Method for recycling metals from porous materials comprising metals

Abstract

To provide a method for recycling metals from porous materials comprising metals.SOLUTION: A method comprises: (1) at least one step of heat treatment of a porous material A which comprises at least one mineral oxide and has a sulphur content of 2 wt.% or more in the presence of oxygen, at a temperature comprised within the range from 350°C to 900°C; (2) at least one step of washing the material derived from step (1) by means of an aqueous solvent; (3) at least one step of extracting one or more metals M selected from among those belonging to the columns 8 to 12 of the periodic table of elements, present at least partially in the form of metal sulphides in A by setting the material derived from step (2) in contact with a solution containing at least one carboxylic acid; and (4) at least one step of depositing at least one portion of the metal(s) M over a porous material B different from the material A, by setting the solution derived from step (3) in contact with the porous material B.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates particularly to the recycling of metals present in porous materials such as traps and adsorbents used in the petroleum refining and petrochemical fields. [Background technology]

[0002] The hydrocarbon conversion process involves a porous material, generally in the form of particles, based on one or more refractory oxides such as alumina, silica, and aluminosilicate (zeolite), and further incorporating an agent commonly called a trap or adsorbent, which contains a substantial amount of metal such as nickel, copper, and zinc. These substances are used, for example, to capture undesirable chemical species that are maintained by adsorption. For instance, traps are typically used in hydrogenation reactors upstream of catalyst beds to capture contaminants present in gasoline feedstock (including compounds containing undesirable metals such as sulfur compounds, mercury, vanadium, arsenic, etc.) and to protect the catalyst from contaminants that could poison the catalyst site and cause premature catalyst deactivation. Therefore, these materials are expected to be contaminated at the end of their service cycle with extremely high concentrations of undesirable compounds, leading to spent materials that are difficult to recycle and / or regenerate. However, it is essential to be able to recycle the metals that are often present in large quantities in these materials.

[0003] The problems with recycling metals present in catalysts differ from those with metals present in traps and adsorbents. On the one hand, the metal content is significantly higher in traps and adsorbents compared to catalysts. On the other hand, the contamination levels are much higher in traps and absorbents, and the properties of the contaminants are different. While prior art has developed methods for recycling metals present in catalysts, these methods are not always effective for recycling metals present in spent traps or absorbents.

[0004] In Chapter 11 of the first edition of the 2010 study titled "Handbook of Spent Hydroprocessing Catalyst" published by Elsevier Science Inc., authors Meena Marafi et al. disclose various techniques for recovering metals from spent hydroprocessing catalysts that substantially contain alumina and metals such as molybdenum, nickel, cobalt, and occasionally vanadium. The most classic method disclosed above is, - This is a high-temperature metallurgical method in which used catalysts are melted in a suitable furnace, and metals are separated from the slag containing alumina and / or silica. Thus, the slag is typically intended for the production of insulation materials such as rock wool, but the metals are recovered, for example, in special alloys, so recycling is carried out in a so-called open loop. -Wet metallurgical methods, which involve calcining and then leaching used catalysts, are generally carried out using strong acidic and / or basic solutions. The use of organic acids or microorganisms (bioleaching) is also disclosed.

[0005] Other technologies are being researched, such as the sublimation of several metals including molybdenum, the volatilization or dissolution of metals in chlorinated media, and reduction combined with magnetic separation. However, these technologies remain difficult to implement on an industrial scale.

[0006] International Publication No. 2007 / 001921 discloses a method for extracting and recovering nickel, cobalt, iron, tungsten, molybdenum, and vanadium from alumina-based materials containing metal oxides (such as catalysts impregnated with hydrocarbons) in an oxygen-containing atmosphere, as well as the reaction of HCl gas with oxidized metals to form volatile compounds containing one or more chlorides and / or acid chlorides. Handling this type of compound, particularly corrosive compounds, requires highly specialized equipment, as well as considerable know-how and safety standards.

