Method for recycling plaster waste and facility for implementing such a method

Abstract

The invention relates to a method for recycling plaster waste from the general public, the method comprising: a step (S1) of sorting the solid waste in order to obtain a "gypsum" portion (A) and a "reject" portion (B); a step (S2) of generating fuel from at least part of the reject portion (B) by an exothermic process; a step (S3) of generating anhydrite from at least part of the gypsum portion (A). The method is characterised in that it further comprises recovering at least part of the heat (C) generated by the exothermic process, and in that step (S3) of generating anhydrite comprises heating the at least part of the gypsum portion (A) using the at least part of the heat (C).

Description

[0001] DESCRIPTION

[0002] Title: Process for the recovery of plaster waste and installation for implementing such a process

[0003] FIELD OF THE INVENTION

[0004]

[0001] The present invention relates to the field of waste recovery, and more specifically to the field of plaster waste recovery.

[0005]

[0002] More specifically, the invention relates to a method and an installation making it possible to increase the recovery of plaster waste.

[0006] TECHNOLOGICAL BACKGROUND

[0007]

[0003] Plaster is a hydraulic binder typically obtained from gypsum, a material found in its natural state, mined in quarries.

[0008]

[0004] Plaster waste from the general public comes from various sources and is often mixed intimately with other materials. For example, we can cite: so-called simple plaster, for example any plate composed of gypsum covered with a paper facing, plaster tiles, plaster molds, plaster from ceilings and mixed with linen, reeds, wood lath, etc. so-called complex plaster, covered for example with glass wool, rock wool, polystyrene, etc. plaster covered with earthenware, metal, plastic from electrical conduits, etc.

[0009]

[0005] Operating costs, environmental problems and resource depletion have led to the development of plaster waste recycling solutions to recover gypsum. Recycling plaster waste involves, in particular, successive stages of crushing and sorting, making it possible to separate the gypsum from other waste, which may include, in particular, metal elements, wood, polystyrene, paper and cardboard.

[0010]

[0006] The recycled gypsum can then be recovered, in particular to be used again in the manufacture of plaster, or transported and sent to treatment centers to be transformed into anhydrite, which is used in particular as an input in agriculture.

[0011]

[0007] The other waste must then be treated. In general, they are then transported to a site other than the recycling site where specific facilities for their treatment are provided.

[0008] The transport and treatment of other waste thus pose problems in terms of ecology and recovery.

[0012]

[0009] In addition, the recycling of plaster waste and the treatment of waste are items that consume energy, which implies additional costs, and therefore reduces the recovery of plaster waste.

[0013]

[0010] The invention thus aims to provide an ecological solution to the treatment of plaster waste, in particular by increasing its recovery.

[0014]

[0011] SUMMARY OF THE INVENTION

[0015]

[0012] Thus, according to a first aspect, the invention relates to a method for recovering plaster waste from the general public, the method comprising:

[0016] A step of crushing and sorting solid waste in order to obtain at least one portion called gypsum comprising mainly gypsum, and a portion called rejects comprising mainly any material other than gypsum, the rejects portion comprising at least in part organic matter;

[0017] A step of generating fuel from at least a portion of the refuse portion by an exothermic process;

[0018] A step of generating anhydrite from at least a portion of the gypsum portion.

[0019]

[0013] The method further comprises recovering at least a portion of the heat generated by the exothermic process. The anhydrite generation step then comprises heating the at least a portion of the gypsum portion, and said heating is carried out from the at least a portion of the heat recovered during the fuel generation in order to use it for heating the gypsum portion.

[0020]

[0014] Thanks to these provisions in particular, the process makes it possible to improve the recovery of plaster waste. In fact, the waste from the plaster recycling stage is here transformed directly to produce electrical energy, and this transformation is further used to recover heat and use it to transform the gypsum into anhydrite. The process thus makes it possible to limit external energy inputs, reducing the costs of implementation and therefore of production, in particular of anhydrite.

[0021]

[0015] According to different aspects, it is possible to provide one and / or the other of the characteristics below taken alone or in combination.

