Method for extracting scandium from red mud

Abstract

The invention provides a method for extracting scandium in red mud, and relates to the technical field of red mud resourceful treatment. The method comprises the following steps: firstly, performing activation pretreatment on red mud to obtain activated red mud slurry; carbon dioxide is introduced into the activated red mud slurry for dealkalization carbonization, carbonized red mud slurry is obtained, and a leaching aid is generated; and adding a leaching agent and an extraction agent into the carbonized red mud slurry, and carrying out one-step extraction leaching on the red mud to finally obtain a scandium product. The method is high in leaching and extraction efficiency, the leaching agent and the extraction agent can be recycled, the process is simple, the cost is low, and the method is suitable for batch treatment.

Description

Technical Field

[0001] The present application relates to the technical field of red mud resource processing, and in particular to a method for extracting scandium from red mud. Background Art

[0002] Red mud is a solid waste generated in the process of alumina production. It has a large emission volume. It is estimated that the annual red mud emission in China exceeds 100 million tons. However, the comprehensive utilization rate of red mud is less than 10% at this stage. Scandium is a typical rare earth element, which is widely used in luminescent materials, aerospace industry, alloys and batteries. It is mainly distributed in bauxite, the raw material used in alumina production. Existing studies have shown that the content of scandium in the red mud produced in the alumina production process is between 0.004% and 0.01%, depending on the properties of bauxite and the processing technology. Due to the scarcity of scandium, if the scandium content in the ore is between 0.002% and 0.005%, the ore is regarded as an important scandium resource. Therefore, how to extract scandium resources from red mud deserves in-depth study.

[0003] At present, the extraction of scandium from red mud is mainly through the leaching-extraction method, and the leaching means mainly include acid leaching and alkaline buffer solution immersion. If acid leaching is performed directly, other metal impurities except scandium are easily leached at the same time, which affects the later extraction and separation effect, and a large amount of acid wastewater will also be produced. In the prior art, before soaking in an alkaline buffer solution, it is necessary to first enrich the scandium element and then leach it. Although it avoids the problems of large dosage of traditional acidic leaching agents, co-leaching of impurity elements, interference with subsequent separation, and difficulty in handling waste acid, the leaching means are simple, the leaching rate of metal scandium is not high, and a large amount of aluminum is leached. Floccules are easily generated under alkaline conditions, causing the extractant to emulsify and the alkali in the red mud to not be removed, and the red mud is not utilized in the next step. Summary of the invention

[0004] The present application provides a method for extracting scandium from red mud to solve the following technical problem: improving the extraction efficiency of the scandium element.

[0005] The present invention provides a method for extracting scandium from red mud, wherein the red mud contains scandium, comprising the following steps:

[0006] Carbonizing and dealkalizing the red mud slurry prepared from the red mud to obtain carbonized red mud slurry;

[0007] adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0008] performing a leaching reaction and an extraction reaction on the first mixed slurry simultaneously, and then separating to obtain a scandium-rich organic phase; and

[0009] The scandium-rich organic phase is stripped to obtain a scandium-rich solution.

[0010] Optionally, the extractant comprises, by mass fraction, 25% to 45% of an organic amine, 15% to 45% of an organic phosphonic acid and 25% to 60% of a diluent.

[0011] Optionally, the organic amine includes at least one of the following: monoethanolamine, diethanolamine, diisopropanolamine, N-methyldiethanolamine, isopropanolamine, diethylamine, triethylamine, trioctylamine, triisooctylamine, n-dodecyl(trialkylmethyl)amine, trialkylmethylamine fluoride and trioctyldecyl tertiary amine; and / or

[0012] The organic phosphate ester includes at least one of the following: tributyl phosphate, di(2-ethylhexyl)phosphoric acid, 2-ethylhexyl phosphate mono(2-ethylhexyl) ester, isopropyl monooctyl phosphate, di(2,4,4-trimethylpentyl)phosphonic acid and di(2-ethylhexyl)phosphinic acid.

[0013] Optionally, the diluent is selected from kerosene, industrial white oil, light white oil, ethylene glycol dimethyl ether, resin diluent, propylene carbonate, diethylene glycol methyl ether and No. 260 solvent oil.

[0014] Optionally, the volume ratio of the extractant to the first mixed slurry is 1:10 to 1:4.

