METHOD FOR MANUFACTURED A CONSTRUCTION MATERIAL FROM CLAY-SILTY MUD, METHOD FOR TREATMENT OF SAID MUD AND ASSOCIATED FORMATION SYSTEM

Abstract

The invention relates to a process for manufacturing (100) a construction material from quarry effluent, comprising: - a flocculation step (110) to form a clay-silt sludge; - a collection step (120) of the clay-silt sludge having a dry matter content greater than or equal to 20%; - a formation step (190) of a construction material, comprising adding it to a construction material mix; - a degradation step (150) of the flocculating agent and / or an addition step (180) of an organic deflocculating agent. The invention further relates to a process for treating clay-silt sludge to form a sludge cake suitable for the formation of a construction material. The invention also relates to a manufacturing process (400) for a construction binder, a system for forming (1) a construction binder, and an associated mechanical dewatering system for a sludge. Figure to be published with the abbreviation: Figure 5

Description

Title of the invention: 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 more than 4 billion tons produced each year worldwide. 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 of the world, there is a constant demand for the supply of construction binders, more specifically 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 (WO2020178538), prefabrication elements (WO2020178538), low-carbon construction materials with summer comfort (WO2022157209Al), or even compressed concrete blocks (WO2023001996A1). 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 stages of crushing clay blocks. This crushing stage is a stage which induces 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 construction 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] Different solutions have been proposed for this treatment, a first solution consists of treating the sludge with quicklime. A second solution described in document no. FR2937266 - consists of treating the sludge with a sulfo-aluminous binder and with a source of sulfate and a catalyst for the hydration reactions of the sulfo-aluminous binder.

[0008] However, all the solutions proposed for the treatment of sludge by solidification thereof 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 flocculation of a quarry effluent comprising a clay-silt matrix using a flocculating agent to form a clay-silt mud; - a step of collecting the clayey-silty mud comprising the clayey-silty matrix, said clayey-silty mud having a dry matter content greater than or equal to 20%; - a step of forming a construction material, preferably a construction binder, comprising the addition of the clay-silt matrix of the clay-silt mud 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 the consumption of network water in quarries. Furthermore, this can make it possible to reduce the impact of a quarry on local flora and fauna by reducing its footprint and providing the possibility of using unconsumed water 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 iso mechanical performances.

[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% compared to the dry matter weight of clayey-silty mud; - a concentration of heavy metals less than 0.1% relative to the weight of dry matter in the clayey-silty mud; - a concentration of radioactive elements less than 0.05% relative to the weight of dry matter in 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;

[0015] - an anionic agent such as an anionic agent selected from: sulfonates alkylaryl, 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-l-propano 1; mono-, di- or triethanolamine; isopropanolamines (l-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.

[0016] According to a second object, the invention relates to a method for treating a clayey-silty mud so as to form a mud cake suitable for the formation of a construction material, said method comprising: - A stage 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 addition of an organic deflocculating agent to the clay-silt matrix of the mud cake.

[0017] According to other optional characteristics of the method, the latter may optionally include one or more of the following characteristics, alone or in combination: - the mechanical dehydration step comprises the use of a filter press, preferably selected from: screw filter press; belt filter press; plate filter press; fin filter press; vertical filter press.

[0018] According to a third subject, the invention relates to a mud cake capable of being obtained 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.

[0019] 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 product of mud cake which has a D50 less than 50 pm and a D90 less than 100 pm; - a step of forming a construction binder comprising the addition of an activation composition to the ground mud cake.

[0020] According to a fifth object, the invention relates to a method of manufacturing a construction binder, said method comprising: - a step of collecting a clayey-silty sludge comprising a clayey-silty 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 clayey-silty matrix relative to the dry weight of said sludge; - a step of mechanical dehydration of 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; and - a step of forming a construction binder from the mud cake grind comprising mixing the mud cake grind with an activating composition; said method further comprising a step of degradation of the flocculating agent when said sludge comprises the flocculating agent and / or a step of adding an organic deflocculating agent to the clay-silt matrix.