[0022]

[0016] According to one embodiment, the fuel generation step may comprise a gasification step, so that the fuel produced is gaseous. This then makes it possible to easily store it, and to use it on demand to produce, for example, electrical energy.

[0017] According to one embodiment, at least part of the fuel may be used in an electrical energy system to supply an electrical network. This electrical network may be the one supplying the recovery process, and / or an industrial network and / or a city network. The electrical energy thus produced may therefore be sold, increasing the recovery of plaster waste.

[0023]

[0018] According to one embodiment, at least a portion of the recovered heat can be used in the fuel generation step. The fuel generation step can indeed comprise endothermic reactions, although it is generally exothermic. By injecting a portion of the heat produced during the fuel generation step into this step, the latter is then self-sustaining, not requiring any external energy input.

[0024]

[0019] According to one embodiment, the reject portion may comprise at least in part paper or cardboard. These materials are commonly found associated with plaster in building demolition waste in particular. They can therefore be recovered in the fuel generation stage.

[0025]

[0020] According to one embodiment, the anhydrite generation step comprises, after heating, grinding the anhydrite to a determined particle size. The anhydrite can thus be supplied to buyers according to the buyers' needs and requests. For example, the particle size can be determined according to a requested final form and / or the needs for mixing with other components according to a recipe, for example for soil amendment. The recovery process thus makes it possible to directly deliver the anhydrite in the form requested by a buyer.

[0026]

[0021] According to one embodiment, the upgrading process may comprise recovering residual heat remaining after heating the anhydrite generation step, so as to increase the efficiency of the process.

[0027]

[0022] According to a second aspect, the invention relates to an installation for recovering plaster waste from the general public for implementing the method as presented above, the installation comprising: at least one station for crushing and sorting the waste in order to obtain at least one so-called gypsum portion comprising mainly gypsum, and a so-called reject portion comprising mainly any material other than gypsum, the reject portion comprising at least in part organic matter; at least one transformation station for generating fuel from at least part of the reject portion by an exothermic process; at least one anhydrite station for generating anhydrite from at least part of the gypsum portion.

[0023] Furthermore, the anhydrite station comprises at least one heating device and the installation further comprises at least one heat exchange module between the transformation station and the heating device.

[0028]

[0024] The installation thus formed ensures high recovery of all plaster waste by treating both the gypsum portion and the reject portion from the grinding and sorting stage.

[0029]

[0025] According to one embodiment, the transformation station may comprise at least one gasification reactor making it possible to transform the refuse portion into gaseous fuel.

[0030]

[0026] According to one embodiment, the at least one reactor is for example of the co-current fixed bed type. This technology proves to be particularly suitable for treating the reject portion here of the plaster waste.

[0031]

[0027] According to one embodiment, the anhydrite station may further comprise at least one grinder downstream of the heating device, in order to grind the anhydrite obtained to a particle size determined by the needs of the buyers.

[0032]

[0028] According to one embodiment, the transformation station for fuel generation and the anhydrite station can be located on the same site. The heat recovered in the transformation station for fuel generation can then be injected into the anhydrite station with high efficiency, the path to be covered being limited. On the same site, all the installations necessary for the high recovery of plaster waste can then be installed. At the site input, the waste, which is worthless in its raw state, is supplied; and at the site output, energy and anhydrite, which are of high value, are recovered.

[0033] BRIEF DESCRIPTION OF THE DRAWINGS

[0034]

[0030] Embodiments of the invention will be described below with reference to the drawings, briefly described below:

[0035]

[0031] [Fig. 1] schematically illustrates the steps of a method for recovering plaster waste according to an embodiment in accordance with the invention.

[0036]

[0032] [Fig. 2] schematically represents a waste recovery installation seen from above according to one embodiment

[0037]

[0033] [Fig. 3] schematically represents a transformation station for obtaining gaseous fuel according to one embodiment.

[0038]

[0034] [Fig. 4] schematically represents an anhydrite installation according to one embodiment.

