FR2839509A1 - SYNTHETIC STONE, MANUFACTURING PROCESS AND INSTALLATION FOR ITS IMPLEMENTATION - Google Patents

Abstract

The invention relates to a process for manufacturing synthetic stones or restructured stones, according to which: - a binder mainly consisting of a vitrifiable material is prepared, - aggregates of rocks or minerals are prepared with a particle size such that the proportion of grains of size less than a threshold of at least about 0.1 mm is substantially zero, - the binder is melted and it is brought into contact with the aggregates, - it is applied to the aggregates and to the binder fusion a compression suitable for causing the molten binder to fill the interstices between the aggregates.

Description

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 The present invention relates to the industrial synthesis of rocks. The term synthesis here designates the physical operation which consists in combining and agglomerating, by means of a binder consisting of a mineral or a combination of vitrifiable minerals, aggregates of one or more crushed granular or non-granular minerals between them, or aggregates of igneous or metamorphic rocks or of any type of rocks with one or more crushed granular or non-granular minerals, or alternatively to combine different aggregates of igneous and / or metamorphic rocks together, in order to obtain compositions rocks that do not meet a priori in nature.

 It also relates to a particular case of synthetic rock which is the restructuring of igneous rocks, or metamorphic rocks of igneous origin and more particularly granite type rocks. These restructured rocks are called synthetic igneous rocks, synthetic metamorphic rocks and / or synthetic granite and restructuring designates the physical operation which consists in aggregating together the aggregates of the same rock by means of a binder which is that same rock.

State of the art
It is well known that igneous rocks, as well as some of the metamorphic rocks have a magmatic origin. When the magmas cool in the open air they form volcanic or effusive rocks. On the other hand, when the magmas cool down within the Earth's crust, they form plutonic or intrusive type rocks. According to CE Wegmann, the

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 most plutonic rocks form in the deep parts of the earth's crust upon contact with pre-existing rocks. Subjected to relatively high pressures and temperatures, they are impregnated with a pegmatic solution. On cooling they acquire the properties of a migma and recrystallize without going through a molten state. These rocks, which are called migmatic metaplutons, have a granitic or dioritic composition. The recrystallization process which gives them birth takes the name of granitization.

 Geologists, mineralogists, physicists and chemists have long experimented in the laboratory with the reproduction of rocks in order to understand the mechanisms which are at the origin of their constitution. These experiments try to reproduce the extremely complex conditions in which these rocks were formed. These researchers have the greatest difficulty in making these reproductions because of the considerable values to be implemented, in principle over a long period, both at the level of the temperature which can reach several thousand degrees, and at the level of the pressures to be applied simultaneously and which can reach, or even exceed, three million bars. These considerable values can only be obtained in the laboratory and are not applicable industrially, the greatest difficulty to be overcome being the time value. The interest of this research lies in the important lessons it brings to a large number of professions, such as petrochemistry, petrography, geochemistry, geophysics, geotechnics, applied geology and all related professions. Similarly, the study of minerals and the syntheses carried out in the laboratory under high pressure help to understand the process of rock formation. But all of this research has never had the purpose, nor allowed, the industrial synthesis of rocks or stones (these two terms are, within the framework of this presentation, considered as equivalent).

 Mineable natural stones, and particularly granites, are among the most common materials on our planet. However, the use of these stones for the building, public works, decoration and funeral industries imposes many constraints which make it a noble material

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 and expensive. The extraction of blocks in quarries requires the use of heavy equipment and poses many problems of loss of material due to imperfections in the rocks. The transport of these bulky blocks, of considerable weight, poses many handling problems, the processing factories often being several hundreds, even several thousands of kilometers from the places of extraction. Then, sawing blocks in slices requires the use of imposing multi-blade diamond saws whose penetration in the hardest mineral materials varies from 45 to 90 mm per hour. The calibration and polishing of the wafers finally requires the use of large grinding and polishing benches. This set of constraints, generally very expensive, makes natural stone a high-end product.

 This is why the building, public works, decoration and funeral industries have long used artificial or reconstituted stones. But these imitations are always based on hydraulic binders, or organic or a reaction product of a mineral binder and an organic binder, and do very poorly restore the beauty of the stones and natural rocks they pretend to copy. They all have in common the use of an opaque binder which remains dull when polishing. Hydraulic binders have a very low index of refraction of light when polished, mainly due to their natural opacity due to the powdered clay and limestone materials used in their composition. Organic binders and reaction product binders of an inorganic binder and an organic binder remain dull on polishing due to the temperatures resulting from polishing of the aggregates which, despite cooling with water, tend to overheat the organic binders. In addition, for reasons of dimensional stability and in an attempt to improve the mechanical characteristics, these binders are generally loaded with fillers and / or micron fillers which, as in the paint industries, opacify them. Indeed, even the charges from transparent stones or translucent stones or minerals of the achromatic or alochromatic groups become white and opaque after having been reduced to micron powder. Consequently,

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 none of these reconstructions falls within the definition of synthetic stones which use as binder minerals or combinations of vitrifiable minerals. However, it is thanks to such binders that we can hope to obtain stones with a beautiful natural appearance and which can become shiny when polished.

 In another field, glass-ceramicists use the fusion of minerals and manufacture materials with good decorative effect which are sometimes used in place of natural stones and which sometimes seek to imitate certain aesthetic characteristics. However, the techniques for manufacturing vitrocerams are very generally techniques originating directly from the glass industry, generally consisting in introducing and dispersing into a vitreous mass at very high temperature titanium oxides or zirconium oxides or still lithium silicates which promote the partial crystallization of the glassy phase, this crystallization being in the form of crystals of micrometric size, which in practice prevents the production of shiny polished surfaces. In addition, the presence of a small or even zero quantity of aggregates in the vitreous phase generally leads to an appearance very different from that which is commonly associated with stones or rocks.

 Subject of the invention.

 The subject of the invention is the industrial manufacture of synthetic stones, in all useful forms and conformities, and particularly in the form of flat products, by restoring as well as possible the technical, physical and aesthetic qualities (in particular the shine of polished surfaces) that we traditionally expect stones or rocks, this manufacturing aiming to restructure natural stones, or on the contrary to create new stones.

It also relates to the suppression of a certain number of expensive operations in the stone trades, and preferably the suppression of the extraction of the blocks of mineral matter, the suppression of the sawing of these blocks in slices, and the suppression the calibration of these slices. It aims for this purpose, not only a process, but also a stone thus obtained and a

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 installation suitable for implementing this process.

Presentation of the invention
To this end, the invention proposes a process for manufacturing synthetic stones, or even restructured stones, according to which: - a binder is mainly prepared consisting of one or more vitrifiable materials, - aggregates of rocks or minerals are prepared with a particle size such that the proportion of grains of size less than a threshold of at least of the order of 0.1 mm is substantially zero, - the binder is melted and it is brought into contact with the aggregates, - applies compression to the aggregates and to the binder in fusion so as to cause the molten binder to fill the interstices between the aggregates.

 The invention thus proposes to apply industrially a process which, although departing from the natural granitization process, makes it possible to obtain by melting the mineral binder and bringing it into contact with aggregates having a controlled particle size, then by compression of the whole, either rocks and stones substantially identical to natural stones, or compositions of rocks which are not found in nature. There may or may not be heating of the aggregates before the compression is applied (the obtaining of thin sheets could indeed have been carried out in the absence of heating, even if heating of the aggregates may seem useful in many cases).