[0007] International Publication No. 03 / 080878 discloses a method for extracting nickel from a spent catalyst by leaching with sulfuric acid in the presence of a persulfate-based additive. The leached solution is then treated to obtain a by-product containing high content alumina and crystals of nickel sulfate or nickel hydroxide. The nickel hydroxide is then reduced to obtain metallic nickel or nickel oxide powder. Subsequently, nickel hydroxide is reduced to obtain metallic nickel or nickel oxide powder.

[0008] Korean Published Patent No. 20120128913 discloses a method for recovering valuable metals contained in waste by leaching using an aqueous solution of organic acid. [Overview of the project]

[0009] The applicant has now discovered a method for efficiently recycling metals present in porous materials, particularly traps and adsorbents. The method according to the present invention makes it possible to selectively extract these metals, including when the material containing the metals is highly contaminated, and to redeposit them into another material for reuse.

[0010] Accordingly, the object of the present invention is a method for recycling one or more metals M selected from groups 8 to 12 of the periodic table, which are present at least partially in the form of metal sulfides in a porous material A that contains at least one inorganic oxide and has a sulfur content of 2% by mass or more. The method according to the present invention is as follows: (1) At least one step of heat treatment of substance A in the presence of oxygen at a temperature within the range of 350°C to 900°C, (2) At least one step of washing substance A' obtained from step (1) with an aqueous solvent, (3) At least one step of extracting metal M by placing substance A'' obtained from step (2) in contact with solution S containing at least one carboxylic acid, and (4) A series of steps including at least one step of depositing at least a portion of metal M on porous material B which is different from material A, by placing the solution S' obtained from step (3) in contact with material B.

[0011] Thus, the present invention enables the recycling of one or more metals M belonging to groups 8 through 12 of the periodic table, which are present on a porous material A based on inorganic oxides contaminated with undesirable compounds containing at least sulfur, which exist in the form of metal sulfides and other sulfiding compounds such as sulfur hydrocarbons. Typically, material A is a spent trap or absorbent after use in a hydrocarbon processing unit.

[0012] Substance B may be any porous material capable of receiving deposits of metal M. Advantageously, substance B may be metal-free, in which case the present invention enables the preparation of catalysts, traps and / or adsorbents intended, among other things, for use in hydrocarbon processing units. A more advantageous option is that substance B is a catalyst, trap or adsorbent in a new or recycled (regenerated) state, in which case the present invention enables the modification of its activity.

[0013] The method according to the present invention is simple in appearance and does not require the use of toxic or corrosive substances. It enables the efficient reuse of metals present in spent starting material A. Furthermore, it regenerates the metals into a catalytically active form, on the one hand preparing new active substances such as catalysts, traps and / or absorbents, and on the other hand enhancing the activity of existing catalysts, traps and / or absorbents.

[0014] The recycling rate of metals can reach 50-75% by mass of the metals initially contained in substance A. Furthermore, solution S containing one or more carboxylic acids can be reused as is without any additional purification treatment. Other objects, features, embodiments, and advantages of the present invention will become clearer upon reading the following description and examples. Next, unless otherwise specified, the boundaries of a value range are included within this range, particularly in the expressions "consisting of" and "range from... to...". Furthermore, as used herein, "at least one" and "at least" respectively correspond to the expressions "one or more" and "more than". (Detailed Description)

[0015] (Starting Material A (Metal Donor Substance)) The present invention is applicable to starting material A, which is a substance particularly contaminated with sulfur and is selectively extracted to transfer to substance B, which is mainly an uncontaminated substance intended for use, and contains one or more metals M. One or more metals M are selected from those belonging to Groups 8 to 12 of the Periodic Table of the Elements. Here, reference is made to the version of the Periodic Table of the Elements issued by IUPAC (International Union of Pure and Applied Chemistry). In starting material A, all or part of one or more metals M exist in the form of metal sulfides (i.e., sulfides of metals). If one metal (or metals) M is not completely in the form of metal sulfides, it (or they) may also be in the form of any other chemical species such as metal oxides, elemental metal forms, etc. Preferably, one or more metals M are selected from iron, cobalt, nickel, copper, and zinc, and more preferably nickel, copper, and zinc.