[0039]

[0035] [Fig. 5] schematically represents a site on which an anhydrite installation according to one embodiment and a transformation installation for the generation of fuel are installed.

[0040]

[0036] In the drawings, like references designate identical or similar objects.

[0041] DETAILED DESCRIPTION

[0042]

[0037] Figure 1 schematically shows a process for recovering plaster waste from the general public, which is intimately mixed with other materials.

[0043]

[0038] Thus, in a preliminary sorting step S1, the waste is sorted in order to obtain a portion A called gypsum and a portion B called reject. For example, the sorting step S1 may typically comprise one or more grinding operations prior to or alternating with one or more screening operations. The gypsum portion A comprises mainly gypsum, i.e. more than 50% by mass of gypsum, or even more than 70% and more preferably at least 90% by mass of gypsum. The reject portion B is therefore low in gypsum. Given the origin of the plaster waste, the reject portion comprises organic matter, or biomass, for example paper and / or cardboard and / or wood, and may comprise various other materials, for example metal, brick, polystyrene or nylon. This first step S1 is, for example, a plaster recycling step, examples of which are known.

[0044]

[0039] At the output of the sorting step S1, the portion B of reject is, at least in part, and preferably totally, used in a step S2 of generating fuel G. This step S2 notably involves a globally exothermic process, so that the fuel G generated is at a temperature higher than that of the ambient temperature. More precisely, the step S2 of generating fuel G may involve endothermic reactions, but the result is an exothermic process.

[0045]

[0040] For example, the exothermic process comprises gasification, so that the fuel G generated is gaseous. For this purpose, the portion B of refuse may undergo pretreatment before the generation step S2, for example in order to sort the organic matter from the other materials, and / or in order to control the particle size, and / or in order to densify the material of the portion B of refuse to present it in a particular form, such as logs or pellets. The portion B of refuse, pretreated or not, may then feed the gasification process. For example, the gasification process may comprise:

[0046] - a drying phase;

[0047] - a pyrolysis phase in an atmosphere low in oxidizing agent, during which volatile materials such as carbon monoxide, carbon dioxide, hydrogen, methane, water vapor and gaseous hydrocarbons are produced, as well as coal;

[0048] - an at least partial oxidation phase, in which, in an atmosphere enriched with an oxidizing agent, for example air, and / or oxygen, and / or water vapor, on the one hand the volatile materials are oxidized, and on the other hand the gaseous hydrocarbons are destroyed by thermal cracking;

[0049] - a gasification phase itself, involving reduction and combustion reactions, during which the coal is converted into gas called “synthesis gas” or “syngas” in English, this gas being a fuel rich in carbon monoxide and dihydrogen in particular.

[0050]

[0041] The order of these phases, as well as their presence or absence, may follow the presentation above, but not necessarily.

[0051]

[0042] The exothermic process therefore produces heat C which can be recovered at least in part and used for example to maintain the possible endothermic reactions of step S2 of gaseous fuel generation. As will be seen later, the heat C is at least in part recovered to be used in a subsequent step of the recovery process. According to the example of a gaseous fuel generation process presented below, the partial oxidation phase is exothermic.

[0052]

[0043] As will be seen later, all the phases of gaseous fuel generation can take place in the same reactor, or in separate enclosures.

[0053]

[0044] At the output of the sorting step S1, the gypsum portion A is sent at least in part to an anhydrite step S3. For example, the gypsum portion A is separated into a fraction A1 intended to be used for example as a recycled fraction in a plaster manufacturing process P, and a fraction A2 intended to be sent to the anhydrite step S3.

[0054]

[0045] Step S3 anhydrite notably comprises heating the gypsum, preferably gently, to a temperature above 100°C (degrees Celsius), to dehydrate it. Thus, step S3 anhydrite is heat-consuming.

[0055]

[0046] The recovery process according to the invention then comprises the recovery of at least part of the heat generated by the exothermic process during step S2 of gaseous fuel generation, and the use of this heat in order to heat the gypsum in step S3 anhydrite.