 Insofar as such a process may appear to have similarities with a sintering process, it should be noted that sintering has already been used in the world of ceramics and vitroceramics. However, the manufacturing techniques are radically different since sintering applies in principle to molded parts and since the vitrifiable materials used are cold mixed with the other constituents. In addition, conventional sintering is generally a mixture of homogeneous grains, which is not a priori the case in the production of synthetic stones; furthermore, such homogeneous grains are generally not intended to preserve their

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 individuality after sintering, which is not the case for aggregates of synthetic stone. In any case, the ceramists have never really looked into the manufacture of rocks, although they know all the technical bases. Their research is all focused on improving the mechanical and physical performance of ceramics. They have made a very large number of discoveries, be it cermets, new ceramics, composite ceramics, superconducting ceramics. They have become essential in high-tech industries such as aeronautics, space, nuclear, electronics, electrical, or in the fields of everyday life, taps, household appliances, etc ... but never they never really got involved in the stone world.

 It can also be noted that the fusion of minerals has long been mastered in various fields, if only in the glass, glass furnace, or ceramic industry. It should also be noted that the ceramic industry and many other industries have long used isostatic compression by rolling. However, none of these industries has sought or succeeded in reproducing or creating rocks or stones industrially.

 The invention also provides a stone comprising mineral aggregates compressed so that they are all in contact with each other, and agglomerated together by a binder in the glassy phase. The aggregates have a particle size such that the proportion of aggregates of size less than a threshold of at least about 0.1 mm is substantially zero and the mass proportion of binder is at most 36.34%.

 Indeed, even when the invention is implemented to obtain restructured stones, aiming to reproduce a natural stone as well as possible, the stone obtained by the invention is identifiable, in particular because of the granulometry of the aggregates which is devoid of fine particles, in combination with a glassy phase which represents at most around a third of the whole.

 The invention also proposes, for implementing the method according to a particular mode, an installation comprising:

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 a substantially flat support, a device for depositing aggregates suitable for depositing a layer of aggregates on the support, - a device for heating and depositing binders suitable for depositing a strip of molten binder in contact with the layer of aggregates, - a compression device arranged downstream of the aggregate depositing and binder depositing devices, here made up of cylinders, adapted to compress the layer of aggregates and the binder blade in fusion so as to bring the aggregates together from each other so that they are in close contact with each other and forcing the binder to fill the spaces between the aggregates.

 Such an installation allows the continuous manufacture of synthetic stones from which various products can then be obtained, and very particularly the continuous manufacture of plates in synthetic igneous rocks, in synthetic metamorphic rocks of igneous origin and more particularly in synthetic granites. This installation implements a compression mode by which the agglomeration of aggregates and minerals can be adjusted at will according to the hardness of the materials used and according to the desired thickness. In practice, this installation makes it possible in particular to manufacture products in the form of sheets or plates having a thickness of between 5 mm and 100 mm or more and a width of between 10 mm and 3000 mm or more. It also makes it possible to continuously manufacture tiles and pavers of all shapes or even certain profiles.

 Other advantageous features of the invention, possibly combined, are discussed below.

 * the aggregates or grains have a form factor which preferably falls in the ratio 1 to 1, or 1 to 2.

 * the aggregates are preferably selected according to a predetermined particle size section whose significant order of magnitude is found in the ratio of 1 to 15; due to the size threshold below which the proportion of aggregates is substantially zero, the grain size curve is

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 a truncated grain size curve which takes into account only part of a normal grain size curve. The grains or aggregates eliminated in the standard grain size curve are preferably the grains forming part of fine sands (from 0.315 mm to 0.125 mm), the grains forming part of very fine sands (from 0.125 mm to 0.05 mm) and fines or silts (from 0.05 mm to 0.005 mm). No fine and no aggregate smaller than the standard particle size 0.315 mm / No. 23 sieve fits into the particle size selection. It is indeed essential to leave a percentage of void between the aggregates and that these voids are continuous and intercommunicating with respect to each other so that the molten mineral can, at the time of compression, preferably isostatic or isodynamic, fuse and s '' infiltrate into intercommunicating voids between aggregates. The percentage of intercommunicating void is at most equal to 36.34%, preferably less than 20%, or even 15%, and advantageously equal to 12% of the volume of the solid to be produced.

Preferably, 90% of the grain size curve is between the grain size 0.63 mm (sieve No. 29) and the grain size 10 mm (sieve No. 41).

 The aggregates and minerals included in the composition will have been washed and dried beforehand in order to be rid of all fines and all foreign bodies. The size of the largest aggregate and the resulting particle size curve will depend on the desired aesthetic effect and the thickness of the rock to be produced. All truncated grain size curves are achievable. It is even possible to use only one particle size, the percentage of voids (in this case around 36.34% maximum) being filled by the molten mineral acting as a binder. In this case, it is preferable not to exceed an aggregate size greater than 8mm.

Preferably, the size of the largest aggregate must be, at most, equal to half the thickness of the plate to be produced.

 The aggregates included in the selection can be either aggregates of any rock, of an igneous and / or metamorphic rock, or of a crushed and / or granular mineral, or of a combination of rocks, igneous and / or metamorphic rocks, or

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 of an association of crushed and / or granular minerals, or finally of an association of one or more rocks and / or igneous and / or metamorphic rocks with one or more crushed and / or granular minerals. In the case of a restructuring of an igneous or metamorphic rock, the aggregates used are aggregates from this same rock.

* The volume of molten binder used in the composition corresponds to the ratio expressed as a percentage of the volume of voids Vv to the total volume of compressed aggregates Vac without binder: Volume of molten binder =
Void volume = Vv (%)
Total volume of compressed aggregates Vac
The percentage of molten binder (expressed by volume) relative to the total mixture of the aggregate solid / compressed binder can be between 3% and 36.34% by volume. When aggregates of a single particle size are used, and they are vibrated before compression, the percentage of binder in fusion entering the composition is preferably between 26% and 36.34%.

When using aggregates according to a spread granulometric curve (but truncated as indicated above), the percentage of binder in fusion returning to composition relative to the total mixture aggregates / binder is advantageously between 3% and 26%. Preferably, the percentage of molten binder entering into composition relative to the total aggregate / binder mixture is between 15 and 20%, advantageously between 10% and 14%.

 * The aggregates are advantageously brought to a temperature between 600 C and 1000 C in the case of the use of a binder melted without the addition of fluxes and to a temperature between 300 C and 600 C in the case of use of 'A molten mineral binder added with fluxes, for example alkalis and in particular sodium sulphates or carbonates and / or potassium sulphates or carbonates. The heat treatment bringing the aggregates to high temperature is preferably carried out by means of a rotary furnace with heat treatment, but it can be carried out by means of any type of oven and / or by means of any heat treatment. .

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 It has been observed that for the production of plates equal to or less than 20 mm, the aggregates can be used at room temperature, more or less 20 ° C., but that in this case it is recommended to use a mineral binder in fusion with very high temperature, above 900 C, added with alkalis which have the ability to lower the viscosity rate of the molten binder.

