LU84896A1 - PROCESS FOR THE RECONSTRUCTION OF ROCKS AND PARTICULARLY SLATES - Google Patents

Description

The subject of the invention is a method for reconstituting rocks, more particularly slates, from waste of these rocks, in particular slate waste.

From earliest times, = 5 natural rocks have been used to construct buildings and structures both as load-bearing elements and as cladding, decoration and covering. In areas without suitable quarries, it is necessary to import the rocks to be used, for example marbles, granite, slate, etc., which considerably increases their cost due to transport costs, together with large quantities of waste from these rocks are produced at the quarry sites, since only "healthy" blocks are likely to be marketed, all of which further increases the cost of using the stone in the constructions.

On the other hand, the use of blocks or plates of natural rock considerably increases the weight of the construction, the foundations and structures of which must be provided and constructed so as to be able to support this additional weight due to the blocks of stone used as wall coverings or stone slabs used as roof coverings.

Numerous attempts have already been made to alleviate these difficulties, due to the weight of natural rock, to the shortage of healthy blocks to meet the demand for "noble" appearance building materials in areas which do not have them. by nature, using "artificial" parts which are generally based on more or less small pieces of natural rock and a hydraulic binder 30 or, more modernly, synthetic.

However, such artificial stones with hydraulic binders cannot be used universally, because their mechanical properties are not always comparable to those of the original natural stone, or because their weight is substantially identical to that of the said natural stone. natural stone 2, so that no advantage is obtained, especially when the artificial stones must be used for covering purposes without appreciable increase in the weight of the construction.

5 On the other hand, artificial stones with synthetic binders are difficult to use in areas where constructions have to withstand bad weather and normally undergo more or less pronounced degradations due to atmospheric agents such as light, ultra-violet rays, rain, etc .; moreover, they deteriorate under the effect of friction, so that they cannot be used as floors in constructions either.

Attempts have also been made to artificially make plates of reconstituted rock, having the appearance of natural slate, for covering roofs, based on asbestos, cement and pigments, according to semi-artisanal processes, ie that is to say by making one by one the artificial slate slabs. This process presents enormous ecological risks due to the use of asbestos 20 whose use is being questioned in developed countries, until it is banned, because it is considered as an undoubted source of very serious occupational diseases for people exposed to its action.

The main object of the invention is to achieve an industrial process for reconstituting rocks, in particular slate, which is capable of eliminating all the drawbacks mentioned above.

Thanks to the process of the invention, it is possible to take advantage of rock residues of any size, so that it can be considered that the exploitation of the quarries becomes integral.

The method according to the invention makes it possible to manufacture construction materials for the finishing of constructions, without appreciably increasing the weight thereof and, therefore, without increasing the price of their structures in order to bear excessive weight.

The building materials produced by the process of the invention are stable to the weather, so that they can be perfectly used in the exterior parts of buildings, such as roofs, terraces, stairs, facades, outdoor furniture in general, etc.

In what follows, reference will be made more particularly to a method of reconstituting slates, without there being any reason to consider this choice as limiting in any way, since the method claimed also applies to any other type of natural rock.

According to the process of the invention, one starts from waste or residues of the rock considered, concretely 15 slates in the present case, as indicated in the preceding paragraph, or else material having the appearance slate and which has certain drawbacks for being used as natural slate and this slate waste is subjected to grinding which begins with a cone crusher 20, followed subsequently by grinding in a bar crusher and finally, the grinding product is subjected to screening in a cyclone-type screen, dry.

From the screening carried out in the dry cyclone, at least five fractions with different particle sizes are collected, the intervals of which are between 0 and 30 mm, especially between 0 and 16 mm.

In a subsequent operation, storage is carried out in at least five different silos, in each of which a fraction of the grinding product is stored within a determined particle size range, taking into account that the minimum interval of dimensions particle size must be between 0 and 0.25 mm and the maximum interval must be between 6 and 30 mm, preferably between 8 and 16 mm.

The synthetic binder, which can be a synthetic methacrylic resin, of the “MAMMA” type of the “DEGAMENT 1370 EGUSSA” type, which contains a cobalt polymerization accelerator, for example, is placed in separate steel or polyethylene tanks. which has the following characteristics: In the liquid state

Viscosity less than 10 mPa.s 3

Specific weight at 20 ° C, 0.950 g / cm Refractive index nD 20 ° C value = 1.415 10 Color A.P.H.A. less than 50

Acidity index below pH 1 In solid state 3

Apparent specific weight 1.2 g / cm 2 Flexural strength greater than 150 N / mm 2 15 Pressure resistance greater than 80 N / mm 2

Traction greater than 60 N / mm Elasticity greater than 3%

Thermal conductivity 0.2 W-mk Heat stability above 80 ° C 20 Coefficient of linear expansion 8 x 10- ^

Water absorption -0.1%.

Independently, a polymerization catalyst of the synthetic resin, of the organic peroxide type, such as benzoyl peroxide, in the phlegmatized state, is loaded into a separate container.