[0016] According to a preferred embodiment, substance A contains one single metal M belonging to Groups 8 to 12 of the Periodic Table of the Elements. In this embodiment, the metal M is preferably nickel, copper, or zinc. According to another preferred embodiment, substance A does not contain any metals belonging to Group 6 of the Periodic Table of the Elements. Substance A further contains one or more refractory inorganic oxides selected particularly from alumina, silica, silica-alumina, zeolites, zirconia (zircones), titanium, and boron oxide, and mixtures of such oxides. When the inorganic oxide is a metal oxide, it is selected from oxides of metals not belonging to Groups 8 to 12 of the Periodic Table of the Elements. Preferably, the substance A contains one or more inorganic oxides selected from alumina, silica, silica-alumina, and more preferably alumina.

[0017] The substance A is represented in the form of the ratio of the total mass of the oxide of metal M to the total mass of the inorganic oxide, and advantageously contains one or more metals M in the content mainly within the range of a ratio of 0.2 to 5.5, preferably 1 to 4. To measure this ratio, the mass of metal M present in substance A is expressed based on the total equivalent of the corresponding metal oxide. The starting substance A also contains sulfur at a content of at least 2% by mass. Advantageously, this content is expressed as the mass of sulfur element (i.e., element S) relative to the mass of substance A heat-treated at a temperature of 250 °C for 2 hours under nitrogen. In other words, the sulfur content of the starting substance A is measured with the substance obtained after treating at a temperature of 250 °C for 2 hours under nitrogen and then cooling to room temperature under nitrogen. Generally, the starting substance A is in the form of solid particles such as beads, cylindrical particles, extrudates, tablets, etc. It has a specific surface area of generally 50 to 250 m 2 / g, a porous volume in the range of 0.2 to 0.8 ml / g measured by nitrogen adsorption, and an average pore diameter in the range of 10 to 40 nm measured by nitrogen adsorption.

[0018] (Substance B (metal receiver substance)) The substance B used in step (4) may be any porous substance different from the starting substance A. Advantageously, it contains one or more refractory inorganic oxides that can be selected from alumina, silica, silica-alumina, zeolite, zirconia, titanium, and boron oxide, as well as mixtures of such oxides. Preferably, substance B comprises one or more inorganic oxides selected from alumina, silica, silica-alumina, and preferably alumina.

[0019] According to the first embodiment, substance B contains no metal whatsoever. In this embodiment, the method according to the present invention makes it possible to prepare, for example, new traps, adsorbents, and catalysts from unused inorganic oxides. According to the second embodiment, substance B comprises one or more metals M', which may be the same as or different from the metal M. In particular, the metal(s) M' may be selected from metals belonging to groups 6 to 12 of the periodic table. If present, the metal M' is preferably in the form of a metal oxide or an element. In this embodiment, the method according to the present invention makes it possible to particularly enhance the effectiveness of the trap, adsorbent and catalyst.

[0020] According to a preferred embodiment, substance B is sulfur-free. Regarding the sulfur-free aspect, it should be understood that the sulfur content, expressed in the form of elemental sulfur S, is less than 0.5% by mass relative to the mass of substance B. Preferably, substance B is in the form of solid particles such as beads, cylindrical particles, or extruded products. It is measured by the BET method and is generally 50-300m 2 It has a specific surface area per g, a porous volume in the range of 0.2 to 1 ml / g measured by nitrogen adsorption, and an average pore diameter in the range of 7 to 40 nm measured by nitrogen adsorption.

[0021] (Process 1) Step (1) consists of heating the starting material A in the presence of oxygen at a temperature within the range of 350 to 900°C. This process aims to remove volatile compounds (hydrocarbons, water, etc.) and carbon compounds (including coke) present on the surface of substance A. Preferably, this heat treatment step is carried out at a temperature within the range of 400 to 600°C, more preferably 450 to 580°C, and even better, 480 to 570°C. The temperature of this process can be controlled by a method known in itself, for example, by a thermocouple appropriately placed on a mass of material A.

