamètre au plus égal à 70 µm,
• à préparer une barbotine par addition d'eau et d'un défloculant,
• à réaliser l'atomisation de la barbotine pour obtenir des granules sphériques dont l'humidité est comprise entre 0,5 et 10%,
• et à réaliser le pressage des granules à l'intérieur d'un moule sous une pression supérieure à 300 kg/cm² (1 kg/cm² = 101 300 Pa).

To this end, the process which it concerns, consists of:

• crushing the clay in the form of particles with a diameter at most equal to 70 μm ,
• preparing a slip by adding water and a deflocculant,
• atomizing the slip to obtain spherical granules whose humidity is between 0.5 and 10%,
• and carrying out the pressing of the granules inside a mold under a pressure greater than 300 kg / cm ² (1 kg / cm ² = 101,300 Pa).

Advantageously, the pressing pressure of the granules is between 300 and 600 kg / cm ² (1 kg / cm ² = 101,300 Pa).

This process has the primary advantage of limiting the importance the tile manufacturing facility, as far as one can eliminate the drying phase of these. However, it is possible preheat before cooking to lower the rate humidity, if it is too high.

In addition, dry shaping allows better respect of the dimensions of the tiles, and a better surface condition than forming in plastic paste. Indeed, there does not exist, in a tile obtained by the process according to the invention the shrinkage phenomena that are known during the drying of the tiles obtained by the traditional process.

Finally, from an economic point of view, the process according to the invention is advantageous, since the drying phase is removed, it allows significant energy savings.

According to one characteristic, this process consists in preparing a slip with 0.2 to 1% by mass of deflocculant, the deflocculant being, by example, sodium pyrophosphate.

The granulation is obtained by atomization of the slip which is sent into a cylinder where hot air circulates, which dries instantly slip droplets, which become particles spherical in different sizes, depending on the size and shape of the nozzles projecting the slip, as well as according to the power of the jet. The humidity is temperature controlled.

Granules of spherical shape are thus obtained, located in a range of grain sizes, with a moist heart surrounded by a dry shell, advantageous structure because allowing, during pressing, a good distribution in the mold.

Advantageously, the humidity of the granules obtained is controlled by temperature and is less than 10% and preferably of around 8%.

According to one possibility, consists in using a clay illicit type.

The powder formed by the granules is pressed in a two-cavity mold, which can have several moving parts, the relative to each other, in order to achieve thickness differences, curves, ribs, baffles, as is the case for tiles obtained by the traditional technique, while allowing ensure uniform pressure at all points in the mass of granules pressed during molding.

The mold filler shoe may also have a preform.

As is clear from the above, this manufacturing process, which includes very specific phases of implementation, allows to obtain by dry pressing, tiles having good mechanical characteristics, as well as good impermeability and good ingenuity.

It goes without saying that the invention is not limited to the single mode implementing this method described above by way of example, it on the contrary embraces all variants of implementation. This is how in particular that the nature of the deflocculant could be different or that the clay used could be other than an illicit clay, without this goes beyond the scope of the invention.

Claims (8)

1. Process for manufacturing fitting tiles, characterized in that it consists in:

   grinding clay in the form of particles having a diameter of at most 70 µm;

   preparing a slip by adding water and a deflocculant;

   atomizing the slip in order to obtain spherical granules, the moisture content of which is between 0.5 and 10%; and

   pressing the .granules in a mould under a pressure of greater than 300 kg/cm² (1 kg/cm² = 101 300 Pa) .
2. Process according to Claim 1, characterized in that the pressure for pressing the granules is between 300 and 600 kg/cm² (1 kg/cm² = 101 300 Pa).
3. Process according to either of Claims 1 and 2, characterized in that it consists in preparing a slip with 0.2 to 1% by weight of deflocculant.
4. Process according to any one of Claims 1 to 3, characterized in that the deflocculant is sodium pyrophosphate.
5. Process according to any one of Claims 1 to 4, characterized in that the moisture content of the granules obtained is controlled by the temperature and is less than 10%.
6. Process according to Claim 5, characterized in that the moisture content of the granules is about 8%.
7. Process according to any one of Claims 1 to 6, characterized in that it consists in using an illitic-type clay.
8. Process according to any one of Claims 1 to 7, characterized in that it consists in moulding the tiles in a mould comprising movable parts, in order to ensure uniform pressing at all points on the mass of granules pressed during the moulding.