EXPANDED PERLITE FOR A COMPOSITION THAT INCLUDES PLASTER

Description

2. Quantity increases logistics costs. Thus, transporting expanded perlite to the factory or over long distances requires appropriate methods to minimize mechanical damage and guarantee the integrity of the material until it reaches the point of use. Generally, manufacturers can use Archimedes screws to transport the perlite beads, but these are not very effective as they can break the beads. Furthermore, it is known to use pneumatic conveying, which requires the application of a certain pressure to blow the perlite beads along the container walls. However, this creates friction on the container walls, which breaks some of the perlite beads. A loss of valuable material occurs during transport, impacting production yields and the cost of the industrial installation. For these reasons, there is a real need to provide a process for transporting perlite beads, ensuring efficient transport on industrial sites in order to allow for use with large quantities of material.while minimizing as much as possible the losses generated linked to the formation of fragments of perlite beads whose low porosity is of little advantage to the user. To solve this problem, the present invention provides a method for transporting expanded perlite beads intended for a composition comprising 20 of plaster, said method comprising the following steps: - Supplying raw perlite to a furnace equipped with a flame located in the lower part of the furnace and having a temperature between 900 and 1400°C, preferably about 1200°C, - Bringing the supplied raw perlite into contact with the flame 25 of said furnace with the formation of an upward gas flow relative to the direction of supply of the raw perlite, - Heating the raw perlite until it reaches a temperature between 700 and 760°C, preferably a temperature between 720 and 740°C, forming expanded perlite beads and a 30 fine fraction, compared to said expanded perlite beads,and conveying said expanded perlite beads and said fine fraction BE2024 / 5914 3 by said gas flow formed towards the upper part of the furnace, located opposite said flame, -Particle size separation between said expanded perlite beads and said fine fraction, -Collection of said expanded perlite beads and transport thereof on an elevator equipped with at least one bucket chain to a receiving silo where said perlite beads are ready for use, characterized in that the elevator equipped with said at least one bucket chain extends over at least 3 transport zones, the first zone being flat or (and then) ascending, the second zone being flat and the third zone being descending, all defined with respect to ground level,Since the said third zone is connected to the receiving silo, the raw perlite is supplied to the upper part of the furnace and reaches the lower part of the furnace to allow contact with the flame. The raw perlite is then heated to allow its expansion into perlite beads, which constitute the material of interest. The temperature allows the desired conversions to be carried out with regard to the targeted properties, particularly when added to a composition that includes plaster. This generates a gas flow that preferentially comprises air and combustion gases. This flow rises towards the top of the furnace, in its upper part, and carries with it the expanded perlite beads and the fine fraction. This fine fraction may include fine particles and dust generated during the heating stage of the raw perlite. It is characterized as being fine relative to the size of the expanded perlite beads. The particle size separation stage allows the expanded perlite beads to be recovered on the one hand, and a fine fraction,On the other hand, the collection of perlite beads can thus take place, for example, using a collection hopper. Then, transport is carried out directly and advantageously continuously within the process so as to prepare the perlite beads for their final use. It has been observed that using an elevator equipped with at least one bucket chain ensures continuous and stable transport without risk of destroying the perlite beads that may reach the receiving silo. Thus, determined quantities of expanded perlite beads can be transported by the elevator to the receiving silo while guaranteeing that the structure of the expanded perlite beads remains preserved. Thus, the present invention makes it possible to provide a final product directly usable on industrial sites by safely and efficiently providing for the expansion of raw perlite, the transport of expanded perlite beads and advantageously the mixing with a composition intended for civil engineering, construction… The final application may include lightweight coatings,Insulating mortars or (reinforced) plasterboard, or any material that can be mixed with 10 expanded perlite beads. This process is therefore particularly advantageous for the user who wishes to integrate all these steps within the same production site. The process according to the invention requires little handling and offers improved profitability compared to known processes. Thus, the ratio between the quantity of raw, heat-treated perlite and the quantity of formed perlite beads that reach the receiving silo is between 0.89 and 1, preferably between 0.95 and 1. This is particularly remarkable and allows for minimal material loss. This is particularly advantageous since adding perlite20 to a final product, for example a composition containing plaster, will result in a lighter material. If the plaster is to be sprayed onto a wall,It is preferable to ensure that a maximum quantity of initially added perlite remains present in the plaster while retaining its porous and lightweight properties during application. Its activity is thus essential to benefit from its 25 properties. The challenge lies in controlling all processing stages of the starting