Method for leaching vanadium from red mud through supercritical oxidation

Abstract

The invention relates to a method for leaching vanadium from red mud through supercritical oxidation, and belongs to the technical field of vanadium recovery. The method comprises the following steps: dispersing red mud in a leaching solution to obtain red mud slurry which can provide conditions for subsequent reaction; an oxidizing agent is added into the red mud slurry, the red mud slurry containing the oxidizing agent is subjected to a supercritical oxidation leaching reaction, and a reaction mixture is obtained; vanadium in the red mud forms vanadium oxide in an oxidation state under the action of an oxidizing agent, and the vanadium oxide is leached in a supercritical water system and dissolved in leachate. As the vanadium oxide has higher solubility in the leachate, the leaching reaction can be promoted to be continuously carried out until the vanadium is completely leached or the leachate is saturated, and the reaction is finished. And after the reaction is finished, a reaction mixture is obtained, solid-liquid separation is conducted on the reaction mixture, and finally vanadium leaching liquid is obtained. According to the method, few types of reagents are used in the implementation process, the reaction process is simple, the vanadium leaching efficiency is high, and a foundation is laid for follow-up vanadium recycling and reusing.

Description

Technical Field

[0001] This application relates to the technical field of vanadium recovery, and particularly to a method for leaching vanadium from red mud by supercritical oxidation. Background Art

[0002] Red mud is an alkaline solid waste generated during the production of alumina, which contains 0.038% - 0.14% valuable vanadium elements. Part of the vanadium comes from the accumulation of sodium metavanadate in the mother liquor, which precipitates supersaturated and enters the red mud. The other part is the undissolved vanadium in the bauxite, which usually exists in the forms of roscoelite and illite, and its valence states are mostly trivalent and tetravalent.

[0003] Currently, the technologies with more research and relatively mature for vanadium extraction mainly include calcium method for vanadium extraction and sodium method for vanadium extraction. Among them, the calcium method for vanadium extraction destroys the spinel structure through calcification roasting, converting the vanadium in the spinel into acid-soluble calcium vanadate, and then using sulfuric acid as the leaching agent to leach the vanadium slag. This method has high energy consumption and generates an increase in red mud, and is not suitable for the leaching of vanadium in red mud. The sodium method for vanadium extraction destroys the spinel structure through sodium roasting, converting the vanadium in the spinel into water-soluble sodium vanadate, and then using water as the leaching agent to leach the vanadium slag. Acidic gases such as HCl, Cl2, and SO2 are generated during the sodium leaching process, resulting in serious pollution.

[0004] Therefore, it is necessary to develop a method suitable for leaching vanadium from red mud in view of the phase structure of red mud ore and its structure-activity relationship. Summary of the Invention

[0005] This application provides a method for leaching vanadium from red mud by supercritical oxidation to solve the following technical problem: how to efficiently leach vanadium from red mud.

[0006] An embodiment of this application provides a method for leaching vanadium from red mud by supercritical oxidation, including the following steps:

[0007] Disperse red mud in a leaching solution to obtain a red mud slurry;

[0008] Add an oxidant to the red mud slurry, and perform a supercritical oxidation leaching reaction on the red mud slurry containing the oxidant to obtain a reaction mixture;

[0009] Perform solid-liquid separation on the reaction mixture to obtain a leaching solution of vanadium.

[0010] Optionally, the leaching solution has a certain solubility for vanadium-containing compounds.

[0011] Optionally, the leaching solution includes at least one of ionic liquids, inorganic salts, and organic amines.

[0012] Optionally, the ionic liquid comprises at least one of the following: 1-(3-aminopropyl)-3-methylimidazolium chloride, triethylamine hydrochloride, and 1-ethyl-3-methylimidazolium glycinate.

[0013] Optionally, the inorganic salt substance comprises at least one of the following: carbonate, bicarbonate, sulfate, and hydrochloride.

[0014] Optionally, the mass concentration of the ionic liquid in the leaching solution is 10% to 20%; and / or,

[0015] the mass concentration of the salt substance is 5% to 20%.

[0016] Optionally, the liquid-solid ratio of the leaching solution to the red mud is 3 to 10.

[0017] Optionally, the oxidant comprises at least one of the following: hydrogen peroxide, ozone, sodium hypochlorite, and sodium nitrate.

[0018] Optionally, adding an oxidant to the red mud slurry and performing a supercritical oxidation leaching reaction on the red mud slurry containing the oxidant to obtain a reaction mixture, specifically including:

[0019] Preheating the red mud slurry and adding an oxidant to the preheated red mud slurry;

[0020] Placing the red mud slurry containing the oxidant in a supercritical water reaction system to perform a supercritical oxidation leaching reaction to obtain a reaction mixture.

