Method for producing a construction material from a clay-silt sludge, method for treating the sludge, and associated forming system

Abstract

The invention relates to a method (100) for producing a construction material from a quarry effluent, the method comprising: - a flocculation step (110) for forming a clay-silt sludge; - a step (120) of collecting the clay-silt sludge having a dry matter content of 20% or greater; - a step (190) of forming a construction material, comprising adding the sludge to a construction material mixture; - a step (150) of breaking down the flocculant and / or a step (180) of adding an organic deflocculant. The invention further relates to a method (200) for treating a clay-silt sludge so as to form a sludge cake suitable for forming a construction material. The invention lastly relates to a method (400) for producing a construction binder, a system (1) for forming a construction binder and a system for mechanically dehydrating a sludge, which are associated therewith.

Description

Description Title: METHOD FOR PRODUCING A CONSTRUCTION MATERIAL FROM A CLAY-SILTY MUD, METHOD FOR TREATING SAID MUD AND ASSOCIATED FORMING SYSTEM Technical field

[0001] The invention relates to the field of construction and more particularly to the recovery of quarry sludge and waste for the formation of low-carbon, low-resource and low-energy consumption construction materials. In particular, it relates to a method for treating a clayey-silty sludge. Furthermore, the invention relates to a method for manufacturing a construction binder and an associated production system. Prior art

[0002] Below we describe the known prior art from which the invention was developed.

[0003] Cement is the second most consumed resource in the world, with over 4 billion tons produced worldwide each year. This consumption is constantly increasing, driven by the growing demand for housing and infrastructure. Cement is particularly used for the manufacture of masonry units that rely on cementitious materials as binders. Due to the constant development of new infrastructure in most countries around the world, there is a constant demand for the supply of construction binders, especially mineral resources for the formation of cements, especially Portland cements.Many alternative solutions aimed at replacing or at least limiting the use of Portland cement have emerged. Among these solutions, raw clay-based cement appears to be one of the most promising solutions, particularly implemented in raw clay concrete plants (EP4186667A1), or more generally for the formation of construction binders (WO2020141285) usable for the formation of construction materials such as site concretes (W02020178538), prefabrication elements (W02020178538), low-carbon construction materials with summer comfort (WO2022157209A1), or even compressed concrete blocks (W02023001996A1). The clay stocks currently being recovered may come in particular from the recovery of quarry waste.

[0004] The recovery of clay from waste rock generally requires clay block crushing steps. This crushing step is a step that involves significant energy consumption.

[0005] There is therefore a need for sources of raw clay that can further reduce the energy consumption required for the preparation of building materials.

[0006] The invention aims to overcome the drawbacks of the prior art. In particular, the invention aims to propose a method for treating a clayey-silty mud to make it compatible with the manufacture of a construction material having an improved carbon footprint and ensuring compressive strength close to that of Portland cement.

[0007] Various solutions have been proposed for this treatment. One solution is to treat the sludge with quicklime. A second solution, described in document no. FR2937266, consists of treating the sludge with a sulfoaluminate binder and a source of sulfate and a catalyst for the hydration reactions of the sulfoaluminate binder.

[0008] However, all the solutions proposed for the treatment of sludge by solidification are very complex to implement, time-consuming and labor-intensive. For this, some have sought to develop a solution aimed at dispensing with the formation of a solid material. Patent document No. FR3102985 presents a solution aimed at incorporating, as part of the granular skeleton, fines in particular in the form of aqueous sludge, which come from the washing / hydrocycloning treatment of land or are made up of marine or river sediments. Summary of the invention

[0009] The invention aims to overcome these drawbacks.

[0010] The invention relates in particular to a method for manufacturing a construction material from a quarry effluent, said method comprising: a step of flocculating a quarry effluent comprising a clay-silt matrix using a flocculating agent to form a clay-silt sludge; a step of collecting the clay-silt sludge comprising the clay-silt matrix, said clay-silt sludge having a dry matter content greater than or equal to 20%; a step of forming a construction material, preferably a construction binder, comprising adding the clay-silt matrix of the clay-silt sludge to a mixture for construction material; said method comprising a step of degradation of the flocculating agent and / or a step of addition of an organic deflocculating agent to the clay-silt matrix.

[0011] A method according to the invention makes it possible to take advantage of a raw material which has a mineralogical profile suitable for use in the preparation of construction materials.

[0012] The use of quarry washing residues comprising a silty-clay mineral fraction makes it possible, with mechanical resistance, to reduce energy consumption. Furthermore, in certain embodiments which are presented further in the detailed description, the present invention allows recycling of the washing water. This leads to a significant reduction in network water consumption in quarries. In addition, this can reduce the impact of a quarry on local flora and fauna by reducing its footprint and allowing the unconsumed water to be used for other activities, in particular agriculture.

[0013] Thus, the present invention allows the manufacture of a construction material and especially a construction binder that is even more efficient from an energy point of view. This is made possible by a reduction in water consumption, a reduction in transported volumes, a reduction in artificialized surfaces and a reduction in energy consumption compared to a conventional method with the same mechanical performance.

[0014] According to other optional features of the method, the latter may optionally include one or more of the following features, alone or in combination: - the quarry effluent has the following characteristics: an organic matter concentration of less than 1% relative to the dry matter weight of the clayey-silty mud; a heavy metal concentration of less than 0.1% relative to the dry matter weight of the clayey-silty mud; a radioactive element concentration of less than 0.05% relative to the dry matter weight of the clayey-silty mud; a dry matter content greater than or equal to 20%. - the flocculating agent is an organic flocculating agent, preferably the organic flocculating agent is selected from: polyacrylamides; polysaccharides; polyamines such as polyDADMAC; or polyethyleneimine. - a step of degradation of the organic flocculating agent, said degradation step is selected from: UV irradiation, heat treatment, and / or oxidizing treatment. - the degradation stage of the organic flocculating agent involves UV irradiation or advanced oxidation during the collection stage of the clayey-silty mud. - it comprises a step of degradation of the organic flocculating agent, said degradation step comprises a heat treatment at a temperature below 400°C, the degradation step preferably being carried out before a step of grinding the clayey-silty mud. - a step of adding an organic deflocculating agent to the clayey-silty mud and characterized in that the organic deflocculating agent is selected from: a non-ionic surfactant such as a polyoxyethylene ether; an anionic agent such as an anionic agent selected from: alkylaryl sulfonates, amino alcohols, carbonates, silicates, fatty acids, humates (eg sodium humates), carboxylic acids, lignosulfonates (egsodium lignosulfonates), polyacrylates, phosphates or polyphosphates such as sodium hexametaphosphate, sodium tripolyphosphate, sodium orthophosphate, carboxymethylcelluloses, polyphosphonates, polycarboxylates and mixtures thereof; a polyacrylate such as a polyacrylate selected from sodium polyacrylate or ammonium polyacrylate; an amine such as an amine selected from: 2-amino-2-methyl-1-propanol; mono-, di- or triethanolamine; isopropanolamines (1-Amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines; or mixtures thereof. - the clayey-silty mud collected at the collection stage has a water content of at least 50%. - the collected clayey-silty mud comprises at least 1% by weight of clayey-silty matrix relative to the dry weight of the clayey-silty mud, said clayey-silty matrix comprising mineral clays selected from the following clays: Illite, Kaolinite, Smectite, Vermiculite, Chlorite, Montmorillonites, Muscovite, Halloysite, Sepiolite, Interstratified, Pyrophyllite, talcs, Serpentines, Palygorskite and combinations thereof.

[0020] According to a second object, the invention relates to a method of treating a clayey-silty mud so as to form a mud cake suitable for the formation of a construction material, said method comprising: A step of collecting a clayey-silty mud comprising a clayey-silty matrix and a flocculating agent; A step of mechanical dehydration of the clayey-silty mud, so as to obtain a mud cake comprising the clayey-silty matrix; said method comprising a step of degradation of the flocculating agent and / or a step of adding an organic deflocculating agent to the clayey-silty matrix of the mud cake.

[0015] According to other optional features of the method, the latter may optionally include one or more of the following features, alone or in combination: - the mechanical dehydration step involves the use of a filter press, preferably selected from: screw filter press; belt filter press; plate filter press; fin filter press; vertical filter press.

[0016] According to a third subject, the invention relates to a mud cake obtainable by the method for treating a clayey mud according to the invention, the mud cake comprising a water content of at most 40%, at least one clay-silt matrix, a flocculating agent residue and / or an organic deflocculating agent.

[0017] According to other optional characteristics of the mud cake, the latter may be composed of 30% to 70%, preferably 40% to 60% by weight of SiO2 and / or CaO.

[0018] According to a fourth object, the invention relates to a method of manufacturing a construction binder, said method comprising: - a step of providing a mud cake, preferably a mud cake comprising a clay-silt matrix and optionally a flocculating agent; - a mud cake drying step; - a step of grinding the mud cake so as to obtain a ground mud cake which has a D50 of less than 50 pm and a D90 of less than 100 pm (preferably a D90 of less than or equal to 100 pm); - a step of forming a construction binder comprising the addition of an activation composition to the mud cake grind.

[0019] According to a fifth subject, the invention relates to a method for manufacturing a construction binder, said method comprising: a step of collecting a clay-silt sludge comprising a clay-silt matrix and optionally a flocculating agent, said sludge having a D50 less than or equal to 200 μm and comprising at least 5% by weight of clay-silt matrix relative to the dry weight of said sludge; a step of mechanically dewatering the clayey-silty mud so as to form a mud cake, said mud cake having a water content of less than 40%; a step of drying the mud cake so as to achieve a water content of less than 20%; a step of grinding the mud cake so as to obtain a ground mud cake which has a D50 of less than 50 pm and a D90 of less than 100 pm (preferably a D90 of less than or equal to 100 pm); and a step of forming a construction binder from the ground mud cake comprising a mixture of the ground mud cake with an activating composition; said method further comprising a step of degrading the flocculating agent when said mud comprises the flocculating agent and / or a step of adding an organic deflocculating agent to the clayey-silty matrix.