[0022] The first step is carried out in the presence of oxygen, for example, using gaseous steam containing oxygen. For example, this gas may consist of air mixed with pure or additional oxygen or an inert gas 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 a mixture of other gases containing oxygen. Preferably, the oxygen content of the gas is controlled to better control the temperature in step (1). This content may be fixed, or conversely, may change over time during the first step. The gas flow rate is also controlled to regulate combustion. This heat treatment process may include several steps carried out at different temperatures and / or in the presence of a variable amount of oxygen. Generally, the total time required for this initial step depends on the amount of substance A being processed, its composition, the amount of volatile compounds present on its surface, and the operating conditions (temperature, oxygen content). Higher temperatures will further shorten this time. Generally, it includes 0.1 to 20 hours, preferably 0.2 to 10 hours. Substance A after processing in step (1) is denoted as substance A'.

[0023] (Process 2) This step involves washing substance A' obtained from step (1) with an aqueous solvent. Such washing consists of placing the surface of substance A' in contact with the aqueous solvent and then removing the solvent. Regarding aqueous solvents, please understand that this refers to any solvent that includes water. Therefore, in addition to water, the solvent may include any water-soluble organic solvent that can be selected from, for example, alcohols and polyols. Any organic or inorganic additive may be added to the aqueous solvent. According to a preferred embodiment, the aqueous solvent comprises at least 50% by mass of water, preferably at least 75% by mass, and better 90% by mass of water. More preferably, the solvent comprises water (with a water content higher than 99% by mass). Advantageously, the volume of aqueous solvent used in this process is greater than the total porous volume of the treated substance A' sample. In particular, this volume may be in the range of 2 to 20 times the total porous volume of substance sample A', preferably 5 to 10 times the porous volume.

[0024] Step (2) can be carried out at any suitable temperature in the range of room temperature (20°C) to 150°C. Preferably, this step is carried out under photothermal heating, i.e., in a temperature range of 25 to 100°C, preferably 30 to 70°C. During this process, it is advantageous to allow the mixing of substance A' and the aqueous solvent to proceed, ensuring effective cleaning of the substance's surface. This process can be carried out continuously or discontinuously (so-called "batch" mode), and the amount of water used can be limited, so discontinuous mode is preferred. This process can be carried out using any solid / liquid extractor unit or industrial mixer (e.g., a conical mixer or a biconical mixer). The substance A' after processing in step (1) is denoted as A''.

[0025] (Step 3) This step involves extracting the metal M by contacting the substance A'' obtained from step (2) with a solution S containing at least one carboxylic acid. This step allows for the extraction of the metal from substance A'' by dissolving the metal from substance A'' in the form of an organic acid salt. Solvent S may be selected from water, organic solvents (especially alcohols and polyols), and mixed solvents of water and organic solvents. Preferably, the solvent S contains at least 50% by mass of water, preferably at least 60% by mass of water, based on the total mass of the solution S. The carboxylic acids present in solution S may be monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids. Preferably, they contain 1 to 8 carbon atoms. According to a preferred embodiment, the carboxylic acid is selected from acetic acid, citric acid, maleic acid, glycolic acid, and mixtures thereof. Preferably, the carboxylic acid is selected from acetic acid, citric acid, and mixtures thereof.

[0026] Solution S contains a total carboxylic acid content that is typically in the range of 5 to 50% by mass, preferably 10 to 30% by mass, relative to the total mass of solution S. Advantageously, the volume of solution S used in step (3) is greater than the total porous volume of the sample of substance A'' that was treated. In particular, this volume may be within the range of 2 to 50 times the total porous volume of the sample of substance A'', preferably 5 to 20 times the porous volume, and even better, 10 to 15 times the porous volume.

