Method for recycling metals from porous materials including them

Abstract

The present invention relates to a method for recycling one or more metals M chosen from those belonging to columns 8 to 12 of the periodic table of elements, present at least in part in the form of metallic sulfides in a porous material A comprising at least one mineral oxide and having a sulfur content greater than or equal to 2% by weight.The said method comprises the following successive steps: (1) at least one heat treatment step of material A in the presence of oxygen, at a temperature in the range of 350°C to 900°C, (2) at least one washing step of material A' from step (1) with an aqueous solvent; (3) at least one extraction step of the metal(s) M by contacting material A' from step (2) with a solution S containing at least one carboxylic acid; and (4) at least one deposition step of at least a part of the metal(s) M onto a porous material B different from said material A, by contacting the solution S' from step (3) with said material B.

Description

Title of the invention: Method for recycling metals from porous materials comprising them

[0001] The present invention relates to the recycling of metals present in porous materials such as traps and adsorbent agents used in the fields of petroleum refining and petrochemicals. PREVIOUS STATE OF THE ART

[0002] Hydrocarbon transformation processes employ agents commonly referred to as traps or adsorbents, which are porous materials generally in the form of particles, based on one or more refractory oxides such as alumina, silica, aluminosilicates (zeolites), and which also contain a substantial amount of a metal such as nickel, copper, zinc.

[0003] These materials are used to trap, for example by retaining by adsorption, undesirable chemical species. For example, traps are typically used in hydrotreating reactors upstream of the catalyst beds to trap contaminants present in the petroleum feedstock (including sulfur compounds, compounds containing undesirable metals such as mercury, vanadium, arsenic, etc.) and to protect the catalyst from such contaminants that could poison the catalytic sites and cause its premature deactivation.

[0004] These materials are thus destined to be contaminated by undesirable compounds at very high levels, which at the end of their use cycle leads to used materials that are difficult to recycle and / or regenerate.

[0005] However, it becomes essential to be able to recycle the metals present in often significant quantities in these materials.

[0006] The problem of recycling metals present in catalysts is different from that of recycling metals present in traps and adsorbents, firstly because the metal content is significantly higher in traps and adsorbents than in catalysts, secondly because the level of contamination is much higher in traps and adsorbents and the nature of the contaminants is different.

[0007] Methods for recycling metals present in catalysts have been developed in the prior art, but these are not always effective for recycling metals present in used traps or adsorbents.

[0008] In the book entitled "Handbook of Spent Hydroprocessing Catalyst", Elsevier Science Ltd, 1st edition, 2010, in chapter 11, the authors Meena Marafi et al. describe Various techniques exist for recovering metals from spent hydrotreating catalysts, which primarily contain alumina and metals such as molybdenum, nickel, and cobalt, and sometimes vanadium. The most common techniques described are: - Pyrometallurgical processes, in which spent catalysts are melted in a suitable furnace to separate the metals from a slag containing alumina and / or silica. Recycling thus takes place in an open loop, since the metals are recovered, for example, in special alloys, while the slag is typically used to produce insulating materials such as rock wool. - Hydrometallurgical processes, in which spent catalysts are subjected to calcination followed by leaching, generally carried out with solutions of strong acids and / or bases. The use of organic acids or microorganisms (bio-leaching) is also described.

[0009] Other techniques have been studied, employing, for example, sublimation of certain metals such as molybdenum, volatilization or dissolution of metals, for example in a chlorinated medium, or reduction coupled with magnetic separation. These techniques remain difficult to exploit on an industrial scale.

[0010] Patent application WO 2007 / 001921 describes a process for extracting and recovering nickel, cobalt, iron, tungsten, molybdenum, and vanadium from an alumina-based material (such as a hydrocarbon-impregnated catalyst) comprising the oxidation of the metals in an oxygen-containing atmosphere, and the reaction of the oxidized metals with gaseous HCl to form volatile compounds comprising one or more chlorides and / or oxychlorides. Handling these types of highly corrosive compounds requires very specific equipment, as well as significant expertise and a high level of safety.

[0011] Application WO 03 / 080878 describes a process for extracting nickel from a spent catalyst by leaching with sulfuric acid in the presence of a persulfate-based additive. The leaching liquor is then treated to obtain a by-product containing a high alumina content, and nickel sulfate crystals or nickel hydroxide. The nickel hydroxide is then reduced to obtain metallic nickel powder or nickel oxide.