[0021] 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 mud cake drying step is carried out using a device selected from: oven, solar dryer, laminar dryer, dryer, natural drying for example in ventilated sheds. - the mud cake grinding step 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 process comprises a step of degradation of 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; EN 197-1 cements; sulfo-aluminous cements; supersulfated cements; lime; silicates; carbonates or their combinations.

[0022] According to a sixth object, the invention relates to a system for forming a construction binder from a clayey-silty mud comprising a clayey-silty matrix, said system comprising: - a collection device adapted to receive a clayey-silty sludge comprising a clayey-silty matrix 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 relative to the dry weight of said mud; - a mechanical dehydration device configured to generate a mud cake (B2) comprising the clay-silt matrix, said mud cake having a water content of less than 40%; - a mud cake dryer, configured to bring the mud cake to a water content of less than 20%; - a grinder 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; - a mixer configured to form a construction binder from the mud cake grind and an activating composition; the system further comprising a device for degrading the flocculating agent when said sludge comprises the flocculating agent and / or a device for adding an organic deflocculating agent to the clay-silt matrix.

[0023] According to other optional features of the system, the latter 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, based on the physicochemical characteristic values, 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.

[0024] 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 a device for adding an organic deflocculating agent to the sludge or to the sludge cake.

[0025] 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 device for degrading the flocculating agent 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. Description of the embodiments

[0026] 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.

[0027] [Fig-1] [Fig. 1] represents an embodiment of a method for manufacturing a construction material from a quarry effluent.

[0028] [Fig.2] [Fig.2] represents an embodiment of a method for processing a clayey-silty mud so as to form a mud cake suitable for the formation of a construction material.

[0029] [Fig.3] [Fig.3] represents an embodiment of a first method of manufacturing of a construction binder.

[0030] [Fig.4] [Fig.4] represents an embodiment of a second method of manufacturing a construction binder.

[0031] [Fig.5] [Fig.5] represents an embodiment of a system for forming a construction binder.

[0032] The figures do not necessarily respect the scales, in particular in thickness, and this is for illustration purposes.

[0033] Aspects of the present invention are described with reference to flowcharts and / or functional diagrams of methods, systems according to embodiments of the invention.

[0034] 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.

[0035] Below, we describe a summary of the invention and the associated vocabulary, before presenting the disadvantages of the prior art, and then finally showing in more detail how the invention overcomes them.

[0036] 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.

[0037] 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 of 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, that is to say one or more rock materials based on phyllosilicates, hydrated silicates or aluminosilicates of 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 clay-silt matrix may thus comprise a mixture of such rock materials which may for example comprise kaolinite, serpentine, pyrophyllite, talc, smectite, vermiculite, illite, glauconite, mica, chlorite, palygorskite, sepiolite, interstratified materials or their mixtures (Alain Meunier. Clays, 2005).

[0038] 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, without this being limiting, from the treatment of quarry effluents.

[0039] By "concrete" is meant a mixture of aggregates, possibly sand, with a construction binder (for example 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.

[0040] The expression "raw mineral fraction" or "mineral fraction" corresponds, within the meaning of the invention, to a mineral fraction which 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 which has not undergone a temperature rise 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 rise 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.

[0041] 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.

[0042] The term “binder” or “construction binder” within the meaning of the invention can be understood as a formulation making it possible to ensure the agglomeration of materials between them, in particular during the setting and then hardening of a construction material. Thus, it allows in particular to ensure 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 on contact with water.

[0043] 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 (CaSO4 • 2 H2O) or various traces of metals.

[0044] 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%.

[0045] The term "D50" corresponds to the median diameter for which 50% (by volume or mass, preferably by volume) of the grains, particles, aggregates or sediments have a size less 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 greater than 5.8 mm and 50% are less than 5.8 mm. The D50 is generally used to represent the particle size of a group of particles. The D50 can 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).

[0046] 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.

[0047] The construction industry must evolve to optimize its productivity while meeting 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 compared to existing methods.

