A device for treating alkaline industrial waste in aqueous solution combining metal separation and carbonation, and a process for treating alkaline industrial waste implementing said device.

Abstract

A device for treating alkali industrial waste in aqueous solution, combining metal separation and carbonation and minimizing discharges, said device comprising: A mixing tank (10), with a raw substrate inlet (11) and a recycled process water inlet (12), and A magnetic separation unit (20), with a recycled process water inlet (21), and A density separation unit (30), and A transfer unit (40), and A carbonation unit (50), equipped with at least one carbonation reactor (51), said carbonation reactor being configured with an external water inlet (52), a recycled process water inlet (53) and with at least one CO2 injection zone (54), and A water treatment unit (60) configured to produce recycled process water for the mixing tank (10) and / or the magnetic separation unit (20) and / or the carbonation unit (50).

Description

Title of the invention: Device for the treatment of alkaline industrial waste in aqueous solution combining metal separation and carbonation, and process for the treatment of alkaline industrial waste implementing said device.

[0001] The present invention relates on the one hand to a device for treating alkaline industrial waste in aqueous solution combining metal separation and carbonation and minimizing discharges, on the other hand to the use of the device for the treatment of alkaline industrial waste and on the third hand to a process for treating alkaline industrial waste implementing the said invention. State of the art

[0002] It is recalled that the alkali and alkaline-earth elements include the elements of groups 1 and 2 of the periodic table, such as lithium, sodium, potassium, magnesium and calcium.

[0003] Carbonation is a chemical reaction involving gaseous CO2 and metal oxides in the presence of water, to produce carbonates. For example, calcium hydroxide reacts with CO2 in the presence of water to produce calcium carbonate and water according to the following reaction: Ca(OH)2 + CO2 + H2O -> CaCO3 + 2H2O (equation 1).

[0004] Alkaline industrial waste refers to materials containing, on the one hand, fractions of metallic elements and, on the other hand, oxides of alkali or alkaline earth metals originating from industrial processes and having undergone combustion or heat treatment resulting in decarbonation. These materials may include, for example, ash from the bottom chambers of solid fuel boilers or incinerators, fly ash, or slag from foundries or steelworks. In this document, they will be referred to interchangeably as substrate.

[0005] The carbonation of alkaline industrial waste aims to use carbon dioxide and substrates to produce carbonates, sequestering carbon, stabilizing pollutants in waste, and facilitating their reuse as a mineral additive.

[0006] The following forms for the substrate are also defined within the framework of this document: a. The raw substrate is used as the raw material to be processed within the framework of the invention; b. The ferrous substrate is produced by extracting the ferrous elements from the raw substrate; c. The demetallized substrate is produced by extracting dense metallic elements from the de-ferrous substrate; d. The carbonate substrate results from the carbonation of the demetallized substrate.

[0007] Furthermore, the term suspension, in this document, refers to a heterogeneous mixture of water and substrate, in any of the preceding forms. The substrate is thus dispersed without being dissolved in the aqueous solution. The L / S ratio is also defined as the mass ratio of the quantity of water divided by the quantity of substrate.

[0008] Leaching is defined as the release of ions or soluble substances from a solid by dissolution in a liquid.

[0009] An oxyanion is also defined as a polyatomic ion in solution, negatively charged and resulting from an oxidation, such as for example: CrO42 (chromate ion with an oxidation state of +VI), SbO43 (antimonate ion with an oxidation state of +V).

[0010] We recall that the solubility of a chemical species corresponds to the concentration (expressed here in g / L) of this species in solution at thermodynamic equilibrium.

[0011] The dissolution of CO2 in an aqueous solution decreases the pH (this is called acidification). The dissolution of calcium aluminates is triggered by the dissolution of CO2. The solubility of CO2 in water at ambient temperature and pressure is 1.6 g / L. This value is reached when the available atmospheric CO2 dissolves in the stagnant water.

[0012] In France, the production of raw substrates of the type of waste incineration bottom ash is estimated at around 3 Mt / year, while that of foundry or steelworks slag amounts to around 4.9 Mt / year.