[0012] Application KR 20120128913 describes a method for recovering precious metals contained in waste, by leaching with an aqueous solution of organic acid. Summary of the invention

[0013] The Applicant has now discovered a method that makes it possible to efficiently recycle metals present in porous materials such as, in particular traps and adsorbent agents. The method according to the invention makes it possible to selectively extract these metals, including when the material containing them is very heavily contaminated, and to redeposit them on another material in which they will be reused.

[0014] Thus, the present invention relates to a method for recycling one or more metals M selected from those belonging to columns 8 to 12 of the periodic table of elements, present at least partially as metal sulfides in a porous material A comprising at least one mineral oxide and having a sulfur content greater than or equal to 2% by weight, expressed as weight of elemental sulfur relative to the weight of material A after heat treatment at a temperature of 250°C for 2 hours under nitrogen. The method according to the invention comprises the following successive steps: (1) at least one heat treatment step of material A in the presence of oxygen, at a temperature in the range of 350°C to 900°C, (2) at least one step of washing the material A' from step (1) using an aqueous solvent; (3) at least one extraction step of the metal(s) M by contacting the material A" from step (2) with a solution S containing at least one carboxylic acid; and (4) at least one step of depositing at least a part of the metal(s) M onto a porous material B different from said material A, by contacting the solution S' from step (3) with said material B.

[0015] The invention thus makes it possible to recycle one or more metals M belonging to columns 8 to 12 of the periodic table present on a porous material A based on mineral oxide, contaminated by undesirable compounds including at least sulfur in the form of metal sulfides and other sulfur compounds such as sulfur hydrocarbons. The material A is typically a used trap or adsorbent agent, following its use in a hydrocarbon processing unit.

[0016] Material B can be any porous material suitable for receiving a deposit of the metal(s) M. Advantageously, material B can be metal-free, and in this case, the invention allows, among other things, the preparation of catalysts, traps, and / or adsorbents for use in hydrocarbon processing units. According to an equally advantageous alternative, material B is a catalyst, trap, or adsorbent, either virgin or recycled (regenerated), and in this case, the invention allows its activity to be modified.

[0017] The method according to the present invention is simple to implement and does not require the use of toxic or corrosive agents. It allows for the efficient reuse of the metal(s) present on the starting material A. Furthermore, the metals are recycled in a catalytically active form, which allows, on the one hand, to to prepare new active materials such as catalysts, traps and / or ad-sorbent agents, and on the other hand to increase the activity of existing catalysts, traps and / or ad-sorbent agents.

[0018] The metal recycling rate can reach 50 to 75% by weight of the metals initially contained in material A.

[0019] Furthermore, the solutions S containing one or more carboxylic acids can be reused as is, without additional purification treatment.

[0020] Other objects, features, aspects and advantages of the invention will become even clearer upon reading the description and examples that follow.

[0021] In what follows, and unless otherwise indicated, the bounds of a range of values ​​are included in that range, in particular in the expressions "between" and "ranging from ... to ...". Furthermore, the expressions "at least one" and "at least" used in this description are respectively equivalent to the expressions "one or more" and "greater than or equal to". DETAILED DESCRIPTION

[0022] The starting material A (metal donor material) The present invention applies to a starting material A, which is a material contaminated in particular by sulfur, and which contains a metal or several metals M which we wish to selectively extract in order to transfer it (them) to a material B, which is typically an uncontaminated material intended for use.

[0023] The metal or metals M are chosen from those belonging to columns 8 to 12 of the periodic table of elements. Reference is made here to the version of the periodic table of elements as published by the IUPAC (International Union of Pure and Applied Chemistry).

[0024] In the starting material A, the metal or metals M are present, in whole or in part, in the form of metal sulfides (i.e., metal sulfides). When the metal(s) M are not entirely in the form of metal sulfides, they may also be present in the form of any other chemical species such as metal oxides or elemental metallic forms.

[0025] Preferably, the metal or metals M are chosen from iron, cobalt, nickel, copper, and zinc and more preferably from nickel, copper, and zinc.