[0048] To this end, the inventor selected a currently neglected source of raw material, namely quarry effluents, in particular quarry wash water. In particular, the inventor identified wash waters that are particularly suitable for use in the manufacture of construction materials.

[0049] 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 manufacture of construction materials with advantageous mechanical properties.

[0050] Thus, according to a first aspect, the present invention relates to a method 100 for manufacturing a construction material from a quarry effluent.

[0051] As illustrated in [Fig.l], 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 collection of the clayey-silty mud and a step 190 of formation of a construction material from the clayey-silty mud.

[0052] As mentioned, a quarry effluent, such as quarry wash water, advantageously comprises a clayey-silty matrix.

[0053] Quarry effluent, in particular 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.

[0054] 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.

[0055] 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.

[0056] 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 clayey-silty matrix. Thus, the dry matter of the wash water may comprise at least 50% by weight of a clayey-silty matrix fraction, preferably it comprises at least 60% by weight of a clayey-silty 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.

[0057] 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.

[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 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 μm.

[0059] 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.

[0060] Furthermore, the inventor has determined other selection criteria which can influence the mechanical resistance of construction materials manufactured from quarry effluent.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] A method according to the present invention may comprise a flocculation step 110, 220 of a quarry effluent comprising a clay-silt matrix.

[0065] Advantageously, before the flocculation step, the quarry effluent will have undergone a step of mechanical separation of a fraction composed of particles whose diameter is greater than 67 μm. 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 the use of a cyclone.

[0066] The flocculation step 110, 220 may include the use of a lagoon system or a decanter.

[0067] The flocculation step 110, 220 may be carried out using a flocculating agent to form a clayey-silty sludge. Alternatively, the flocculation step may comprise the implementation of electro-flocculation 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.

[0068] 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%, more preferably at most 70%, more preferably at most 65% and even more preferably at most 60%. The water content is here calculated by dividing the mass of water by the total mass of the sludge.

[0069] Advantageously, the flocculation step 110, 220 comprises a double flocculation.

[0070] A method according to the present invention may comprise a step 120, 230 of collecting the silty-clayey mud comprising the clayey-silty matrix.

[0071] 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).

[0072] 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 content of water 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%.

[0073] 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 mud.

[0074] 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.

[0075] Furthermore, the clayey-silty mud collected within the framework 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.

[0076] The collected clayey-silty sludge will generally include a flocculant. Indeed, the use of a flocculant makes it possible to significantly accelerate the flocculation process and the recovery of the mineral fraction of interest, namely the clayey-silty matrix. Advantageously, the clayey-silty sludge will include an organic flocculant. Indeed, the mechanical properties of the construction material are improved with organic flocculants as opposed to inorganic flocculants.

[0077] For example, the organic flocculant is selected from: polyacrylamides; polysaccharides; polyamines such as polyDADMAC; or even polyethyleneimine.

[0078] Alternatively, or in addition, the clayey-silty mud may comprise 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.

[0079] A method according to the present invention may comprise a step 190, 290 of forming a construction material.

[0080] The construction material formed at this stage may be selected from: a construction binder, concrete, coating, mortar, tile adhesive and any other secondary product containing cement.

[0081] Preferably, the construction material formed in this step is a construction binder.

[0082] The step 190, 290 of forming a construction material comprises adding the clay-silt matrix to a mixture for construction material.

[0083] 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 else use the clay-silt matrix after transformation of the clay-silt mud into cake.

[0084] 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.

[0085] In particular, when the 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 coating, concrete, mortar, tile adhesive and any other secondary product containing cement.

[0086] 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% and then a grinding step. The ground material is then used in combination with, in particular, an activation composition to form a construction binder.

[0087] The activation composition is preferably an alkaline activation composition. The activation composition may be selected from: clinker; EN197-1 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.

[0088] The step 190 of forming a construction binder may comprise an addition of a precursor. The precursor may comprise a source of carbonates in combination or not with silicates. In particular, the precursor may comprise sodium or potassium carbonate. The sodium or potassium carbonate may further be mixed with sodium or potassium silicate.

[0089] 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.