[0013] Several studies have been conducted to accelerate the carbonate of raw substrates in aqueous solution, such as, for example, the publication by Wehrung, Q.; Bemasconi, D.; Destefanis, E.; Caviglia, C.; Curetti, N.; Di Felice, S.; Bicchi, E.; Pavese, A.; Pastero, L. Aqueous Carbonation of Waste Incineration Residues: Comparing BA, FA, and APCr Across Production Scenarios. Minerals 2024, 14, 1269. https: / / doi.org / 10.3390 / minl4121269

[0014] This publication presents a device for carbonating a certain type of crude substrate in aqueous solution. Carbonating crude substrates in aqueous solution is an efficient way to maximize mass transfer within the reactor.

[0015] Raw substrates are generally considered waste. Their reuse is subject to strict rules, in particular compliance with discharge standards related to leaching tests. However, substrate carbonation This can positively or negatively influence the mobility of pollutants in substrates. In particular, chromium and antimony are species whose leaching is enhanced after carbonation. Furthermore, the publication by Wehrung et al., 2024, indicates that in bottom ash, chromium is bound to iron. Carbonation of the substrate dissolves a layer of calcium aluminate covering the ferrous and ferric particles, accelerating the release of chromium into both the carbonation products and the process water. However, the publication does not address the issues related to metal separation and effluent treatment.

[0016] Furthermore, there are substrate processing devices that include metal separation and carbonation. In particular, patent application WO2024 / 112673 A1 describes, according to a first claim, a process for concentrating one or more metals from municipal solid waste incineration (MSWI) ash comprising at least one step selected from: a. reducing the size of the MSWI ash by grinding and calibrating particles thereof from about 100 to about 400 mesh; b. adding the MSWI ash to a foam flotation solution to separate the MSWI ash into a foam flotation fraction and a residue fraction, the foam flotation solution comprising a sulfide and a cation collector; c.d. Contacting municipal solid waste incineration ash with a magnetic field to provide a magnetic ash fraction and a non-magnetic ash fraction; d. Adding municipal solid waste incineration ash to a flotation / descent solution with a specific gravity of 2.4-3.0 to provide a flotation fraction and a descent fraction; e. Placing municipal solid waste incineration ash in an aqueous solution and treating it with a carbon dioxide gas to generate calcite-coated lime; f. Treating the ash with a leaching solution to provide a leachate; or g. Preparing a chemically separated ash fraction by solvent extraction, ion exchange, selective precipitation, or membrane passage.

[0017] This solution has several drawbacks. First, the system does not specify how to treat the generated waste, particularly aqueous effluents. Treating alkaline industrial waste may seem promising for recovering metallic fractions, but its economic and environmental benefits quickly diminish if it generates additional hazardous waste. Second, the system involves using acidic solvents (for leaching in step f) or solvents for solvent extraction (step g) or flotation solutions (in step d). This use of chemicals can lead to significant additional costs and difficulties in treating the waste.

[0018] The following problems are known: a. The carbonation of slags is mainly controlled by the dissolution of calcium aluminate phases, accompanied by a concomitant release of chlorides, sulfates and oxyanions. b. Chromium, and respectively antimony, in the form of chromate and antimoniate oxyanions, are among the most critical elements in terms of leaching after carbonation, due to their mobility. This phenomenon must be controlled to limit the leaching of these elements into solid residues and / or liquid effluents. This control is crucial to ensure the viability of the treatment process and, where applicable, to allow the reclassification of substrates as inert waste. c. Furthermore, current metal recovery processes in substrates such as dry-phase incineration bottom ash (overband magnetic separation, eddy currents) are ineffective at extracting small-diameter particles, typically less than 2 mm. As a result, valuable metals (zinc, copper, lead, nickel, zirconium, chromium, tin, silver, tungsten, gold) are lost in significant quantities. d. Carbonation of substrates in the liquid phase can involve significant water consumption and effluent discharge. The objective is therefore to minimize discharges and the use of chemicals, particularly strong acids or solvents.