[0026] According to a preferred embodiment, the material A contains a single metal M belonging to columns 8 to 12 of the periodic table of elements. In this embodiment, the metal M present is preferably nickel, copper, or zinc.

[0027] According to another preferred embodiment, material A does not contain any metal belonging to column 6 of the periodic table of elements.

[0028] Material A further contains one or more refractory mineral oxides, which may be selected in particular from aluminas, silicas, silica-aluminas, zeolites, zircons, titanium and boron oxides, and mixtures of such oxides. When said mineral oxide(s) are metallic oxides, they are selected from metal oxides not belonging to columns 8 to 12 of the periodic table of elements.

[0029] Preferably, material A contains one or more mineral oxides chosen from aluminas, silicas, silica-aluminas, and more preferably aluminas.

[0030] The material A contains one or more metals M in a content, expressed as the ratio of the total weight of the oxide(s) of metal M to the total weight of said or said mineral oxide(s), within the range of ratio typically from 0.2 to 5.5, preferably from 1 to 4. To measure this ratio, the mass of metals M present in the material A is expressed on the basis of the total equivalent quantity of oxides of the corresponding metals.

[0031] The starting material A also contains sulfur, at a content of at least 2% by weight.

[0032] This content is expressed as the weight of elemental sulfur (i.e., element S) relative to the weight of material A that has undergone heat treatment at a temperature of 250°C for 2 hours under nitrogen. In other words, the sulfur content of the starting material A is measured in the material obtained after treatment for 2 hours at a temperature of 250°C under nitrogen, followed by cooling under nitrogen to ambient temperature.

[0033] The starting material A is generally in the form of solid particles such as beads, cylindrical particles, extrudates, pellets. It has a specific surface area, measured by the BET method, generally between 50 and 250 m2 / g, a pore volume, determined by nitrogen adsorption, ranging from 0.2 to 0.8 ml / g, and an average pore diameter, determined by nitrogen adsorption, ranging from 10 to 40 nm.

[0034] Material B (metal receiving material) Material B used in step (4) can be any porous material, different from the starting material A.

[0035] It advantageously comprises one or more refractory mineral oxides, which may be selected in particular from aluminas, silicas, silica-aluminas, zeolites, zirconias, titanium and boron oxides, and mixtures of such oxides.

[0036] Preferably, material B contains one or more mineral oxides chosen from aluminas, silicas, silica-aluminas, and more preferably aluminas.

[0037] According to a first embodiment, material B does not contain metals. In this embodiment, the method according to the invention allows, for example, the preparation new traps, adsorbents and catalysts from virgin inorganic oxide supports.

[0038] According to a second embodiment, the material B contains one or more metals M', which may be identical to or different from said metals M. The metal(s) M' may, in particular, be chosen from those belonging to columns 6 to 12 of the periodic table of elements. Said metals M', when present, are preferably in the form of metal oxides or in elemental form. In this embodiment, the method according to the invention makes it possible, in particular, to improve the efficiency of traps, adsorbents, and catalysts.

[0039] According to a preferred embodiment, material B is sulfur-free. By sulfur-free, it is meant that the sulfur content, expressed as elemental sulfur S, is less than 0.5% by weight relative to the weight of material B.

[0040] Material B is preferably in the form of solid particles such as beads, cylindrical particles, or extrudates. It has a specific surface area, measured by the BET method, generally between 50 and 300 m² / g, a pore volume, determined by nitrogen adsorption, ranging from 0.2 to 1 ml / g, and an average pore diameter, determined by nitrogen adsorption, ranging from 7 to 40 nm.

[0041] Step fl) Step (1) consists of a heat treatment of the starting material A in the presence of oxygen, at a temperature in the range of 350°C to 900°C.

[0042] This step aims to eliminate volatile compounds (such as hydrocarbons, water) and carbon compounds (including coke) present on the surface of material A.

[0043] Preferably, this heat treatment step is carried out at a temperature in the range of 400 to 600°C, more preferably from 450 to 580°C and even better from 480 to 570°C.

[0044] The temperature of this stage can be controlled, in a manner known per se, for example by means of thermocouples appropriately arranged in the mass of material A.