product, in this case, raw perlite, up to its arrival at the receiving unit, to allow for quality use with the specific needs of the market. According to a preferred method, the supply stage is carried out in a supply module comprising a hopper equipped with a rotating valve arranged to release a predefined quantity of raw perlite, said hopper being BE2024 / 5914 5, followed by a downward vibrating wall towards the lower part of said kiln, a portion of which extends into said kiln. Preferably, the particle size separation stage is carried out in a separation module, part of which is connected to the elevator, preferably by means of a hopper for collecting the expanded perlite beads. Indeed,The separation module 5 may include a receiving tank for the fine fraction and the gas stream. The separation module may be connected to a collection module which includes the collection hopper for recovering the expanded perlite beads which will be directed to a transport module which includes the elevator equipped with at least one bucket chain and the receiving silo. 10 More advantageously, the collection module which may include the expanded perlite bead collection hopper is connected to a transport module which includes the elevator equipped with at least one bucket chain and the receiving silo. The invention provides that the lifting device and at least one bucket conveyor extend over at least three transport zones, the first zone being flat or (and then) ascending, the second zone being flat, and the third zone being descending, all defined relative to ground level, and that said third zone is connected to said receiving silo. In this way,It is possible to carry out the expansion step to form the perlite beads and recover them with all the necessary precautions thanks to the process according to the invention. More preferably, the elevator and the said bucket chain extend over 4 transport zones: the first zone being flat, the second zone being ascending, the third zone being flat and the fourth zone being descending, all defined with respect to ground level, and insofar as the said fourth zone is connected to the receiving silo. Advantageously, the said raw perlite has a residence time in said furnace of between 0.1 and 10 seconds, preferably between 0.1 and 8 seconds, more preferably between 0.1 and 5 seconds, corresponding to the time spent in said furnace, preferably until it reaches the top, in its upper part. This allows the raw perlite to be processed efficiently while carrying out the expansion in order to provide perlite beads exhibiting the desired properties. BE2024 / 5914 6 More preferably,The expanded perlite beads reaching the upper part of the furnace have a temperature between 630 and 720°C, preferably between 640 and 700°C, and more preferably between 645 and 665°C, preferably at the furnace outlet. This allows the expanded perlite beads to be recovered in a cooler state. Thus, slow cooling is achieved and controlled expansion of the perlite beads is ensured. More advantageously, the furnace is a vertical furnace. Thus, the furnace has a lower part that includes the flame and an upper part that supplies the furnace with raw perlite and also has an outlet for the gas flow and the fine fraction that rise, opposite the flame. According to a preferred method, said separation is carried out with a separator designed to simulate a vortex or with a cyclone separator. This allows for a particle size separation of sufficient quality to recover the perlite beads forming the material of interest. This step is advantageous because it maintains the structure of the perlite beads without damaging them. According to a particularly preferred method,The supply of said raw perlite to said furnace is carried out in a controlled manner by means of a hopper equipped with a rotating valve which is arranged to release a predefined quantity of raw perlite which, by the effect of gravity, reaches a downward vibrating wall, a portion of which extends into said furnace (in its upper part) in order to allow contact with said flame. Indeed, the supplied raw perlite reaches the bottom of the furnace where the flame is located. Controlling the quantity of perlite ensures a stable process, preferably implemented continuously. It is therefore possible to ensure a controlled and regular supply to the furnace. Preferably, the fine fraction has a particle size distribution of less than 90 µm. Preferably, at least 70% by weight, preferably at least 80% by weight, more preferably 85% by weight of the said raw perlite supplied 30 has a particle size distribution greater than 200 µm. This allows for a sufficient number of particles to be expanded. BE2024 / 5914 7 More preferably still,The raw perlite supplied has a moisture content of less than 0.5% by volume. If it is too humid, energy is lost in the furnace and the final product becomes sticky. To avoid heat loss and prevent clumping in the feeding system, selecting the moisture content allows for adequate expansion of the perlite beads. Advantageously, the ready-to-use expanded perlite beads also include a quantity of unexpanded perlite of less than 0.2% by volume relative to the total volume of the expanded perlite beads. Maintaining a quantity of unexpanded perlite of less than 0.2% by volume ensures uniformity, optimal insulation, weight reduction, and improved handling of the expanded perlite beads, thus enhancing their performance and versatility in various applications. More advantageously,The said ready-to-use expanded perlite beads comprise an amount of over-expanded perlite of less than 10% by volume per 15 relative to the total volume of said expanded perlite beads. Limiting the amount of over-expanded perlite to less than 10% ensures mechanical stability, uniform density, optimal insulating properties, increased resistance to moisture, and improved handling of the final product, thus