[0019] Thus, there is no solution that combines the following characteristics: a. An accelerated carbonation process for alkaline industrial waste in aqueous solution; b. Combining metal recovery and carbonation; c. Suitable for a raw substrate particle size of 0 to 2 mm; d. Reducing effluents and the use of chemicals; e. Reducing the risks of leaching of species made mobile by carbonation such as chromium and antimony both during leaching tests of solid residues and on effluents; f. Enabling the production of a mineral additive with constant physicochemical characteristics, suitable for recycling in civil engineering.

[0020] Object of the invention

[0021] The present invention aims to remedy all or part of these drawbacks.

[0022] Device for treating alkaline industrial waste in aqueous solution combining metal separation and carbonation

[0023] To this end, a first object of the present invention relates to a device for treating alkaline industrial waste in aqueous solution, integrating the separation of metals and carbonation, while minimizing effluents.

[0024] According to a first aspect, the device that is the subject of the present invention comprises: a. A mixing tank, with an inlet for raw substrate and an inlet for recycled process water, and b. A magnetic separation unit, with an inlet for recycled process water, and c. A density separation device, and d. A transfer organ, and e. A carbonation unit, equipped with at least one carbonation reactor, configured with a water inlet and with at least one CO2 injection zone, and f. A water treatment unit configured to produce recycled process water for the mixing tank and / or the magnetic separation unit and / or the carbonation unit.

[0025] Mixing tank

[0026] According to one embodiment, the raw substrate introduced into the mixing tank has a particle size of less than 2 mm and according to a particular embodiment, the raw substrate has a particle size of less than 1 mm.

[0027] According to some embodiments, in the mixing tank, the L / S ratio is less than 5, and according to some particular embodiments less than 3.

[0028] According to some embodiments, the pH in the mixing tank is greater than 9.

[0029] According to one embodiment, the suspension of raw substrate in the mixing tank is maintained via an agitator. This prevents the materials from settling.

[0030] According to one embodiment, the substrate suspension is transferred from the mixing tank to the separation element by a grout pump.

[0031] Magnetic separation element

[0032] The magnetic separation device operates on the principle of a flow passing near a magnetic field, the latter attracting magnetic particles (and therefore essentially ferrous particles).

[0033] According to one embodiment, the magnetic separation element operates in two alternating modes: a capture mode during which the magnetic field is active, and a discharge mode during which the magnetic field is inactive. This improves the separation of ferrous metallic elements.

[0034] According to one embodiment, the magnetic separation element can be fed *either by raw substrate and it then operates in capture mode, *or by recycled process water, it then operates in discharge mode.

[0035] According to a particular embodiment, the magnetic separation unit has two separate outlets and operates alternately in capture and discharge modes. During an initial period, the raw substrate flows through the magnetic separation unit, and ferromagnetic particles are trapped by an activated magnetic field in capture mode. The ferromagnetic flow is directed to the first outlet, in the direction of the density separation unit. At the end of this initial period, the first outlet is closed, and the second outlet is opened, deactivating the magnetic field. Recycled process water flows through the magnetic separation unit in discharge mode. The ferromagnetic particles are released and carried by the recycled process water flow to the dedicated filtration system of the magnetic separation unit. At the end of this second period, the cycle begins again.

[0036] To reduce leaching, it is imperative that, in the context of the emptying mode, the magnetic separation unit be supplied with recycled process water having the lowest possible CO2 level to avoid carbonation of the calcium aluminate layer covering the ferrous particles, and thus avoid the leaching of chromate ions.

[0037] According to one embodiment, the magnetic separation element has two separate outlets and operates alternately in capture mode and in discharge mode, and in the discharge mode, the magnetic separation element is supplied with recycled process water;

[0038] According to one embodiment, the dedicated filtration system of the magnetic separation member includes at least one centrifuge-type device.

[0039] According to one embodiment, the dedicated filtration system of the magnetic separation unit separates the ferrous metal-rich stream into a solid ferrous concentrate on the one hand, and a liquid fraction called the first supernatant on the other.