[0045] The first step is carried out in the presence of oxygen, for example by means of a gas stream containing oxygen. This gas may consist, for example, of air, pure or mixed with additional oxygen or an inert gas, so as to increase or decrease the oxygen content of the air. This gas may also consist of a mixture of oxygen and an inert gas such as nitrogen, or other gas mixtures comprising oxygen.

[0046] The oxygen content of the gas is preferably controlled, so as to better control the temperature of step (1). This content can be fixed, or on the contrary vary over time during the first step.

[0047] The gas flow rate is also controlled, in order to control the combustion.

[0048] This heat treatment step may include several phases, carried out at different temperatures and / or in the presence of varying amounts of oxygen.

[0049] The total duration of this first step generally depends on the quantity of material A to be treated, its composition, the quantity of volatile compounds present on its surface, and the operating conditions (temperature, oxygen content). This duration is shorter the higher the temperature. It is generally between 0.1 and 20 hours, preferably between 0.2 and 10 hours.

[0050] The material A after treatment in step (1) is called material A'.

[0051] Step (2) This step consists of washing the material A' from step (1) with an aqueous solvent. Such washing involves bringing the surface of the material A' into contact with the aqueous solvent, and then removing said solvent.

[0052] By aqueous solvent, we mean any solvent containing water. The solvent can thus include, in addition to water, any organic solvent miscible with water, which can be chosen for example from among alcohols, polyols.

[0053] The aqueous solvent can be supplemented with any additive, organic or inorganic.

[0054] According to a preferred embodiment, the aqueous solvent contains at least 50% by weight of water, preferably at least 75% by weight, and even better at least 90% by weight of water. More preferably, the solvent consists of water (water content greater than 99% by weight).

[0055] The volume of aqueous solvent used in this step is advantageously greater than the total pore volume of the material sample A' to be treated. This volume may, in particular, be in the range of 2 to 20 times the total pore volume of the material sample A', preferably 5 to 10 times said pore volume.

[0056] Step (2) can be carried out at any suitable temperature, for example from room temperature (20°C) to 150°C. Preferably, this step is carried out under slight heating, i.e. at a temperature ranging from 25 to 100°C, preferably from 30 to 70°C.

[0057] During this step, it is advantageous to mix the material A' and the aqueous solvent, so as to ensure effective washing of the surface of the material.

[0058] This step can be carried out in continuous mode or in discontinuous mode (so-called "batch" mode), the discontinuous mode being preferred all the more as it allows limiting the quantity of water used.

[0059] This step can be carried out in any solid / liquid extractor type unit or industrial mixer (for example a conical or biconical mixer).

[0060] The material A' after treatment in step (1) is referred to as material A".

[0061] Step 13) This step consists of extracting the metal(s) M by contacting the material A" from step (2) with a solution S containing at least one carboxylic acid. This step allows the metals to be extracted from material A" by dissolving them as salts of organic acids.

[0062] The solution S comprises a solvent which can be chosen from water, organic solvents (in particular alcohols, polyols), and mixtures of water and organic solvents.

[0063] Preferably, the solution S contains at least 50% by weight of water, preferably at least 60% by weight of water, relative to the total weight of the solution S.

[0064] The carboxylic acid(s) present in solution S may be mono-acids, di-acids or tri-carboxylic acids. They preferably comprise from 1 to 8 carbon atoms.

[0065] According to a preferred embodiment, the carboxylic acid(s) are selected from acetic acid, citric acid, maleic acid, glycolic acid, and mixtures of these acids. Preferably, the carboxylic acid(s) are selected from acetic acid, citric acid, and mixtures thereof.

[0066] Solution S contains a total carboxylic acid content typically in the range of 5 to 50% by weight, preferably 10 to 30% by weight, relative to the total weight of solution S.

[0067] The volume of solution S used in step (3) is advantageously greater than the total porous volume of the sample of material A" to be treated.

[0068] This volume may in particular be in the range of 2 to 50 times the total porous volume of the sample of material A", preferably 5 to 20 times said porous volume, and even better 10 to 15 times said porous volume.

[0069] Step (3) can be carried out at any suitable temperature, for example from ambient temperature (20°C) to 150°C. Preferably, this step is carried out hot, i.e. at a temperature ranging from 50 to 130°C, preferably from 80 to 120°C.