[0056]

[0047] According to one embodiment, the heat recovered from the gaseous fuel generation step S2 is sufficient to heat the gypsum in the anhydrite step S3 and obtain the transformation into anhydrite, so that no additional heat input is necessary. Furthermore, after heating the gypsum, the remaining heat can be recovered to be reinjected elsewhere in the recovery process and / or to be stored and / or to be converted into electrical energy.

[0057]

[0048] According to one embodiment, step S3 anhydrite may comprise, after heating the gypsum, grinding the gypsum to a controlled particle size.

[0058]

[0049] According to one embodiment, step S3 anhydrite may comprise, after heating and where appropriate grinding, packaging of the anhydrite, for example in a sachet.

[0059]

[0050] The anhydrite thus obtained and packaged can be placed directly on the market, particularly as an input for agriculture.

[0060]

[0051] According to one embodiment, at least a portion of the gaseous fuel G produced in the generation step S2 is sent to an energy generation step S4. This energy may in particular be in two forms: mechanical and thermal. Indeed, on the one hand, the gaseous fuel G may be used to obtain mechanical energy. For this purpose, for example, the generation step S4 comprises the introduction of the gaseous fuel G into a generator such as a gas engine, which may be coupled to an alternator to produce electrical energy. On the other hand, the heat of the gaseous fuel may be recovered at least in part as thermal energy. Indeed, the gaseous fuel G produced may have, at the output of the generation step S2, a temperature greater than 400°C, and in particular a temperature between 500°C and 700°C.Thus, the generation step S4 may comprise the recovery of heat from the gaseous fuel G and its conversion into electrical energy according to any known method.

[0052] According to a particular embodiment, step S4 is a so-called cogeneration step, in which both mechanical energy and thermal energy are generated. For example, before passing through a gas engine, the recovery process may comprise a step of pretreatment of the gaseous fuel G, during which it is in particular cooled and cleaned of any substances unsuitable for the gas engine. Thus, the heat may advantageously be recovered during the pretreatment step. Furthermore, the operation of the gas engine may also generate heat to be recovered. Finally, the alternator coupled to the gas engine may in turn produce heat which will be advantageously recovered.

[0061]

[0053] More generally, the heat can be recovered whenever it is available throughout the recovery process. The thermal energy thus generated can be reinjected all or part directly into the recovery process, for example in order to maintain the reactions of the gaseous fuel generation step S2 or in order to heat the gypsum in the anhydrite step S3. Alternatively or in combination, the thermal energy can be used all or part to produce electrical energy. Thus, according to one embodiment, at least the gaseous fuel generation step S2, the anhydrite step S3 and the energy generation step S4 are self-sufficient in energy, that is to say that no external energy input is required. Optionally, the entire recovery process is self-sufficient in energy.

[0062]

[0054] The electrical energy thus produced can be sent to an electrical network, for example in a town or to the site of an installation implementing the recovery process in order to operate the various stations.

[0063]

[0055] The recovery process thus makes it possible to recover as much as possible both the portion A of rejects and the portion B of gypsum from the sorting and grinding step S1, by transforming them respectively into energy and into input, while limiting energy consumption. The advantageous use of the heat C produced during the step S2 of generating fuel G from the rejects B to treat a portion A2 of gypsum promotes a high recovery of the products from the recycling step S1.

[0064]

[0056] An example of an installation 1 for recovering plaster waste from the general public for the implementation of the process presented above will now be described with reference to figure 2.

[0065]

[0057] According to this example, the installation 1 comprises a sorting station 2, in which the plaster waste undergoes one or more successive sorting operations, in order to obtain the portion A of refuse and the portion B of gypsum mentioned above. The sorting station 2 is for example a plaster waste recycling station as known in the state of the art, and which may in particular comprise crushers and sorting devices of the sieve type.

[0066]

[0058] The installation 1 can then comprise a storage station 3, which comprises a zone 3a for storing the portion A of gypsum and a zone 3b for storing the portion B of refuse.

