CZ379096A3 - Process for producing a structural element containing mineral wool - Google Patents

Abstract

The invention concerns a process for producing construction elements of the terracotta-based brick or tile type incorporating a given amont of mineral wool. According to the invention, between 0.5 and 25 wt.% of mineral wool waste is incorporated in the paste which consists essentially of clay. The addition of these fibres accelerates the drying of the unbaked bricks, improves the mechanical properties and permits baking at a slightly lower temperature.

Description

A method of manufacturing a structural element comprising a mineral wool

Technical field

JAi OH 3ΛΠ

and

The invention relates to processes for the manufacture of structural elements of a brick or tile based on baked clay containing a certain amount of mineral wool, as well as such construction elements.

BACKGROUND OF THE INVENTION

Although the manufacture of bricks or tiles is the subject of proven techniques, there remains a need to find improvements, particularly in terms of manufacturing costs and / or properties of the products produced.

In order to be able to burn the production costs, the energy aspect needed is particularly desirable. Thus, all interventions that reduce these costs without affecting other parameters are particularly desirable.

In this sense, one of the methods which makes it possible to operate at a temperature lower than that of clay itself is to use fluxes. However, the cost of materials suitable for preparing fluxes does not lead to their economically advantageous use.

SUMMARY OF THE INVENTION

According to the invention, it has been found that the use of mineral wool residues can lead to energy savings in the burning of bricks or tiles, if these residues are contained in corresponding amounts. In particular, incorporating an appropriate amount of these residues into the raw bricks or tiles (in the unburned state) makes it possible to work at a temperature slightly lower and facilitates firing of the bricks or tiles. The use of these residues is also economically advantageous. Moreover, it has been found according to the invention that this use has had other advantageous accompanying effects, such as a reduction in drying on drying or that it leads to products with reduced bulk density with unchanged mechanical properties. Incorporation of the abovementioned residues also results in faster drying of the raw bricks or tiles and improved mechanical properties of the bricks or tiles, especially in the unburned state.

Usable residues from mineral wool production can be very diverse in practice. These may be residues or by-products of production or secondary raw materials and so on. It must, in principle, allow easy introduction into the soil and lead to a non-crumbly material which is easy to process. These products are, in particular, fibers recovered from the washing water which is continuously used in production facilities, in particular from conveyors and the peripheral walls from which the recovered fibers are collected. The fibers entrained by these wash waters are recovered in particular by decanting or filtering in the form of a wet filter cake.

Except for these products coming directly from the production lines, all mineral wool materials are suitable for carrying out the invention, the dimensions to be adjusted as described below. In general, it is the insulators themselves or parts thereof that form an important part of the mineral wool products. In this case, the possibility of incorporation depends essentially on the dimensions of the particles introduced into the clay. The same applies to the possibility of incorporating the fibers mentioned above.

If the mineral wool residues or byproducts constitute the most important source for carrying out the invention, the other source consists of the materials used, being materials used as insulation or, in particular, mineral wool used as a horticultural substrate. The latter products, which are widely used for extinct cultures, are regularly replaced, inter alia, every year or every two years. After one or more cultures, they no longer have the desired properties, especially sterility. Users must dispose of these very bulky materials for which they no longer have use. Until now, these materials have been landfilled or have been used as industrial landfills. Their ability to associate with the clay slurry - they are indeed easily wettable making products well usable for embodiments of the invention, which products are particularly suitable for making brick-like structural members.

In practice, the mineral wool residues are mixed with the wet clay either in the form of loose fibers, such as fibers recovered from the wash water, or in the form of small-sized felt particles. The latter case arises in particular in the case of the reuse of spent products which are initially in the form of felt. In this case, the felt is torn or crushed to form particles whose dimensions are such that they do not prevent the formation of a homogeneous mixture with the clay in the presence of an appropriate amount of water. Typical dimensions of commonly torn products are generally less than 20 mm and preferably less than 10 mm. Under these conditions, irrespective of their original structure, good particle distribution is achieved for the purpose of good mixing into the clay. If loose fiber residues are incorporated, these fibers are also preferably present in a length of 0.5 to 2 mm, in particular to facilitate their dosing and mixing with the clay. On the other hand, the fibers used preferably have a diameter of less than 7 microns.