[0021] Optionally, the reaction temperature of the supercritical oxidation leaching reaction is greater than 374 °C, and the reaction pressure is greater than 22.1 MPa.

[0022] Optionally, the reaction time of the supercritical oxidation leaching reaction is 30 min to 240 min.

[0023] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0024] The present application provides a method for leaching vanadium from red mud by supercritical oxidation of red mud, which includes the following steps: dispersing red mud in a leaching solution. Since the leaching solution has a certain solubility for vanadium, the obtained red mud slurry can provide conditions for subsequent reactions; adding an oxidant to the red mud slurry, and performing a supercritical oxidation leaching reaction on the red mud slurry containing the oxidant to obtain a reaction mixture; vanadium in the red mud forms vanadium oxides in the oxidized state under the action of the oxidant, and the vanadium oxides are leached in the supercritical water system and dissolved in the leaching solution. Since the vanadium oxides have a large solubility in the leaching solution, the leaching reaction can be promoted to continue until the vanadium is completely leached or the leaching solution reaches saturation, and then the reaction ends. The reaction mixture obtained after the reaction ends includes red mud waste residue and a vanadium-containing leaching solution. Separating the solid and liquid of the reaction mixture, and finally obtaining the leaching solution of vanadium.

[0025] In the embodiment of the present application, the supercritical water system can be used to accelerate the reaction between hydrogen ions and alkali-containing minerals with strong stability in red mud, destroy the mineral phase structure, improve the mineral phase structure-activity relationship of red mud, strengthen the mass transfer and heat transfer efficiency in the leaching reaction process of vanadium oxides in red mud, and improve the contact efficiency between the leaching solution and vanadium elements, thereby increasing the leaching rate of vanadium. At the same time, supercritical water has unique characteristics such as a reduced dielectric constant, ionic product, weakened hydrogen bonds, enhanced diffusion performance and non-polar characteristics, which promote the formation of a homogeneous system during the oxidation process, and increase the oxidation rate and oxidation efficiency.

[0026] In the implementation process of this method, the types of reagents used are few, the reaction process is simple, and the vanadium leaching efficiency is high, which lays a foundation for the subsequent recycling and reuse of vanadium. Description of the Drawings

[0027] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments that conform to the present application, and are used together with the specification to explain the principles of the present application.

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a schematic flow diagram of a method for leaching vanadium from red mud by supercritical oxidation of red mud according to some embodiments of the present application. Detailed Embodiments

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts fall within the scope of protection of this application.

[0031] The various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within that range, such as 1, 2, 3, 4, 5, and 6, regardless of the range; in addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0032] In this document, terms such as "including" mean "including but not limited to". Relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. "And / or" describes the associated relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, or B exists alone; where A and B may be singular or plural. "At least one" means one or more, and "multiple" means two or more; "at least one kind", "at least one of the following items (pieces)", or similar expressions refer to any combination of these items, including any combination of single items (pieces) or plural items (pieces); for example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively. The "parts representation method" such as parts by weight and parts by mass represents the proportional relationship between components. In the proportional relationships involved in this document, the parameters that need to be described by proportions should be understood as the antecedents of the proportion formula in the order of description, and the proportional numbers should be understood as the consequents of the proportion formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one by one with the proportional numbers in the proportion formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0033] Unless otherwise specified, various raw materials, reagents, instruments, and equipment used in this article can be obtained through market purchases or prepared by existing methods.

[0034] Figure 1 It is a schematic flow diagram of a method for leaching vanadium from red mud by supercritical oxidation according to some embodiments of the present application;

[0035] As Figure 1 shown, the embodiments of the present application provide a method for leaching vanadium from red mud by supercritical oxidation, including the following steps:

[0036] S1. Disperse the red mud in the leaching solution to obtain a red mud slurry;

[0037] In step S1, the dry red mud to be extracted with vanadium is dispersed in the leaching solution, which can not only provide reaction conditions for the subsequent leaching reaction, but also the leaching solution has a certain solubility for the leached vanadium, which can promote the leaching reaction and improve the leaching efficiency.