After the selection of the size ranges of the crushed slate and the loading of the resin containers, with the accelerator and the catalyst, the desired proportions are sent, by means of an automatic mixer and through individual pipes. crushed resin, accelerator and catalyst material to an initial mixing zone; the time necessary for the execution of this mixture depends both on the natural properties of the constituents and on their temperature as well as on the ambient temperature.

5

Thus, for example, at room temperature, the mixing time is generally between 10 and 20 minutes, and a total hardening in the mold is obtained after about one hour at most. The polymerization of the resin ends when the maximum temperature of about 70 ° C. is reached and the product thus prepared can be left to "mature" for a few days, taking into account that the relative humidity of the ambient air should not exceed 2% after molding.

10 According to the method of the invention, it is fundamental to maintain a correlation between the thickness of the part manufactured and the quantity of resin used, thus for example the following correlations have been found thanks to the work carried out during the invention: 15 Thickness in mm% of resin 10 4-10 7 6-11 2.5 8-14 1 10-16 20 The mixture indicated above being prepared, it is poured into molds which must be perfectly cleaned and dry, but which can, if necessary, be covered with a film of a release agent such as, for example, a silicone.

These molds are preferably made of polyethylene or steel and, if necessary, are reinforced appropriately. In the process of the invention, account must be taken of the fact that · the molds must not deform at a temperature less than or equal to around 30 ° C. and, moreover, these molds must be free of resonance band in order to to prevent the components from dissociating during the compaction operation of the mixture and deformation of the molded parts.

Once the molds have been loaded with the composition 35 prepared during the initial phase of the process, they are transferred by any known means, manual, mechanical or pneumatic, to a vibration installation, in the absence of any resonance. , and vibration of the molds loaded with the composition is carried out with this installation, for example on vibrating metal tables, in a vibration range of between 100 and 150 Hz, depending on the thickness of the mass contained in the mold. Optionally, the product can be subjected, after vibration, to compression in the mold, or compression between two half-molds, at a pressure of between 40 and 120 bars.

According to the process of the invention, the compositions formed by grains of slate, synthetic resins, catalyst and accelerator, in the present example can be subjected in addition before and / or during and / or after the vibration of the molds, a coloring operation using natural and / or synthetic pigments compatible with the resin and the other products used, which means that this coloring can take place in the mass or superficially, or else in a combined manner , 20 if appropriate. In general, the coloring is carried out in the mass by means of synthetic pigments, such as Bayer Green and the surface coloring by means of natural pigments such as smoke black and carbon black, although this is not limiting.

When the vibration of the molds has been carried out and the curing of the composition has ended, in some cases a layer of natural insulator, such as fiberglass, can be bonded to the non-visible side of the molded product and the 30 finished products can then be removed from the molds, which may have dimensions ranging from 1 cm × 1 mm to 50 cm × 50 cm × 1 cm, or * more, as required, these indications being only nonlimiting examples .

The molded parts can also have different reliefs and / or different shapes, or, in certain cases, they can contain metal inserts allowing their anchoring, in order to eliminate the preparation work necessary for their application, these inserts and / or these auxiliary elements being incorporated before the vibration and hardening of the resin composition and of the slate grains.

The molded parts must be stored in a flat or well ventilated place, until they have completely cooled, since they are liable thereafter to have to withstand the mechanical and chemical stresses specific to a natural stone.

The slate sheets obtained according to the method of the invention can also be used in the construction of electrical devices, as insulators, because of their good electrical resistance and their lower weight compared to natural slate.

We will now give nonlimiting examples of implementation of the method of the invention.

EXAMPLE 1 Slate waste is crushed in a cone crusher, then in a bar crusher and the ground product is sieved so that fractions with the following particle size intervals are collected: 1) from 8 to 16 mm? 2) from 4 to 8 mm; 3) from 2 to 4 n; 4) from 1 to 2 mm; 5) from 0.5 to 1 mm; 6) from 0.25 to 0.5 mm; 7) from 0 to 0.25 mm.

During a second operation, the following parts by weight (pp) of the fractions, indicated below, are combined simultaneously: 26 pp of fraction 4; 10 pp of fraction 5; 8 pp of fraction 6, 35 with 2 pp of the catalytic composition and 14 pp of the resin 8 which contains the polymerization accelerator, at room temperature, for a period of approximately 10 minutes, then poured into polyethylene molds in the shape of slabs of approximately 15 cm x 15 xm x 1 cm, the bottom 5 of which simulates the texture of natural slate, and which has been treated beforehand by spraying with a silicone oil for release from the mold. The molds thus loaded are transferred to a vibration installation where the vibration takes place between 100 and 150 Hz and the polymerization of the resin 10 for a period of approximately 1 to 5 minutes, until a temperature is reached. about 70 ° C. After about 2 to 3 hours, a layer of natural insulation such as fiberglass is bonded to the face of the molded mass visible in the mold, and then, when the insulation is bonded, it is removed from the mold. the pieces thus produced, which have an excellent natural slate appearance and are stored in a flat and ventilated place for a few days.

Said molded parts are colored either in the mass or on the surface, as indicated above.

20 Examples 2 to 4

The operations of Example 1 are repeated, but by modifying the proportions in pp of the different fractions of the molded slate product and of the resins used according to the following table.