The mineral wool content introduced into the clay may vary greatly depending on the importance of the desired purpose, the exact nature of the fibrous materials, the presence of the foreign elements it contains, the moisture content of the processed material, the nature of the clay used, the type of bricks and tiles produced. In practice, the weight of the mineral wool does not exceed 25% of the total weight of the dry mixture in order to obtain a material which is well processed, in particular not too crumbly and / or does not require too much water content. Preferably, this percentage is less than 15%.

Of course, if a small amount of fibrous material can be incorporated, the effect obtained is also small. For this reason, the fiber content is usually not less than 0.5% and preferably not less than 2% by weight, particularly preferably not more than 4% by weight.

Preferably, the mineral wool residues used are glass wool residues. On the other hand, it has been found according to the invention that in order to achieve a significant reduction in the burning temperature, it is good that the glass fibers contain a certain amount of boron. The boron content of these fibers is at least 0.4% and preferably 0.5%. In practice, the glass compositions used in the production of the insulating wool have a boron content of about 2 to 20% and most often 4 to 15% and are therefore suitable for use in the invention. In products intended for extinct crops, the boron content is about 0.5%. Preferably, the boron content of the fibers is less than 8%.

In a particularly preferred embodiment, glass wool residues having the following composition in percent by weight are used as residues:

SiO ₂ 45 to 70% sodium oxide Na ₂ O 10 to 23% potassium oxide K ₂ O 0 to 3% Manganese oxide MgO 1 to 5% aluminum oxide A1 ₂ O ₃ O, 3 to 7% iron oxide Fe ₂ O ₃ 0 to 1% calcium oxide CaO 5 to 13 % fluorine F 0 to 3% boron trioxide B ₂ O ₃ 0, 5 to 15%

(and preferably less than 8%) residue up to 5%

The preparation of the [mu] / mineral wine (or fiber) mixture mainly requires mixing the ingredients. Incorporation can be accelerated by ensuring better mass uniformity.

Unlike clay alone, the clay / fiber mixture may require a slightly higher water content to obtain adequate plasticity.

Preferably, the incorporated residues have a bulk density of greater than 150 kg / m ³ to be easily removed from their storage facilities, easy to dispense and to allow a uniform supply at the production process level, having a bulk density of less than 500 kg / m ³ , These conditions can form a homogeneous mixture with the clay.

According to one preferred embodiment of the invention, the conventional components of the bricks or tiles are dosed, for example by means of a belt dispenser supplying the crushing or mixing device, as well as mineral fibers which have to be incorporated into the bricks or tiles and the components and the above fibers and shaping the resulting mixture (e.g. by extrusion) followed by slicing, optionally accumulated before drying at a temperature of preferably about 120 ° C and then fired at a temperature of preferably from 900 to 1100 ° C for bricks and from 1000 to 1050 ° C for bags wherein the firing temperature depends on the type of clay used.

Preferably, the mineral fibers are distributed inside the bricks or tiles in a directionally disordered manner.

The incorporation of mineral wool residues according to the invention is particularly advantageous when the bricks or tiles are based on lime or lime clay or clays. The use of the mineral wool residues according to the invention makes it possible, in particular, to reduce the frost sensitivity of bricks or tiles based on these clays. Similarly, the porosity (pore volume per total volume) of the bricks or tiles obtained according to the invention has been shown to be at least 5% higher than the porosity of the bricks or tiles without mineral wool residues and that the degree of porosity (porometric distribution) higher.

The invention is further described in detail by reference to exemplary embodiments.

DETAILED DESCRIPTION OF THE INVENTION

Three series of tests were performed with the following samples:

(A) river clay (bronze color after firing) (B) the same clay enriched with 10% by weight silicone-free mineral wool (C) the same clay enriched with 10% by weight of garden substrate residues

The composition of these glasses may be, for example, as follows

glass insulation glass garden SiO ₂ 64.1% silica SiO ₂ 61,53% aluminum oxide A1 ₂ O ₃ 3.4% sulfur trioxide SO ₃ 0.28 i calcium oxide CaO 7.2 i iron oxide Fe ₂ O ₃ 0,19% magnesium oxide MgO 3% aluminum oxide A1 ₂ O ₃ 6.6% sodium oxide Na? O 15.75% calcium oxide CaO 7.4% potassium oxide K ₂ O 1.15% magnesium oxide MgO 2,45% boron oxide B ₂ O ₃ 4,5% sodium oxide Na ₂ 0 17,6% sulfur trioxide and iron oxide 0.9% SO ₃ + Fe ₂ O ₃ potassium oxide K ₂ O 1.4% boron oxide B ₂ O ₃ 0,5% titanium dioxide TiO ₂ 2.05

The products were subjected to a study of their drying behavior.