[0038] S2. Add an oxidant to the red mud slurry, and perform a supercritical oxidation leaching reaction on the red mud slurry containing the oxidant to obtain a reaction mixture;

[0039] In step S2, an oxidant is added to the red mud slurry to oxidize the vanadium element in the red mud to form vanadium oxide, which facilitates the subsequent leaching reaction; the supercritical reaction conditions can accelerate the reaction between hydrogen ions and alkali-containing minerals with strong stability in the red mud, destroy the mineral phase structure, improve the mineral phase structure-activity relationship of the red mud, and enhance the mass transfer and heat transfer efficiency of the vanadium oxide leaching reaction process in the red mud, improve the contact efficiency between the leaching solution and the vanadium element, thereby increasing the leaching rate of vanadium. At the same time, supercritical water has unique characteristics such as a reduced dielectric constant, ionic product, weakened hydrogen bonds, enhanced diffusion performance, and non-polar characteristics, which promote the formation of a homogeneous system during the oxidation process and increase the oxidation rate and oxidation efficiency. After the reaction, the obtained reaction mixture includes red mud waste residue and a vanadium-containing leaching solution.

[0040] S3. Perform solid-liquid separation on the reaction mixture to obtain a leaching solution of vanadium.

[0041] In step S3, the red mud waste residue and the vanadium-containing leaching solution in the reaction mixture can be separated by gravity filtration, pressure filtration, vacuum filtration, or centrifugal filtration to obtain a leaching solution of vanadium.

[0042] In the above-described embodiment, first, the red mud is dispersed to obtain a red mud slurry, providing conditions for the subsequent supercritical oxidation leaching reaction; meanwhile, the leaching solution has a certain solubility for the leached vanadium, and the vanadium leached through the leaching reaction can continuously dissolve in the leaching solution, accelerating the realization of the leaching reaction until the vanadium is completely leached. Secondly, an oxidant is added to the red mud slurry to create an oxidizing environment. During the reaction, the vanadium in the red mud is first oxidized to vanadium oxide, and then according to the supercritical reaction system and reaction conditions, the vanadium oxide is leached. The leached vanadium oxide quickly dissolves in the leaching solution, causing the chemical equilibrium to shift to the right and promoting the leaching reaction again. Finally, red mud waste residue and a leaching solution of vanadium are obtained. After solid-liquid separation, the leaching solution of vanadium is obtained, achieving maximum leaching of vanadium.

[0043] As an alternative embodiment, the leaching solution has a certain solubility for vanadium-containing compounds to better dissolve the vanadium leached from the red mud and improve the leaching rate of vanadium in the red mud.

[0044] As an alternative embodiment, the leaching solution includes at least one of ionic liquids, inorganic salt substances, and organic amines.

[0045] Among them, the ionic liquid is a salt substance composed of organic cations and inorganic or organic anions. The inorganic salt substance is a compound formed by the combination of metal ions (or ammonium ions) and acid root ions through ionic bonds, and the organic amine refers to an organic compound containing amino groups (-NH2, -NHR, -NR2).

[0046] In the above-described embodiment, the components in the leaching solution can be as follows:

[0047] 1) Include ionic liquids, excluding inorganic salt substances and organic amines;

[0048] 2) Include inorganic salt substances, excluding ionic liquids and organic amines;

[0049] 3) Include organic amine substances, excluding inorganic salt substances and ionic liquids;

[0050] 4) Include inorganic salt substances and ionic liquids, excluding organic amines;

[0051] 5) Include inorganic salt substances, ionic liquids, and organic amines.

[0052] As an alternative embodiment, the ionic liquid includes at least one of the following: 1-(3-aminopropyl)-3-methylimidazolium chloride, triethylamine hydrochloride, and 1-ethyl-3-methylimidazolium glycinate.

[0053] In the above embodiments, the ionic liquid contains more amino groups (-NH2) or nitrogen-containing functional groups, which improves the coordination ability of amino ions in the leaching reaction system to metal vanadium ions, reduces the adsorption of vanadium by the porous structure of red mud, increases the solubility of vanadium in the leaching solution, and strengthens the leaching and extraction process of vanadium metal in red mud.

[0054] As an alternative embodiment, the inorganic salt substances include at least one of the following: carbonate, bicarbonate, sulfate, and hydrochloride.

[0055] In the above embodiments, the carbonate can provide an alkaline environment in the leaching solution to promote the dissolution of vanadium oxides, such as sodium carbonate, potassium carbonate, etc.; the bicarbonate can provide a weak alkaline environment in the leaching solution to promote the dissolution of vanadium oxides; at the same time, the bicarbonate also provides hydrogen ions, which react with the alkali-containing minerals with strong stability in red mud to destroy the mineral phase structure, improve the structure-activity relationship of the red mud mineral phase, and strengthen the leaching reaction process of valuable vanadium in red mud; the sulfate can provide sulfate ions in the leaching solution, and the sulfate ions form soluble complexes with vanadium to reduce the agglomeration and precipitation of vanadium in the solution and improve the leaching efficiency; the chloride ions provided by the hydrochloride also have a certain complexing effect on metal ions, and at the same time, in combination with the acidity adjustment of the hydrochloride solution, the leaching rate of vanadium is increased.