 * According to an important aspect of the invention, the binder is a mineral, or a combination of minerals, fused, before compression, which on cooling becomes vitrified and therefore in principle becomes shiny on polishing. Advantageously, the molten mineral can be a mineral which, during vitrification, becomes transparent, such as the adularia which is a variety of orthosis. The molten mineral can be a silica, a variety of silica a mixture of silica, or a silicate, a variety of silicate or a mixture of silicates. The molten mineral can also be a potassium feldspar, such as orthosis, sanidine, microcline, anorthosis, or any other potassium feldspar, but it can also be a mixture of the various minerals forming the family of potassium feldspars. It can be a sodium-sodium feldspar, or plagioclase, such as albite, anorthite, oligoclase, andesine, labradorite, bytownite, or any other sodium-sodium feldspar, but it can also be a mixture various minerals forming the family of sodium-calcium feldspars. It can be a barytic feldspar, such as celsian, hyalophane, or any other barytic feldspar, but it can also be a mixture of the various minerals forming the family of barytic feldspar. It can be a mixture of different feldspars. It can be a quartz or a variety of quartz. It can be obsidian, tectite, fulgurite or any variety or mixture of volcanic glass or it can be a pyroclastic rock. It can be an industrial glass of the silica-soda-lime type, of the silico-boro-lime type, it can be a glass of lithium, titanium, lead, or potash, it can be a glass of which one of the constituents is alumina AL203 of antimony oxide, it can be any type of industrial and / or non-industrial glass, whether it is loaded or not, colored or not. It can be any mixture of industrial or non-industrial glass. Finally, it can be any type and any mixture of glass waste or any type and any mixture of recycled glass. It can be any mineral

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 molten or any combination of fused minerals which, upon cooling, vitrifies. The mineral or the combination of fused minerals which, at the time of vitrification, becomes transparent to translucent, may be charged with one or more mineral or metallic oxides in order to modify its color and / or structure physical while retaining the characteristics of gloss when polished: for example it can be loaded with a tantalum oxide or a thorium oxide which have the property of considerably increasing the refractive index, or an oxide of lead which has the ability to give an extremely bright and clear appearance to polishing. It can also be charged with any charges changing the physical and / or optical properties of the binder, for example, cobalt salts which color the binder in blue, iron and chromium salts which color it in green, nickel salts which color it in gray, cadmium or selenium salts which color it in red or orange, gold salts which color it in ruby color, or it can be charged with luminescent, phosphorescent, thermoluminescent or photochromic charges by adding to a transparent or translucent binder of tiny grains of silver chloride or bromide. In the particular case of a restructuring of a synthetic igneous or metamorphic rock, the same molten rock is preferably used as a binder, or even advantageously the mineral used as a binder is the majority fundamental constituent of this igneous or metamorphic rock. Finally, advantageously, in order to speed up the melting process, cullet or currant can be added to the vitrifiable mixture.

 * The process advantageously includes a step according to which a blade of molten binder (process for manufacturing laminated glass in continuous casting, or process for making drawn glass Pittsburgh process or Libbey-Owens process, or any type of window glass process ) is deposited on the hot aggregates before compression. In this case, the aggregates can be deposited on a scrolling support or, alternatively, this support is fixed while, in particular, the elements ensuring the compression are movable relative to the support.

 * Compression is advantageously compression

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 isostatic or isodynamic applied to the layer (s) of hot aggregates and molten mineral or to the molten mineral / aggregate mixture.

Preferably, the mixture is agglomerated by means of rolling on a plate support with a counter-support cylinder, the mixture or the layers being deposited on the plate support. The force exerted by the cylinder or the larger large roller on the aggregate / mineral layer (s) or aggregate / mineral / aggregate, in fusion, or on the aggregate / mineral mixture, supported by the plate support has a fixed value, for example 50 tonnes. This force is in practice adjusted as a function of the hardness of the minerals entering the composition, certain minerals being liable to be reduced to powder if the force exerted by the compression cylinder on the aggregates or the mixture is too strong. Other minerals, on the contrary, withstand very high pressures. Agglomeration can also be achieved by isodynamic compression between two rollers, or between two large rollers, of the rolling / rolling type. In this case, the aggregate layer (s) / mineral or the mixture is deposited on the apron of the lower cylinder. The agglomeration can finally be achieved by means of a powerful press.

 * When using the technique in successive alternating layers (at least 2 layers of aggregates), for example aggregates / molten binder blade / aggregates, it is possible to produce reinforced plates by incorporating between two layers a wire mesh or wire mesh or tensile fibers or wire. It may be noted that it is possible to introduce between two layers of aggregates glass fibers and / or ceramic fibers or any fiber or son reinforcing the structure.

 It should be noted that the production of synthetic stones according to the invention makes it possible to obtain stones industrially having technical and physical characteristics very close to natural stones.

It makes it possible to create rocks which do not meet in nature by mixing the aggregates of two or more igneous and / or metamorphic and / or sedimentary rocks. It also makes it possible to create new rocks based on aggregates of igneous and / or metamorphic rocks and / or

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 sedimentary mixed with one or more crushed granular or non-granular minerals or new rocks based on one or more crushed granular or non-granular minerals. It also makes it possible to produce rocks based on river or sea sand (very large to medium sands or 2mm to 0.25mm) free of fines or also based on minerals in granular form in their natural state. Finally, it makes it possible to produce all the decorative patterns that one can imagine, whether these patterns are repetitive or random, by juxtaposing two or more zones of minerals or mixtures of minerals of different origins, or even by combining rock aggregates igneous and / or metamorphic and / or sedimentary to each other, or by associating one or more types of igneous and / or metamorphic and / or sedimentary rock aggregates with one or more crushed granular or non-granular minerals, or by associating one or more granular or non-granular minerals crushed together.

 It may also be noted, according to a particularly interesting aspect of the invention, that the optical properties of the synthetic rocks obtained are extremely close, even identical to the optical properties of igneous and metamorphic rocks of natural origin. In fact, even if the mineral or the combination of minerals used as a binder in the structuring of a rock loses its crystalline state, it retains, while vitrifying on cooling, part of its original optical properties. In addition, and preferably, when the mineral binder is chosen from the range of minerals which, upon cooling, vitrify by becoming transparent, it lets light penetrate inside the restructured synthetic stone. Light can thus diffuse inside aggregates made up of transparent to translucent and translucent to opaque minerals without being stopped by an opaque binder leaving the minerals all their optical properties of refraction, birefringence, polarization, relief effect. , of brightness, of color, of transparency, etc .... This optical effect, which only the invention makes it possible to reproduce, is however one of the primordial peculiarities of the beauty of polished natural stones of igneous origin and particularly of granites .

 It may also be mentioned, according to the invention, that the particular case of the

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 restructuring of igneous and / or metamorphic rocks makes it possible to obtain industrially and continuously stones having practically the same technical, physical, chemical, optical and aesthetic characteristics as the original natural stones. The mechanical performance of the stones obtained is identical to that of natural igneous or metamorphic rocks, or even higher, because these stones are free from microcracking due to constant compression.