optimizing its technical performance and durability. Preferably, at least 75% by weight, preferably 80% by weight, more preferably 85% by weight of said ready-to-use expanded perlite beads have a particle size distribution greater than 200 µm. This makes it possible to supply perlite beads which exhibit the best properties, particularly when they are part of a composition which includes 25% plaster. According to an advantageous embodiment, at least 55% by weight, preferably about 60% by weight of said ready-to-use expanded perlite beads have a particle size distribution greater than 0,5 mm. If too large a proportion of the expanded perlite beads has a particle size distribution of less than 0.5 mm, the desired effects cannot be guaranteed. BE2024 / 5914 8 Advantageously, less than 15% by weight, preferably less than 10% by weight of said ready-to-use expanded perlite beads have a particle size distribution greater than 1.250 mm. Indeed, if the expanded perlite beads have a particle size distribution that is too coarse, i.e., greater than 1.250 mm (in the largest proportion), they risk causing scratches when they are part of a composition, for example plaster, and this is applied to a substrate. Preferably, said ready-to-use expanded perlite beads have a density between 40 and 80 kg / m³, preferably between 50 and 65 kg / m³. Expanded perlite beads with a density between 40 and 80 kg / m³, and preferably between 50 and 65 kg / m³, offer advantages in terms of lightness, mechanical resistance, thermal and acoustic insulation,Moisture resistance and ease of integration into various industrial and construction applications. 15 Preferably, after transporting said expanded perlite beads to the receiving silo, a volumetric dosage of said expanded perlite beads is carried out to mix them into a composition that includes plaster. This makes it possible to provide an easy-to-implement solution depending 20 on the type of final composition, advantageously plaster. Depending on the final application, the quantities of expanded perlite beads are adjusted in order to provide a composition that exhibits the desired properties. Precise volumetric dosing guarantees an exact proportion of expanded perlite beads in the plaster mix. This ensures consistent and homogeneous properties in the final product, whether it be lightweight plasters, insulating mortars, or reinforced plasterboard. The precise dosing thus contributes to better material quality in the finished product, with optimized performance in terms of weight.thermal insulation and mechanical resistance. More preferably, said volumetric dosing comprises the following 30 steps: BE2024 / 5914 9 - Provision of a boiler which includes within it a rack arranged to move a probe between a minimum position and a maximum position, said minimum position corresponding to a filling level equal to 0% by volume, where said boiler is empty and said maximum position corresponding to a filling level equal to 100% by volume, where said boiler is completely filled with said expanded perlite beads. Volumetric dosing with a tank equipped with a rack and pinion and a probe offers advantages such as dosing accuracy, operational flexibility, mixing efficiency, automation, and reproducibility, thus allowing for the optimization of the quality and performance of plaster and expanded perlite-based products. Advantageously, said expanded perlite beads are introduced into said tank in a predetermined quantity, preferably a quantity between 0,5 and 50% by volume relative to the total volume of said boiler, advantageously 15 depending on the desired plaster composition, in an automated manner. Preferably, the process according to the invention comprises a step of adding said expanded and dosed perlite beads to a composition which includes plaster. More advantageously, at least 15% by weight, preferably at least 20% by weight, more preferably at least 30% by weight, advantageously at least 40% by weight of said expanded perlite beads present in said composition comprising plaster remain active in said composition when applied to a substrate, the percentage by weight being defined in relation to the initial quantity of perlite beads in said composition comprising plaster. 25 The advantage of maintaining at least 15% by weight, preferably at least 20% by weight, more preferably at least 30% by weight,Advantageously, at least 40% by weight of active expanded perlite beads in a composition that includes plaster, when applied to a substrate, lies mainly in optimizing the functional properties of the plaster, coating, or final material.30 These "active" expanded perlite beads retain their physical and mechanical properties after mixing with the plaster, which allows them to fully play their role as an improver. In particular, they contribute to reducing the overall density of the composition, making the plaster lighter and therefore easier to handle and apply to the substrate. This also reduces the weight exerted on the structures, an important advantage for applications such as ceiling coatings, drywalls, or load-bearing structures.5 The presence of a significant percentage of active perlite beads also helps maintain excellent thermal and acoustic insulation properties. Thanks to their porous structure and their ability to trap air,These beads limit heat transfer and reduce noise. This improves the thermal and acoustic comfort of buildings where plaster is applied. 