[0090] As illustrative examples, the source of carbonate may be limestone, dolomite, chalk, aragonite or even vaterite.

[0091] Alternatively, the limestone may also be magnesium carbonate and / or a mixture of magnesium carbonate and dolomite.

[0092] Preferably, the limestone is a natural limestone mainly consisting of calcium carbonate with different polymorphs, such as calcite and / or aragonite, but also containing a certain amount of magnesium carbonate and / or dolomite. The limestone may also be a clayey limestone or a natural marl.

[0093] In addition, the precursor may comprise a siliceous filler or “quartz flour”. For example, the siliceous filler may comprise corpuscular silica and kaolinite.

[0094] The precursor may also comprise calcined schists, diatomite, phonolite, paper mill sludge ash, or crushed glass.

[0095] Alternatively or in addition, the precursor may further be selected from: blast furnace slag; calcined clay; flash calcined clay; fly ash, silica fumes; rice husk fumes; glass powder; and combinations thereof, Pozzolans; Siliceous ash; Silica fumes; calcium ash; schists; limestones.

[0096] The step 190 of forming a construction material may include adding fillers such as sand, aggregates or others.

[0097] In the wake of this first aspect, the inventor has 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 [Fig.2]. - A mud cake suitable 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 [Fig.3].

[0098] Furthermore, following this first advance, the inventor has developed numerous optimizations which are described below in connection with one or more of the aspects mentioned above.

[0099] 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.

[0100] As illustrated in [Fig.l], a manufacturing method 100 according to the present invention may comprise a step 105 of determining the treatment conditions of the clayey-silty mud.

[0101] The determination step 105 may comprise a measurement of the physicochemical properties of a quarry effluent and / or of a clayey-silty mud comprising a clayey-silty matrix.

[0102] 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.

[0103] 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.

[0104] Preferably, a manufacturing method 100 according to the invention may comprise a step of mechanical dehydration 140 of the clayey-silty mud.

[0105] This step can in particular be used to form a mud cake.

[0106] Such a mechanical dehydration step 140 is preferably implemented so as to obtain a mud cake comprising the clay-silt matrix.

[0107] 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%.

[0108] 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.

[0109] The dehydration step 140 may comprise the use of a means selected from: filter press or screw press. Preferably, the dehydration step 140 may involve 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.

[0110] A manufacturing method 100 according to the present invention may comprise a step 150 of degradation of the organic flocculant.

[0111] The degradation step 150 of the organic flocculant may comprise: UV irradiation, heat treatment, oxidizing treatment or combinations thereof.

[0112] 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 occur between the collection of the sludge and the use of the sludge in the mixture to form the construction material.

[0113] If the clayey-silty sludge is used after a mechanical dehydration step then, preferably, the degradation of the flocculant occurs after the mechanical dehydration step, for example at the time of a step of drying the silty-clayey mineral fraction, before a step of grinding the clayey-silty mineral fraction or during a step of grinding the clayey-silty sludge cake.

[0114] 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.

[0115] 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.

[0116] 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. However, a heat treatment is 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.

[0117] 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.

[0118] 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%.

[0119] The drying step 160 of the mud cake can be carried out by using a device selected from: oven, solar dryer, laminar dryer, dryer, natural drying for example in ventilated sheds. The drying step 160 can in particular comprise several steps. For example, while the mud cake has a water content of the order of 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%.

[0120] 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%.

[0121] 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%.

[0122] In certain embodiments, the drying step 160 and the grinding step 170 which are described below are concomitant or overlap at least partially 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%.

[0123] Indeed, all or part of the drying step 160 can precede the grinding step 170.

[0124] Also, all or part of the drying step 160 can follow the grinding step 170.

[0125] A manufacturing method 100 according to the present invention may comprise a step 170 grinding of the clayey-silty matrix and in particular of the clayey-silty mud cake.

[0126] 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.

[0127] This step can make it possible to obtain a ground clay-silt matrix (e.g. mud cake ground) which has a D90 less than or equal to 100 pm. Preferably, it makes it possible to obtain a ground clay-silt matrix which has a D90 less than or equal to 90 pm, more preferably a D90 less than or equal to 80 pm, even more preferably, a D90 less than or equal to 70 pm.