[0056] As an alternative embodiment, the mass concentration of the ionic liquid in the leaching solution is 10% to 20%.

[0057] In the above embodiments, the concentration of the ionic liquid directly affects the coordination ability between the nitrogen-containing functional groups or -NH2 and vanadium oxides. If the mass concentration is too high, it may increase the solution viscosity of the leaching solution and affect the mass transfer and separation efficiency; if the mass concentration is too low, it may lead to insufficient leaching efficiency. Exemplarily, the concentration of the ionic liquid can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%.

[0058] As an alternative embodiment, the mass concentration of the inorganic salt substances is 5% to 20%.

[0059] In the above embodiments, the mass concentration of the inorganic salt substances affects the solubility of vanadium oxides in the leaching solution. If the mass concentration is too high, it will cause an increase in the viscosity of the leaching solution, affecting the mass transfer efficiency and stirring effect, resulting in a decrease in the leaching reaction rate and a decline in the leaching efficiency of vanadium. At the same time, high-concentration salt substances may also undergo side reactions with other impurities (such as silicon, aluminum, iron, etc.), generating insoluble precipitates that wrap the vanadium oxides, hindering the leaching of vanadium. If the mass concentration is too low, it cannot ensure complete leaching of vanadium. Exemplarily, the mass concentration of the inorganic salt substances can be 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 16%, 18%, 20%.

[0060] As an alternative embodiment, the mass concentration of the organic amine substances is 10% - 20%; the organic amine can be at least one of ethanolamine, propanolamine, or diethylamine, or any one of the organic compounds containing amino groups (-NH2, -NHR, -NR2).

[0061] In the above embodiments, the concentration of the organic amine directly affects the coordination ability between -NH2 and vanadium oxides. If the mass concentration is too high, it may increase the solution viscosity of the leaching solution, affecting the mass transfer and separation efficiency; if the mass concentration is too low, it may lead to insufficient leaching efficiency. Exemplarily, the concentration of the organic amine can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%.

[0062] As an alternative embodiment, the liquid-solid ratio of the leaching solution to the red mud is 3 - 10.

[0063] In the above embodiments, the liquid-solid ratio of the leaching solution to the red mud is the ratio of the volume (L) of the leaching solution to the mass (kg) of the red mud, which is a key parameter. If the liquid-solid ratio is too low, the amount of the leaching solution is insufficient, resulting in incomplete leaching reaction, too high viscosity of the leaching solution, and a decline in the mass transfer efficiency and vanadium leaching rate; if the amount of the leaching solution is too much, it will cause waste of the leaching agent, too low vanadium concentration in the leaching solution, and increase the difficulty of subsequent concentration and recovery. Exemplarily, the liquid-solid ratio can be 3, 4, 5, 6, 7, 8, 9, 10.

[0064] As an alternative embodiment, the oxidant includes at least one of the following: hydrogen peroxide, ozone, sodium hypochlorite, and sodium nitrate.

[0065] In the above embodiments, the role of the oxidant is to oxidize the vanadium in the red mud from a low valence state to a high valence state oxide, so that it can react with the salt substances or ionic liquids in the leaching solution to achieve the leaching process. At the same time, considering the subsequent treatment process, an oxidant that is convenient for subsequent treatment is selected.

[0066] As an alternative embodiment, the addition amount of the oxidant is 5% to 10% more than the theoretical value. The calculation process of the theoretical value is based on the total amount of vanadium in the raw red mud to calculate the amount of the oxidant required to oxidize all vanadium, which is used as the theoretical value.

[0067] In the above embodiment, the reason why the actual addition amount of the oxidant is 5% to 10% more than the theoretical value is that an excessive amount of the oxidant helps to accelerate the reaction process and can also ensure complete oxidation of vanadium to achieve the leaching process. However, if the amount of the oxidant exceeds a certain level, some side reactions may occur and resources will be wasted. Therefore, by way of example, the actual addition amount of the oxidant can be 5%, 6%, 7%, 8%, 9% or 10% more than the theoretical value.

[0068] As an alternative embodiment, adding an oxidant to the red mud slurry and performing a supercritical oxidation leaching reaction on the red mud slurry containing the oxidant to obtain a reaction mixture specifically includes:

[0069] Preheating the red mud slurry and adding an oxidant to the preheated red mud slurry;

[0070] Placing the red mud slurry containing the oxidant in a supercritical water reaction system to perform a supercritical oxidation leaching reaction to obtain a reaction mixture.