[0027] Step (3) can be carried out at any suitable temperature within the range of room temperature (20°C) to 150°C. Preferably, this step is carried out at a high temperature, i.e., at a temperature in the range of 50 to 130°C, preferably 80 to 120°C. During this process, it is advantageous to allow mixing of substance A'' and solution S to proceed, ensuring optimal contact between the solution and the surface of the substance. This process can be carried out continuously or discontinuously ("batch" mode) in any suitable unit, such as a solid / liquid extractor or an industrial mixer (e.g., a conical mixer or a biconical mixer). Upon completion of step (3), the solution S' containing the salt of one (or more) metals M is separated from substance A'' by any suitable separation method, such as filtration or centrifugation.

[0028] (Step 4) During this process, one or more metals M, which exist in the form of salts in the solution S' obtained from step (3), are deposited onto the porous material B. This is carried out by placing the solution S' containing the metal salts obtained from step (3) in contact with the material B. According to a preferred embodiment, step (4) is carried out by impregnating substance B with the solution. This is carried out by dry impregnation (i.e., using a solution volume smaller than the porous volume of substance B), saturation impregnation of porous volume (i.e., using a solution volume greater than or equal to the porous volume of substance B), or immersing substance B in a large excess of solution S'.

[0029] This contact may be momentary or last for up to several days. Preferably, solution S' is in contact with substance B for a period ranging from 1 to 30 hours, preferably 5 to 25 hours, and even better, 10 to 20 hours. Step (4) can be carried out at a pressure in the range of atmospheric pressure to 5 bar, preferably under atmospheric pressure. Step (4) can be carried out at any suitable temperature in the range of 10 to 50°C, for example. Preferably, this step is carried out at a temperature in the range of 10 to 30°C. Generally, step (4) should be carried out under conditions that allow as much metal M as possible to be deposited on the surface of material B.

[0030] In a preferred embodiment, step (4) is repeated once or several times (for example, up to five times) to increase the amount of metal M deposited on substance B. In this embodiment, it is advantageous that substance B may be brought into contact again with the same solution S', or into contact with a different solution S0' obtained from the treatment of a different starting material A0 by steps (1) to (3) and containing one or more metals M0' that are the same as or different from one or more metals M. If step (4) is repeated, it may be advantageous to proceed with the intermediate drying of substance B before repeating step (4), as described below. Preferably, upon completion of the method according to the present invention, the total amount of metal(s) M deposited on substance B in the form of metal oxides is at least 1% by mass relative to the final total mass of substance B. Preferably, this amount consists of 2 to 10% by mass.

[0031] (Other additional steps) In addition to the steps (1) to (4) described above, the method according to the present invention may optionally include one or more additional steps performed before and / or after the steps, or inserted between these steps. Accordingly, the method according to the present invention may include a step of drying substance B after step (4), which can be carried out at a temperature in the range of 80 to 300°C, preferably 100 to 150°C. Drying can be carried out in open air or in the presence of a gaseous stream of air, an inert gas such as nitrogen, or any other suitable gas. The method according to the present invention may optionally include a step of calcining substance B after step (4) at a temperature in the range of 300 to 500°C. Calcination may be carried out in open air or in the presence of a gaseous stream of air, an inert gas such as nitrogen, or any other suitable gas. If the method according to the present invention already includes a drying step, a caking step (if any) is performed thereafter. Finally, the method according to the present invention may include one or more final steps of activating a final substance B, which is intended to activate a metal part. The following embodiments are given to illustrate the present invention and should be construed as limitations on the scope of the invention. [Examples]

[0032] (Substances used) The following examples were prepared based on a donor substance A1, which is a sulfur trap consumed after use in a hydrocarbon hydrogenation treatment unit. The substance A1 is in the form of particles consisting of alumina and nickel (the nickel is in the form of partially reduced and partially re-oxidized nickel and partially nickel sulfide). The substance A1 has a total nickel content expressed based on the equivalent amount of nickel oxide (NiO) such that the NiO:Al2O3 mass ratio is 3.2. This used trap A1 contains 1.7% by mass of carbon and 2.9% by mass of sulfur. These measurements were performed on A1 that had been preheated under nitrogen for 2 hours at a temperature of 250°C in a vertical furnace, using a LECO brand CS230 model analyzer. As the acceptor substance B1, a used and recycled hydrogenation catalyst consisting of 41.8% nickel oxide (NiO) and alumina was used.