[0070] During this step, it is advantageous to mix the material A" and the solution S, so as to ensure optimal contact of the solution with the surface of the material.

[0071] This step can be carried out in continuous mode or discontinuous mode ("batch" mode), in any suitable unit, for example in a solid / liquid extractor or industrial mixer (for example a conical or biconical mixer).

[0072] At the end of step (3), the solution S' containing salts of the metal (metals) M is separated from the material A", by any suitable separation method, for example by filtration or centrifugation.

[0073] Step 14) During this step, the metal or metals M present in the form of salts in the solution S' from step (3) are deposited on the porous material B. This is done by bringing the solution S' containing the metallic salts from step (3) into contact with said material B.

[0074] According to a preferred embodiment, step (4) is carried out by impregnating the material B with said solution. This can be done by dry impregnation (i.e., using a volume of solution less than the porous volume of the material B), by saturation impregnation of the porous volume (i.e., using a volume of solution greater than or equal to the porous volume of the material B), or by soaking the material B in a large excess of solution S'.

[0075] This contact can be instantaneous or last up to a few days. Preferably, the solution S' has remained in contact with said material B for a period of 1 to 30 hours, preferably 5 to 25 hours, and even better 10 to 20 hours.

[0076] Step (4) can be carried out at a pressure ranging from atmospheric pressure to 5 bars, preferably at atmospheric pressure.

[0077] Step (4) can be carried out at any suitable temperature, for example from 10°C to 50°C. Preferably, this step is carried out at a temperature from 10 to 30°C.

[0078] In general, step (4) must be carried out under conditions allowing the deposition on the surface of material B of the largest possible quantity of metal M.

[0079] According to a preferred embodiment, step (4) is repeated one or more times (for example, repeated up to 5 times), so as to increase the amount of metal M deposited on material B. In this embodiment, it is advantageous to re-contact material B with the same solution S', or with a different solution So', obtained from the treatment by means of steps (1) to (3) of a starting material Ao different from A, and which contains a metal or several metals Mo' which may be identical or different from the metal or metals M.

[0080] In the case where step (4) is repeated, it may be advantageous to carry out an intermediate drying of the material B, as described below, before each repetition of step (4).

[0081] Preferably, at the end of the method according to the invention, the total quantity of metal (metals) M deposited on the material B, expressed in the form of metal oxide, is at least 1% by weight relative to the final total weight of the material B. Preferably, this quantity is between 2 and 10% by weight.

[0082] Other additional steps The method according to the invention may, in addition to steps (1) to (4) described above, include optionally one or more additional steps, carried out before and / or after said steps, or even inserted between these steps.

[0083] The method according to the invention may thus include, after step (4), a drying step of the material B, which may be carried out at a temperature ranging from 80°C to 300°C, preferably from 100°C to 150°C. The drying may be carried out in open air or in the presence of a gaseous flow of air, an inert gas such as nitrogen, or any other suitable gas.

[0084] The method according to the invention may also optionally include, after step (4), a calcination step of the material B, which can be carried out at a temperature ranging from 300°C to 500°C. The calcination can be carried out in open air or in the presence of a gaseous flow of air, an inert gas such as nitrogen, or any other suitable gas.

[0085] When the method according to the invention already includes a drying step, the calcination step (if there is one) is then carried out after this one.

[0086] Finally, the method according to the invention may include one or more final activation step(s) of the final material B, the purpose of which is to activate the metallic sites.

[0087] The following examples are given as an illustration of the invention, and should not be interpreted in such a way as to limit its scope. EXAMPLES

[0088] Materials used The following examples were produced using a donor material, Al, which is a spent sulfur trap from a hydrocarbon hydrotreating unit. The Al material consists of particles made up of alumina and nickel (the nickel being partly as reduced and partially reoxidized nickel, and partly as nickel sulfide). This Al material has a total nickel content, expressed on the basis of the equivalent amount of nickel oxide (NiO), such that the NiO:Al₂O₃ mass ratio is 3.2.

[0089] This spent Al trap contains 1.7% by weight of carbon and 2.9% by weight of sulfur. These measurements were carried out using a LECO CS230 analyzer on the Al product, which had been previously heat-treated in a vertical oven at a temperature of 250°C for 2 hours under nitrogen.