[0020] According to other optional features of the method, the latter may optionally include one or more of the following features, alone or in combination: the drying step and the grinding step are carried out concomitantly. the step of drying the mud cake is carried out by using a device selected from: oven, solar dryer, laminar dryer, dryer, natural drying for example in ventilated sheds. the step of grinding the mud cake is carried out by using a device selected from: ball mill, orbital mill, hammer mill; wheel mill; pendulum mill; attrition mill; vertical mill; deagglomerator. the step of forming a construction binder is carried out by using a device selected from: powder mixer; horizontal mixer.the step of forming a construction binder comprises an addition of a precursor, said precursor preferably being selected from: blast furnace slag; calcined clay; flash calcined clay; fly ash, silica fumes; rice husk fumes; glass powder. when the method comprises a step of degrading the flocculating agent, the flocculating agent is an organic flocculating agent and said degradation step comprises UV irradiation during the drying step and / or during the grinding step. the activation composition is an alkaline activation composition, preferably it is selected from: clinker; EN197-1 cements; sulfoaluminous cements; supersulfated cements; lime; silicates; carbonates or combinations thereof.

[0021] According to a sixth object, the invention relates to a system for forming a construction binder from a clayey-silty slurry comprising a clayey-silty matrix, said system comprising: a collection device adapted to receive, preferably comprising, a clayey-silty slurry comprising a clayey-silty matrix and optionally a flocculating agent, said slurry having a D50 less than or equal to 200 pm and comprising at least 5% by weight of clayey-silty matrix relative to the dry weight of said slurry; a mechanical dewatering device configured to generate a slurry cake (B2) comprising the clayey-silty matrix, said slurry cake having a water content of less than 40%; a slurry cake dryer, configured to bring the slurry cake to a water content of less than 20%;a mill configured to grind the mud cake comprising the clay-silt matrix so as to form a ground material having a D50 of less than 50 pm and a D90 of less than 100 pm (preferably a D90 of less than or equal to 100 pm); a mixer configured to form a construction binder from the mud cake ground material and an activating composition; the system further comprising a device for degrading the flocculating agent when said mud comprises the flocculating agent and / or, preferably, a device for adding an organic deflocculating agent to the clay-silt matrix.;

[0022] Depending on other optional features of the system, the system may optionally include one or more of the following features, alone or in combination: - the crusher includes drying means configured to dry the mud cake. - a measuring device positioned at the inlet of the collection device, the measuring device being configured to determine values ​​of physicochemical characteristics of the clayey-silty mud. - a processor coupled to the measuring device, the processor being configured to, depending on the values ​​of physicochemical characteristics, determine a quantity of an organic deflocculating agent to be added to the mud cake and / or a quantity of a flocculating agent, preferably an organic flocculating agent, to be added to the clayey-silty mud. - the physicochemical characteristic values ​​include X-ray fluorescence values ​​and / or particle size values. - the collection device comprises a clarifier arranged to allow separation between a clarified phase and a concentrated phase of the clayey-silty mud, said clarifier being arranged to bring the concentrated phase of the clayey-silty mud into the mechanical dewatering device.

[0023] According to a seventh object, the invention relates to a system for mechanical dehydration of a sludge, preferably a clayey-silty sludge, so as to form a sludge cake suitable for the formation of a construction material, said system comprising: - a support structure designed to support a plurality of movable filter plates; - a plurality of filter plates mounted on the support structure, each having a power supply and being movable between an open configuration and a closed configuration; - a feeding device connected to the filter plates to distribute the sludge; - a guide device configured to control the movement of the set of filter plates; and - a compression device configured to at least partially dehydrate the sludge and form a sludge cake; said system further comprising a device for degrading a flocculating agent present in the sludge and / or, preferably, a device for adding an organic deflocculating agent to the sludge or to the sludge cake.

[0024] According to other optional features of the system, the latter may optionally include one or more of the following features, alone or in combination: it comprises a device for degrading the flocculating agent, the flocculating agent is an organic flocculating agent and the degradation device is positioned at the feed device connected to the filter plates or upstream of the feed device connected to the filter plates, said flocculating agent degradation device being selected from: a UV irradiation device, a heat treatment device, an oxidizing treatment device. it comprises a device for adding an organic deflocculating agent, said device for adding a deflocculant is configured to add the organic deflocculating agent before a compression step, during the compression step or after the compression step. the feed device communicates fluidically with a collection device arranged to conduct the sludge to said feed device and in that the sludge is a clayey-silty sludge comprising a clayey-silty matrix and a flocculating agent, said sludge having a D50 less than or equal to 200 pm and comprising at least 5% by weight of clayey-silty matrix relative to the dry weight of said sludge. the feed device comprises a clarifier arranged to allow separation between a clarified phase and a concentrated phase of the clayey-silty sludge, said clarifier being arranged to bring the concentrated phase of the clayey-silty sludge to the filter plates. Description of the embodiments

[0025] Other characteristics and advantages of the invention will be better understood on reading the description which follows and with reference to the appended drawings, given for illustrative purposes and in no way limiting.

[0026] [Fig. 1] Figure 1 represents an embodiment of a method for manufacturing a construction material from quarry effluent.

[0027] [Fig. 2] Figure 2 shows one embodiment of a method of treating a clayey-silty mud so as to form a mud cake suitable for forming a construction material.

[0028] [Fig. 3] Figure 3 represents an embodiment of a first method of manufacturing a construction binder.

[0029] [Fig. 4] Figure 4 shows an embodiment of a second method of manufacturing a construction binder.

[0030] [Fig. 5] Figure 5 shows one embodiment of a system for forming a construction binder.

[0031] The figures do not necessarily respect the scales, particularly in thickness, and this is for illustration purposes.

[0032] Aspects of the present invention are described with reference to flowcharts and / or functional diagrams of methods, systems according to embodiments of the invention.

[0033] In the figures, flowcharts and block diagrams illustrate the architecture, functionality, and operation of possible implementations of systems and methods according to various embodiments of the present invention. In this regard, each block in the flowcharts or block diagrams may represent a system, device, module, or code, which includes one or more executable instructions for implementing the specified logical function(s). In some implementations, the functions associated with the blocks may appear in a different order than shown in the figures. For example, two blocks shown in succession may, in fact, be executed substantially simultaneously, or the blocks may sometimes be executed in reverse order, depending on the functionality involved.Each block of the block diagrams and / or flowchart, and combinations of blocks in the block diagrams and / or flowchart, may be implemented by special hardware systems that perform the specified functions or acts or carry out combinations of special hardware and computer instructions.

[0034] Below, we describe a summary of the invention and the associated vocabulary, before presenting the disadvantages of the prior art, and finally showing in more detail how the invention overcomes them.

[0035] In the remainder of the description, the term "% by weight" in relation to the construction binder, must be understood as being a proportion relative to the dry weight of the construction binder. The dry weight corresponds to the weight before the addition of water, for example, necessary for the formation of a construction material. When the values ​​of % by weight are given in the form of intervals, the limits are included.

[0036] The expression "clay-silt matrix", within the meaning of the invention, may correspond to one or more rock materials based on phyllosilicates, hydrated silicates or aluminosilicates with a lamellar structure. The clay-silt matrix is ​​composed of at least 75% by weight of particles having a diameter of less than 67 μm as measured by well-known laser granulometry methods. A clay-silt matrix according to the invention further comprises one or more mineral clays, i.e. one or more rock materials based on phyllosilicates, hydrated silicates or aluminosilicates with a lamellar structure, said mineral clay being composed at least in part of fine particles generally originating from the alteration of silicates with a three-dimensional framework or from the precipitation of a supersaturated fluid.A clayey-silty matrix can thus contain a mixture of such rock materials which may, for example, contain kaolinite, serpentine, pyrophyllite, talc, smectite, vermiculite, illite, glauconite, mica, chlorite, palygorskite, sepiolite, interstratified rocks or their mixtures (Alain Meunier. Clays, 2005).

[0037] The expression "clayey-silty mud", within the meaning of the invention, may correspond to a mixture of a set of dry materials, composed mainly of mineral matter comprising a clayey-silty matrix, and water. The clayey-silty mud may come from, without this being limiting, the treatment of quarry effluents.

[0038] By "concrete" is meant a mixture of aggregates, possibly sand, with a construction binder (e.g. cement) and water, which has set. Thus, the term concrete can correspond to a construction element formed from a mixture of aggregates, mineral or vegetable, possibly including sand, one or more additives, construction binder and water.

[0039] The expression "raw mineral fraction" or "mineral fraction" corresponds, within the meaning of the invention, to a mineral fraction that has not undergone a calcination step. In particular, that is to say, it has not undergone any prior heat treatment. For example, this corresponds to a mineral fraction that has not undergone a temperature increase greater than 300°C, preferably greater than 200°C and more preferably a temperature greater than 150°C. Indeed, the raw mineral fraction may undergo a drying step requiring a temperature increase generally substantially equal to or less than 150°C but no calcination step.A raw mineral fraction may preferably comprise rock materials which may for example comprise kaolinite, serpentine, pyrophyllite, talc, smectite, vermiculite, illite, glauconite, mica, chlorite, palygorskite, sepiolite, interstratified rocks or mixtures thereof.

[0040] For the purposes of the invention, a “deflocculating agent”, “deflocculant” or “defloculation agent” may correspond to a compound capable of dissociating aggregates and colloids, particularly in aqueous suspension. Deflocculating agents have, for example, been used in the context of drilling or oil extraction to make clay more fluid and facilitate extraction or drilling.

[0041] The term "binder" or "construction binder" within the meaning of the invention may be understood as a formulation enabling the agglomeration of materials with each other, in particular during the setting and then hardening of a construction material. Thus, it enables in particular the agglomeration of sand and other aggregates with the constituents of the binder. The binder according to the invention is in particular a hydraulic binder, that is to say that hardening takes place upon contact with water.

[0042] The term "Portland cement" refers to a hydraulic binder composed mainly of hydraulic calcium silicates whose setting and hardening is made possible by a chemical reaction with water. Portland cement generally contains at least 95% clinker and a maximum of 5% secondary constituents. such as alkalis (Na2O, K2O), magnesia (MgO), gypsum (CaSC>4 ■ 2 H2O) or various traces of metals.

[0043] The term "substantially equal" within the meaning of the invention corresponds to a value varying by less than 20% compared to the compared value, preferably by less than 10%, even more preferably by less than 5%.

[0044] The term "D50" refers to the median diameter for which 50% (by volume or mass, preferably by volume) of the grains, particles, aggregates or sediments are smaller than a given diameter. For example, if a sieve and sedimentometry analysis method indicates a D50 = 5.8 mm, then 50% of the particles in the sample (by volume or mass, preferably by volume) are larger than 5.8 mm and 50% are smaller than 5.8 mm. D50 is generally used to represent the particle size of a group of particles. D50 may be measured by any method known to the person skilled in the art. The D50 is preferably measured according to the ASTM D422-63 standard, according to the XP P 94-041 (1995), NF ISO 11277 (2020), NF EN ISO 17892-4 (2018) standard or according to the ASTM D6913-04 (2009) standard or in particular for fine particles the ISO 13320:2020 standard (eg D10 or <65 pm).