[0071] In the above embodiment, preheating the red mud is actually a simple activation of the red mud under the reaction system. If dry red mud is used in the implementation process, the preheating process can also infiltrate and open the pore structure of the red mud, facilitating subsequent leaching reactions.

[0072] Using a supercritical water system can accelerate the reaction between hydrogen ions and alkali-containing minerals with strong stability in red mud, destroy the mineral phase structure, improve the mineral phase structure-activity relationship of red mud, strengthen the mass transfer and heat transfer efficiency of the vanadium oxide leaching reaction process in red mud, improve the contact efficiency between the leaching solution and vanadium elements, and thus increase the leaching rate of vanadium. At the same time, supercritical water has unique characteristics such as a reduced dielectric constant, ionic product, weakened hydrogen bonds, enhanced diffusion performance, and non-polar characteristics, which promote the formation of a homogeneous system during the oxidation process, increasing the oxidation rate and oxidation efficiency.

[0073] As an alternative embodiment, the preheating temperature is 70°C to 120°C.

[0074] In the above embodiment, the reason for controlling the preheating temperature to be 70°C to 120°C is that the appropriate preheating temperature can not only meet the effect of activating red mud, but also avoid heat waste. If the preheating temperature is too low, it may lead to insufficient activation effect of red mud, unable to fully infiltrate and open the pore structure of red mud, which is also not conducive to the subsequent leaching reaction. Exemplarily, the temperature of the preheating can be 70°C, 80°C, 90°C, 100°C, 110°C, 120°C.

[0075] As an alternative embodiment, the reaction temperature of the supercritical oxidation leaching reaction is greater than 374°C, and the reaction pressure is greater than 22.1 MPa.

[0076] In the above embodiment, controlling the reaction temperature and reaction pressure of the supercritical oxidation leaching reaction aims to keep the supercritical water reaction system in a supercritical state. Supercritical reaction refers to a reaction that occurs when a substance is under conditions exceeding its critical temperature and critical pressure. For water, its critical temperature is 374°C and its critical pressure is 22.1 MPa. When the temperature and pressure exceed these critical values, water enters the supercritical state, showing unique physical and chemical properties, such as having a unique dielectric constant, reduced ionic product, weakened hydrogen bonds, enhanced diffusion performance and non-polar characteristics, promoting the formation of a homogeneous system during oxidation, and increasing the oxidation rate and oxidation efficiency. Exemplarily, the reaction temperature can be 375°C, 380°C, 385°C, 390°C, 400°C. The reaction pressure can be 22.2 MPa, 22.5 MPa, 23 MPa, 23.5 MPa, 24 MPa.

[0077] As an alternative embodiment, the time of the supercritical oxidation leaching reaction is 30 min to 240 min.

[0078] In the above embodiment, the time of the supercritical oxidation leaching reaction is related to the reaction temperature, reaction pressure, and also related to the vanadium content of red mud, the particle size of red mud, and the action of the oxidant. During the implementation process, the reaction time can be controlled according to actual needs. When there is no new vanadium oxide in the leaching solution, it indicates that the leaching reaction is over. Exemplarily, the reaction time can be 30 min, 40 min, 50 min, 60 min, 80 min, 100 min, 120 min, 140 min, 150 min, 160 min, 180 min, 200 min, 220 min, 240 min.

[0079] The following further elaborates on this application in combination with specific embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually determined according to national standards / industry standards; if there are no corresponding national standards / industry standards, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0080] Example 1

[0081] This example provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 23 μm to 48 μm is used as the raw material, and the vanadium content in the raw red mud is 0.033%. This method includes the following steps:

[0082] S1. Disperse the red mud in a leaching solution containing 1-(3-aminopropyl)-3-methylimidazolium chloride with a mass concentration of 10% and sodium carbonate solution with a mass concentration of 5%, and stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 7.

[0083] S2. Add NaClO as an oxidant to the red mud slurry, and its dosage is 5% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 374 °C and the reaction pressure reaches 22.1 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 120 min.

[0084] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Perform liquid-solid separation on the reaction mixture by vacuum filtration to obtain a leaching solution of vanadium, analyze the vanadium content in the leaching solution of vanadium, and calculate the vanadium leaching rate.

[0085] Example 2

[0086] This example provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 48 μm to 75 μm is used as the raw material, and the vanadium content in the raw red mud is 0.046%. This method includes the following steps:

[0087] S1. Disperse the red mud in a leaching solution containing triethylamine hydrochloride with a mass concentration of 10% and sodium carbonate solution with a mass concentration of 5%, and stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 7.