[0033] (Sulfur scavenging capacity evaluation test) These tests allow for the evaluation of the ability of porous materials to capture sulfur in hydrocarbon raw materials and are conducted using two sulfur organic compound models: n-butyl mercaptan and thiophene. The test consists of placing a solution of one of these two compounds in contact with the substance in a pressurized reactor under specific conditions, and measuring the amount of sulfur captured by the test substance. Before each test, the substance is activated under a flow of hydrogen (H2) at 450°C for 4 hours.

[0034] For the mercaptan capture test, a test solution containing n-butyl mercaptan in a toluene / n-hexane mixture (volume ratio 50 / 50) is used. This solution has a sulfur content of 1000 ppm by mass, expressed as elemental sulfur (S), relative to the total mass of the test solution. For the thiophene capture test, a test solution containing thiophene in a toluene / n-hexane mixture (volume ratio 50 / 50) is used. This solution has a sulfur content of 1000 ppm by mass, expressed in the form of elemental sulfur (S), relative to the total mass of the test solution.

[0035] The reactor used above consists of two parts: a cylinder made of Teflon (PTFE) with a lid, and a metal reactor body (PARR4749 type) that ensures airtightness and pressure maintenance inside the reactor. The reactor is filled as follows: the PTFE cylinder and its lid are weighed, and then filled with 15 mL of one of the two organic sulfur compounds in a test solution. In the mercaptan capture test, 0.05 g of the porous material to be tested is added to the reactor under an inert atmosphere. For the thiophene capture test, 0.5 g of the porous material to be tested is added to the reactor under an inert atmosphere. Next, the PTFE cylinder is closed with its lid and placed in a metal reactor. The latter is then sealed and placed in a thermostat container at 185°C for 17 hours.

[0036] Subsequently, the reactor is cooled to room temperature before opening it under an inert atmosphere. The PTFE cylinder and its lid are weighed, and then the liquid sample is collected for analysis using an Antek 9000 sulfur content analyzer. The difference in sulfur content between the solution before and after the test allows for the calculation of the amount of sulfur captured by the porous material. This amount is expressed as the mass percentage of captured sulfur compared to the weight of the porous material.

[0037] (Comparative Example 1) A first test of recycling nickel from substance A1 to substance B1 was carried out according to a comparative procedure consisting of steps (1), (3), and (4) described below. (Process 1) The substance A1 underwent a heat treatment process by being maintained in a muffle furnace under air at a temperature of 550°C for 2 hours. In this way, substance A1' was obtained. This substance contains 0.1 mass% carbon and 2.8 mass% sulfur. These contents were measured using a LECO brand CS230 model analyzer.

[0038] (Step 3) 50 g of substance A1' was placed in a rotary vial equipped with a mechanical stirrer, and solution S1, obtained by mixing 103 g of water and 146.6 g of 50% by mass aqueous citric acid solution, was added. The contents of the vial were stirred under reflux at a temperature of 100°C for 2 hours. After cooling, the mixture is filtered, and solution S1' (containing solution S1 and nickel salt) is recovered in this manner.

[0039] (Step 4) Next, solution S1 is placed in contact with substance B1, and impregnation is carried out in a porous volume using 43.4 g of solution S1' for 100 g of substance B1. Let the mixture rest at room temperature for 16 hours. Next, substance B1 is dried in a 130°C oven for 1.5 hours, and the impregnation in the porous volume is repeated in the same manner using the same amount of solution S1' for 16 hours. Finally, the substance is subjected to a final drying (1.5 hours in an oven at 130°C). The modified substance obtained by the above comparison method is B1 c It will display as follows.