[0045] The expression “dehydration of the sludge” may correspond, within the meaning of the invention, to a reduction in the percentage by weight of water included in the sludge relative to the total weight of the sludge.

[0046] The construction industry must evolve to optimize productivity while addressing societal and environmental challenges. In this context, the inventor has developed a process for manufacturing low-carbon construction materials that achieves an even smaller environmental footprint than existing methods.

[0047] To this end, the inventor selected a currently neglected source of raw material: quarry effluent, particularly quarry wash water. In particular, the inventor identified wash water that is particularly suitable for use in the manufacture of construction materials.

[0048] Indeed, the most suitable wash waters are those which contain a clay-silty mineral fraction. Such wash waters allow the preparation of construction materials which can achieve mechanical strengths similar to construction materials of type C16 / 20, C25 / 30, C30 / 37, C35 / 45 or more resistant. Thus, while aggregate wash waters are generally used to remove residues which are harmful to the mechanical strength of construction materials, the wash waters selected and treated according to the present invention allow the production of construction materials with advantageous mechanical properties.

[0049] Thus, according to a first aspect, the present invention relates to a method 100 for manufacturing a construction material from a quarry effluent.

[0050] As illustrated in Figure 1, a manufacturing method 100 according to the invention comprises the following steps: a step 110 of flocculation of a quarry effluent, for example quarry wash water, to form a clayey-silty mud, a step 120 of collecting the clayey-silty mud and a step 190 of forming a construction material from the clayey-silty mud.

[0051] As mentioned, a quarry effluent, such as quarry wash water, advantageously comprises a clay-silt matrix.

[0052] Quarry effluent, particularly quarry wash water, will generally have a low dry matter content. Indeed, quarry wash water is generally used to wash rubble from residues that may impair their effectiveness when used as construction materials. On the contrary, in the present invention, when these residues have a clay-silt matrix, then they can be reused in the preparation of a construction material.

[0053] In particular, the quarry effluent such as wash water will have a dry matter content of less than or equal to 200 g / L, preferably less than or equal to 150 g / L, more preferably less than or equal to 150 g / L, even more preferably less than or equal to 150 g / L.

[0054] However, it is preferable that the residues are not too diluted. Thus, the quarry wash water may have a dry matter content greater than or equal to 20 g / L, preferably greater than or equal to 25 g / L, more preferably greater than or equal to 30 g / L, even more preferably greater than or equal to 35 g / L. The dry matter is measured according to standard NF EN 15934.

[0055] Generally, to obtain better results, the dry matter of the quarry effluent such as quarry wash water will comprise by weight a majority of a clay-silt matrix. Thus, the dry matter of the wash water may comprise at least 50% by weight of a clay-silt matrix fraction, preferably it comprises at least 60% by weight of a clay-silt matrix, more preferably it comprises at least 70% by weight of a clay-silt matrix, even more preferably it comprises at least 80% by weight of a clay-silt matrix. The clay-silt matrix content is measured by known type of particle size measurement techniques.

[0056] Thus, the dry matter of the quarry effluent, such as the wash water, may comprise at least 30% by weight of silt, preferably at least 40% by weight of silt, more preferably at least 45% by weight, even more preferably at least 50% by weight.

[0057] Advantageously, in order to improve the mechanical strength of the construction material produced, the dry matter of the quarry effluent, such as quarry wash water, may comprise at most 5% by weight of sand, preferably at most 4% by weight of sand, more preferably at most 3% by weight of sand, even more preferably at most 2% by weight of sand. The sand is characterized by particles having a diameter greater than 67 pm.

[0058] Advantageously, in order to improve the mechanical strength of the construction material produced, the dry matter of the quarry effluent, such as quarry wash water, may comprise at least 5% by weight of clay, preferably at least 10% by weight of clay, more preferably at least 15% by weight of clay, even more preferably at least 20% by weight of clay. The clay, silt and sand contents are measured according to the granulometric method defined by standard NF ISO 13320-1.

[0059] Furthermore, the inventor has determined other selection criteria that can influence the mechanical strength of construction materials made from quarry effluent.

[0060] Advantageously, the quarry effluent has an organic matter concentration of less than 5% by weight relative to the dry matter weight of the quarry effluent. Preferably, the quarry effluent has an organic matter concentration of less than or equal to 4% by weight relative to the dry matter weight of the quarry effluent; more preferably, less than or equal to 3% by weight; even more preferably, less than or equal to 2% by weight relative to the dry matter weight of the quarry effluent.

[0061] Also, the quarry effluent preferably has a heavy metal concentration of less than 1 mg / L. Preferably, the quarry effluent has a heavy metal concentration of less than or equal to 800 pg / L; more preferably, less than or equal to 600 pg / L; even more preferably, less than or equal to 200 pg / L. The heavy metal concentration may correspond to the sum of the arsenic, lead, mercury and cadmium contents.

[0062] Also, the quarry effluent preferably has a concentration of radioactive elements less than or equal to 200 pg / L. Preferably, the quarry effluent has a concentration of radioactive elements less than or equal to 150 pg / L; more preferably, less than or equal to 100 pg / L; even more preferably, less than or equal to 50 pg / L.

[0063] A method according to the present invention may comprise a flocculation step 110, 220 of a quarry effluent comprising a clay-silt matrix.

[0064] Advantageously, before the flocculation stage, the quarry effluent will have undergone a stage of mechanical separation of a fraction composed of particles whose diameter is greater than 67 pm. The prior removal of all or part of this fraction makes it possible to improve the subsequent efficiency of a process according to the invention. This separation can, for example, be carried out by using a cyclone.

[0065] The flocculation step 110, 220 may include the use of a lagoon system or a decanter.

[0066] The flocculation step 110, 220 may be carried out using a flocculating agent to form a clayey-silty slurry. Alternatively, the flocculation step may comprise the implementation of electroflocculation or mechanical flocculation. Advantageously, the flocculation step 110, 220 may comprise a combination of methods such as flocculation using a flocculating agent combined with mechanical flocculation.

[0067] Preferably, the flocculation step 110, 220 is implemented so as to generate a clayey-silty sludge having a water content of at most 80%, preferably at most 75%, preferably at most 70%, more preferably at most 65% and even more preferably at most 60%. The water content is calculated here by dividing the mass of water by the total mass of the sludge.

[0068] Advantageously, the flocculation step 110, 220 comprises double flocculation.

[0069] A method according to the present invention may include a step 120, 230 of collecting the silty-clayey mud comprising the clayey-silty matrix.

[0070] Indeed, advantageously, a method according to the present invention comprises the use or transformation of a clayey-silty mud. The inventor has determined preferred physicochemical characteristics for this clayey-silty mud so as to obtain the best properties for construction materials. The preferred mineralogical characteristics of the quarry effluent also apply to the clayey-silty mud (e.g. clayey-silty matrix and sand, clay and silt content).

[0071] At this stage, the clayey-silty mud generally contains a significant amount of water. For example, the clayey-silty mud has a water content greater than or equal to 40%; preferably, the silty-clayey mud has a water content greater than or equal to 45%; more preferably, it has a water content greater than or equal to 50%; and even more preferably, a water content greater than or equal to 55%.

[0072] In addition, the clayey-silty mud will, for example, have a minimum level of dry matter. Indeed, a certain level of dry matter makes it possible to reduce the environmental footprint of the manufactured construction material. For example, the clayey-silty mud has a dry matter content greater than or equal to 20%; Preferably, the clayey-silty mud has a dry matter content greater than or equal to 30%; more preferably, it has a dry matter content greater than or equal to 35%; and even more preferably, a dry matter content greater than or equal to 40%. The dry matter content is calculated here by dividing the mass of dry matter by the total mass of the sludge.

[0073] When collected, the sludge may have a D50 of less than or equal to 200 pm. Preferably, the clayey-silty sludge has a D50 of less than or equal to 150 pm and even more preferably less than or equal to 125 pm.

[0074] Furthermore, the clayey-silty mud collected within the scope of the invention comprises at least 1% by weight of clayey-silty matrix, preferably at least 3% by weight of clayey-silty matrix and even more preferably at least 5% by weight of clayey-silty matrix relative to the dry weight of said mud.

[0075] The collected clayey-silty sludge will generally contain a flocculant. Indeed, the use of a flocculant significantly accelerates the flocculation process and the recovery of the mineral fraction of interest, namely the clayey-silty matrix. Advantageously, the clayey-silty sludge will contain an organic flocculant. Indeed, the mechanical properties of the construction material are improved with organic flocculants as opposed to inorganic flocculants.

[0076] For example, the organic flocculant is selected from: polyacrylamides, for example an anionic polyacrylamide; polysaccharides; polyamines such as polyDADMAC; or even polyethyleneimine.

[0077] Alternatively, or in addition, the clayey-silty mud may include an inorganic flocculant. The inorganic flocculant may, for example, be selected from: an aluminum-based flocculant, an iron-based flocculant, a magnesium-based flocculant, and / or a calcium-based flocculant. Preferably, the inorganic flocculant is selected from: an aluminum-based flocculant, an iron-based flocculant, and / or a magnesium-based flocculant.

[0078] A method according to the present invention may comprise a step 190, 290 of forming a construction material.

[0079] The construction material formed at this stage can be selected from: a construction binder, concrete, coating, mortar, tile adhesive and any other secondary product containing cement.

[0080] Preferably, the building material formed at this stage is a building binder.

[0081] The step 190, 290 of forming a building material comprises adding the clay-silt matrix to a building material mixture.

[0082] As presented in the remainder of the description, the step of forming a construction material can implement the clay-silt matrix by directly using the clay-silt mud comprising a water content greater than 20% and less than 40% after dehydration or use the clay-silt matrix after transformation of the clay-silt mud into cake.

[0083] The step of forming 190, 290 a construction material, such as a construction binder, is for example carried out by using a mixer. The mixer may for example correspond to a powder mixer; a belt mixer; a concentric ribbon mixer; a ploughshare mixer; a horizontal mixer. The mixer may be continuous or discontinuous.

[0084] In particular, when clayey-silty mud is used directly after dehydration, it is used as a filler added to a construction binder to form a final construction material such as a plaster, concrete, mortar, tile adhesive and any other secondary product containing cement.