[0040] According to one embodiment, the magnetic separation unit is configured, on the one hand, to receive the mixture of the raw substrate and recycled process water, on the other hand, to produce a stream of ferrous-free substrate, and finally to produce a stream rich in ferrous elements, said stream being separated by a dedicated filtration system into a ferrous solid concentrate and a liquid stream referred to as the first supernatant. The magnetic separation unit operates alternately in capture mode or discharge mode

[0041] Density separation element

[0042] According to one embodiment, the density separation element comprises at least one device of the type of vibrating wet table (commonly called a wet shaking table in English).

[0043] According to one embodiment, the density separation element comprises at least one centrifugal separator.

[0044] According to some embodiments, the density separation element comprises at least two vibrating wet tables arranged in series.

[0045] According to some embodiments, the density separation element is configured with at least one vibrating wet table or at least one centrifugal separator.

[0046] According to certain embodiments, the separation of the ferrous substrate in at least one stage of the density separation unit is carried out according to a reference density setting. Particles composed mainly of heavy metallic elements (zinc, copper, lead, silver, tungsten, etc.) are found in the heavy density stream, i.e., the stream containing particles whose density is greater than the reference density. The other particles, composed mainly of low-density elements such as calcium, aluminum, and silicon, as well as water, are found in the light density fraction, forming a suspension of demetallized substrate.

[0047] According to some embodiments, the adjustment of the separation element by density is carried out according to a reference density of 3 g / L.

[0048] According to one embodiment, the dedicated filtration system of the density separation unit is of the centrifuge type.

[0049] According to one embodiment, the dedicated filtration system of the density separation unit separates the heavy density stream rich in metals, on the one hand, into a solid metal concentrate, and on the other hand a liquid fraction called a second supernatant.

[0050] According to one embodiment, the first and second supernatants obtained from the magnetic and density separation filtration systems are collected and reintroduced into the mixing tank. This reduces the water input and maximizes the capture rate of ferrous and non-ferrous metals.

[0051] According to one embodiment, the density separation unit is configured, on the one hand, to receive a stream of ferrous-free substrate, on the other hand, to produce a stream of demetallized substrate, and finally to produce a stream rich in non-ferrous metallic elements, said stream being separated by a dedicated filtration system into a metallic solid concentrate and a liquid stream called a second supernatant.

[0052] Transfer unit

[0053] According to one embodiment, the transfer element connects the density separation element to the carbonation element on the one hand and to the mixing reservoir on the other hand.

[0054] According to one embodiment, the transfer element comprises a measuring element for the quantity of metals in the demetallized substrate suspension at the outlet of the density separation element, as well as a flow control element allowing a portion of the demetallized substrate flow to be recirculated to the mixing tank. This allows for substrate recirculation and improves the performance of the density separation.

[0055] According to one embodiment, the measurement of the quantity of metals suspended in the demetallized substrate is carried out by a Coriolis type flowmeter.

[0056] According to one embodiment, the transfer element is configured with a connection to the density separation element, a connection to the carbonation element, and a connection to the mixing tank. The transfer element includes a measuring element for the metallic element content in the demetallized substrate stream. It also includes a flow control element for regulating the flow of demetallized substrate from the density separation element, directing a portion to the carbonation element and another portion to the mixing tank.

[0057] Carbonation organ

[0058] Generally, the carbonation unit comprises at least one carbonation reactor.

[0059] In some embodiments, the carbonation reactor operates in batch mode. It is first charged with demetallized substrate and water to achieve an optimal L / S ratio. CO2 is then injected. As the suspension absorbs CO2, the pH decreases until a final reference pH value is reached. Once the final reference pH value is reached, the reactor is drained and the cycle can begin again.

[0060] In certain embodiments, the carbonation unit comprises two carbonation reactors operating in batch mode, in parallel and alternately. When one of the reactors is being emptied or recharged, the other is being injected with CO2. This ensures continuous CO2 consumption by carbonation and maximizes the production capacity of the device of the invention.

[0061] In some embodiments, the optimal L / S ratio is between 1 and 10, and in some specific embodiments between 2 and 5.

[0062] In some embodiments, the final reference pH value is between 6.3 and 8.

[0063] According to some embodiments, the carbonation reactor is equipped with a stirrer. This maximizes the performance of the carbonation process.