[0067]

[0059] A conveying system, not shown, makes it possible to convey at least a portion of the portion B of refuse into a transformation station 4 for the generation of gaseous fuel G. The transformation station 4 may comprise in particular a gasification zone 4a, a pretreatment zone 4b and a cogeneration zone 4c.

[0068]

[0060] An example of the gasification zone 4a is illustrated in Figure 3. According to this example, the gasification zone 4a comprises in particular a gasification reactor 41, fed from a hopper 42 for example in a portion B of reject using a conveying system not shown. The reactor 41 is for example of the co-current fixed bed type, the materials moving vertically from an upper part of the reactor 41 to a lower part, and allows the phases of the step S2 of generation of gaseous fuel as described above to be carried out. Thus, the feed from the hopper 42 is done from an upper part of the reactor 41. The reactor 41 can in particular be equipped with hot gas inlets (not shown) for the drying and pyrolysis phases, as well as an air injector 43 in order to inject air for the oxidation phase.The residual solid R phase is recovered in the lower part of reactor 41, and can be considered as a final product. It is mainly ash. The gaseous G fuel produced is in turn recovered in the lower part of reactor 41.

[0069]

[0061] The installation 1 may comprise several reactors 41 within which all of the phases of the step S2 of gaseous fuel generation occur, or several separate and successive enclosures, within which only part of the phases occur.

[0070]

[0062] Any other type of reactor capable of producing fuel G may be installed as a replacement or in combination in the transformation station 4. In particular, the fuel G produced may be in a form other than gas.

[0071]

[0063] According to the example presented, the gaseous fuel G leaving the reactor 41 is conveyed by any known means into the pretreatment zone 4b, which comprises a pretreatment device 44, during which the fuel G is in particular cleaned and cooled, the heat being recovered in a first heat exchanger 45a, to recover a first fraction C1 of heat. The pretreated gaseous fuel G is then transmitted into an electrical energy generating system. The electrical energy generating system comprises for example a generator 46, for example a gas engine, where it is transformed into mechanical energy. A second heat exchanger 45b can make it possible to recover a second fraction C2 of heat generated in the generator 46.The electrical energy generating system may further comprise an alternator 47 coupled to the generator 46, in which the mechanical energy M produced is used to produce electrical energy in the cogeneration zone 4c. A third heat exchanger 45c may make it possible to recover a third fraction C3 of heat generated by the alternator 47.

[0072]

[0064] The fractions C1, C2 and C3 of heat recovered by the heat exchangers 45a, 45b, 45c can be used to be reinjected in part into the reactor 41, or into any device of the installation 1 or of the site of the installation 1 requiring a heat supply, and in particular for the transformation of gypsum into anhydrite as will be explained later. As a variant or in combination, the fractions C1, C2 and C3 of recovered heat can be transformed into electrical energy.

[0073]

[0065] The electrical energy produced can at least partly supply an electrical network, which is for example that of installation 1 or a city network.

[0074]

[0066] Finally, a fourth heat exchanger 48 makes it possible to recover a fraction C4 of heat produced by the exothermic process in the reactor 41, for example during the oxidation phase.

[0075]

[0067] The installation 1 finally comprises an anhydrite station 5, in which the portion A of gypsum is conveyed by any known means in order to be transformed into anhydrite.

[0076]

[0068] More specifically, the anhydrite station 5 comprises at least one heating device 50, which may for example be of the dryer tube type, and which transforms, by heating the gypsum to a temperature of at least 100°C, more preferably at least 180°C, and at most °C, and more preferably at most 300°C, the gypsum into anhydrite. The temperature for transforming the gypsum into anhydrite is controlled in order to obtain active anhydrite, which can be rehydrated. This is then referred to as semi-hydrates. Indeed, below 300°C, the heat transforms the gypsum into anhydrite, which can be rehydrated for the most part. Above 300°C, rehydration is more difficult. Generally speaking, the higher the temperature, the more difficult the anhydrite obtained will be to rehydrate. Above 450°C, rehydration is considered very difficult, if not impossible.