[0085] When the sludge is transformed, the clay-silt matrix can be used to form a construction binder. In this case, and as will be detailed later, the sludge can undergo an additional dehydration step aimed at achieving a water content of less than 20%, followed by a grinding step. The ground material is then used in combination with, in particular, an activating composition to form a construction binder.

[0086] The activation composition is preferably an alkaline activation composition. The activation composition may be selected from: clinker; EN 197-1 cements; sulfoaluminous cements; supersulfated cements; lime; silicates; carbonates or combinations thereof. Preferably, the activation composition may be selected from: clinker; EN197-1 cements; sulfoaluminous cements; supersulfated cements; lime; silicates; carbonates or combinations thereof.

[0087] The step 190 of forming a construction binder may include adding a precursor. The precursor may include a source of carbonates in combination or not with silicates. In particular, the precursor may include sodium or potassium carbonate. The sodium or potassium carbonate may further be mixed with sodium or potassium silicate.

[0088] Preferably, the precursor may comprise a source of calcium carbonate. The source of calcium carbonate may correspond to a solid material composed mainly of carbonate minerals such as calcite or dolomite minerals.

[0089] As illustrative examples, the source of carbonate can be limestone, dolomite, chalk, aragonite or even vaterite.

[0090] Alternatively, the limestone can also be magnesium carbonate and or a mixture of magnesium carbonate and dolomite.

[0091] Preferably, the limestone is a natural limestone mainly consisting of calcium carbonate with different polymorphs, such as calcite and / or aragonite, but also containing some magnesium carbonate and / or dolomite. Limestone can also be a natural clayey limestone or marl.

[0092] In addition, the precursor may comprise a siliceous filler or “quartz flour”. For example, the siliceous filler may comprise corpuscular silica and kaolinite.

[0093] The precursor may also include calcined shale, diatomite, phonolite, paper mill sludge ash, or crushed glass.

[0094] Alternatively or in addition, the precursor may further be selected from: blast furnace slag; calcined clay; flash calcined clay; fly ash, silica fume; rice husk fume; glass powder; and combinations thereof, Pozzolans; Siliceous ash; Silica fume; Calcium ash; schists; limestones.

[0095] The step of forming 190 a construction material may include the addition of fillers such as sand, aggregates or the like.

[0096] Following this first aspect, the inventor developed this technology in several aspects such as: A method of treating 200 a clayey-silty mud allowing the formation of a mud cake suitable for the formation of a construction material and in particular a construction binder. Such a method is illustrated in Figure 2. A mud cake usable for the preparation of a construction material obtainable from a method of treating a clayey-silty mud according to the present invention. A method of manufacturing 300 a construction binder from a mud cake comprising a clay-silt matrix. Such a method is illustrated in Figure 3.

[0097] Furthermore, following this first advance, the inventor developed numerous optimizations which are described below in connection with one or more of the aspects mentioned above.

[0098] For example, as illustrated in Figures 1 to 4, a method according to the present invention may comprise one or more of the following steps: a step of determining the treatment conditions of a quarry effluent; a step of mechanical dewatering of the sludge; a step of degrading the flocculating agent; a step of drying the sludge cake; a step of grinding the clayey-silty sludge; and a step of adding an organic deflocculating agent to the clayey-silty matrix.

[0099] As illustrated in Figure 1, a manufacturing method 100 according to the present invention may comprise a step 105 of determining the treatment conditions of the clayey-silty mud.

[0100] The determination step 105 may comprise a measurement of the physicochemical properties of a quarry effluent and / or of a clay-silt mud comprising a clay-silt matrix.

[0101] For example, the step 105 of determining the treatment conditions according to the invention may include a measurement of physicochemical characteristics and in particular of values ​​for one or more of the following parameters: a clay richness by measuring the blue value; a granulometry; a chemical composition by X-ray fluorescence spectrometry.

[0102] Furthermore, the method may comprise a step of selecting values ​​of flocculant, flocculant concentration, deflocculant, deflocculant concentration and / or process parameter values, which are adapted to the clay-silt matrix.

[0103] Preferably, a manufacturing method 100 according to the invention may comprise a step of mechanical dehydration 140 of the clayey-silty mud.

[0104] This step can be used in particular to form a mud cake.

[0105] Such a mechanical dehydration step 140 is preferably implemented so as to obtain a mud cake comprising the clay-silt matrix.

[0106] For example, a mud cake formed during this step will have a water content of less than or equal to 40%. Preferably, a mud cake formed during this step will have a water content of less than or equal to 35%, more preferably less than or equal to 30%, or even more preferably less than or equal to 25%.

[0107] Other preferred characteristics of the mud cake are described in the remainder of the description in connection with a clayey-silty mud cake according to the present invention.

[0108] The dewatering step 140 may comprise the use of a means selected from: filter press or screw press. Preferably, the dewatering step 140 may comprise the use of a filter press. For example, a belt filter press; a plate filter press; a fin filter press; or a vertical filter press. Conventionally, the use of a filter press makes it possible to generate several sludge cakes simultaneously.

[0109] A manufacturing method 100 according to the present invention may comprise a step 150 of degradation of the organic flocculant.

[0110] The degradation step 150 of the organic flocculant may comprise: UV irradiation, heat treatment, oxidative treatment or combinations thereof.

[0111] The degradation step 150 of the organic flocculant may for example occur during the sludge collection step, during the drying step and / or during the grinding step. Preferably, if the clayey-silty sludge is used directly in a mixture without a mechanical dehydration step, then the degradation of the organic flocculant may intervene between the collection of the mud and the use of the mud in the mixture to form the building material.

[0112] If the clayey-silty sludge is used after a mechanical dewatering step then, preferably, the degradation of the flocculant occurs after the mechanical dewatering step, for example at the time of a drying step of the silty-clayey mineral fraction, before a grinding step of the clayey-silty mineral fraction or during a grinding step of the clayey-silty sludge cake.

[0113] Preferably, the step 150 of degrading the organic flocculant comprises “UV” irradiation for ultraviolet. The UV irradiation may for example occur during the step 120 of collecting the sludge, during the drying step 160 and / or during the grinding step 170. According to one embodiment, the step 150 of degrading the organic flocculant comprises UV irradiation before, during or after the step of collecting the clayey-silty sludge. Preferably, during or after the step of collecting the silty-clayey sludge. According to another embodiment, the step 150 of degrading the organic flocculant comprises UV irradiation between the mechanical dehydration step and the use in a mixture to form the construction binder.

[0114] The degradation step 150 of the organic flocculant may comprise a treatment with an oxidizing agent. In addition, the UV irradiation may be enhanced in the context of advanced oxidation. Thus, the degradation step 150 of the organic flocculant may comprise UV irradiation coupled with the addition of an oxidizing agent such as a peroxide or ozone.

[0115] The degradation step 150 of the organic flocculant may comprise a heat treatment. Preferably, a heat treatment in the context of the present invention is carried out before a grinding step. A heat treatment is generally carried out at a temperature of at least 100°C, preferably at least 150°C. A heat treatment is however generally carried out at a temperature below 400°C to limit the degradation of the mineral phases. Preferably, the heat treatment is carried out at a temperature of at most 350°C; more preferably at a temperature of at most 300°C and even more preferably at a temperature of at most 250°C.

[0116] A manufacturing method 100 according to the present invention may comprise a step 160 of drying the mud cake or more broadly the clay-silt matrix.

[0117] This step may in particular allow the clayey-silty mineral fraction and in particular the clayey-silty mud cake to reach a water content of less than or equal to 20%. Preferably, this step makes it possible to reach a water content of less than or equal to 15%, more preferably less than or equal to 10%, and even more preferably a water content of less than or equal to 5%.

[0118] The drying step 160 of the mud cake can be carried out by implementing a device selected from: oven, solar dryer, laminar dryer, dryer, drying natural, for example in ventilated sheds. The drying step 160 may in particular comprise several steps. For example, while the mud cake has a water content of around 20%, a method according to the invention comprises a first drying step, for example natural, making it possible to reduce the water content to less than 15%, preferably less than 10%. The method then comprises a drying / grinding step which makes it possible to pass onto a powder with a relative humidity of less than 5%.

[0119] In one embodiment, when the clay-silt matrix is ​​used in combination with a construction binder for the preparation of a construction material (it is then used mainly as a filler), then the drying step can be limited and make it possible to obtain a composition, comprising the clay-silt matrix, having a water content of less than or equal to 20%.

[0120] However, when the clay-silt matrix is ​​used in combination with an activator for the formation of a construction binder then the drying step 160 is carried out so that the water content of the composition comprising the clay-silt matrix (for example the mud cake) has a water content of less than 5%; preferably less than 4%, more preferably less than 3%, more preferably less than 2% and even more preferably less than 1%.

[0121] In certain embodiments, the drying step 160 and the grinding step 170 which are described below are concomitant or at least partially overlap in time. For example, the drying step may be initiated upstream of the grinding and then continued during the grinding. In this case, advantageously, the drying step 160 is continued until generating a ground mud cake having a water content of less than 20%, preferably less than 15%, more preferably less than 10%.

[0122] Indeed, all or part of the drying step 160 may precede the grinding step 170.

[0123] Also, all or part of the drying step 160 may follow the grinding step 170.

[0124] A manufacturing method 100 according to the present invention may comprise a step 170 of grinding the clay-silt matrix and in particular the clay-silt mud cake.

[0125] This step can make it possible to obtain a ground material of clay-silt matrix (e.g. mud cake ground material) which has a D50 less than or equal to 50 pm. Preferably, it makes it possible to obtain a ground material which has a D50 less than or equal to 40 pm, more preferably a D50 less than or equal to 30 pm, even more preferably, a D50 less than or equal to 20 pm.

[0126] This step can make it possible to obtain a clay-silt matrix ground material (e.g. mud cake ground material) which has a D90 of less than or equal to 100 pm. Preferably, it makes it possible to obtain a clay-silt matrix ground material which has a D90 of less than or equal to 90 pm, more preferably a D90 of less than or equal to 80 pm, even more preferably, a D90 of less than or equal to 70 pm.

[0127] In particular, this step is carried out so as to obtain a clay-silt matrix ground material which has a D50 less than or equal to 50 pm and a D90 less than or equal to 100 pm. Preferably, it makes it possible to obtain a clay-silt matrix ground material which has a D50 less than or equal to 40 pm and a D90 less than or equal to 90 pm, more preferably a D50 less than or equal to 30 pm and a D90 less than or equal to 80 pm, even more preferably, a D50 less than or equal to 20 pm and a D90 less than or equal to 70 pm.