[0128] In particular, this step is implemented so as to obtain a ground clay-silt matrix 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 ground clay-silt matrix 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.

[0129] 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.

[0130] 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.

[0131] For example, the step 180 of adding a deflocculant comprises the addition of an organic deflocculant to the collected clayey-silty mud.

[0132] For example, the step 180 of adding a deflocculant comprises the addition of an organic deflocculant into the clayey-silty mud cake.

[0133] 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.

[0134] The step 180 of adding a deflocculant can be combined with the step 120 of collecting the clayey-silty mud, the step 140 of mechanical dehydration, the step 160 of drying, the step 170 of grinding the mud cake, and / or the step 190 of forming the construction material.

[0135] The organic deflocculating agent may be selected from a non-ionic surfactant, an anionic agent, a polyacrylate, an amine or mixtures thereof.

[0136] 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.

[0137] 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.

[0138] Also, the organic deflocculating agent may be a polyacrylate selected from: sodium polyacrylate or ammonium polyacrylate or mixtures thereof.

[0139] Finally, the organic deflocculating agent may be an amine selected from: 2-amino-2-methyl-l-propanol; mono-, di- or triethanolamine; isopropanolamines (l-Amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines; and mixtures thereof.

[0140] Preferably, the organic deflocculating agent is selected from: a lignosulphonate (eg sodium lignosulphonate), a polyacrylate, a humate and mixtures thereof.

[0141] Preferably, the organic deflocculating agent is selected from: a lignosulphonate (eg sodium lignosulphonate), a polyacrylate, a humate, a polycarboxylate such as an ether polycarboxylate, and mixtures thereof.

[0142] More preferably, the organic deflocculating agent comprises a humate, a lignosulphonate and / or a polyacrylate.

[0143] 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.

[0144] The organic deflocculating agent is preferably in the form of a salt.

[0145] 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.

[0146] The organic deflocculating agents that can be used according to the present invention may take a solid form or a liquid form.

[0147] Thus, according to one aspect, the invention relates to a method 200 for treating a clayey-silty mud. This treatment method is in particular intended to form a mud cake which is suitable for the formation of a construction material, preferably a construction binder.

[0148] 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 dehydration 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] A clay-silt mud cake according to the present invention will comprise a clay-silt matrix.

[0153] 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.

[0154] Furthermore, advantageously, a clayey silty mud cake according to the present invention comprises an organic deflocculating agent.

[0155] 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%.

[0156] 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; more preferably, a thickness of at most 30 mm; and even more preferably, a thickness of at most 20 mm.

[0157] 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.

[0158] 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.

[0159] 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 of 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 weight of dry matter of the clayey-silty mud; - a dry matter content greater than or equal to 20%.

[0160] 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.

[0161] As illustrated in [Fig.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 matrix clayey-silty; a step 340 of grinding the mud cake comprising the clayey-silty matrix; a step 360 of forming a construction binder comprising the addition of an activation composition to the ground mud cake comprising the clayey-silty matrix.

[0162] 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.

[0163] 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.

[0164] 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.

[0165] Advantageously, the method will comprise drying and grinding steps making it possible 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.

[0166] 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.

[0167] According to another aspect, the invention relates to a system 1 for forming a construction binder from a clayey-silty mud 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.

[0168] The collection device 20 is adapted to receive 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.

[0169] 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.

[0170] 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 clayey-silty mud B1. Indeed, the characterization of the clayey-silty mud may make it possible to implement particular treatment steps to optimize the formation of a construction binder. For this, the determined physicochemical characteristics may correspond to X-ray fluorescence values ​​and / or particle size values.

[0171] Optionally, the clayey-silty mud may comprise a flocculating agent.

[0172] Thus, the collection device 20 can be adapted to implement a flocculation step in connection with the methods according to the invention.

[0173] 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%.