10 Finally, this optimal percentage of active beads ensures simplified application and homogeneous distribution of the beads in the plaster matrix, avoiding component segregation problems and guaranteeing consistent performance across the entire treated surface. Even more advantageously, the gas flow and the fine fraction, which includes fine particles and dust from the furnace, are cooled, after the separation stage, preferably with a heat exchanger, by lowering their temperature to a value between 160 and 190°C, preferably between 170 and 180°C, before entering a filter. This improves filtration efficiency while protecting the 20 downstream pieces of equipment. Furthermore, this cooling also optimizes the trapping of fine particles. At lower temperatures, particles are less likely to pass through the filter.This improves the efficiency of dust collection. Preferably, the process according to the invention comprises passing said fine fraction through said filter, preferably a bag filter, and recovering said fine fraction. More preferably, said recovered fine fraction is reintroduced after the separation step. More preferably still, said gas stream generated during the contacting step is drawn in by a fan located at said filter. By drawing in air directly at the filter, the fan facilitates the trapping of fine particles and dust contained in the gas stream. This ensures that the particles are immediately directed towards the filter for capture, thus improving filtration efficiency. Other embodiments of the process according to the invention are indicated in the attached claims. The invention also relates to a device for transporting expanded perlite beads intended for a composition comprising plaster,said device comprising: - A furnace equipped with a flame located in its lower part and having a temperature between 900 and 1400°C, preferably about 1200°C, said furnace being arranged to be supplied with raw perlite and arranged to form expanded perlite beads, - A supply module comprising a hopper equipped with a rotary valve arranged to release a predefined quantity of raw perlite, said hopper being followed by a vibrating wall extending downwards towards the lower part of said furnace and a portion of which extends into said furnace, - A particle size separation module arranged to separate expanded perlite beads and a fine fraction, - A collection module, preferably comprising a hopper, -A transport module linked to the collection module comprising an elevator equipped with at least one bucket chain arranged to transport the expanded perlite beads to a receiving silo, said transport module comprising at least 3 transport zones: the first zone being flat or (and then) ascending,The second zone being flat and the third zone being descending, all defined with respect to ground level, and insofar as the said first zone is connected to the said collection module and the said third zone is connected to the said receiving silo. More preferably, the said transport module extends over 4 transport zones: the first zone being flat, the second zone being ascending, the third zone being flat and the fourth zone being descending, all defined with respect to ground level, and insofar as the said fourth zone is connected to the said receiving silo. BE2024 / 5914 12 Preferably, the device comprises a volumetric dosing module located after the receiving silo and a mixing module arranged to provide a composition which comprises plaster and expanded perlite beads. It should be noted that all the characteristics related to the process can be transposed to the device. Thus,All the preceding paragraphs can also be applied to the device. Other embodiments of the device according to the invention are indicated in the attached claims. The invention also relates to the use of expanded perlite beads supplied according to the process of the present invention in a plaster composition. Other embodiments of this use according to the invention are indicated in the attached claims. Within the scope of the present invention, expanded perlite beads can be added to a composition intended for civil engineering or construction. Preferably, the expanded perlite beads are part of a composition that includes plaster, which is particularly preferred. It is advantageous to incorporate them into lightweight plasters, insulating mortars, reinforced plasterboard,spray plaster or any other material whose properties are improved by the presence of expanded perlite beads according to the invention. It should be noted that the expression "composition comprising plaster" can be replaced by "plaster composition." The latter may include various additives and formulators known to those skilled in the art. In the context of the present invention, the expression "fine fraction" designates a fraction comprising fine particles and dust produced during the heating stage of the raw perlite. This fraction is called fine with respect to the size of the expanded perlite beads. Preferably,The process according to the present invention can be implemented using a device comprising at least one furnace and several modules. A supply module advantageously comprising a hopper equipped with a rotating valve. A separation module preferably comprising a tank for receiving the fine fraction and the gas flow. A collection module advantageously comprising a collection tank for the expanded perlite beads. A transport module comprising the elevator equipped with at least one bucket chain and the receiving silo. The furnace is preferably a vertical furnace comprising a lower part at its base, which is in contact with the ground, and an upper part located at the top of the furnace. The lower part houses the flame, which operates at a temperature between 900 and 1400°C, preferably around 1200°C. Preferably,The supply module includes a hopper equipped with a rotating valve and also includes a downward vibrating wall directed towards the lower part of said furnace, a portion of which extends into said furnace. Said hopper is arranged to release a predefined quantity of raw perlite. The vibrating wall brings the raw perlite into contact with the flame. A particle size separation module allows for the separation of expanded perlite beads and a fine fraction. A collection module, preferably including a hopper. A transport module connected to the