[0128] The grinding step 170 may be carried out by implementing any grinding means capable of reducing the D50 of a mineral fraction. For example, the grinding step 170 may be carried out by implementing a device selected from: ball mill, orbital mill, hammer mill; grinding mill; pendulum mill; attrition mill, vane mill. In addition, the grinding step may be preceded by a deagglomeration step using, for example, a deagglomerator.

[0129] Preferably, a manufacturing method 100 according to the invention will comprise a step 180 of adding an organic deflocculant to the clay-silt matrix of the mud cake.

[0130] For example, the step of adding a deflocculant 180 involves adding an organic deflocculant to the collected clayey-silty mud.

[0131] For example, the deflocculant addition step 180 involves adding an organic deflocculant to the clay-silt mud cake.

[0132] During the step 180 of adding a deflocculant, the deflocculant may be in solid or liquid form. For example, the deflocculant may be added in aerosol form. Advantageously, the organic deflocculant may be sprayed onto the clay-silt mud cakes. Thus, according to one embodiment of a manufacturing method 100 according to the invention, the addition of the organic deflocculant is preferably carried out to the clay-silt mud cake, for example at the time of deflocculation.

[0133] The step 180 of adding a deflocculant may be combined with the step 120 of collecting the clay-silt mud, the step 140 of mechanical dewatering, the step 160 of drying, the step 170 of grinding the mud cake, and / or the step 190 of forming the construction material.

[0134] The organic deflocculating agent may be selected from a non-ionic surfactant, an anionic agent, a polyacrylate, an amine or mixtures thereof.

[0135] In particular, the organic deflocculating agent may be a polyoxyethylene ether. The polyoxyethylene ether may, for example, be selected from: a lauryl poly(oxyethylene) ether.

[0136] Also, the deflocculating agent may be an anionic agent such as an anionic surfactant. In particular, the anionic agent may be selected from: alkylaryl sulfonates, amino alcohols, carbonates, silicates, fatty acids, humates (e.g. sodium humates), carboxylic acids, lignosulfonates (e.g. sodium lignosulfonates), polyacrylates, phosphates or polyphosphates such as sodium hexametaphosphate, sodium tripolyphosphate, sodium orthophosphate, carboxymethylcelluloses and mixtures thereof.

[0137] Also, the organic deflocculating agent may be a polyacrylate selected from: sodium polyacrylate or ammonium polyacrylate or mixtures thereof.

[0138] Finally, the organic deflocculating agent may be an amine selected from: 2-amino-2-methyl-1-propanol; mono-, di- or triethanolamine; isopropanolamines (1-Amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines; and mixtures thereof.

[0139] Preferably, the organic deflocculating agent is selected from: a lignosulphonate (e.g. sodium lignosulphonate), a polyacrylate, a humate and mixtures thereof.

[0140] Preferably, the organic deflocculating agent is selected from: a lignosulphonate (e.g. sodium lignosulphonate), a polyacrylate, a humate, a polycarboxylate such as an ether polycarboxylate, and mixtures thereof.

[0141] More preferably, the organic deflocculating agent comprises a humate, a lignosulphonate and / or a polyacrylate.

[0142] Alternatively, the organic deflocculating agent may be a mixture of compounds, such as a mixture comprising at least two compounds selected from: non-ionic surfactant, anionic agent, polyacrylate, amine and organophosphorus compound.

[0143] The organic deflocculating agent is preferably in the form of a salt.

[0144] However, the invention cannot be limited to the deflocculating agents mentioned above; any type of deflocculating agent known to those skilled in the art can be used instead of the said deflocculating agents mentioned above.

[0145] The organic deflocculating agents that can be used according to the present invention may take a solid form or a liquid form.

[0146] Thus, according to one aspect, the invention relates to a method 200 for treating a clayey-silty slurry. This treatment method is in particular intended to form a slurry cake which is suitable for the formation of a construction material, preferably a construction binder.

[0147] A treatment method 200 according to the present invention may further comprise one or more of the steps selected from: a step 230 of collecting a clayey-silty sludge and a step 240 of mechanical dewatering of the clayey-silty sludge. In addition, such a treatment method 200 according to the present invention may further comprise one or more steps selected from: a step 210 of determining the treatment conditions of a quarry effluent, a step 220 of flocculation of a quarry effluent, a step 250 of degradation of the organic flocculant, a step 260 of drying the sludge cake, a step 270 of grinding the sludge cake and in particular the clayey-silty sludge and a step 280 of adding an organic deflocculant.

[0148] A treatment method 200 according to the present invention may include all the advantageous, preferred or non-preferred characteristics described above in connection with the corresponding steps of the manufacturing method 100 of a construction material.

[0149] According to another aspect, the present invention relates to a clayey-silty mud cake obtainable by the treatment method 200 according to the present invention. In particular, the present invention relates to a mud cake directly obtained by a treatment method 200 according to the present invention.

[0150] A clayey-silty mud cake according to the present invention may include all the advantageous, preferred or non-preferred characteristics described above in connection with the manufacturing method 100 of a construction material.

[0151] A clay-silt mud cake according to the present invention will comprise a clay-silt matrix.

[0152] Furthermore, advantageously, a clayey-silty mud cake according to the present invention comprises a flocculating agent and / or one or more degradation products of a flocculating agent. Preferably, a clayey-silty mud cake according to the present invention comprises one or more degradation products of a flocculating agent.

[0153] Furthermore, advantageously, a clayey silty mud cake according to the present invention comprises an organic deflocculating agent.

[0154] Alternatively or additionally, a silty clay mud cake according to the present invention may in particular be composed of 30% to 70%, preferably 40% to 60% by weight of SiO2 and / or CaO. As illustrative examples, the silty clay mud cake may be composed of at least 30% by weight of SiO2, preferably at least 40% by weight of SiO2, even more preferably at least 50% by weight of SiO2, preferably at least 60% by weight of SiO2 and most preferably at most 70% by weight of SiO2.

[0155] Still by way of illustrative example, the silty clay mud cake may be composed of at least 30% by weight of CaO, preferably at least 40% by weight of CaO, even more preferably at least 50% by weight of CaO, preferentially at least 60% by weight of SiO2 and most preferably at most 70% by weight of CaO. Alternatively, the clayey silty mud cake may be composed of a mixture of CaO and SiO2 which represents at least 30% by weight of the composition of the clayey silty mud cake, preferably at least 40% by weight of the composition of the clayey silty mud cake, even more preferably at least 50% by weight of the composition of the clayey silty mud cake, preferably at least 60% by weight of the composition of the clayey silty mud cake and most preferably at most 70% by weight of the composition of the clayey silty mud cake.

[0156] Such proportions ensure optimal mechanical resistance to compression while maintaining a rheology which allows satisfactory workability of the construction material at a young age (1 day), in particular a rheology characterized by the measurement of the cone spreading value, according to standard NF EN 1015-3, greater than 180 mm.

[0157] Furthermore, it is provided that the treatment method 200 may comprise a step of adding a filler comprising silica and / or lime when in particular the clayey-silty mud does not comprise a CaO and / or SiO2 content as mentioned previously, so that the CaO and / or SiO2 content of said clayey-silty mud is adjusted to any one of the previously mentioned contents.

[0158] Advantageously, a clayey-silty mud cake according to the present invention has a water content of at most 40%. Preferably, a mud cake according to the present invention has a water content of at most 35%, more preferably at most 30% and even more preferably a water content of at most 35%.

[0159] Advantageously, a mud cake according to the present invention has a thickness of at most 50 mm; preferably, a thickness of at most 40 mm; preferably more preferably, a thickness of at most 30 mm; and even more preferably, a thickness of at most 20 mm.

[0160] Advantageously, a mud cake according to the present invention has a thickness of at least 1 mm; preferably, a thickness of at least 2 mm; more preferably, a thickness of at least 3 mm; and even more preferably, a thickness of at least 4 mm.

[0161] Advantageously, a mud cake according to the present invention has a thickness of from 1 mm to 50 mm; preferably, a thickness of from 2 mm to 40 mm; more preferably, a thickness of from 3 mm to 30 mm; and even more preferably, a thickness of from 4 mm to 30 mm.

[0162] For example, a mud cake according to the present invention will have at least one of the following characteristics: water content less than 30%, or thickness between 5 mm and 20 mm, absence of heavy metal pollution, preferably with a heavy metal concentration less than 0.1% relative to the dry matter weight of the clayey-silty mud; absence of radioactive compounds, preferably with a concentration of radioactive elements less than 0.05% relative to the dry matter weight of the clayey-silty mud; a dry matter content greater than or equal to 20%.

[0163] According to another aspect, the present invention relates to a method 300 for manufacturing a construction binder. In particular, the method 300 for manufacturing a construction binder according to the present invention uses a clayey-silty mud cake.

[0164] As illustrated in Figure 3, the method according to the invention comprises the following steps: a step 310 of providing the mud cake comprising a clay-silt matrix, a step 330 of drying the mud cake comprising the clay-silt matrix; a step 340 of grinding the mud cake comprising the clay-silt matrix; a step 360 of forming a construction binder comprising the addition of an activation composition to the ground mud cake comprising the clay-silt matrix.

[0165] Also, the manufacturing method 300 of a construction binder according to the present invention may comprise the addition 350 of an organic deflocculant and / or the degradation 320 of an organic flocculant.

[0166] A method 300 for manufacturing a construction binder from a clay-silt mud cake according to the present invention may include all the advantageous, preferred or non-preferred characteristics described above in connection with the method 100 for manufacturing a construction material.

[0167] In particular, during the step 310 of providing the mud cake, it preferably comprises a clay-silt matrix and a flocculant, for example an organic flocculant.

[0168] Advantageously, the process will comprise drying and grinding steps to generate a powder from the clayey-silty matrix of the mud cake having a water content of less than 5%. In addition, this powder has a D50 of less than 50 pm and a D90 of less than 100 pm (preferably a D90 of less than or equal to 100 pm).

[0169] Advantageously, during the step 360 of forming a construction binder, the mixture comprises an organic deflocculant. The organic deflocculant may be included in the mud cake used at the start of the process. Alternatively, the organic deflocculant may be added at the time of drying the mud cake, at the time of grinding the mud cake or before or at the time of mixing with the other constituents of the construction binder mixture.