[0174] For this, the mechanical dehydration device 30 can communicate fluidically with the collection device 20 via a second conveying conduit. The mechanical dehydration device 30 can be arranged to allow the recovery of a filtrate corresponding to an aqueous phase resulting from the mechanical dehydration of the clayey-silty mud.

[0175] 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%.

[0176] 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. The grinder 60 can be connected to the dryer 40 via the first conveying means such as belt conveyors or chain conveyors. In particular, the grinder 60 can be adapted to implement a grinding step described in connection with the methods according to the invention.

[0177] In an optional embodiment of the formation 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%.

[0178] 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.

[0179] 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 a device 90 for adding an organic deflocculating agent to the clay-silt matrix B1-1.

[0180] The flocculating agent degradation device 80 can be positioned at the outlet of the collection device 20.

[0181] 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.

[0182] In addition, it is provided that the flocculating agent can be added directly into the collection device 20 even when the clayey-silty sludge conveyed is devoid of it in order to facilitate the recovery of the entire clayey-silty 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 clayey-silty sludge B1, a quantity Q1Fide 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.

[0183] 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 may be connected to the mixer 70 and further comprise a reversible opening means 11-2 configured to add to the ground mud cake B2 and to the activation composition, a quantity Q1Di of deflocculant to form a construction binder LL. In particular, the addition device 90 may be adapted to implement a step of adding a deflocculating agent described in connection with the methods according to the invention.

[0184] 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 values ​​of physicochemical characteristics, determine a quantity Q1Di of the organic deflocculating agent DI to be added to the mud cake B2 and / or a quantity Q1Fi of a flocculating agent Fl, preferably an organic flocculating agent, to be added to the clayey-silty mud Bl.

[0185] 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.

[0186] According to another aspect, the present invention relates to a system for mechanical dewatering of a sludge. In particular, a system for mechanical dewatering of a sludge according to the invention is a system for mechanical dewatering of a clayey-silty sludge. Preferably, it is a system specifically designed for the mechanical dewatering of a sludge, in particular a clayey-silty sludge.

[0187] 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 during 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 during the formation of a construction binder. This mud cake generally has a dry matter content of at least 30%.

[0188] A dewatering system according to the present invention may comprise: a support structure, a plurality of filter plates, a feed device 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 a device 90 for adding an organic deflocculating agent to the sludge B1-1 or to the sludge cake.

[0189] 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 their delivery to the filter plates.

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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.

[0194] 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 for reusing the effluents collected in the quarry operations.

[0195] 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.

[0196] The dehydration system according to the present invention may comprise a guiding device configured to control the movement of the set of filter plates.

[0197] 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 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.

[0198] A dehydration 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, as a function of physicochemical characteristics of the sludge.

[0199] A dewatering system according to the invention may comprise a cake removal device. A cake removal device is preferably configured to automate the unloading of the 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: mobile filter elements, vibrating filter elements, vibrators, plate strikers, scrapers, vibrating plates, or even cloth spreaders.

[0200] 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.

[0201] 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 of the system.

[0202] 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.

[0203] The dehydration 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.

[0204] 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.

[0205] The addition device 90 may comprise a metering device configured to introduce a predetermined or predeterminable amount of organic deflocculation agent into the sludge. Preferably, the metering device is configured to introduce a quantity of organic deflocculation agent depending on the sludge flow rate and / or physicochemical properties of the sludge.

[0206] 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, a screw feeder, a rotating disc feeder, and / or a pneumatic distributor.

[0207] Advantageously, the addition device 90 comprises a metering device configured to introduce a predetermined or predeterminable quantity of organic deflocculation agent into the mud cake. Preferably, the metering device may implement: a spraying device, an injection nozzle, and / or a coating device.

[0208] Finally, a dewatering system according to the present invention further comprises 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.

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 degradation step (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. A 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 (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-l-propanol; mono-, di- or triethanolamine; isopropanolamines (l-Amino-2-propanol, diisopropanolamine and triisopropanolamine) and N-alkylated ethanolamines; or - mixtures thereof.