 The invention makes it possible to reproduce industrially all the igneous rocks, or granular metamorphic rocks of which the families of feldspar are one of the fundamental constituents, whether it is the families of alkaline feldspar or the families of plagioclase feldspar, said calcosodium feldspar, potassium feldspaths. or barytic feldspar. It also makes it possible to reproduce igneous rocks whose fundamental constituents are feldspathoids, micas, amphiboles, piroxenes, olivine and even volcanic glass.

 The different types of reproducible igneous rocks are in particular: - in the granite families: the so-called normal granites, the alkaline and hyperalcaline granites, the leucogranites, the charnockitic granites, the adamellites, the trondhjemites, the microgranites formerly called porphyries, the granophyres, pegmatites, aplites, lamprophyres, greisens, luxulliante, and all the rocks of the granite family.

 - in the families of diorites: diorites, tonalites, hornblendites, orbicular diorites hardly achievable according to the position of minerals, anorthosites, and plumasite, and all the rocks of the family of diorites.

 - in the families of gabbros and basic and ultrabasic intrusive rocks: gabbros stricto sensu, norites, euphotide, dolerites, anorthosites, pyroxenites, peridotites, dunites, picrites, biotites, micaceous peridotites , kimberlites, biotite pyroxenes, eclogites, and serpentinites, and all rocks of the gabbros family and basic and ultra-basic intrusive rocks.

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 in the syenite families: the sodium-rich syenites, the albites, the larvikite, the shonkinite, the monzonites, the feldspathoid syenites, the borolanite, the malignite, the foyait, the moriupolite, the monmouthite, the cancrinite syenites, the zircon syenites, eudialite syenites, sodalite syenites, analcime syenites, corundum syenites, and all rocks of the syenite family.

 - in the families of alkaline, calc-alkaline, basic and ultra-basic intrusive rocks: kentalenite, esexite, theralites, tesenites, urtite, ijolites, melteigite, fergusites, missourite and limburgites and all rocks in the family of intrusive alkaline, calc-alkaline, basic and ultra-basic rocks.

 - in the lamprophyre families: let us quote the kitten, the vogesite, the alnoïte, the monchiquite, the kersantites, the spessarites, the camptonites and all the rocks of the lamprophyres family.

 - all the rocks of the quartz porphyry family and their subcomponents.

 - all the rocks of the family of rocks with quartz phenocrysts and their sub-components.

 - all the rocks of the andesites family and their sub-components.

 - all the rocks of the basalt family and their sub-components.

 - all the rocks of the family of trachytes and phonolites and their subcomponents - all the rocks of the family of trachy-andesites and trachybasaltes and their subcomponents.

 - all rocks of the family of basic and ultrabasic feldspathoid rocks and their subcomponents.

 - all the rocks of the pyroclastic family of rocks and their subcomponents.

 The different types of reproducible metamorphic rocks are notably rocks that derive from the metamorphism of igneous rocks, such as

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 crystalline schist or orthoschist, gneiss or orthogneiss, amphibolites from the metamorphisms of basic igneous and pyroclastic rocks, eclogites, granulites and quartzites.

 It should be noted that the use as quarry waste aggregates and as a binder for recycled glass protects the reserves of natural stones and thus makes the process according to the invention relevant from an ecological point of view.

 The synthetic stones produced according to the process of the invention appeared typically to have the following technical characteristics: - Resistance to rupture in tensile bending for an unreinforced product: 10 - 20 MPa.

 - Compressive strength: 150 to 200 MPa.

 - Hardness according to Mohs equal to the hardness of the aggregates used.

 - Moisture absorption of less than 0.5% in 48 hours.

 - Frost resistance at least equal to 100 cycles.

Description
List of Figures
Objects, characteristics and advantages of the invention appear from the following description, given by way of nonlimiting illustrative examples, with reference to the appended drawings in which: - Figures 1 and 1a are schematic elevation views of part of the installation - Figure 2 is a schematic elevation view of a second part of the installation.

 - Figure 3 is a schematic cross-sectional view of the compression assembly.

 - Figure 4 is a sectional view of an intrusive igneous Gabro rock with amphibole - (P) Plagioclases twinned Labradorite type - (H) Green Hornblende. (size of minerals not respected - theoretical representation) - Figure 5 is a sectional view of an effusive igneous rock Pyroclastic rock - Basaltic tuff - Minerals of the zeolite family (Z)

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immersed in a vitreous mass (V). (size of minerals not respected theoretical representation) - Figure 6 is a sectional view of a synthetic rock according to the invention, compressed aggregates linked by a vitrified binder (the black part representing the vitrified binder, the white part the aggregates ). (size of aggregates not respected - theoretical representation)
The world concerned by the invention is the world of stone crafts. The men in these trades perfectly master the techniques of extracting, cutting, calibrating and polishing stones. The research and innovations they undertake go in the direction of improving these techniques. Upstream of their profession, geologists and mineralogists reproduce minerals, rocks, or certain natural phenomena in the laboratory, such as deformation of rocks, sedimentation or magmatic intrusion. The aim of this research is to study the mechanisms of rock formation in order to determine its constitutive laws.

These laws subsequently make it possible to better define the places of mining and petroleum research. Downstream of the stone trades, manufacturers of tiles and building materials try to reproduce natural stones. These pale attempts at imitation and the complexity of the laboratory work of geologists and mineralogists comfort the men of the stone trades in the idea that it is not possible to industrially restructure a natural rock or to industrially produce a rock of synthesis.

First example of creation of synthetic stones
The installation in FIGS. 1 to 3 mainly comprises: - a substantially flat support, - a device for depositing aggregates suitable for depositing a layer of aggregates on the support, - a device for heating and depositing binders suitable for depositing a strip of molten binder in contact with the layer of aggregates, - a compression device arranged downstream of the devices for depositing aggregates and for depositing binders, here consisting of cylinders, suitable for

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 compress the layer of aggregates and the blade of molten binder so as to bring the aggregates closer to one another and force the binder to fill the spaces between the aggregates.

 Aggregates and minerals are selected and stored by grain size in vertical silos 23, here online. The respective outputs 24 of the silos 23 each overhang the input orifice of a weighing device 25 which is capable of admitting determined quantities of aggregates at regular intervals, by means of two scales.

 The aggregates are evacuated alternately from the scales' trays and fall into a hopper 26 which pours onto a continuous strip 10 which pours onto an elevator 11 which conveys the aggregates to a mixer 34.

 Each silo 23 simultaneously delivers on the continuous strip 10 the quantity of aggregates corresponding to the predetermined particle size section.

 The outlet 35 of the mixer 34 overhangs the inlet 43 of a rotary gaseous fuel oven 42. The rotary oven, slightly inclined with respect to the horizontal, has in smaller the classic characteristics of the ovens used in the cement industry. It raises the temperature of the aggregates from the mixer to a determined temperature, for example 650 C.

 At the outlet of the rotary kiln 42, the aggregates fall into the inlet orifice 50 of an insulated weighing device 51. The said device is capable of admitting, at regular time intervals, predetermined weights of aggregates, thanks to two scales. Each balance discharges the quantity of predetermined aggregates into two spouts 53 / 54. These two spouts located at the outlet of the weighing device supply, in hot aggregates, identical hoppers 60 and 61 respectively located in a heat-insulated enclosure 59. Each hopper of distribution 60 and 61 is connected by its upper edge 62 to the lower orifice 55 at the outlet of the spouts 53 and 54.