[0064] According to some embodiments, the injection of CO2 into the carbonation reactor is carried out in several zones by gas-liquid mixing tools to minimizing the size of the gas bubbles. This maximizes the dissolution of CO2 in water.

[0065] According to one embodiment, the carbonation reactor operates at a pressure greater than 1.5 bar and typically greater than 5 bar. This makes it possible to reduce the pH and increase the amount of CO2 dissolved in the aqueous solution.

[0066] According to one embodiment, the water supply to the device of the invention is carried out at the carbonation unit. The carbonation reactor is thus supplied with water from an external source and / or from the water treatment unit. The carbonation unit is therefore supplied with water that is relatively cleaner than the water present in the other components of the device. This makes it possible to reduce the quantity of chloride and sulfate ions in the reactor and to maximize the performance of the carbonation process.

[0067] According to one embodiment, the carbonation unit is equipped with a device for allowing the addition of chemical additives. This makes it possible to modify the parameters of the aqueous medium.

[0068] In certain particular embodiments, the additive is an alkali hydroxide such as NaOH (caustic soda) or KOH (potassium hydroxide), or a dilute solution containing these chemical elements. In the presence of a concentrated CaCl2 solution, the addition of such additives combined with the injection of CO2-rich gas causes the precipitation of nearly pure calcium carbonates.

[0069] According to one embodiment, the dedicated filtration system of the carbonation unit is of the press filter type. This makes it possible to generate a liquid phase and a solid phase, the latter containing the carbonate products.

[0070] According to one embodiment, the carbonation unit also includes a secondary reactor. This secondary reactor can be positioned either downstream of a carbonation reactor and thus be fed with supernatant from the carbonation reactor, or downstream of the dedicated filtration system of the carbonation unit and thus be fed with filtration water. This allows for the selective precipitation of certain dissolved fractions by the addition of additional CO2 and / or additives, without interrupting the main reaction in the carbonation reactor.

[0071] For example, the recarbonation of supernatant in the secondary reactor in the presence of caustic soda type additives is characterized by the overall reaction: CaCl2xH2O + 2NaOH + CO2 -> CaCO3 + 2NaCl + (x+l)H20 (equation 2).

[0072] According to one embodiment, the carbonation unit includes a dissolved CO2 depressurization unit. This makes it possible to reduce the amount of CO2 dissolved in the recycled process water.

[0073] The dissolved CO2 concentration, measured in g / L, at the end of the reaction is a key parameter for enabling process water recycling. If this concentration is too high, the dissolution of calcium aluminates will begin in the mixing tank, leading to the release of pollutants. The goal is to remove the CO2 present in solution to achieve a target dissolved CO2 concentration. Here, removal refers to the act of removing dissolved CO2 either by chemical reaction (as in the case of carbonation) or by physical removal (as in the case of degassing).

[0074] In some embodiments, the recycled process water has a target dissolved CO2 level of less than 1 g / L, and in some particular embodiments, a target dissolved CO2 level of less than 0.05 g / L.

[0075] In certain embodiments, the transfer element allows for the additional addition of demetallized substrate to the carbonation element at the end of the reaction, i.e., once the target pH value has been reached. This makes it possible to eliminate dissolved CO2 by carbonating the substrate, while reducing the risk of oxyanion release, which would not be possible with raw substrate.

[0076] In some embodiments, the carbonation unit includes a compressed air inlet and an air diffusion device. This allows air to be injected into the suspension and thus to remove dissolved CO2.

[0077] In some embodiments, the removal of CO2 dissolved in the carbonation unit is achieved by a combination of additional addition of demetallized substrate and / or injection of air into the suspension.

[0078] In certain embodiments, the carbonation unit is configured: *firstly with at least one carbonation reactor, *secondly, with a water inlet, *thirdly with at least one CO2 injection zone, *fourthly with a pH measurement, *fifthly with an air injection and *sixthly with a dedicated filtration system, said filtration system being configured **with a first outlet for solid products, and **with a second outlet for the liquid phase.

[0079] Water treatment unit

[0080] According to one embodiment, the water treatment unit comprises a reverse osmosis unit and produces recycled water and brine. This allows for the treatment of salts dissolved in the water, including chlorides and sulfates present in solution.