[0170] According to another aspect, the invention relates to a system 1 for forming a construction binder from a clayey-silty slurry comprising a clayey-silty matrix, the system comprises a collection device 20, a mechanical dewatering device 30, a dryer 40, a grinder 60 and a mixer 70.

[0171] The collection device 20 is adapted to receive a clayey-silty mud B1 comprising a clayey-silty matrix B1-1, preferably the collection device 20 comprises a clayey-silty mud B1 comprising a clayey-silty matrix B1-1. The collection device 20 may for example correspond to a tank connected to a first conduit for conveying the clayey-silty mud B1. In particular, the collection device 20 may be adapted to implement a collection step described in connection with the methods according to the invention.

[0172] The clayey-silty mud has a D50 of less than or equal to 200 pm and comprises at least 5% by weight of clayey-silty matrix B1-1 relative to the dry weight of said mud.

[0173] In the context of the invention, the system may comprise a measuring device 10 positioned at the inlet of the collection device 20. The measuring device 10 may be configured to determine values ​​of physicochemical characteristics of the sludge. clayey-silty B1. Indeed, the characterization of clayey-silty mud can allow the implementation of specific treatment steps to optimize the formation of a construction binder. For this, the determined physicochemical characteristics can correspond to X-ray fluorescence values ​​and / or particle size values.

[0174] Optionally, the clayey-silty mud may include a flocculating agent.

[0175] A collection device 20 may for example correspond to a clarifier and be arranged to allow separation between a clarified phase, that is to say which comprises mainly water, and a concentrated phase, which comprises mainly sludge particles suspended in water, of the clayey-silty sludge in particular by gravity sedimentation in a decanter. The clarifier may be arranged to bring the concentrated phase of the clayey-silty sludge into the mechanical dewatering device 30. This makes it possible to obtain a clayey-silty sludge which has a homogeneous particle size distribution and improves the workability of said sludge.

[0176] Thus, the collection device 20 can be adapted to implement a flocculation step in connection with the methods according to the invention, in particular a step of adding a flocculant to the clayey-silty mud in the collection device.

[0177] The system according to the invention comprises a mechanical dewatering device 30 configured to generate a mud cake B2 which comprises the clay-silt matrix B1-1, said mud cake having a water content of less than 40%. In particular, the mechanical dewatering device 30 may be adapted to implement all or part of a drying step described in connection with the methods according to the invention and to make it possible to move onto a mud cake having a water content of less than 40%.

[0178] For this, the mechanical dewatering device 30 can communicate fluidically with the collection device 20 via a second conveying conduit. The mechanical dewatering device 30 can be arranged to allow the recovery of a filtrate corresponding to an aqueous phase resulting from the mechanical dewatering of the clayey-silty mud.

[0179] The system according to the invention further comprises a dryer 40 of the mud cake B2 configured to bring the mud cake B2 to a water content of less than 20%.

[0180] Still in the invention, the system includes a grinder 60 configured to grind the mud cake B2 comprising the clay-silt matrix B1-1 so as to form a ground material having a D50 of less than 50 pm and a D90 of less than 100 pm (preferably a D90 of less than or equal to 100 pm). The grinder 60 can be connected to the dryer 40 by via the first conveying means such as belt conveyors or chain conveyors. In particular, the crusher 60 can be adapted to implement a crushing step described in connection with the methods according to the invention.

[0181] In an optional embodiment of the forming system 1 according to the invention, the mill 60 may comprise drying means 50 configured to dry the mud cake B2. In particular, the drying means 50 may be adapted to implement all or part of a drying step described in connection with the methods according to the invention and make it possible to pass over a powder with a relative humidity of less than 5%.

[0182] A system according to the invention also comprises a mixer 70 configured to form a construction binder L1 from the mud cake grind B2 and an activating composition. The mixer 70 can be directly connected to the grinder 60 via second conveying means identical to the first conveying means.

[0183] In an optional embodiment, the system according to the invention may further comprise a device 80 for degrading the flocculating agent when said sludge comprises a flocculating agent and / or, preferably, a device 90 for adding an organic deflocculating agent to the clay-silt matrix B1-1.

[0184] The flocculating agent degradation device 80 can be positioned at the outlet of the collection device 20.

[0185] Preferably, the degradation device 80 of the flocculating agent is selected from: a UV irradiation device, a heat treatment device, an oxidizing treatment device. The oxidizing treatment device can for example generate ozonation and / or an advanced oxidation treatment.

[0186] In addition, it is provided that the flocculating agent can be added directly into the collection device 20 even when the clay-silt sludge conveyed is devoid of it in order to facilitate the recovery of the entire clay-silt matrix. For this, a flocculant addition device F1 can be connected to the collection device 20 and further comprise a reversible opening means 11-1 configured to add to the clay-silt sludge B1, a quantity Q1 FI of flocculant. In particular, the flocculant addition device F1 can be adapted to implement a step of adding a deflocculating agent as part of a flocculation step described in connection with the methods according to the invention. Alternatively or in addition, the system according to the invention may comprise a device 90 for adding an organic deflocculating agent to the clay-silt matrix B1-1. Like the flocculant addition device F1, the device 90 for adding a deflocculating agent can be connected to the mixer 70 and further comprise a reversible opening means 11-2 configured to add to the mud cake grind B2 and to the activation composition, a quantity Q1 DI of deflocculant to form a construction binder L1. In particular, the addition device 90 can be adapted to implement a step of adding a deflocculating agent described in connection with the methods according to the invention.

[0187] In order to optimize the treatment of a clayey-silty mud and consequently the formation of a construction binder adapted to the composition of the clayey mud in question, the system according to the invention may comprise a processor 12 coupled to the measuring device 10, the processor 12 being configured to, as a function of the physicochemical characteristic values, determine a quantity Q1 DI of the organic deflocculating agent D1 to be added to the mud cake B2 and / or a quantity Q1 FI of a flocculating agent F1, preferably an organic flocculating agent, to be added to the clayey-silty mud B1.

[0188] For this, the processor 12 can be integrated into the measuring device 10, or be included in a separate computer device and communicate via a wired or wireless communication bus with the reversible closing means 11-1, 11-2.

[0189] According to another aspect, the present invention relates to a system for mechanically dewatering a sludge. In particular, a system for mechanically dewatering a sludge according to the invention is a system for mechanically dewatering a clayey-silty sludge. Preferably, it is a system specifically designed for the mechanical dewatering of a sludge, in particular a clayey-silty sludge. In the context of the invention, the mechanical dewatering device 30 may correspond to a system for mechanically dewatering a sludge as will be presented below.

[0190] A dewatering system according to the present invention makes it possible to form a mud cake. This mud cake, by its design, is advantageously usable in the formation of a construction material. Preferably, the dewatering system according to the present invention is specifically designed for the formation of a mud cake usable in the formation of a construction binder. This mud cake generally has a dry matter content of at least 30%.

[0191] A dewatering system according to the present invention may comprise: a support structure, a plurality of filter plates, a feeder connected to the filter plates for distributing the sludge, a guide device configured to control the movement of the filter plates, a compression device; said system further comprising a device 80 for degrading a flocculating agent and / or, preferably, and a device 90 for adding an organic deflocculating agent to the sludge B1-1 or to the sludge cake.

[0192] In particular, the dewatering system according to the present invention may comprise a sludge conditioning unit configured to treat the aqueous sludge with coagulants or flocculants before it is conveyed to the filter plates.

[0193] In particular, the dehydration system according to the present invention comprises a support structure adapted to support a plurality of movable filter plates. Preferably, the support structure extends longitudinally. The support structure may comprise mechanisms for the rotary and automatic movement of the filter plates.

[0194] The dewatering system according to the present invention may comprise a plurality of filter plates mounted on the support structure. Preferably, each filter plate comprises a sludge feed. Furthermore, the filter plates are advantageously movable between an open configuration and a closed configuration, the closed configuration allowing the formation of a compression chamber between two filter plates.

[0195] The filter plates may preferably be made of a material suitable for operations requiring a pressure of more than 2 Bar. In addition, the filter plates may include elements for improving sealing such as gaskets, fabrics, and / or magnetic elements.

[0196] In particular, the system may further comprise filter elements capable of retaining solids and allowing water to pass through. Preferably, the filter elements are selected from: filter cloths, non-woven fabrics or textiles, metal meshes, and / or polymer membranes. The filter elements are generally associated with each filter plate, preferably each filter element being configured to be attached to a filter plate. Preferably, a system according to the invention further comprises filter cloths associated with each filter plate, preferably each filter cloth being configured to be attached to a filter plate. The filter cloths may be made of a microporous material capable of filtering particles down to a specified micrometric size.

[0197] Each of the filter plates may include one or more integrated water outlets. Thus, advantageously, the system further includes a device for collecting the filtrates generated during compression. This filtrate collection device may include a water recycling module to reuse the effluents collected in quarry operations.

[0198] The dewatering system according to the present invention may comprise a feed device connected to the filter plates. It is advantageously configured to distribute the sludge to the filter plates. Preferably, the feed device is equipped with a pressure control device.

[0199] The dehydration system according to the present invention may comprise a guide device configured to control the movement of the set of filter plates.

[0200] The dewatering system according to the present invention may comprise a compression device configured to at least partially dewater the sludge. The compression device may in particular implement one or more clamping cylinders as well as one or more pumps. The compression of the sludge will result in an expulsion of the water from the compression chamber and the formation within a compression chamber of a sludge cake which may be considered as a dewatered sludge cake. In addition, the compression device is advantageously configured to apply a two-stage compression to the sludge. The compression device is advantageously configured so that the sealing pressure applied to the junction elements between the filter plates is greater than the internal pressure of the developed chamber.

[0201] A dewatering system according to the invention may comprise a pressure control device. In particular, the pressure control device is configured to adjust a pressure applied to the filter plates, and in particular to the compression chamber, depending on the physicochemical characteristics of the sludge.

[0202] A dewatering system according to the invention may include a cake removal device. A cake removal device is preferably configured to automate the unloading of cakes. It allows the cakes to be moved out of the dewatering system, often using vibrations or mechanical movements. It is preferably configured to eject the dewatered sludge cakes from the compression chambers. A cake removal device may, for example, be selected from one or more of: mobile filter elements, filter elements vibrators, vibrators, plate beaters, scrapers, vibrating plates, or even canvas spreaders.

[0203] The dehydration system according to the present invention may further comprise a device 80 for degrading a flocculating agent present in the sludge B1-1.