[0040] (Substance B1 c (Determination of the properties of) Nickel content analysis (by X-ray fluorescence): Substance B1 c It has a nickel oxide content of 46.8% by mass. Therefore, the method comprising steps (1), (3), and (4) made it possible to increase the NiO content of receiver material B1 from 41.8% by mass to 46.8% by mass. Sulfur capture capacity: The two sulfur capture tests described above were performed on the original substance B1 and on substance B1 C The above procedure was performed. The results are detailed in Table 1 below.

[0041] [Table 1] The results show that although the substance modified by the comparative method has a higher nickel content than the starting material B1, it still exhibits slightly reduced activity compared to substance B1.

[0042] (Example 2 according to the present invention) A second test for recycling nickel from substance A1 to substance B1 was carried out according to the procedure according to the present invention consisting of the following steps (1), (2), (3) and (4). - Steps (1), (3) and (4) are exactly the same as those in Example 1 above. - Between steps (1) and (3), step (2) described below is inserted.

[0043] (Step 2) 50 g of substance A1' was placed in a rotary vial equipped with a mechanical stirrer, and then 100 ml of deionized water was added. The contents of the vial were stirred at a temperature of 50 °C for 2 hours. After cooling to room temperature, the water was removed by filtration, and the substance A” thus recovered was placed again in the vial for carrying out step (3). The substance obtained at the completion of step (4) after final drying is designated as B1 I-1 and shown as.

[0044] (Substance B1 I-1 Determination of properties) Analysis of nickel content (by X-ray fluorescence): The substance B1 I-1 has a nickel oxide content of 46.5% by mass. Thus, the method according to the present invention including steps (1), (2), (3) and (4) has made it possible to increase the NiO content of the receiver B1 from 41.8% by mass to 46.5% by mass. Sulfur capture ability: The two sulfur capture tests were carried out on the original substance B1 and on the substance B1<000001o>The results are detailed in Table 2 below.

[0045]

Table 2

[0046] (Example 3 of the present invention) A third test for recycling nickel from substance A1 to substance B1 was carried out according to the procedure of the present invention, consisting of steps (1), (2), (3), and (4) described later. (Process 1) The substance A1 underwent a heat treatment process by being maintained in a muffle furnace under air at a temperature of 550°C for 2 hours. In this way, substance A1' was obtained. This substance contains 0.1% by mass of carbon and 2.8% by mass of sulfur. These contents were measured using a LECO CS230 analyzer. (Process 2) 50 g of substance A1' was placed in a rotary vial equipped with a mechanical stirrer, and then 100 mL of demineralized water was added. The contents of the vial were stirred at 50°C for 2 hours. After cooling to room temperature, the water was removed by filtration, and the recovered substance A1'' was placed back into the vial.

[0047] (Step 3) Solution S2, obtained by mixing 176 g of water and 22.8 g of 99% by mass pure acetic acid in water, was added to substance A1'' in the vial. The contents of the vial were stirred under reflux at 100°C for 2 hours. After cooling, the mixture is filtered, and solution S2' (containing solution S2 and nickel salt) is recovered in this manner. (Step 4) Next, solution S2 is placed in contact with substance B1, and impregnation is carried out in a porous volume using 35.5 g of solution S2' to impregnate 100 g of substance B1. Let the mixture rest at room temperature for 16 hours. Next, substance B1 is dried in a 130°C oven for 1.5 hours, and the impregnation in the porous volume is repeated in the same manner using the same amount of solution S2' for 16 hours. Finally, the substance is subjected to a final drying (1.5 hours in an oven at 130°C). The modified substance obtained by the above comparison method is B1 I-2 It will display as follows.

[0048] (Substance B1 I-2 (Determination of the properties of) Nickel content analysis (by X-ray fluorescence): Substance B1 I-2 It has a nickel oxide content of 45.4% by mass. Therefore, the method according to the present invention, comprising steps (1), (2), (3) and (4), made it possible to increase the NiO content of the acceptor substance B1 from 41.8% by mass to 45.4% by mass. Sulfur capture capacity: The two sulfur capture tests described above were performed on the original substance B1 and on substance B1 I-2 The above procedure was performed. The results are detailed in Table 3 below.