 Inside each hopper, a distribution device enables the aggregates to be distributed equally over the entire width of the hopper. The distribution hoppers 60 and 61 positioned above a train of support plates 70 will distribute the aggregates uniformly and evenly over the width of the plates 71 of the train of plates which may be of the order of 3 meters. Each

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 hopper is vertical.

 The lower inner part of the wall 63 of the hopper, downstream side, household with the upper face 72 of the plate 71 a rectangular orifice of the width of the hopper, favorably with a height of 15 cm. The other three sides of the hopper 64-65- (66 not shown) descend, to the plate train for the first hopper 60, and to the molten binder blade for the second hopper 61, confirming the exit of the aggregates towards compression.

 The exit from the orifice of each hopper 60 and 61 is controlled by a motorized cylinder 83 and 84 whose external surface 85 and 86 is substantially tangent to the anterior wall on the side 63 of the hopper. The motorization of the cylinder is adjusted so that the external surface of the cylinder 85 and 86 has a synchronous running speed at the running speed of the external surface 92 of the compression cylinder 90 and of the external surface 93 of its counter-pressing cylinder. 91 and the running speed of the train of support plates 70. Favorably, the running speed is set to a speed of 3 linear meters per minute.

 The cylinders 83 and 84 are adjustable in height making it possible to deliver on the train of plates, for the first hopper 60, and on the molten binder for the second hopper 61, quantities of predetermined aggregates. Favorably the quantity of aggregates delivered by the first hopper on the plate support corresponds to 200% of the quantity of aggregates delivered by the second hopper.

 The train of plates 70, well known in the state of the art, supporting the aggregates, is constituted by the juxtaposition of a succession of rectangular plates 71, with a width of 3 meters and a length which can be 7 , 22 meters. The train of plates 71 is driven towards compression by means of two groups of two motors 88 and 89 situated upstream and downstream of the heated enclosure 59, on which pairs of pinions mesh on two racks 73 situated under the plates.

 Upstream of the first hopper 60, the plate train 70 enters the heated and insulated enclosure 59. In this enclosure are placed the first hopper 60, a calendering machine 143, the second hopper 61 and the rolling unit 95, composed of cylinders 90 and 91.

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 Upstream of this calendering machine, and according to well-known techniques for the manufacture of laminated glass, the vitrifiable minerals serving as a binder are stored in silos (not shown). The minerals, or vitrifiable mixture, have previously been crushed so as to obtain a fine particle size of between 0.1 and 0.6 millimeters. The respective outlets (not shown) of the silos overhang the inlet of a weighing device (not shown). Said weighing device is suitable for admitting, at regular time intervals, determined weights. Thanks to two scales, the mineral powder falls into a hopper (not shown) which pours onto a continuous strip which feeds a hopper (not shown), located above the melting zone, at the entrance to a gaseous fuel tank 142.

 As in the glass industry, the mineral or minerals are melted at a temperature between 1300 and 1800 C. Refining agents are introduced into the superheated bath in order to lower the viscosity.

These refining agents can be nitrates, sulfates and oxides. Stabilizers such as lime and dolomite are used as a stabilizer on the mixture.

 Opposite the hopper is, at the outlet of the basin oven, the calendering machine 143. The basin oven and the calendering machine have, in addition, the classic characteristics of basin ovens and calendering machines used in the glass, although it is a new application and a very different field.

 The silo delivers on the continuous strip the quantity of mineral powder corresponding to the predetermined quantity of the molten mineral at the outlet of the calender. The calender has a width slightly less than the width of the support plates. It is equipped with two cylinders of the same size 144/145, motorized, adjustable in height which allow the thickness of the molten binder blade to be calibrated. The axis of the upper cylinder is slightly offset towards the outside of the calendering machine with respect to the axis of the lower cylinder.

 The calendering machine unrolls a calibrated ribbon or a blade of the mineral or minerals fused on the first layer of aggregates from the

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 hopper 60. The second hopper 61 deposits on the mineral binder blade a second layer of aggregates of a predetermined thickness. The layer of aggregates / binder / aggregates progresses at the speed of the plates 71 which support it. These are driven by the two motor groups 88/89 to the compacting group.

 The rolling / compacting group comprises an upper cylinder 90 and a lower cylinder 91 against the support. The cylinder group consists of a frame 95 on which the axis 96 of the lower counter-pressing cylinder is positioned.

 The back-up cylinder serves as a support for the plate train 70 which passes through the compacting group. Two toothed wheels 101/102, located on either side of the axis 96 of the back-up cylinder, mesh with two motors. The motorization of the back-up cylinder 91 is adjusted so that the external face of the cylinder 93 has a speed synchronous to the running speed of the train of support plates.

 The upper cylinder is supported by a mobile assembly 98 carried by two slides which bear on the fixed frame 95. The axis of the cylinder 97 is positioned on the mobile assembly 98. The mobile assembly makes it possible to adjust the cylinder as desired compression 90 by moving it closer or away from the support plates 71 to allow the interval to be varied. The device for adjusting the height of the cylinder 90 is constituted by two endless screws 99 and 100 located on either side of the cylinder. The two endless screws, held by the fixed frame 95 make it possible to slide the mobile assembly 98 on the slides. The force exerted by the cylinder on the aggregate / binder / aggregate mixture is exerted by means of two hydraulic cylinders 105 and 106 positioned on either side of the cylinder 90 on the axis 97 of the cylinder and on the fixed frame 95 of the group. of rolling. The force is adjusted to a determined value, for example 50 tonnes, which corresponds to more than one tonne per square centimeter. Two toothed wheels 103 and 104, located on either side of the axis of the compression cylinder 97 mesh with two motors. The motor speed is adjusted so that the external surface of the cylinder 92 has a speed of travel synchronous with the speed of travel of the support plates

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At the vertical of the right axis and at the vertical of the left axis of the compression cylinder 90 and the back-up cylinder 91 two rollers 121 and 122 (see FIG. 3) substantially tangent to the right and left lateral edges of the support plates 70 keep the right and left edges of the aggregate / binder in fusion / aggregates during compression compressed. The rollers 121 and 122 are driven by friction on the right and left lateral faces of the support plates 70 and on the right and left lateral faces of the external face 92 of the compression cylinder 90.

 The rollers are interchangeable allowing different thicknesses of products to be produced. They are also shirtable in order to be able to print on the edge of the synthetic stone during compression a pattern or a linear profile.

 The support plate / layer to be compacted assembly passes through the rolling group under the combined effect of the drive of the plate train and under the effect of the drive originating from the rotation of the cylinders 90 and 91. At the time of compaction , the expanding aggregates are highly compressed and agglomerated. Simultaneously the mineral serving as a binder, which is in a viscous and fluid form, fuses and infiltrates between the interstices and the intercommunicating voids between aggregates. The binder, while expelling air, is itself violently compressed between the aggregates, thereby creating an adherent bond around the periphery of each aggregate and between each aggregate, thus forming a mass conglomeration. The stone thus produced is put at its maximum density. This manufacturing process, although far from the natural process, is close to the theory of granitization of C.E.

Wegmann according to which preexisting rocks subjected to pressures and high temperatures are impregnated with a pegmatic solution.