The first measurement is the measurement of the moisture diffusion coefficient (K) by the Pfefferkorn test. This finding makes it possible to compare the suitability of the products for drying. The higher the coefficient, the easier it is to dry the products. The values of products A, B and C are 4.1; 4.7 and 4.9.

Determination of the porosity of the products clearly shows a higher porosity of the glass wool-containing products.

The bulk density of dry products varies depending on the incorporation of the fibers. It amounts to products A, B and C after 1975, 1645 and 1800 kg / m ^{3 respectively} . The glass wool products produced thus have a significantly lower bulk density.

The presence of glass wool in clay also alters the dimensional stability during drying. The shrinkage of the dry product as a percentage of the wet product dimensions of these samples is 7.8; 3.7 and 5.5. Products obtained by incorporating glass fibers are less deformed, although, as mentioned above, the mass originally contains more water.

In general, clay / glass fiber mixtures thus result in better drying and less risk of deformation and cracking.

Test samples of these three products were prepared to determine their mechanical properties. These tests were carried out on dry products not yet subjected to firing. The flexural strength at three points was 1510, 1860 and 1760 N. The presence of fibers thus greatly increases the flexural strength.

The same samples were fired in a gas laboratory oven at 1050 ° C. The bulk density of the products according to the invention after firing is again significantly lower this time. Results are 1780, 1715 and 1690 kg / m ³ .

The products were then examined by thermomechanical analysis during firing. For these analyzes, the samples are placed in an oven in which the temperature gradually increases by 1 CC per minute.

Shape changes are temperature dependent. The degree of firing was compared with the degree of shrinkage. A drying value of 1% was selected and the temperature corresponding to this drying was monitored.

For these products and compared to those made from clay alone, 1% drying is achieved for Sample B at less than 40 ° C, and for Sample C at less than 25 teplotě C. These differences clearly show the possibility of firing under more economical conditions in the products according to the invention.

Claims (13)

1. A method of manufacturing a structure characterized in that mainly clay is introduced into the wet mass of fibers in an amount of from 0.5 to 25 material. Claims * JA10 0Η3ΛΠΎ Bricks or tapes, αν, in addition to traditional materials, incorporate mineral wastes by dry weight Method according to claim 1, characterized in that the fibers contained are either separated from one another, do not take the form of felt particles whose dimensions are not more than 20 mm. Method according to claim 1 or 2, characterized in that the fibers have a length of from 0.5 to 2 mm. Method according to one of claims 1 to 3, characterized in that the fibers have a diameter of less than 7 µm. Method according to one of Claims 1 to 4, characterized in that the fibers contained are derived from production residues. Method according to one of Claims 1 to 4, characterized in that the fibers contained are derived from used insulation materials or used horticultural extraneous substrates. Method according to one of Claims 1 to 6, characterized in that the fibers are glass fibers. Method according to one of Claims 1 to 7, characterized in that the fibers present have a boron content higher than 0.4% by weight. Method according to either of Claims 7 or 8, characterized in that the fibers are glass fibers comprising the following composition expressed in weight percent: oxide silica SiO _; 45 up to 70% oxide sodium Na _; 0 10 up to 23% oxide Potassium ICO 0 up to 3% oxide Manganese MgO 1 up to 5% oxide aluminum A1 ₂ O ₃ 0, 3 to 7% oxide ferric Fe ₂ O ₃ 0 up to 1% oxide calcium CaO 5 up to 13% fluorine F 0 up to 3% oxide boron B ₂ O ₃ 0, 5 to 15% residue 0 up to 5% Method according to one of Claims 1 to 9, characterized in that the residues have a bulk density of 150 to 500 kg / m ³ . Brick or tile, characterized in that it is obtained by a method according to one of the preceding claims. 12. A brick or tile comprising clay and 0.5 to 25% by weight of dry material of mineral fiber residues. AND Brick or tile according to one of claims 11 or 12, characterized in that it comprises calcium clay.