FRACTION EXAMPLE 2 pp EXAMPLE 3 (pp) EXAMPLE 4 1 0 0 26 2 0 26 20 3 26 19 33 30 4 19 13 10 5 12 * 9 7 6 10 6 4 7 33 27 20

Catalyst 2 22 35 Resin + Catalyst 11 9 6 9

Products similar to those of Example 1 are obtained.

The mechanical properties of the products obtained according to the process of the invention, based on formulations are given below. 5 made from Tannus quartzite with rounded edges, /

Unless otherwise indicated, the values indicated are applicable to a normal climate such as that defined in standard 23/50 DIN 50 014 (23cC ± 2 ° C and 50 ± 5% relative air humidity). The values given in the first place refer to formulations with low resin contents and the values indicated in the second place for formulations with high resin contents: ο Compressive strength 150 - 115 N / mm 2 Resistance to bending 29 - 34 N / mm 15 Flexural strength at -20 ° C 35 - 40 N / mm ^

Modulus of elasticity 30,000 - 21,000 N / mm ^

Dimensional stability at

heat 100 - 110 ° C

3

Thermal conductivity 8.36 - 6.27 x 10 J / m.h. ° K.

20 Electrical resistance 10 *** ohm.cm 13 Surface resistance 10 ohms

Water absorption 0.1% -5

Coefficient of expansion 1 - 2.5. 10

Linear contraction during * 25 polymerization 0.1 - 0.15%

These values of the mechanical and physical properties, as well as the chemical characteristics specified below, were determined as the average of 115 samples, to take account of the fact that the formulation is made up 30. by about 90% of mineral matter.

The products obtained by the process of the invention * have the following characteristics with respect to chemical agents, a meaning "chemically stable", 35 b meaning "swollen, resistant under certain conditions after a short-term action", c meaning "not resistant".

Aqueous solutions

Distilled water a 5 Rainwater a * Sodium cyanide solution a

20% sodium sulfate solution a

30% hydrogen peroxide a

Sea water a. 10 Sodium detergent a

Saturated sodium sulfate a

3% hydrogen peroxide a

Saturated sodium solution a

Alcalis 15 10% potash detergent a

10% caustic soda

50% potash detergent a

50% caustic soda

Acids 20 10% formic acid a

Citric acid, saturated solution a

Concentrated acetic acid c

10% nitric acid a

Hydrochloric acid 10% a "25 Sulfuric acid 10% a

10% tartaric acid a

50% formic acid b

10% acetic acid a

10% lactic acid a 30 Concentrated nitric acid c

20% hydrochloric acid a

50% sulfuric acid c

10% tartaric acid a

Organic solvents 3 5 Acetone c 11

60% ethanol in water a

Gasoline (fuel) a

Butane c

Chloroform c 5 Glycerin h Methanol b

Mineral oil a

Pyridone c

Essence super b 10 Trichlorethylene c

Ethanol b

Ethyl acetate c

Benzene c

Butyl acetate c 15 Diesel fuel a

Isopropanol b

Methylene chloride c

Paraffin oil a

Feed oil a 20 Toluene c

Xylene c

After having sufficiently described the process of the invention, as well as the manner of implementing it, it will be mentioned that it goes without saying that the arrangements indicated above are susceptible of modifications of detail, insofar as they do not change not its fundamental principle.

Claims (4)

12 1. A method of reconstituting slates, comprising operations consisting in treating rock shales with synthetic resins, characterized in that said slate is subjected to, during a first operation, by grinding so to obtain seven particle-size fractions having the following dimensions: from 8 to 16 mm; from 4 to 8 mm; from 2 to 4 mm; from 1 to 2 m; from 0.5 to 1 mm; from 0.25 to 0.5 ram; and from 0 to 0.25 mm, maximum 10; during a second operation, a synthetic resin containing an appropriate accelerator is combined simultaneously with a polymerization catalyst and with the ground slate, according to the particle size fractions indicated, while stirring at a temperature substantially equal to the temperature ambient, and this combination is continued while stirring for a period of about 20 minutes at most, reaching at most in the reactor a temperature of about 70 ° C; during a third operation, the product coming from the second operation is poured into a mold which is subjected to a vibration of between approximately 100 and 150 Hz and, then, the mold is optionally subjected, after the vibration treatment, a compression of between 40 and 120 bars or, between them two half-molds having undergone a vibration treatment beforehand, under the same pressure and, if necessary, bonding, on the face of the molded part visible in mold a layer of natural and / or synthetic insulation. 2. Method according to claim 1, characterized in that the resin is a methacrylic resin in which is incorporated an accelerator, such as a cobalt accelerator, and in that the ground slate is combined in such a proportion that the final product contains, at most, 20% by weight of said resin with the accelerator incorporated. 3. Method according to claim 1, characterized 13 in that the catalyst and the resin are combined, with the incorporated accelerator and the ground slate in a proportion such that the catalyst represents 10% by weight, at most, of the finished product. 4. Method according to claim 1, characterized "in that one carries out a coloring in the mass, before the casting in the molds, or else a surface coloring of the molded product before, during or after the vibration of the molds."