 At the compression outlet, the layer of stone thus compacted and cylindrical passes through a cooling tunnel (not shown). The cooling is carried out uniformly over the entire width and over the entire thickness of the strip so that the cooling takes place with a linear temperature gradient between 3 and 12 C / min. Once the

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 temperature reached 350 C, cooling (not shown) to room temperature can be achieved, always uniformly, using cold or refrigerated compressed air.

 The hardened stone exits the cooling tunnel in the form of a hard and rigid strip. The upper face of the plate is sucked against an air vacuum device which detaches the stone tape from the 5 / 10th of a millimeter support plate.

 The support plate is driven by rollers rotating at a speed greater than the running speed of the plate train (not shown). It is detached from the train of plates and will be positioned on a lifting table which lowers and which quickly returns the plate to the start of the chain (not shown). The plate moves from downstream to upstream on a roller track located under the production line (Figure 2). The plate is cooled by water, air-dried and returned to the start of the chain where it attaches and is positioned on the plate train thanks to its lugs (not shown).

 The stone ribbon continues its path on a pebble path towards the cutting area and the polishing area.

 All the cylinders used in the installation are cooled by means of a cold water circuit passing through the axis of each cylinder. Vibrators can be placed on the hoppers 60/61 in order to favor a better placement of the grains on the support plates 70. The train of plates can pass on vibrators, located under the train of plates between the hoppers 60/61 and between the hopper 61 and the compacting unit 95 in order to once again favor the positioning of the grains on the plates. It should be noted that the vibratory intensity applied to the plates is of low intensity so as not to destructure the work of positioning the grains carried out at the level of the hoppers 60/61.

 Depending on the minerals used, and in the event that microcracks appear during cooling, these can be removed by surface annealing at a temperature between 450 C and 550 C.

 Preferably, two pre-compacting cylinder groups are positioned in the heated enclosure 59, between the first hopper 60 and the

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 calendering machine 143 for the first pre-compacting cylinder group 196, and between the calendering machine 143 and the compression cylinder 90 for the second pre-compacting cylinder group 197. The pre-compacting cylinder group comprises an upper cylinder 201 and a cylinder lower 202 supported by a frame. The lower cylinder serves as a counter-support for the plates of the plate train which pass through the pre-compacting group. The upper cylinder of the pre-compacting group is adjustable in height. The two cylinders of the group are motorized and adjusted so that the external surface of the cylinders 203/204 has a running speed synchronous to the running speed of the external surface of the compacting cylinder 90. The second pre-compacting group is identical to the first group. The pre-compacting groups are used in the case of the use of aggregates of large particle size in order to cause a rearrangement of the aggregates.

 It should be noted that the embodiment of aggregates in two layers with an intermediate layer of mineral in fusion is the most favorable embodiment for a good distribution of the mineral in fusion, but the embodiment can also be a single layer of '' aggregates with deposit of molten mineral blade and isostatic compression, as it can be in case of significant thickness in tri-layer with two blades of binder in intermediate fusion.

 According to a variant of this first embodiment of synthetic stones, the upper cylinder 90 of the compacting cylinder group is lined so that it prints, on the upper part of the strip of stone being structured, the hollow patterns or embossed shirt.

These patterns can be decorative as they can be the precut of the stone ribbon in plates or they can be the precut or the cut of the ribbon in any shape or in tiles of all shapes or sizes, or finally of paving stones or certain profiles.

 According to a second variant of this first embodiment, the molds are supported by the train of support plates 70.

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Second example of realization
According to a second embodiment, the train of plates is eliminated in favor of two endless metal bands, located on either side, upstream and downstream, of the compacting group which is itself composed of two cylinders of same size compaction. The aggregates from the hoppers 60 and 61 as well as the molten mineral from the calendering machine 143 are deposited on the endless belt which takes the mixture to the compacting group.

The compacted assembly is taken on another endless belt to the cooling tunnel.

Third embodiment example
According to a third embodiment, the aggregates at high temperature are coated with a molten mineral binder by means of spraying, in a rotary oven for example. The passage time in the heat treatment furnace is calculated so that the molten mineral binder sprayed on the external part of the aggregate remains in the molten state until the moment of compression. The outlet of the rotary kiln directly overhangs the distribution hopper 61 which is in the thermally insulated enclosure 59 and which distributes the aggregates uniformly on the plate train 70. The distribution hopper is placed as close as possible to the compacting group 95, so that between the outlet of the rotary kiln and the rolling / compacting group the aggregates do not undergo a violent temperature drop and that the binder is always in a molten state when it reaches the compacting group. At the time of passage into the compacting group of the support plate and of the aggregates coated with the binder in the molten state, the latter in the state of expansion are compressed and agglomerated so that the aggregates are violently brought into contact with one another, repelling in the interstices the binder coating the aggregates.

 At the compression outlet, the layer of stone thus compacted and cylindrical passes through a cooling tunnel. As in the previous description, the stone ribbon put at its maximum density provides panels finished by simple cutting. The support plates are water cooled,

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 air-dried and returned to the start of the chain to be reintegrated into the plate train.

Examples of synthetic stones
By volume, the percentage of aggregates or minerals included in the composition is between 63.66% and 97%. The percentage by volume of vitrifiable mineral binder entering into composition is between 3% and 36.34%.

 As an example we will give two realizations having for final the realization of a blue granite of Brazil known as "Bleu de Bahia".

 - Synthetic "Bahia Blue" produced only from aggregates of the original stone. Aggregates from Brazil.

 Particle size curve corresponding to the normalized average particle size.

N of sieve 0 of grains in mm In% of grains In% of the composition
38 5/10 13.73 12.09
35 2.5 / 5 17.67 15.53
32 1.25 / 2.5 37.08 32.64
29 0.63 / 1.25 24.80 21.83
26 0.315 / 0.63 6.72 5.91
12% mineral binder - Synthetic stone made from sodalite aggregates (Brazil origin), milky white quartz (France origin) and Cape black granite (South Africa origin) and having an aspect very close to blue granite, called "Bahia Blue".

 Particle size curve corresponding to the normalized average particle size.

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N sieve 0 grains / mm% of grains% of grains% of grains% composition
Sodalite Quartz white Granite Black
38 5/10 3.20 10.53 12.09
35 2.5 / 5 6.22 11.45 15.53
32 1.25 / 2.5 5.04 22.04 32.64
29 0.63 / 1.25 16.80 6.22 1.78 21.83
26 0.315 / 0.63 2.48 4.24 5.91
Mineral binder 11.98% - Cobalt salts 0.2%
Difference between natural stones or rocks and synthetic stones or rocks according to the invention
A) Difference between natural stones or rocks and synthetic stones or rocks
Synthetic stones are easily differentiated from natural stones because they use combinations of minerals or aggregates that are not found in nature.

 B) Difference between igneous and metamorphic rocks of natural igneous origin and igneous and metamorphic rocks and rocks of synthetic igneous origin.