[0204] The flocculating agent degradation device 80 may be positioned at the feed device connected to the filter plates or upstream of the feed device connected to the filter plates; preferably it is positioned at a sludge feed to the system.

[0205] Preferably, the degradation device 80 of the flocculating agent is selected from: a UV irradiation device, a heat treatment device, an oxidizing treatment device. The oxidizing treatment device can for example generate ozonation and / or an advanced oxidation treatment.

[0206] The degradation device 80 may advantageously be configured to implement degradation conditions depending on the flocculant present in the sludge B1-1. The degradation conditions may be preprogrammed in the degradation device 80 so that when a user indicates, via a dedicated interface, the type of flocculant present in the sludge B1-1, the degradation device 80 is configured to select a suitable degradation condition. Alternatively, the measuring device 10 may further be configured to determine the presence of a particular type of flocculant and to communicate the identified flocculant to the degradation device 80.

[0207] As illustrative examples, the degradation conditions may correspond to a specific degradation temperature range of a flocculant, a range of UV emission wavelengths, an oxidant concentration implemented for a predetermined duration.

[0208] The dewatering system according to the present invention may further comprise a device 90 for adding an organic deflocculating agent to the sludge B1-1 or to the sludge cake.

[0209] The device 90 for adding an organic deflocculating agent may be configured to add the organic deflocculating agent before a compression step, during the compression step, or after the compression step. Preferably, the device 90 for adding an organic deflocculating agent is configured to add the organic deflocculating agent during or after the compression step.

[0210] The addition device 90 may comprise a metering device configured to introduce a predetermined or predeterminable amount of organic deflocculating agent into the sludge. Preferably, the metering device is configured to introduce an amount of organic deflocculating agent depending on the sludge flow rate and / or physicochemical properties of the sludge.

[0211] The addition device 90 may comprise a metering device configured to introduce a predetermined quantity of organic deflocculating agent into compression chambers formed by the filter plates. Preferably, the metering device may be specifically designed to introduce an organic deflocculating agent in liquid or solid form. For example, the metering device may implement: a peristaltic pump, a diaphragm pump, a metering pump, a piston pump, a gear pump, a Venturi injector, and / or a volumetric distributor. In addition, it may be associated with an injection nozzle such as a high-pressure injection nozzle or a nozzle for injecting a viscous form of the deflocculating agent to improve its diffusion within the mud cake. The organic deflocculating agent may also be introduced in solid form.For example, it may take the form of a powder, a capsule designed to rupture at a specific pressure, or a solid designed to disperse at least partially in the presence of water under the effect of pressure. For example, the dosing device may then implement: a volumetric solid feeder, a hopper, an endless screw, a rotating disc feeder, and / or a pneumatic distributor.

[0212] Advantageously, the addition device 90 comprises a dosing device configured to introduce a predetermined or predeterminable quantity of organic deflocculation agent into the mud cake. Preferably, the dosing device may implement: a spraying device, an injection nozzle, and / or a coating device.

[0213] Finally, a dewatering system according to the present invention may further comprise sensors for real-time monitoring of physicochemical characteristics of the sludge, pressure at the filter plates and physicochemical characteristics of the filtrate. Preferably, the sensors are connected in communication with a control unit of the constituent and automated elements of the system.

[0214] EXAMPLES

[0215] The invention is described in more detail below with reference to the following experimental examples. These examples are provided for illustrative purposes only and are not intended to be limiting unless otherwise indicated. Thus, the invention should in no way be construed as being limited to the following illustrative examples, but rather should be construed as encompassing all variations that become apparent as a result of the teaching provided herein.

[0216] Below we describe various tests carried out in the context of sludge treatments using a mechanical dehydration device in order to obtain sludge cakes which were used in a construction binder for the formation of a construction material, in this case a mortar whose cone spreading and mechanical resistance characteristics were measured.

[0217] Mud characterization

[0218] The type of sludge was analyzed by X-ray fluorescence according to the indications of standards NF EN 196-2 and NF EN 15309.

[0219] X-ray fluorescence tests on compressed beads or pellets are carried out in order to define the chemical composition of a sample, i.e. to quantify its major elements and possibly its trace elements. The analyzed samples have a particle size < 1 mm and are dried. The dried clay matrix is ​​packaged in the form of a bead or pellet.

[0220] The results obtained in percentage of oxides concern the major elements: Al, Ca, Cr, Fe, K, Mg, Na, P, Pb, Si, Ti, V and W are presented in Table 1 below. The loss on ignition (LOI) measured during the preparation of the samples makes it possible to predict the potential presence of organic matter, carbonates and / or sulfates.

[0221] [TABLE 1] Preparation of sludge

[0222] In order to illustrate the effect of different parameters on the formation of sludge cake and their influence on the mechanical properties of construction binders, two types of sludge are mainly used. A first type of "raw" sludge, noted BB, has not undergone any treatment step before passing through a dewatering device. mechanical and a second type of sludge, noted BC was pretreated by passing through a clarifier. The different types of sludge were then passed through a filter press, dried and then ground so as to set the particle size targets at D10: 3 pm, D50: 22 pm and D90: 100 pm. Humidity is measured as described in ISO 12570:2000.

[0223] Methodology for measuring the mechanical properties of construction binders.

[0224] The construction binders described in Table 3 above are prepared in test specimens and their mechanical strength is measured at different times.

[0225] The mechanical resistance of a test piece is its compressive strength, such compression being measured according to standard NF EN 771-3+A1 / CN and is expressed in Mega Pascal (MPa).

[0226] Methodology for measuring the consistency of construction binders:

[0227] Once the constituents have been mixed, the consistency, hereinafter called rheology, of the freshly mixed mortars is determined by measuring the cone spreading value as described in standard NF EN 1015-3.

[0228] Preparation of a construction binder and then a construction binder material

[0229] Once ground, the mud cake is combined in a mixer with blast furnace slag, an activator (e.g. clinker), a deflocculant and water. The mixtures are made such that the construction binder comprises between 30% and 60% by weight of raw clay matrix; between 15% and 30% by weight of blast furnace slag; between 30% and 50% by weight of an activating composition and between 0.5% and 1.5% by weight of a deflocculant.

[0230] The whole is mixed at low speed, that is to say approximately sixty revolutions per minute for thirty seconds. Then, sand is added and the whole is mixed at higher speed, that is to say approximately 120 revolutions per minute for one minute. The mass ratio of water to dry matter of the construction binder is adjusted to a value between 0.4 and 0.6. In a particular example, the construction material, a mortar, comprises 25% by weight of binder, 75% by weight of sand; this mixture is supplemented with water for a mass ratio of water to dry matter of the binder adjusted to a value of 0.4.

[0231] The mortar based on the construction binder thus produced is then poured into a mold and left to mature at room temperature, i.e., approximately 20 degrees Celsius, for twenty-eight days in water. Alternatively, the mortar may be poured into a mold and then left to mature for less than twenty-four hours in a curing stage, at room temperature, i.e., approximately 25 degrees Celsius, or preferably under heat treatment. During this curing stage, the mold may be made airtight or the top layer of the construction material may be covered with a curing agent to limit / prevent evaporation.

[0232] Table 2 below shows different formulations of construction binders that have or have not undergone treatment with a clarifier in which a flocculant has been added at a rate of 3 g per litre of sludge. Table 2 also includes a reference noted RefO which corresponds to Portland cement type CEM1. [Table 2]

[0233] Methodology for measuring the mechanical properties of construction binders:

[0234] Once maturation is complete, the mechanical resistance is measured. The mechanical resistance of a construction binder is its compressive strength, such compression being measured according to standard NF EN 196-1, for a prism with a side of 40 millimeters and a length of 160 millimeters and is expressed in Mega Pascal (MPa).

[0235] Table 3 below shows the results of mechanical resistance at 1 day and 28 days as well as rheology (cone spreading). [Table 3]

[0236] As shown in Table 3, the construction binders derived from the mud cakes according to the invention have compressive strengths equivalent to or even superior to the compressive strengths obtained with concrete formed with CEM1 cement. In addition, the construction binders derived from the mud cakes according to the invention have compressive strengths at 1 day greater than 8 MPa, which ensures sufficient setting to facilitate formwork removal without compromising the mechanical strength at 28 days. Passing the sludge through a clarifier further improves the compressive strengths while maintaining optimal rheology (greater than 180 mm). In addition, the workability, characterized by the rheology, of the construction binders derived from the mud cakes according to the invention is improved compared to that of the reference CEM1 binder without the need to add water, which would lead to a decrease in mechanical strength.Finally, the present invention allows the use of mud cake whose clay matrix is ​​present at a significant content (more than 30% by weight) and still allows mechanical performance (compressive strengths at 1 and 28 days, rheology) to be maintained which are equivalent to or even superior to Portland cement, thus ensuring the recovery of clay-silt mud and the production of construction materials with a lower ecological footprint.

[0237] The invention may be the subject of numerous variants and applications other than those described above. In particular, unless otherwise indicated, the different structural and functional characteristics of each of the implementations described above should not be considered as combined and / or closely and / or inextricably linked to each other, but on the contrary as simple juxtapositions. Furthermore, the structural and / or functional characteristics of the different embodiments described above may be the subject in whole or in part of any different juxtaposition or any different combination.

Claims

Claims 1. A method of manufacturing (100) a construction material from a quarry effluent, said method comprising: a step of flocculating (110) a quarry effluent comprising a clay-silt matrix using a flocculating agent to form a clay-silt sludge; a step of collecting (120) the clay-silt sludge comprising the clay-silt matrix, said clay-silt sludge having a dry matter content greater than or equal to 20%; a step of forming (190) a construction material, preferably a construction binder, comprising adding the clay-silt matrix of the clay-silt sludge to a mixture for construction material; said method comprising a step of degradation (150) of the flocculating agent and / or a step of addition (180) of an organic deflocculating agent to the clay-silt matrix.

2. Manufacturing method (100) according to claim 1, characterized in that the quarry effluent has the following characteristics: an organic matter concentration of less than 1% relative to the dry matter weight of the clay-silt mud; a heavy metal concentration of less than 0.1% relative to the dry matter weight of the clay-silt mud; a radioactive element concentration of less than 0.05% relative to the dry matter weight of the clay-silt mud; a dry matter content greater than or equal to 20%.