[0049] [Table 3] The results show that the substance modified according to the method of the present invention has significantly higher activity than the original substance B1.

Claims

1. A method for recycling one or more metals M selected from among metals that belong to groups 8 to 12 of the periodic table, contain at least one inorganic oxide, and have a sulfur content of 2% by mass or more, and which are present at least partially in the form of metal sulfides in a porous material A, comprising the following series of steps: (1) At least one step of heat treatment of substance A in the presence of oxygen at a temperature within the range of 350°C to 900°C, (2) At least one step of washing substance A' obtained from step (1) with an aqueous solvent, (3) At least one step of extracting metal M by placing substance A'' obtained from step (2) in contact with a solution S containing at least one carboxylic acid, and (4) A method comprising at least one step of depositing at least a portion of a metal M on a porous material B different from material A by placing the solution S' obtained from step (3) in contact with the material B.

2. The method according to claim 1, wherein the one or more metals M are selected from iron, cobalt, nickel, copper, and zinc, and preferably from nickel, copper, and zinc.

3. The method according to claim 1 or 2, wherein substance A contains a single metal M belonging to group 8 to group 12 of the periodic table, and the metal M is preferably nickel, copper, or zinc.

4. The method according to claim 1 or 2, wherein substance B comprises alumina, silica, silica-alumina, zeolite, zirconia, titanium, and boron oxide, and mixtures of such oxides, and preferably one or more refractory inorganic oxides selected from alumina, silica, silica-alumina, and more preferably alumina.

5. The method according to claim 1 or 2, wherein the heat treatment step (1) is performed at a temperature within the range of 400 to 600°C, preferably 450 to 580°C, and more preferably 480 to 570°C.

6. The method according to claim 1 or 2, wherein the aqueous solvent used in the washing step (2) comprises at least 50% by mass of water, preferably at least 75% by mass of water, and more preferably at least 90% by mass of water, and more preferably the solvent is water.

7. The method according to claim 1 or 2, wherein the washing step (2) is performed at a temperature in the range of 20 to 150°C, preferably 25 to 100°C, and more preferably 30 to 70°C.

8. The method according to claim 1 or 2, wherein the carboxylic acid present in solution S used in step (3) is selected from monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids, and preferably contains 1 to 8 carbon atoms.

9. The method according to claim 8, wherein the carboxylic acid is selected from acetic acid, citric acid, maleic acid, glycolic acid, and mixtures thereof, and preferably from acetic acid, citric acid, and mixtures thereof.

10. The method according to claim 1 or 2, wherein solution S contains a total content of carboxylic acids in the range of 5 to 50% by mass, preferably 10 to 30% by mass, based on the total mass of solution S.

11. The method according to claim 1 or 2, wherein step (3) is performed at a temperature in the range of 20 to 150°C, preferably 50 to 130°C, and more preferably 80 to 120°C.

12. The method according to claim 1 or 2, wherein step (4) is carried out by impregnation of substance B using solution S', which proceeds by dry impregnation, saturation impregnation of porous volume, or immersion of substance B in a large excess of solution S'.

13. The method according to claim 1 or 2, wherein in step (4), solution S' remains in contact with substance B for a period of 1 to 30 hours, preferably 5 to 25 hours, and more preferably 10 to 20 hours.

14. Step (4) involves bringing substance B into contact with the same solution S', or one or more metals M that are different from A and identical or different from one or more metals M. 0 Starting material A, which contains ' 0 Different solutions S obtained from the processing by steps (1) to (3) 0 The method according to claim 1 or 2, wherein the process of repeatedly placing the object in contact with the object is repeated.

15. The method according to claim 1 or 2, further comprising the step of drying substance B at a temperature in the range of 80 to 300°C, preferably 100 to 150°C, after step (4).