 It is much more difficult to make a clear and precise differentiation with the naked eye between a natural stone and an igneous or metamorphic synthetic rock. However, this difference is perfectly visible under the electron microscope. Indeed, the minerals or aggregates of synthetic stones which have been violently compressed against each other are always in contact with each other and always linked to each other by a glassy solution, or, if we have added in the binder of lithium or titanium or zirconium oxides for example, by a solution which has crystallized in micrometric form. However, these two forms of rock are not found in nature, neither for intrusive igneous rocks, nor for metamorphic rocks of igneous origin, nor for effusive rocks. The minerals, of crystalline structure, constitutive of natural intrusive rocks do not

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 are never linked to each other by a glassy solution made up of a mineral or a combination of minerals, nor by a solution which has crystallized in micrometric form. When plutonic intrusive rocks, as C. E.

Wegmann, are formed in the deep parts of the earth's crust in contact with preexisting rocks and are impregnated with a pegmatic solution (essentially formed by silicates), this solution, or the combination of minerals forming this solution, is totally crystallized due to the original temperatures, pressures and cooling time of the rocks. The same is true for rocks formed at the pneumatolytic stage and at the hydrothermal stage. For the other intrusive rocks, the cooling of the magmas being carried out over immense periods all the minerals constituting the original magma have time to crystallize completely (depending on the available space left by the first minerals to have crystallized). Only felsites, which are cryptocrystalline or aphanitic rocks and which are intermediate rocks between intrusive rocks and effusive rocks), and which are effusive rocks which have cooled slowly, have a crystal structure made up of microcrystals, which brings them closer synthetic stones whose binder has been crystallized in micrometric form by the addition of lithium or titanium oxide or zirconium. However, these rocks cannot be confused with synthetic rocks because it is the totality of the rock (felsites) which has this type of structure made up of microcrystals which is never the case with a synthetic rock or only the binder, ie a volume of less than 36.34%, may have crystallized in micrometric form in the case of addition of titanium or zirconium oxides in the binder. In all other cases the binder of synthetic stones occurs in the amorphous phase (glassy phase). So, conversely to synthetic stones, the minerals of natural intrusive rocks are not linked to each other by a glassy solution (amorphous phase), nor by a solution which has crystallized in micrometric form.

 Finally, it is extremely simple to identify a synthetic stone under a microscope when the binder is an industrial glass, or a recovery glass, or even when using a mineral or a combination of minerals.

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 in the amorphous phase becoming completely transparent on cooling.

 C) Difference between effusive or natural pyroclastic stones and rocks and synthetic stones and rocks.

 The effusive rocks are theoretically much more difficult to differentiate since the magmatic constituents in the liquid state of the effusive rocks cool suddenly at the time of the volcanic eruption by letting escape part of their volatile elements because of the sudden fall pressure. The part of the magma in the liquid state freezes in the form of volcanic glass or sometimes in the form of microscopic crystals. However, the minerals and / or aggregates constituting the solid part of the effusive rocks are bathed in a vitreous solution without being compressed against each other as in synthetic rocks. These minerals and / or these aggregates generally formed by the debris of the host rocks of the volcanic chimney (volcanic breccias) or even constituted by fragments of rocks before the volcanic explosion (volcanic tuffs) are particularly heterogeneous from the granulometric point of view. the opposite of synthetic stones which use minerals or aggregates following a predetermined truncated particle size section and whose particle size curve does not include any aggregates or minerals smaller than the particle size 0.315 mm. So, conversely to synthetic rocks, the minerals and aggregates that make up natural effusive rocks are never compressed against each other and are totally heterogeneous from a particle size point of view. Finally, conversely to synthetic rocks, the minerals in effusive rocks are often associated with elongated and filiform volcanic glass debris or associated with volcanic glass in the form of drops. These fragments of volcanic glass are often porous due to the demixing of the gaseous phase dissolved in the glass. Finally, for essentially aesthetic reasons, the effusive stones being generally very dark, are rarely used in the building, public works, decoration, funeral industries, if not locally.

 Synthetic stone can, after cooling, be shaped according to all the techniques of shaping stone or glass.

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 Synthetic stone can be curved by the hot softening technique used in the glass industry.

 Finally the synthetic stone, after cutting, can be hardened to reinforce the resistance of the product, (reinforced synthetic stones cannot be hardened). Favorably quenching is applied to synthetic stones using a silico-boro-calcic binder or a binder comprising lithium or titanium. The synthetic stone, cut and shaped to the desired shape, is conveyed to the quenching furnace, then heated electrically or with gas at a temperature of 700 Celtius. Quenching can be carried out by any vertical or horizontal process. Preferably, the quenching process is a thermal process, the chemical quenching process by immersion in a bath of molten salts tending to modify the color of certain minerals.

 Synthetic stone can also be hardened by the semi-soaking process.

 The invention can be carried out according to all types of process which apply the following processes: - Use, to bind aggregates together, of a mineral binder formed of one or more minerals which vitrify on cooling, or which crystallize in the form micrometer.

 - Melting of the mineral binder before the aggregates / binder compression.

 - Preparation of the product before compression, either by coating the aggregates with the molten binder, or by depositing a binder blade (process for manufacturing laminated glass in continuous casting, or process for making drawn glass, or Pittsburgh process or Libbey-Owens process, or any type of window glass process) on the aggregates or between two layers of aggregates, either by depositing the aggregates on a binder slide.

 - Compression of the preparation carried out, in particular, either by means of rolling on a plate support, or between two cylinders or rollers, or by isostatic compression or by isodynamic compression, or by means of a press or finally by any what other means of compression.

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 The stone produced preferably has the following characteristics: - Mineral aggregates between 63.66% and 97% of the synthetic stone.

 - Vitrified binder in amorphous phase or binder in the form of microcrystals between 3% and 36.34% of the synthetic stone.

 - Binder which becomes shiny when polished.

 - Granulometry of aggregates of a significant order of magnitude from 1 to 15.

 Truncated grain size with no fine and no grain less than 0.315 mm.

 Of course, the present invention is not limited to the described embodiments which have been given only by way of example. In particular, it includes all the means constituting technical equivalents of the means described, as well as their combinations, if these are carried out according to the spirit of the invention. According to advantageous arrangements of this invention: - the binder and the aggregates come from the same natural rock, igneous or metamorphic, - a reinforcement formed of fibers and / or independent threads is deposited between two layers of aggregates or intertwined and the stone obtained contains in its mass a reinforcement formed of fibers and / or independent or intertwined threads, - the force applied to the aggregates and to the molten binder for its compression is between 10 and 200 tonnes, - the size threshold below which the proportion of aggregates is substantially zero is of the order of 0.3 mm, - the proportion of binder is substantially between 10% and 20%, at least 90% of the aggregates have sizes included in a ratio no more than 1 to 15.

 The device for depositing aggregates is in relative movement with respect to the support, in the same direction as the device for depositing aggregates.