[0077]

[0069] An example of the anhydrite station 5 is illustrated in FIG. 4. The heating device 50 is supplied with heat from a heat exchange module 51, which makes it possible, from at least a portion of the heat C produced during the gaseous fuel generation step S2. For example, the heat C corresponds to the sum of the fractions C1, C2, C3 and C4 of heat recovered in the transformation station 4. A portion of it is taken from the heat exchange module 51 to be used in the drying device 50; the remaining residual heat C' can be recovered to be used elsewhere in the recovery installation 1, and for example in the transformation station 4.

[0078]

[0070] The anhydrite station 5 may comprise an input conveyor 52 for the gypsum fraction A2 continuously feeding the heating device 50 with gypsum. The heating device 50 is for example a drying tube, in which the material advances between an inlet and an outlet at the same time as it is heated. The material at the outlet of the heating device 50 is then anhydrite.

[0079]

[0071] According to one embodiment, the anhydrite leaving the heating device 50 is transported to a mill 53, for example a ball mill, which makes it possible to reduce the anhydrite into a powder with a particle size of less than 100 μm for example.

[0080]

[0072] A portion of the anhydrite powder may be stored in a storage silo 54. The storage silo 54 makes it possible to constitute a reserve of anhydrite for various uses.

[0081]

[0073] The other part of the anhydrite powder can be sent to a circular sieve 55. The circular sieve 55 makes it possible to sort and separate exogenous E which would be present in the anhydrite powder, and also makes it possible to calibrate the grains of anhydrite powder to a determined mesh. The exogenous E can be recovered to be returned to the transformation station 4.

[0082]

[0074] The gypsum powder leaving the circular sieve 55 can then be sent to a press 56 which makes it possible to form granules with the gypsum powder. The granules leaving the press 56 can be stored in a storage module 57.

[0083]

[0075] The anhydrite granules can then be taken in bulk directly from the storage module 57 from an output conveyor 58.

[0084]

[0076] Alternatively or in combination, the output of the storage module 57 is connected to a packaging module 59 allowing the granules to be bagged.

[0085]

[0077] Although this has not been described each time, between the different devices of the anhydrite station 5, conveyor belt type conveyors allow the material to be transported, continuously if necessary.

[0086]

[0078] Thus, the anhydrite station 5 makes it possible to propose a complete and direct transformation of gypsum into anhydrite in one or more forms allowing its marketing and therefore its recovery. The anhydrite station 5 is associated with the transformation station 4 for the generation of fuel, so that no external energy supply is necessary, the heat necessary for the anhydrite station 5 being supplied by the transformation station 4 for the generation of fuel.

[0087]

[0079] The transformation station 4 for the generation of gaseous fuel G and the anhydrite station 5 are preferably located on a single site, maximizing the use of the heat C produced during the step S2 of gaseous fuel generation.

[0088]

[0080] Figure 5 shows an example of the implementation of stations 4 and 5 on the same site. According to this example, as previously, a portion A2 of gypsum feeds, preferably continuously, a drying tube 50 via a conveyor 52. The drying tube 50 is associated with the heat exchange module 51 to use the recovered heat C and dry the gypsum to transform it into anhydrite. At the outlet of the drying tube 50, part of the anhydrite can be stored in a silo 54', while the other part is sent to the crusher 53. The crushed anhydrite then passes over the circular sieve 55. The silo 54 of the example in Figure 4, not reproduced here, can also be placed upstream of the sieve 55. At the outlet of the sieve 55, a portion of the crushed anhydrite can be stored in a silo 54”, and the other portion is sent to a mixing station 60, where it can be mixed with other components depending on the desired final product, for example magnesia and lime.Part of the mixture can be stored in a silo 61, and the other part can be sent to the press 56 to form granules, which are then bagged in the packaging module 59.

[0089]

[0081] The presence of silos 54, 54', 54” and 61 makes it possible to recover gypsum in different forms, in order to adjust production according to needs.