[0081] According to some embodiments, the water treatment unit includes a device for treating the oxyanions released by carbonation.

[0082] According to a particular embodiment, the water treatment unit includes a device for treating the antimony present in solution in the liquid phase from the dedicated filtration system of the carbonation unit, via the formation of iron antimonate. This makes it possible to reduce the antimony level in the water.

[0083] According to one embodiment, the device for treating antimony is of the adsorption type on a ferrous medium.

[0084] According to certain particular embodiments, the recycled process water from the water treatment unit, containing water and iron antimonate, is reintroduced into the magnetic separation unit during the emptying mode of said separation unit. This allows the iron antimonate, and therefore the antimony, to be removed along with the fraction of ferrous metallic residues.

[0085] According to some embodiments, the water treatment unit is configured *on the one hand to produce, from the liquid phase coming from the carbonation unit, recycled process water and waste, and *on the other hand, to transfer the recycled process water partly to the carbonation unit and partly to the mixing tank.

[0086] Use of the device

[0087] The second object of the invention is the use of the device according to the first object of the invention to produce, from a substrate of the type of combustion or incineration ash or steelworks or foundry slag, *on the one hand a fraction rich in metallic elements and *on the other hand a fraction of carbonate substrate.

[0088] Process for separating metals and carbonating substrates

[0089] The invention also has as a third object a process for separating metals and carbonating substrates in aqueous solution, characterized in that it is implemented in a device conforming to the first object of the invention, and in that it comprises at least the following steps: a. Introduce substrate and recycled process water into the mixing tank to achieve an initial target L / S value; b. Pass the raw substrate through the magnetic separation unit in capture mode, to produce a stream of ferrous substrate; c. Supply the density separation unit with ferrous substrate; d. Separate in the density separation unit the ferrous substrate into three streams: a stream of demetallized substrate, a solid metallic concentrate, a second supernatant liquid stream; e. Transfer via a transfer device a portion of the demetallized substrate flow to the mixing tank and another portion to the carbonation device, the adjustment being made according to a measurement of the density of the demetallized substrate flow; f. Within the carbonation unit, fill a carbonation reactor with demetallized substrate; g. Add water from the recycled process water stream in the carbonation reactor and makeup water until a second target L / S value is reached; h. Inject CO2 into the carbonation reactor until the pH reaches a final reference value; i. Eliminate CO2 in the carbonation unit to achieve a target dissolved CO2 level; j. Within the carbonation unit, separate the flow of carbonate substrate, on the one hand into a flow of carbonate products and on the other hand into a liquid flow; k. Within the water treatment unit, separate the liquid flow to produce a recycled process water flow and discharges; 1. Recirculate part of the recycled process water to the carbonation unit, part to the magnetic separation unit in drain mode, the rest to the mixing tank; m. Extract the ferrous solid concentrates, respectively metallic, from the magnetic separation unit, respectively from the density separation unit; n. Recycle the supernatant flows from the magnetic separation unit and the density separation unit to the mixing tank;

[0090] In the process of the invention, all the steps are preferably concurrent, except for steps b and 1 which are not concurrent.

[0091] In some embodiments of the process, the first target L / S value is between 1 and 10 and the second target L / S value is between 2 and 5.

[0092] In some embodiments of the process the final reference pH value is between 6.3 and 8.

[0093] In some embodiments of the process the target CO2 level is 1 g / L.

[0094] In some embodiments of the process the target CO2 level is 0.05 g / L.

[0095] In the carbonation reactor, the pH measurement gives an indication of the progress of the carbonation reaction, which is driven by the injection of CO2 and the injection of substrate flux in solution with low metallic element content. Brief description of the drawings

[0096] The invention is illustrated by the figures and examples that follow, but are not limited to them.

[0097] This description is given by way of non-limiting attribution, each feature of one embodiment being able to be combined with any other feature of any other advantageous embodiment. It should be noted from the outset that the figures are not to scale.