8. Manufacturing method (100) according to any one of claims 1 to 7, characterized in that the clayey-silty mud collected at 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 clay-silt 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 degrading (250) the flocculating agent and / or a step of adding (280) 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 clayey-silty matrix, a flocculating agent residue and / or an organic deflocculating agent.

13. A method of manufacturing (400) a construction binder, said method comprising: - a step of collecting (410) a clayey-silty sludge comprising a clayey-silty 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 clayey-silty matrix relative to the dry weight of said sludge; - a step of mechanical dehydration (420) of the clayey-silty sludge so as to form a sludge cake, said sludge cake having a water content of less than 40%; - a step of drying (430) the sludge cake so as to achieve a water content of less than 20%; - a step of grinding (440) the sludge cake so as to obtain a ground sludge cake which has a D50 less than 50 pm and a D90 less than 100 pm; and - a step of forming (470) a construction binder from the mud cake grind comprising a mixture of the mud cake grind with an activating composition;said method further comprising a step of degradation (450) of the flocculating agent when said sludge comprises the flocculating agent and / or a step of addition (460) of an organic deflocculating agent to the clay-silt matrix.;

14. A method of manufacturing (400) a construction binder according to claim 13, characterized in that the drying step (430) and the grinding step (440) are carried out concomitantly.

15. Method of manufacturing (400) a construction binder according to one of claims 13 or 14, 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.

16. A method of manufacturing (400) a construction binder according to any one of claims 13 to 15, 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; wheel mill; pendulum mill; attrition mill; vertical mill; deagglomerator.

17. A method of manufacturing (400) a construction binder according to any one of claims 13 to 16, characterized in that the step of forming (470) a construction binder is carried out by using a device selected from: powder mixer; horizontal mixer.

18. A method of manufacturing (400) a construction binder according to any one of claims 13 to 17, 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.

19. Manufacturing method (400) according to any one of claims 13 to 18, 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).

20. A method of manufacturing (400) a construction binder according to any one of claims 13 to 19, characterized in that 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.

21. System for forming (1) a construction binder from a clayey-silty sludge comprising a clayey-silty matrix, said system comprising: - a collection device (20) adapted to receive a clayey-silty sludge (B1) comprising a clayey-silty matrix (B1-1) 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 clayey-silty matrix (B1-1) relative to the dry weight of said sludge; - a mechanical dewatering device (30) configured to generate a sludge cake (B2) comprising the matrix clayey-silty matrix (B 1-1), 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 clayey-silty matrix (B 1-1) so as to form a ground material having a D50 of less than 50 pm and a D90 of less than 100 pm; - a mixer (70) configured to form a construction binder (L1) from the ground mud cake (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 (B 1-1).

22. A system (1) for forming a construction binder according to claim 21, wherein the mill (60) comprises drying means (50) configured to dry the mud cake (B2).

23. System for forming (1) a construction binder according to one of claims 21 or 22, 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 (Bl).

24. System for forming (1) a construction binder according to claim 23, 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 an amount (Q1Di) of an organic deflocculating agent (Dl) to be added to the mud cake (B2) and / or an amount (QIfi) of a flocculating agent (Fl), preferably an organic flocculating agent, to be added to the clayey-silty mud (Bl).

25. System for forming (1) a construction binder according to one of claims 23 or 24, said physicochemical characteristic values ​​comprising X-ray fluorescence values ​​and / or particle size values.

26. A system for mechanically dewatering a sludge, preferably a clayey-silty sludge, so as to form a sludge cake suitable for forming 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 feed and being movable between an open configuration and a closed configuration; - a feed device connected to the filter plates for distributing the sludge; - a guide device configured to control the movement of all the filter plates; and - a compression device configured to at least partially dewater the sludge and form a sludge cake;said system further comprising a device (80) for degrading a flocculating agent present in the sludge (B 1-1) and / or a device (90) for adding an organic deflocculating agent to the sludge (B 1-1) or to the sludge cake.;

27. ​​System according to claim 26, 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.

28. System according to one of claims 26 or 27, characterized in that when it comprises a device (90) 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.