[0090] As a receiving material B1, a spent and regenerated hydrogenation catalyst, consisting of 41.8% nickel oxide NiO and alumina, was used.

[0091] Sulfur trapping performance evaluation tests These tests allow us to evaluate the ability of a porous material to trap sulfur in a hydrocarbon feed, and are carried out using two model organic sulfur compounds which are n-butyl mercaptan and thiophene.

[0092] The test consists of bringing a solution of one or the other of these two into contact compounds with the material in a pressurized reactor, under given conditions, and to determine the amount of sulfur trapped by the tested material.

[0093] Before each test, the material is activated for 4 hours under a flow of hydrogen (H2) at 450°C.

[0094] For the mercaptan trapping test, a test solution containing n-butyl mercaptan in a toluene / n-hexane mixture (50 / 50 by volume) is used. This solution has a sulfur content, expressed as elemental sulfur S, of 1000 ppm by weight relative to the total weight of the test solution.

[0095] For the thiophene trapping test, a test solution containing thiophene in a toluene / n-hexane mixture (50 / 50 by volume) is used. This solution has a sulfur content, expressed as elemental sulfur S, of 1000 ppm by weight relative to the total weight of the test solution.

[0096] The reactor used consists of two parts: a Teflon (PTFE) cylinder with a cap and a metallic reactor body (of type PARR 4749), which ensures sealing and pressure maintenance within the reactor.

[0097] The reactor is filled as follows: the PTFE cylinder and its cap are weighed, then filled with 15 mL of test solution of one of the two organic sulfur compounds.

[0098] In the case of the mercaptan trapping test, 0.05g of the tested porous material is added, under an inert atmosphere, to the reactor.

[0099] In the case of the thiophene trapping test, 0.5g of the tested porous material is added, under an inert atmosphere, to the reactor.

[0100] The PTFE cylinder is then closed using its cap and placed in the metal reactor. The reactor is hermetically sealed and placed in a thermostatically controlled chamber at 185°C for 17 hours.

[0101] The reactor is then cooled to ambient temperature before being opened under an inert atmosphere. The PTFE cylinder and its cap are weighed, and then a liquid sample is taken for analysis using an Antek 9000 type sulfur content analyzer.

[0102] The difference in sulfur content of the solution after testing compared to the sulfur content before testing allows the amount of sulfur trapped by the porous material to be calculated. This amount is expressed as a percentage by weight of trapped sulfur, relative to the weight of porous material.

[0103] Comparative Example 1 A first attempt at recycling nickel from Al material to B1 material was carried out, following a comparative protocol consisting of steps (1), (3) and (4) described below.

[0104] Step (1) The aluminum (Al) material underwent a heat treatment step, being held at a temperature of 550°C for 2 hours in a muffle furnace under air. This yielded the Al' material. This material contains 0.1% carbon by weight and 2.8% sulfur by weight. These concentrations were measured using a LECO CS230 analyzer.

[0105] Step (3) 50 g of the Al' material were placed in a rotary flask equipped with a mechanical stirrer, and a solution SI obtained by mixing 103 g of water and 146.6 g of a 50% by weight citric acid solution in water was added. The contents of the flask were stirred under reflux at a temperature of 100°C for 2 hours.

[0106] After cooling, the mixture is filtered and a solution SI' (comprising solution S1 and nickel salts) is thus recovered.

[0107] Step (4) The SI' solution is then brought into contact with the Bl material, proceeding by volume pore impregnation using 43.4g of the SI' solution per 100g of BL material

[0108] The mixture is left to mature at room temperature for a period of 16 hours.

[0109] Then the Bl material is dried for 1.5 hours in an oven at 130°C, and the porous volume impregnation is repeated identically, with the same quantity of SI' solution for a period of 16 hours.

[0110] The material is finally subjected to final drying (1.5 hours in an oven at 130°C). The modified material obtained by the comparative method above is called Blc. [YES] Determination of the properties of the Blç material Analysis of nickel content (by X-ray fluorescence): the Blc material has a nickel oxide content of 46.8% by weight. Thus, the method including steps (1), (3) and (4) increased the NiO content of the receiving material Bl from 41.8% to 46.8% by weight.

[0112] Sulfur trapping performance: the two sulfur trapping tests were carried out, on the original Bl material, and on the Blc material. The results are detailed in Table 1 below.