[0098] [Fig. 1] shows a schematic representation of the device for treating alkaline industrial waste in aqueous solution, combining metal separation and carbonation and minimizing discharges, said device comprising: a. A mixing tank (10), with a raw substrate inlet (11) and a recycled process water inlet (12), and b. A magnetic separation unit (20), with an inlet for recycled process water (21), and c. A density separation device (30), and d. A transfer organ (40), and e. A carbonation unit (50), equipped with at least one reactor of carbonation (51), said carbonation reactor being configured with an external water inlet (52), an inlet for recycled process water (53) and with at least one CO2 injection zone (54), and f. A water treatment unit (60) configured to produce recycled process water for the mixing tank (10) and / or the magnetic separation unit (20) and / or the carbonation unit (50).

Claims

1.

2.

3.

4. Demands A device for treating alkaline industrial waste in aqueous solution, combining metal separation and carbonation and minimizing discharges, said device comprising: a. A mixing tank (10), with a raw substrate inlet (11) and a recycled process water inlet (12), and b. A magnetic separation unit (20), with an inlet for recycled process water (21), and c. A density separation device (30), and d. A transfer organ (40), and e. A carbonation unit (50), equipped with at least a carbonation reactor (51), said carbonation reactor being configured with an external water inlet (52), an inlet for recycled process water (53) and with at least one CO2 injection zone (54), and f. A water treatment unit (60) configured to produce recycled process water for the mixing tank (10) and / or the magnetic separation unit (20) and / or the carbonation unit (50). Device according to any one of the preceding claims, characterized in that the carbonation unit (50) comprises two carbonation reactors (51) operating in batch, in parallel and alternately. A device according to any one of the preceding claims, characterized in that: a. the density separation device (30) is configured with at least one vibrating wet table or at least one centrifugal separator; b. and / or the setting of the density separation element (30) is carried out according to a reference density of 3 g / L. A device according to any one of the preceding claims, characterized in that: a. The water treatment unit (60) includes a device for treating the antimony present in solution in the liquid phase from the dedicated filtration system of the carbonation unit, via the formation of iron antimoniate, and b. the recycled process water from the water treatment unit (60) and containing water and iron antimoniate is reintroduced into the magnetic separation unit (20) during the emptying mode of said separation unit.

5. Use of the device according to any one of the preceding claims to produce, from a substrate of the type combustion or incineration ash or steel or foundry slag, *on the one hand a fraction rich in metallic elements and *on the other hand a carbonate substrate fraction.

6. Carbonation process characterized in that it is carried out in a reactor as defined in any one of claims 1 to 4, and in that it comprises at least the following steps: a. Introduce substrate and recycled process water into the mixing tank (10) to achieve a first target L / S value; b. Pass the raw substrate through the magnetic separation unit (20) in capture mode, to produce a stream of ferrous substrate; c. Supply the density separation unit (30) with ferrous substrate; d. Separate in the density separation unit (30) the ferrous substrate into three streams: a stream of demetallized substrate, a solid metallic concentrate, a second supernatant liquid stream; e. Transfer via a transfer device (40) a part of the demetallized substrate flow to the mixing tank (10) and another part to the carbonation device (50), the adjustment being made according to a measurement of the density of the demetallized substrate flow; f. Within the carbonation unit (50), fill a carbonation reactor (51) with demetallized substrate; g. Add water from the recycled process water stream in the carbonation reactor (51) and make-up water until a second target L / S value is reached; h. Inject CO2 into the carbonation reactor (51) until the pH reaches a final reference value; i. Remove CO2 in the carbonation unit (50) to achieve a target dissolved CO2 level; j. Within the carbonation unit (50), separate the flow of carbonate substrate, on the one hand into a flow of carbonate products and on the other hand into a liquid flow; k. Within the water treatment unit (60), separate the liquid stream to produce a stream of recycled process water and discharges; 1. Recirculate part of the recycled process water to the carbonation unit (50), part to the unit magnetic separation (20) in discharge mode, the remainder to the mixing tank (10); m. Extract the solid ferrous, respectively metallic, concentrates from the magnetic separation unit (20), respectively from the density separation unit (30); n. Recycle the supernatant streams from the magnetic separation unit (20) and the density separation unit (30) to the mixing tank (10).

Images