[0088] S2. Add H2O2 as an oxidant to the red mud slurry, and its dosage is 7% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 374 °C and the reaction pressure reaches 22.1 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 240 min.

[0089] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Perform liquid-solid separation on the reaction mixture by vacuum filtration to obtain a leaching solution of vanadium, analyze the vanadium content in the leaching solution of vanadium, and calculate the vanadium leaching rate.

[0090] Example 3

[0091] This example provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 75 μm to 150 μm is used as the raw material, and the vanadium content in the raw red mud is 0.046%. The method includes the following steps:

[0092] S1. Disperse the red mud in a leaching solution containing 1-(3-aminopropyl)-3-methylimidazolium chloride with a mass concentration of 13% and sodium sulfate solution with a mass concentration of 10%, and stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 8.

[0093] S2. Add NaNO3 as an oxidant to the red mud slurry, and its dosage is 5% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 374 °C and the reaction pressure reaches 22.1 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 240 min.

[0094] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Carry out liquid-solid separation on the reaction mixture by pressure filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0095] Example 4

[0096] This example provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 150 μm to 270 μm is used as the raw material, and the vanadium content in the raw red mud is 0.068%. The method includes the following steps:

[0097] S1. Disperse the red mud in a leaching solution containing 1-(3-aminopropyl)-3-methylimidazolium chloride with a mass concentration of 15% and sodium bicarbonate solution with a mass concentration of 15%, and stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 8.

[0098] S2. Add NaNO3 as an oxidant to the red mud slurry, and its dosage is 7% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 374 °C and the reaction pressure reaches 22.1 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 120 min.

[0099] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Carry out liquid-solid separation on the reaction mixture by vacuum filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0100] Example 5

[0101] This example provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 48 μm to 75 μm is used as the raw material, and the vanadium content in the raw red mud is 0.068%. This method includes the following steps:

[0102] S1. Disperse the red mud in a leaching solution containing 15% (mass concentration) of 1-ethyl-3-methylimidazolium glycinate and 15% of sodium carbonate solution, and stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 8.

[0103] S2. Add NaNO3 as an oxidant to the red mud slurry, and its dosage is 10% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. When the reaction temperature of the solution system reaches 400 °C and the reaction pressure reaches 24 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 240 min.

[0104] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Perform liquid-solid separation on the reaction mixture by vacuum filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0105] Example 6

[0106] This example provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 150 μm to 270 μm is used as the raw material, and the vanadium content in the raw red mud is 0.046%. This method includes the following steps:

[0107] S1. Disperse the red mud in a leaching solution containing 10% (mass concentration) of 1-(3-aminopropyl)-3-methylimidazolium chloride and 15% of sodium carbonate solution, and stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 8.

[0108] S2. Add H2O2 as an oxidant to the red mud slurry, and its dosage is 10% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. When the reaction temperature of the solution system reaches 400 °C and the reaction pressure reaches 24 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 240 min.

[0109] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Perform liquid-solid separation on the reaction mixture by vacuum filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0110] Example 7

[0111] This example provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 150 μm to 270 μm is used as the raw material, and the vanadium content in the raw red mud is 0.046%. This method includes the following steps:

[0112] S1. Disperse the red mud in a leaching solution containing 20% by mass of 1-ethyl-3-methylimidazolium glycinate and 15% of sodium carbonate solution, and stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 10.

[0113] S2. Add H2O2 as an oxidant to the red mud slurry, and its dosage is 10% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 400 °C and the reaction pressure reaches 24 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 240 min.

[0114] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Separate the liquid and solid of the reaction mixture by centrifugal filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0115] Example 8

[0116] This example provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 23 μm to 48 μm is used as the raw material, and the vanadium content in the raw red mud is 0.046%. This method includes the following steps:

[0117] S1. Disperse the red mud in a leaching solution containing 15% by mass of sodium carbonate solution, and stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 10.

[0118] S2. Add hydrogen peroxide as an oxidant to the red mud slurry, and its dosage is 10% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 400 °C and the reaction pressure reaches 24 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 240 min.

[0119] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Separate the liquid and solid of the reaction mixture by vacuum filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0120] Example 9

[0121] This embodiment provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 48 μm to 75 μm is used as the raw material, and the vanadium content in the raw red mud is 0.068%. The method includes the following steps:

[0122] S1. Disperse the red mud in a leaching solution containing sodium carbonate solution with a mass concentration of 5%, stir at room temperature for 30 min to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 5.