[0090]

[0082] The heat used in the dryer tube 50 comes from the transformation station 4 for the generation of fuel G. For this purpose, the rejects B can be mixed beforehand with the rejects from the sieve 55 of the gypsum station 5 (broken lines in FIG. 5) in a mixing station 62. Optionally, the mixture of rejects B and rejects from the sieve 55 is prepared before feeding the reactor 41, in order to maximize the yield. For example, the mixture is pre-ground in a pre-ground station 63 and then transformed into pellets in a pelletizing station 64. A silo 65 between the pelletizing station 64 and the reactor 41 can be used to form a buffer zone. The mixture of rejects in the form of pellets comprising the rejects B from the grinding and sorting step S1 then feeds the reactor 41, as described previously.The heat fractions C1, C2, C3 and O4 coming respectively from the pretreatment device 44, the generator 46, the alternator 47 and the reactor 41 can, all or in part, supply the heat exchange module 51.

[0091]

[0083] Any heat produced in a station of the installation can advantageously be recovered to be used to produce anhydrite and / or to produce electrical energy. For example, the press 56 and the pelletizing station 64 can generate heat, for example by friction. This heat can advantageously be recovered by any known means, for example heat exchangers.

[0084] More preferably, the recovery installation 1 is located on a single site, so that all of the stations 2, 3, 4 and 5 making it possible to carry out the steps S1, S2 and S3 are located on this single site.

Claims

CLAIMS

1. Method for recovering plaster waste from the general public, the method comprising: A step (S1) of sorting the solid waste in order to obtain at least one portion (A) called gypsum comprising mainly gypsum, and one portion (B) called reject comprising mainly any material other than gypsum, the reject portion (B) comprising at least in part organic matter; A step (S2) of generating fuel from at least a part of the portion (B) of refuse by an exothermic process; A step (S3) of generating anhydrite from at least a portion of the gypsum portion (A); the method being characterized in that it further comprises recovering at least a portion of the heat (C) generated by the exothermic process, in that the step (S3) of generating anhydrite comprises heating the at least a portion of the gypsum portion (A), and in that said heating is carried out from the at least a portion of the heat (C) recovered during the generation of fuel in order to use it for heating the gypsum portion (A).

2. The method of claim 1, wherein the fuel generation step (S2) comprises a gasification step.

3. A method according to any preceding claim, wherein at least a portion of the fuel is used in an electrical energy system (46, 47) for supplying power to an electrical grid.

4. Method according to the preceding claim, in which at least part of the recovered heat (C) is used in the fuel generation step (S2).

5. A method according to any preceding claim, wherein the reject portion (B) comprises at least in part paper or cardboard.

6. A method according to any preceding claim, wherein the anhydrite generation step (S3) comprises, after heating, grinding the anhydrite to a determined particle size.

7. A method according to any preceding claim comprising recovering residual heat (C') remaining after heating the anhydrite generation step (S3).

8. Installation (1) for recovering plaster waste from the general public for implementing the method according to any one of the preceding claims, the installation comprising: at least one station (2) for sorting the waste in order to obtain at least one portion (A) called gypsum comprising mainly gypsum, and a portion (B) called rejects comprising mainly any material other than gypsum, the reject portion (B) comprising at least in part organic matter; at least one transformation station (4) for generating fuel from at least a portion of the reject portion (B) by an exothermic process; at least one anhydrite station (5) for generating anhydrite from at least a portion of the gypsum portion (A);the installation (1) being characterized in that the anhydrite station (5) comprises at least one heating device (50) and in that the installation (1) further comprises at least one heat exchange module (51) between the transformation station (4) and the heating device (50).;

9. Installation (1) according to the preceding claim, in which the transformation station (4) comprises at least one gasification reactor (41).

10. Installation (1) according to the preceding claim, in which the at least one reactor (41) is of the co-current fixed bed type.

11. Installation (1) according to any one of claims 8 to 10 in which the anhydrite station (5) further comprises at least one grinder (53) downstream of the heating device (50).

12. Installation according to any one of claims 8 to 11, in which the transformation station (4) for fuel generation and the anhydrite station (5) are located on the same site.

Images