[0113] [Tables 1] Material n-Butyl mercaptan trapping test (weight % of trapped S) Thiophene trapping test (weight % of trapped S) Bl 13.3 0.3 Blc 13.1 0.2

[0114] The results show that the material modified according to the comparative method, although it has a higher nickel content than the starting material B1, nevertheless has a slightly reduced activity compared to the Bl material.

[0115] Example 2 according to the invention A second attempt to recycle nickel from material Al to material Bl was carried out, following a protocol according to the invention, consisting of the following steps (1), (2), (3) and (4): - steps (1), (3) and (4) are strictly identical to those of example 1 above; - between steps (1) and (3), a step (2) is inserted, described below.

[0116] Step (2) 50g of the Al' material were placed in a rotating flask equipped with a mechanical stirrer, and then 100 ml of demineralized water was added. The contents of the flask were stirred at a temperature of 50°C for a period of 2 hours.

[0117] After cooling to room temperature, the water was removed by filtration and the Al material thus recovered was placed back in the flask for the implementation of step (3).

[0118] The material obtained at the end of step (4) after final drying is designated BI, h

[0119] Determination of the properties of the material Blj_i Analysis of nickel content (by X-ray fluorescence): the B1L4 material has a nickel oxide content of 46.5% by weight. Thus, the method according to the invention, including steps (1), (2), (3), and (4), increased the NiO content of the receiving material B1 from 41.8% to 46.5% by weight.

[0120] Sulfur trapping performance: the two sulfur trapping tests were carried out, on the original Bl material, and on the B material read. The results are detailed in Table 2 below.

[0121] [Tables2] Material n-Butyl mercaptan trapping test (weight % of trapped S) Thiophene trapping test (weight % of trapped S) Bl 13.3 0.3 B lu 15.5 0.5

[0122] The results show that the material modified according to the method according to the present invention exhibits significantly higher activity than that of the original material Bl.

[0123] Example 3 according to the invention A third trial of nickel recycling from Al material to Bl material was carried out, following a protocol according to the invention, consisting of steps (1), (2), (3) and (4) described below.

[0124] Step (1) The Al material underwent a heat treatment step, being held at a temperature of 550°C for 2 hours in a muffle furnace under air. This yielded the Al' material. This material contains 0.1% carbon by weight and 2.8% sulfur by weight. These contents were measured using a LECO CS230 analyzer.

[0125] Step (2) 50g of the Al' material were placed in a rotating flask equipped with a mechanical stirrer, and then 100 ml of demineralized water was added. The contents of the flask were stirred at a temperature of 50°C for a period of 2 hours.

[0126] After cooling to room temperature, the water was removed by filtration and the Al" material thus recovered was placed back in the flask.

[0127] Step (3) A solution S2, obtained by mixing 176 g of water and 22.8 g of 99% pure acetic acid in water, was added to the material Al" in the flask. The contents of the flask were stirred under reflux at a temperature of 100°C for 2 hours.

[0128] After cooling, the mixture is filtered and a solution S2' (comprising the S2 solution and nickel salts) is thus recovered.

[0129] Step (4) The S2' solution is then brought into contact with the Bl material, proceeding by volume pore impregnation using 35.5g of S2' solution to impregnate 100g of BL material

[0130] The mixture is left to mature at room temperature for a period of 16 hours.

[0131] Then the material B1 is dried for 1.5 hours in an oven at 130°C, and the porous volume impregnation is repeated identically, with the same quantity of solution S2' for a period of 16 hours.

[0132] The material is finally subjected to final drying (1.5 hours in an oven at 130°C). The modified material obtained by the comparative method above is called Bl12.

[0133] Determination of the properties of the material Bl^ Analysis of nickel content (by X-ray fluorescence): the Bl12 material has a nickel oxide content of 45.4% by weight. Thus, the method according to the invention, including steps (1), (2), (3), and (4), increased the NiO content of the receiving material B1 from 41.8% to 45.4% by weight.

[0134] Sulfur trapping performance: the two sulfur trapping tests were carried out, on the original B1 material, and on the Bl12 material. The results are detailed in Table 3 below.