[0123] S2. Add ozone as an oxidant to the red mud slurry, with its dosage 7% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 374 °C and the reaction pressure reaches 22.1 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 120 min.

[0124] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Perform liquid-solid separation on the reaction mixture by vacuum filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0125] Example 10

[0126] This embodiment provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 75 μm to 150 μm is used as the raw material, and the vanadium content in the raw red mud is 0.057%. The method includes the following steps:

[0127] S1. Disperse the red mud in a leaching solution containing sodium bicarbonate solution with a mass concentration of 10%, stir at room temperature for 30 min to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 7.

[0128] S2. Add sodium nitrate as an oxidant to the red mud slurry, with its dosage 10% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 374 °C and the reaction pressure reaches 22.1 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 240 min.

[0129] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Perform liquid-solid separation on the reaction mixture by vacuum filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0130] Example 11

[0131] This embodiment provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 75 μm to 150 μm is used as the raw material, and the vanadium content in the raw red mud is 0.057%. The method includes the following steps:

[0132] S1. Disperse the red mud in a leaching solution containing an ethanolamine solution with a mass concentration of 10%, and stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 7.

[0133] S2. Add NaClO as an oxidant to the red mud slurry, and its dosage is 7% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 374 °C and the reaction pressure reaches 22.1 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 120 min.

[0134] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. The reaction mixture is subjected to liquid-solid separation by pressure filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0135] Example 12

[0136] This embodiment provides a method for leaching vanadium from red mud by supercritical oxidation. Red mud with a particle size range of 150 μm to 270 μm is used as the raw material, and the vanadium content in the raw red mud is 0.046%. The method includes the following steps:

[0137] S1. Disperse the red mud in a leaching solution containing 20% 1-ethyl-3-methylimidazolium glycinate and 15% sodium carbonate solution, and stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 10.

[0138] S2. Add H2O2 as an oxidant to the red mud slurry, and its dosage is 10% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 374 °C and the reaction pressure reaches 22.1 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 240 min.

[0139] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. The reaction mixture is subjected to liquid-solid separation by centrifugal filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0140] Comparative Example 1

[0141] This embodiment provides a method for leaching vanadium from red mud by supercritical oxidation, using red mud with a particle size range of 23 μm to 48 μm as the raw material, and the vanadium content in the raw red mud is 0.046%. The method comprises the following steps:

[0142] S1. Disperse the red mud in a leaching solution containing a sodium carbonate solution with a mass concentration of 5%, stir at room temperature for 30 min to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 5.

[0143] S2. Add sodium nitrate as an oxidant to the red mud slurry, with its dosage 5% more than the theoretical amount, stir evenly, and start the oxidation leaching reaction when the reaction temperature of the solution system reaches 90 °C under atmospheric pressure, where the oxidation leaching time is 240 min.

[0144] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Perform liquid-solid separation on the reaction mixture by pressure filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0145] Comparative Example 2

[0146] This comparative example provides a method for leaching vanadium from red mud by supercritical oxidation, using red mud with a particle size range of 23 μm to 48 μm as the raw material, and the vanadium content in the raw red mud is 0.046%. The method comprises the following steps:

[0147] S1. Disperse the red mud in a leaching solution containing an ethanolamine solution with a mass concentration of 15%, stir at room temperature for 30 min to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 10.

[0148] S2. Add sodium nitrate as an oxidant to the red mud slurry, with its dosage 7% more than the theoretical amount, stir evenly, and start the oxidation leaching reaction when the reaction temperature of the solution system reaches 90 °C under atmospheric pressure, where the oxidation leaching time is 240 min.

[0149] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature, adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Perform liquid-solid separation on the reaction mixture by pressure filtration to obtain a vanadium leaching solution, analyze the vanadium content in the vanadium leaching solution, and calculate the vanadium leaching rate.

[0150] Comparative Example 3

[0151] This embodiment provides a method for leaching vanadium from red mud by supercritical oxidation, using red mud with a particle size range of 23 μm to 48 μm as the raw material, and the vanadium content in the raw red mud is 0.033%. The method comprises the following steps:

[0152] S1. Disperse the red mud in a leaching solution containing 1-(3-aminopropyl)-3-methylimidazolium chloride with a mass concentration of 10% and sodium carbonate solution with a mass concentration of 5%, stir for 30 min at room temperature to obtain a uniformly dispersed red mud slurry; the liquid-solid ratio is 7.