3. Manufacturing method (100) according to one of claims 1 or 2, characterized in that the flocculating agent is an organic flocculating agent, preferably the organic flocculating agent is selected from: polyacrylamides; polysaccharides; polyamines such as polyDADMAC; or else polyethyleneimine.

4. Manufacturing method (100) according to claim 3, characterized in that when it comprises a step of degradation (150) of the organic flocculating agent, said degradation step (150) is selected from: UV irradiation, heat treatment, and / or oxidizing treatment.

5. Manufacturing method (100) according to claim 4, characterized in that the step of degradation (150) of the organic flocculating agent comprises UV irradiation or advanced oxidation during the step of collection (120) of the clayey-silty mud.

6. Manufacturing method (100) according to any one of claims 3 to 5, characterized in that when it comprises a step of degradation (150) of the organic flocculating agent, said degradation step (150) comprises a heat treatment at a temperature below 400°C, the degradation step (150) preferably being carried out before a step of grinding (170) of the clayey-silty mud.

7. Manufacturing method (100) according to any one of claims 1 to 6, wherein said method comprises a step of adding (180) an organic deflocculating agent to the clayey-silty mud and characterized in that the organic deflocculating agent is selected from: - a non-ionic surfactant such as a polyoxyethylene ether; - an anionic agent such as an anionic agent selected from: alkylaryl sulfonates, amino alcohols, carbonates, silicates, fatty acids, humates (eg sodium humates), carboxylic acids, lignosulfonates (eg sodium lignosulfonates), polyacrylates, phosphates or polyphosphates such as sodium hexametaphosphate, sodium tripolyphosphate, sodium orthophosphate, carboxymethylcelluloses, polyphosphonates, polycarboxylates and mixtures thereof; - a polyacrylate such as a polyacrylate selected from sodium polyacrylate or ammonium polyacrylate; - an amine such as an amine selected from: 2-amino-2-methyl-1-propanol; mono-, di- or triethanolamine; isopropanolamines (1-Amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines; or - their mixtures.

8. Manufacturing method (100) according to any one of claims 1 to 7, characterized in that the clayey-silty mud collected in the collection step (120) has a water content of at least 50%.

9. Manufacturing method (100) according to any one of claims 1 to 8, characterized in that the collected clay-silt mud comprises at least 1% by weight of clay-silt matrix relative to the dry weight of the clay-silt mud, said clayey-silty matrix comprising mineral clays selected from the following clays: Illite, Kaolinite, Smectite, Vermiculite, Chlorite, Montmorillonites, Muscovite, Halloysite, Sepiolite, Interstratified, Pyrophyllite, talcs, Serpentines, Palygorskite and combinations thereof.

10. A method of treating (200) a clayey-silty mud so as to form a mud cake suitable for forming a construction material, said method comprising: A step of collecting (230) a clayey-silty mud comprising a clayey-silty matrix and a flocculating agent; A step of mechanical dehydration (240) of the clayey-silty mud, so as to obtain a mud cake comprising the clayey-silty matrix; said method comprising a step of degradation (250) of the flocculating agent and / or a step of addition (280) of an organic deflocculating agent to the clayey-silty matrix of the mud cake.

11. Method for treating (200) a clayey-silty sludge according to claim 10, characterized in that the mechanical dehydration step (240) comprises the use of a filter press, preferably selected from: screw filter press; belt filter press; plate filter press; finned filter press; vertical filter press.

12. Mud cake obtainable by the method of treating (200) a clayey mud according to one of claims 10 or 11, the mud cake comprising a water content of at most 40%, at least one clay-silt matrix, a flocculating agent residue and / or an organic deflocculating agent.

13. Mud cake according to claim 12, the mud cake comprising from 30% to 70%, preferably from 40% to 60% by weight of SiO2 and / or CaO.

14. Method for manufacturing (400) a construction binder, said method comprising: a step of collecting (410) a clay-silt sludge comprising a clay-silt matrix and optionally a flocculating agent, said sludge having a D50 less than or equal to 200 pm and comprising at least 5% by weight of clay-silt matrix relative to the dry weight of said sludge; a step of mechanically dehydrating (420) the clayey-silty mud so as to form a mud cake, said mud cake having a water content of less than 40%; a step of drying (430) the mud cake so as to achieve a water content of less than 20%; a step of grinding (440) the mud cake so as to obtain a ground mud cake which has a D50 of less than 50 pm and a D90 of less than or equal to 100 pm; and a step of forming (470) a construction binder from the ground mud cake comprising a mixture of the ground mud cake with an activating composition; said method further comprising a step of degrading (450) the flocculating agent when said mud comprises the flocculating agent and / or a step of adding (460) an organic deflocculating agent to the clayey-silty matrix.

15. Method for manufacturing (400) a construction binder according to claim 14, characterized in that the drying step (430) and the grinding step (440) are carried out concomitantly.

16. Method of manufacturing (400) a construction binder according to one of claims 14 or 15, characterized in that the step of drying (430) the mud cake is carried out by using a device selected from: oven, solar dryer, laminar dryer, dryer, natural drying for example in ventilated sheds.

17. Method of manufacturing (400) a construction binder according to any one of claims 14 to 16, characterized in that the step of grinding (440) the mud cake is carried out by using a device selected from: ball mill, orbital mill, hammer mill; grinding mill; pendulum mill; attrition mill; vertical mill; deagglomerator.

18. Method of manufacturing (400) a construction binder according to any one of claims 14 to 17, characterized in that the step of forming (470) a construction binder is carried out by using a device selected from: powder mixer; horizontal mixer.

19. A method of manufacturing (400) a construction binder according to any one of claims 14 to 18, characterized in that the step of forming (470) a construction binder comprises an addition of a precursor, said precursor preferably being selected from: blast furnace slag; calcined clay; flash calcined clay; fly ash, silica fumes; rice husk fumes; glass powder.

20. Manufacturing method (400) according to any one of claims 14 to 19, characterized in that when the method comprises a step of degradation (450) of the flocculating agent, the flocculating agent is an organic flocculating agent and said degradation step (450) comprises UV irradiation during the drying step (430) and / or during the grinding step (440).

21. Method of manufacturing (400) a construction binder according to any one of claims 14 to 20, characterized in that the activation composition is an alkaline activation composition, preferably it is selected from: clinker; EN 197-1 cements; sulfoaluminous cements; supersulfated cements; lime; silicates; carbonates or combinations thereof.

22. System for forming (1) a construction binder from a clay-silt mud comprising a clay-silt matrix, said system comprising: a collection device (20) comprising a clay-silt mud (B1) comprising a clay-silt matrix (B1-1) and optionally a flocculating agent, said mud having a D50 less than or equal to 200 pm and comprising at least 5% by weight of clay-silt matrix (B1-1) relative to the dry weight of said mud; a mechanical dewatering device (30) configured to generate a mud cake (B2) comprising the clay-silt matrix (B1-1), said mud cake having a water content of less than 40%; a dryer (40) of the mud cake (B2), configured to bring the mud cake (B2) to a water content of less than 20%;a grinder (60) configured to grind the mud cake (B2) comprising the clay-silt matrix (B1-1) so as to form a ground material having a D50 of less than 50 pm and a D90 of less than or equal to 100 pm; a mixer (70) configured to form a construction binder (L1) from the mud cake ground material (B2) and an activating composition; the system further comprising a device (80) for degrading the flocculating agent when said sludge comprises the flocculating agent and / or a device (90) for adding an organic deflocculating agent to the clay-silt matrix (B1-1).

23. System for forming (1) a construction binder according to claim 22, wherein the mill (60) comprises drying means (50) configured to dry the mud cake (B2).

24. System for forming (1) a construction binder according to one of claims 22 or 23, said system comprising a measuring device (10) positioned at the inlet of the collection device (20), the measuring device (10) being configured to determine values of physicochemical characteristics of the clayey-silty mud (B1).

25. System for forming (1) a construction binder according to claim 24, said system comprising a processor (12) coupled to the measuring device (10), the processor (12) being configured to, depending on the values of physicochemical characteristics, determine a quantity (Q1 DI) of an organic deflocculating agent (D1) to be added to the mud cake (B2) and / or a quantity (Q1 F i) a flocculating agent (F1), preferably an organic flocculating agent, to be added to the clayey-silty mud (B1).

26. System for forming (1) a construction binder according to any one of claims 22 to 25, wherein the collection device (20) comprises a clarifier arranged to allow separation between a clarified phase and a concentrated phase of the clayey-silty mud, said clarifier being arranged to bring the concentrated phase of the clayey-silty mud into the mechanical dewatering device (30).

27. System for forming (1) a construction binder according to any one of claims 24 to 26, said physicochemical characteristic values comprising X-ray fluorescence values and / or particle size values.

28. System for mechanical dewatering of a sludge, preferably a clayey-silty sludge, so as to form a sludge cake suitable for the formation of a construction material, said system comprising: - a support structure designed to support a plurality of movable filter plates; - a plurality of filter plates mounted on the support structure, each having a power supply and being movable between an open configuration and a closed configuration; - a feeding device connected to the filter plates to distribute the sludge; - a guide device configured to control the movement of the set of filter plates; and - a compression device configured to at least partially dehydrate the sludge and form a sludge cake; said system further comprising a device (80) for degrading a flocculating agent present in the sludge (B1-1) and a device (90) for adding an organic deflocculating agent to the sludge (B1-1) or to the sludge cake.

29. System according to claim 28, characterized in that when it comprises a degradation device (80) for the flocculating agent, the flocculating agent is an organic flocculating agent and the degradation device is positioned at the level of the supply device connected to the filter plates or upstream of the supply device connected to the filter plates, said degradation device (80) for the flocculating agent being selected from: a UV irradiation device, a heat treatment device, an oxidizing treatment device.

30. System according to one of claims 28 or 29, characterized in that the device for adding a deflocculant is configured to add the organic deflocculating agent before a compression step, during the compression step or after the compression step.

31. System according to any one of claims 28 to 30, characterized in that the feed device communicates fluidically with a collection device arranged to conduct the sludge to said feed device and in that the sludge is a clayey-silty sludge comprising a clayey-silty matrix and a flocculating agent, said sludge having a D50 less than or equal to 200 pm and comprising at least 5% by weight of clayey-silty matrix relative to the dry weight of said sludge.

32. System according to any one of claims 28 to 31, characterized in that the feed device comprises a clarifier arranged to allow separation between a clarified phase and a concentrated phase of the clayey-silty mud, said clarifier being arranged to bring the concentrated phase of the clayey-silty mud to the filter plates.