[0135] [Tables3] Material n-Butyl mercaptan trapping test (weight % of trapped S) Thiophene trapping test (weight % of trapped S) Bl 13.3 0.3 biL2 15.1 0.5

[0136] The results show that the material modified according to the method according to the present invention exhibits significantly higher activity than that of the original material Bl.

Claims

Demands

1. Method of recycling one or more metals M selected from those belonging to columns 8 to 12 of the periodic table of elements, present at least in part as metal sulfides in a porous material A which comprises at least one mineral oxide and has a sulfur content greater than or equal to 2% by weight, expressed as weight of elemental sulfur relative to the weight of material A after heat treatment at a temperature of 250°C for 2 hours under nitrogen, characterized in that it comprises the following successive steps: (1) at least one heat treatment step of material A in the presence of oxygen, at a temperature in the range of 350°C to 900°C, (2) at least one washing step of material A' from step (1) with an aqueous solvent;(3) at least one step of extracting the metal(s) M by contacting the material A" from step (2) with a solution S containing at least one carboxylic acid; and (4) at least one step of depositing at least a part of the metal(s) M onto a porous material B different from said material A, by contacting the solution S' from step (3) with said material B.;

2. Method according to the preceding claim, characterized in that the metal or metals M are selected from iron, cobalt, nickel, copper, and zinc and preferably from nickel, copper, and zinc.

3. A method according to any one of the preceding claims, characterized in that the material A contains a single metal M belonging to columns 8 to 12 of the periodic table of elements, said metal M preferably being nickel, copper, or zinc.

4. A method according to any one of the preceding claims, characterized in that the material B contains one or more refractory mineral oxides, selected from aluminas, silicas, silica-aluminas, zeolites, zirconias, titanium and boron oxides, and mixtures of such oxides, and preferably from aluminas, silicas, silica-aluminas, and more preferably aluminas.

5. A method according to any one of the preceding claims, characterized in that the heat treatment step (1) is carried out at a temperature in the range of 400 to 600°C, preferably from 450 to 580°C and more preferably from 480 to 570°C.

6. Method according to any one of the preceding claims, characterized in that the aqueous solvent used in the washing step (2) contains at least 50% by weight of water, preferably at least 75% by weight, and better still at least 90% by weight of water, and better still the solvent consists of water.

7. Method according to any one of the preceding claims, characterized in that the washing step (2) is carried out at a temperature ranging from 20°C to 150°C, preferably from 25 to 100°C, and more preferably from 30 to 70°C.

8. Method according to any one of the preceding claims, characterized in that the carboxylic acid(s) present in the solution S used in step (3) are selected from mono-acids, di-acids and tri-carboxylic acids, preferably comprising from 1 to 8 carbon atoms.

9. A method according to the preceding claim, characterized in that the carboxylic acid(s) are selected from acetic acid, citric acid, maleic acid, glycolic acid, and mixtures of these acids, and preferably from acetic acid, citric acid, and mixtures thereof

10. Method according to any one of the preceding claims, characterized in that the solution S contains a total carboxylic acid content in the range of 5 to 50% by weight, preferably 10 to 30% by weight, relative to the total weight of the solution S.

11. Method according to any one of the preceding claims, characterized in that step (3) is carried out at a temperature ranging from 20°C to 150°C, preferably from 50 to 130°C, and more preferably from 80 to 120°C.

12. Method according to any one of the preceding claims, characterized in that step (4) is carried out by impregnating the material B with the solution S' by proceeding by dry impregnation, by saturation impregnation of the porous volume, or by soaking the material B in a large excess of solution S'.

13. A method according to any one of the preceding claims, characterized in that during step (4) the solution S' was maintained in contact with said material B for a period of 1 to 30 hours, preferably 5 to 25 hours, and even more preferably 10 to 20 hours. hours.

14. Method according to any one of the preceding claims, characterized in that step (4) is repeated by contacting the material B either with the same solution S' or with a different solution So', obtained from the treatment by means of steps (1) to (3) of a starting material Ao different from A, and which contains a metal or several metals Mo' which may be identical or different from the metal or metals M.

15. Method according to any one of the preceding claims, characterized in that it comprises, after step (4), a drying step of material B, carried out at a temperature ranging from 80°C to 300°C, preferably from 100°C to 150°C.