[0153] S2. Add NaClO as an oxidant to the red mud slurry, and its dosage is 5% more than the theoretical amount. After stirring evenly, place it in a supercritical water reaction system. After the reaction temperature of the solution system reaches 350 °C and the reaction pressure reaches 20 MPa, start the supercritical oxidation leaching reaction, and the supercritical oxidation leaching time is 120 min.

[0154] S3. After the leaching is completed, lower the temperature of the reaction system to room temperature and adjust the pressure of the reaction system to atmospheric pressure to obtain a reaction mixture. Perform liquid-solid separation on the reaction mixture by vacuum filtration to obtain a leaching solution of vanadium, analyze the content of vanadium in the leaching solution of vanadium, and calculate the vanadium leaching rate.

[0155] Statistically analyze the content of vanadium in the leaching solutions of each example and each comparative example respectively, and calculate and analyze the vanadium leaching rate. The results are shown in Table 1.

[0156] Table 1 Experimental data of each example and comparative example

[0157]

[0158]

[0159] It can be seen from the data in Table 1 that by comparing the experimental data in Examples 1-12 and Comparative Examples 1-3, in the method for leaching vanadium from red mud by supercritical oxidation provided in Examples 1-12 of the present application, using at least one of ionic liquids, inorganic salts, and ethanolamine as the components of the leaching solution is beneficial to increasing the solubility of vanadium oxide in the leaching solution. Then, by controlling the reaction conditions to reach the supercritical conditions, it can accelerate the reaction between the hydrogen ions present in the leaching solution and the alkali-containing minerals with strong stability in the red mud, destroy the mineral phase structure, improve the structure-activity relationship of the red mud mineral phase, and strengthen the mass transfer and heat transfer efficiency in the leaching reaction process of valuable vanadium in the red mud, thereby improving the contact efficiency between the leaching solution and the valuable element vanadium, and finally increasing the vanadium leaching rate.

[0160] The above are only specific embodiments of the present application, which enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but will conform to the widest scope consistent with the principles and novel features claimed in the present application.

Claims

1. A method for leaching vanadium from red mud by supercritical oxidation, comprising the following steps: Disperse the red mud in the leaching solution to obtain a red mud slurry; Add an oxidant to the red mud slurry and conduct a supercritical oxidation leaching reaction on the red mud slurry containing the oxidant to obtain a reaction mixture; Perform solid-liquid separation on the reaction mixture to obtain a leaching solution of vanadium.

2. The method for leaching vanadium from red mud by supercritical oxidation according to claim 1, wherein the leaching solution is soluble in vanadium-containing compounds.

3. The method for leaching vanadium from red mud by supercritical oxidation according to claim 1, wherein the leaching solution comprises at least one of ionic liquids, inorganic salts, and organic amines.

4. The method for leaching vanadium from red mud by supercritical oxidation according to claim 3, wherein the ionic liquid comprises at least one of the following: 1-(3-aminopropyl)-3-methylimidazolium chloride, triethylamine hydrochloride, and 1-ethyl-3-methylimidazolium glycinate; and / or, The inorganic salt comprises at least one of the following: carbonate, bicarbonate, sulfate, and hydrochloride.

5. The method for leaching vanadium from red mud by supercritical oxidation according to claim 2, wherein the mass concentration of the ionic liquid in the leaching solution is 10% - 20%; and / or, The mass concentration of the inorganic salt is 5% - 20%.

6. The method for leaching vanadium from red mud by supercritical oxidation according to claim 1, wherein the liquid-solid ratio of the leaching solution to the red mud is 3 - 10.

7. The method for leaching vanadium from red mud by supercritical oxidation according to claim 1, wherein the oxidant comprises at least one of the following: hydrogen peroxide, ozone, sodium hypochlorite, and sodium nitrate.

8. The method for leaching vanadium from red mud by supercritical oxidation according to claim 1, wherein adding an oxidant to the red mud slurry and conducting a supercritical oxidation leaching reaction on the red mud slurry containing the oxidant to obtain a reaction mixture specifically comprises: Preheat the red mud slurry and add an oxidant to the preheated red mud slurry; Place the red mud slurry containing the oxidant in a supercritical water reaction system to conduct a supercritical oxidation leaching reaction to obtain a reaction mixture.

9. The method for leaching vanadium from red mud by supercritical oxidation according to claim 1 or 8, wherein the reaction temperature of the supercritical oxidation leaching reaction is greater than 374°C and the reaction pressure is greater than 22.1 MPa.

10. The method for leaching vanadium from red mud by supercritical oxidation according to claim 1 or 8, wherein the reaction time of the supercritical oxidation leaching reaction is 30 min - 240 min.

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