collection module includes an elevator equipped with at least one bucket chain arranged to transport the expanded perlite beads to a receiving silo. The said transport module comprises at least 3 transport zones: the first zone being flat or (and then) ascending, the second zone being flat and the third zone being descending, all defined with respect to ground level,and insofar as said first zone is connected to said collection module and insofar as said third zone is connected to said receiving silo. A volumetric dosing module makes it possible to create mixtures, for example, to predefine the precise quantity to be added to a plaster composition to meet specifications in terms of mechanical properties, while taking into account the final application. This module includes a boiler, a rack and a probe. BE2024 / 5914 14 The device according to the invention may also include a volumetric dosing module located after the receiving silo and a mixing module arranged to provide a composition which includes plaster and expanded perlite beads. In practice, and according to an embodiment that allows the process according to the invention to be assimilated, a quantity of raw pearlite is fed into the hopper 5 of said supply module, and the associated rotary washer is operated automatically according to the quantity of raw pearlite to be supplied into said furnace. Thus, when the quantity is released,The raw perlite falls onto the descending vibrating wall to feed the bottom of the furnace (lower part). The flame has a temperature between 900 and 1400°C, preferably around 1200°C. In this way, the raw perlite comes into contact with the flame in order to allow the expansion of the perlite beads. This contact generates a flow of gas which includes air and gases resulting from the combustion of the raw perlite. The raw perlite is heated until it reaches a temperature between 700 and 760°C, preferably between 720 and 740°C, in order to carry out its expansion. The generated gas flow rises towards the top of the furnace, carrying with it a fine fraction and expanded perlite beads. These expanded perlite beads, which reach the top of the furnace, have a temperature between 630 and 720°C, preferably between 640 and 700°C, plus 20, preferably between 645 and 665°C, preferably at the furnace outlet. Indeed, the higher the perlite beads rise towards the top of the furnace, the more they cool. The fine fraction thus formed,and presented within the framework of the invention, is fine compared to said expanded perlite beads. A particle size separation between said expanded perlite beads 25 and said fine fraction is carried out in the separation module. This separation is advantageously carried out with a separator designed to simulate a vortex or with a cyclone separator. This makes it possible to recover the fine fraction which advantageously has a particle size distribution of less than 90 µm. 30 On one side the fine fraction is recovered and on the other the material of interest, the expanded perlite beads. BE2024 / 5914 15 Thus, a collection of said expanded perlite beads is carried out, for example in a collection hopper. Next, transport can be carried out using an elevator equipped with at least one bucket chain. This elevator will ensure careful, stable, and efficient transport to the receiving silo where the said perlite beads are ready for use. More precisely and preferably, the elevator equipped with said bucket chain extends over at least three transport zones.the first zone being flat or (and then) ascending, the second zone being flat and the third zone being descending, all defined in relation to ground level, and insofar as the said third zone is linked to the said receiving island. The perlite beads obtained in the receiving silo have the following characteristics, taken alone or in combination: - At least 70% by weight, preferably at least 80% by weight, more preferably 85% by weight of the supplied raw perlite15 has a particle size distribution greater than 200 µm, - The supplied raw perlite has a moisture content of less than 0.5% by volume, - The ready-to-use expanded perlite beads also include a quantity of unexpanded perlite of less than 0.2% by volume per20 of the total volume of the expanded perlite beads, - The ready-to-use expanded perlite beads include a quantity of over-expanded perlite of less than 10% by volume of the total volume of the expanded perlite beads. -At least 75% by weight, preferably 80% by weight,more preferably 25 85% by weight of said ready-to-use expanded perlite beads have a particle size distribution greater than 200µm, -At least 55% by weight, preferably 60% by weight of said ready-to-use expanded perlite beads have a particle size distribution greater than 0.5mm, 30 -Less than 15% by weight, preferably less than 10% by weight of said ready-to-use expanded perlite beads have a particle size distribution greater than 1.250mm, BE2024 / 5914 16 -Said ready-to-use expanded perlite beads have a density between 40 and 80kg / m³, preferably between 50 and 65kg / m³. After the transport of said expanded perlite beads to the receiving silo,A volumetric dosing of said expanded perlite beads is carried out to mix them into a composition that includes plaster. This volumetric dosing can be carried out in the dosing module which includes a tank containing a rack and a probe. The probe is movable between a minimum position (0% filling of said tank) and a maximum position (100% by volume filling of said tank). Thus, if 20% by volume is to be used for 1 metric ton of plaster, the probe is automatically set to 20% of the tank's volume in order to dose and take the necessary quantity. Then, the mixture with the plaster can be carried out, the plaster being an optional example. If a plaster composition is to include more or fewer expanded perlite beads, the volumetric dosing module (read the probe) will be...