Claims (46)

 1. A method of manufacturing synthetic stones or restructured stones according to which: - a binder mainly consisting of a vitrifiable material is prepared, - aggregates of rocks or minerals are prepared with a particle size such as the proportion of size grains below a threshold of at least about 0.1 mm is substantially zero, - the binder is melted and it is brought into contact with the aggregates, - compression is applied to the aggregates and to the binder suitable for filling the interstices between the aggregates with the molten binder.  2. Method according to claim 1, characterized in that the aggregates are heated before bringing them into contact with the molten binder.  3. Method according to claim 2, characterized in that the aggregates are heated by means of a rotary heat treatment oven.  4. Method according to claim 2 or claim 3, characterized in that the aggregates are heated to a temperature between 600 C and 1000 C.  5. Method according to claim 2 or claim 3, characterized in that fluxes are added to the binder, and the aggregates are heated to a temperature between 300 C and 600 C.  6. Method according to claim 5, characterized in that the fluxes are alkalis.  7. Method according to claim 6, characterized in that the fluxes are carbonates and / or sulfates.  8. Method according to claim 7, characterized in that the fluxes are sodium carbonates or sulphates and / or potassium carbonates or sulphates.  9. Method according to any one of claims 1 to 8, characterized in that the size threshold below which the proportion of the aggregates is substantially zero is at least 0.315 mm. <Desc / Clms Page number 33>  10. Method according to any one of claims 1 to 9, characterized in that at least 90% of the aggregates have sizes comprised in a ratio of at most 1 to 15.  11. Method according to any one of claims 1 to 10, characterized in that 90% of the aggregates have a size of between about 0.63 mm and about 10 mm.  12. Method according to any one of claims 1 to 11, characterized in that the aggregates are aggregates of one or more igneous and / or metamorphic, and / or sedimentary rocks, and / or aggregates of one or more mineral / crushed and / or granular minerals, or a mixture of such aggregates.  13. Method according to any one of claims 1 to 12, characterized in that the binder and the aggregates come from the same natural rock, igneous or metamorphic.  14. Method according to any one of claims 1 to 13, characterized in that the volume percentage of binder within the solid aggregates / compressed binder is between 3% and 36.34%.  15. Method according to any one of claims 1 to 14, characterized in that the compression which is applied to the aggregates and to the molten binder is isostatic or isodynamic compression.  16. Method according to any one of claims 1 to 15, characterized in that the aggregates are deposited on a support in the form of a layer, and the molten binder is deposited on this layer of aggregates.  17. The method of claim 16, characterized in that the aggregates and the binder in fusion are deposited alternately on a support.  18. The method of claim 17 characterized in that there is deposited, between two layers of aggregates, a frame formed of fibers and / or independent or interlaced son.  19. Method according to any one of claims 1 to 18, characterized in that the aggregates and the binder are continuously melted on a moving support. <Desc / Clms Page number 34>  20. Method according to any one of claims 1 to 19, characterized in that the compression is applied to the aggregates and to the binder in fusion by relative passage of these between a cylinder and a counter-support or between two cylinders .  21. Method according to any one of claims 1 to 20, characterized in that the force applied to the aggregates and to the molten binder for its compression is between 10 and 200 tonnes.  22. Method according to any one of claims 1 to 21, characterized in that the binder is made of a material which is transparent in the vitrified state.  23. Method according to any one of claims 1 to 22, characterized in that the binder is formed from one or more elements from the group formed by silicates, potassium feldspar, calcosodium feldspar, barytic feldspar, quartz, pyroclastic rocks, natural glasses, industrial glasses.  24. Method according to any one of claims 1 to 23, characterized in that the binder contains one or more fillers of mineral or metallic oxides.  25. The method of claim 24, characterized in that the binder contains at least one element from the group consisting of tantalum, thorium, lead oxides, cobalt, iron, chromium, nickel, cadmium salts , selenium, gold and silver chlorides and bromides.  26. Method according to any one of claims 1 to 25, characterized in that the binder contains at least one luminescent, phosphorescent, thermoluminescent or photochromic filler.  27. Stone comprising mineral aggregates distributed in a binder in the vitreous phase, the aggregates having a particle size such that the proportion of aggregates of size less than a threshold of at least about 0.1 mm is substantially zero and the mass proportion of binder is at most 36.34%.  28. Stone according to claim 27, characterized in that the aggregates are at least approximately in contact with each other.  29. Stone according to claim 27 or claim 28, <Desc / Clms Page number 35>  characterized in that the size threshold below which the proportion of aggregates is substantially zero is of the order of 0.3 mm.  30. Stone according to any one of claims 27 to 29, characterized in that the proportion of binder is at most 36.34%.  31. Stone according to claim 30, characterized in that the proportion of binder is substantially between 10% and 20%.  32. Stone according to any one of claims 27 to 31, characterized in that at least 90% of the aggregates have sizes comprised in a ratio of at most 1 to 15.  33. Stone according to any one of claims 27 to 32, characterized in that at least 90% of the aggregates have sizes of between about 0.63 mm and about 10 mm.  34. Stone according to any one of claims 27 to 33, characterized in that the aggregates are aggregates of one or more igneous and / or metamorphic, and / or sedimentary rocks and / or aggregates of one or more minerals crushed or granular, or a mixture of such aggregates.  35. Stone according to any one of claims 27 to 34, characterized in that the binder and the aggregates come from the same natural rock, igneous or metamorphic.  36. Stone according to any one of claims 27 to 35, characterized in that the binder is formed from one or more elements of the group or groups formed by silicas, silicates, potassium feldspar, sodium-sodium feldspar, barytic feldspar, quartz, pyroclastic rock, natural glass, industrial silico-soda-lime glass, industrial silico-boro-calcium glass, industrial glass containing lithium and / or titanium, industrial lead glass , potash or finally any type of industrial glass.  37. Stone according to any one of claims 27 to 36, characterized in that the binder contains one or more fillers of mineral or metallic oxides.  38. Stone according to claim 37, characterized in that the binder <Desc / Clms Page number 36>  contains at least one element from the group consisting of tantalum, thorium, lead oxides, cobalt, iron, chromium, nickel, cadmium, selenium, gold salts and chlorides and bromides money.  39. Stone according to any one of claims 27 to 38, characterized in that the binder contains a luminescent, phosphorescent, thermoluminescent or photochromic filler.  40. Stone according to any one of claims 27 to 39, characterized in that it contains in its mass an armature formed of fibers and / or independent or interlaced son.  41. Installation suitable for implementing the method according to any one of claims 1 to 26, comprising: - a substantially flat support (70), - an aggregate depositing device (60) suitable for depositing a layer of aggregates on the support, this device being in relative motion with respect to the support, - a device for heating and depositing binders (142-145) suitable for depositing a strip of molten binder in contact with the layer of aggregates, this device being in relative motion with respect to the support, in the same direction as the device for depositing the aggregates, - a compression device (90, 91) disposed downstream of the devices for depositing aggregates and depositing binders, here made up of cylinders, suitable for compressing the layer of aggregates and the molten binder blade so as to bring the aggregates closer to each other and force the binder to fill the spaces between the aggregates.  42. Installation according to claim 41, characterized in that the support is a moving band with respect to the devices for depositing aggregates and depositing binder.  43. Installation according to claim 41 or claim 42, characterized in that the compression device comprises a cylinder (90) cooperating with a support element (93).  44. Installation according to any one of claims 41 to 43, characterized in that at least one pre-compacting group (196,197) is <Desc / Clms Page number 37>  provided upstream of the compression device.  45. Installation according to claim 44, characterized in that a pre-compacting group (196) is arranged between the device for depositing aggregates and the device for depositing molten binder, and a pre-compacting group (197) is disposed between the device for depositing molten binder and the compression device.  46. Installation according to any one of claims 41 to 45, characterized in that a second device for depositing aggregates is disposed between the device of molten binder and the compression group.