[0015] Optionally, the leaching agent includes a carbonate solution and / or a bicarbonate solution, wherein the molar concentration of the carbonate in the first mixed slurry is 4.16*10 -4 mol / L~15.5*10 -2 mol / L, the molar concentration of the bicarbonate in the first mixed slurry is 2.02*10 -3 mol / L~15.5*10 -2 mol / L.

[0016] Optionally, the step of simultaneously subjecting the first mixed slurry to a leaching reaction and an extraction reaction, and then separating to obtain a scandium-rich organic phase, specifically comprises:

[0017] Using an ultrasonic-microwave composite field, the first mixed slurry is subjected to a leaching reaction and an extraction reaction simultaneously to obtain a second mixed slurry;

[0018] The second mixed slurry is subjected to extraction and separation to obtain a scandium-rich organic phase.

[0019] Optionally, the ultrasonic-microwave composite field meets the following parameters: ultrasonic power is 200W to 1000W, and microwave power is 100W to 500W.

[0020] Optionally, the leaching reaction and the extraction reaction satisfy the following reaction parameters: reaction temperature is 60° C. to 90° C., and reaction time is 1 h to 3.5 h.

[0021] Optionally, the red mud slurry prepared from the red mud is subjected to carbonization and dealkalization to obtain carbonized red mud slurry, specifically comprising: activating the red mud slurry prepared from the red mud to obtain activated red mud slurry; and carbonizing and dealkalizing the activated red mud slurry to obtain carbonized red mud slurry.

[0022] Optionally, the specific steps of the activation treatment include: mixing red mud and water and then stirring and activating them, meeting the following parameters: a mass ratio of red mud to water is 1:8 to 1:4, an activation temperature is 60°C to 90°C, a stirring speed is 100r / min to 400r / min, and an activation time is 0.5h to 3h.

[0023] Optionally, the carbonization dealkalization reaction is carried out using carbon dioxide; wherein the carbonization dealkalization reaction satisfies the following reaction parameters: the carbon dioxide pressure is 0.6MPa to 1.5MPa, and the reaction time is 0.5h to 2h.

[0024] The above technical solution provided by the present invention has the following advantages compared with the prior art:

[0025] The present invention provides a method for extracting scandium from red mud, which comprises the following steps: carbonizing and dealkalizing the red mud slurry, which can rapidly convert the alkali in the red mud into NaHCO3 and Na2CO3, and while reducing the alkalinity of the red mud slurry to obtain the carbonized red mud slurry, can generate leaching aids NaHCO3 and Na2CO3; adding a leaching agent and an extractant to the carbonized red mud slurry, and simultaneously performing a leaching reaction and an extraction reaction, and then separating to obtain a scandium-rich organic phase; this step uses a leaching agent and an extractant to perform a one-step collaborative leaching and extraction, which can not only reduce the process flow, but also the scandium leached in the system can be rapidly extracted by the extractant, maintaining the scandium concentration difference of the carbonized red mud slurry-leaching solution system, promoting the forward movement of the leaching chemical equilibrium, and improving the leaching efficiency. The scandium-rich organic phase is stripped to obtain a scandium-rich solution and an organic phase, wherein the organic phase can be recycled as an extractant again, and the scandium product can be obtained after the scandium-rich solution is precipitated and crystallized.

[0026] The method has high leaching and extraction efficiency, and the leaching agent and the extracting agent can be recycled. The process is simple, the cost is low, and it is suitable for batch processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0029] Figure 1 A flow chart of a method for extracting scandium from red mud provided in this application;

[0030] Figure 2 This is a flow chart of a method for extracting scandium from red mud provided in some embodiments of the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0032] Various embodiments of the present application may be presented 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 understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0033] In this application, in the absence of any contrary description, the terms including "including" and the like mean "including but not limited to". In this article, relational terms such as "first" and "second" and the like are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "the following at least one (individual)" or similar expressions thereof refer to any combination of these items, including any combination of singular (individual) or plural (individual). For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or plural, respectively.

[0034] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0035] The present invention provides a method for extracting scandium from red mud. The red mud contains scandium. The process of the extraction method is as follows: Figure 1 As shown, the following steps are included:

[0036] Carbonizing and dealkalizing the red mud slurry prepared from the red mud to obtain carbonized red mud slurry;

[0037] adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0038] performing a leaching reaction and an extraction reaction on the first mixed slurry simultaneously, and then separating to obtain a scandium-rich organic phase; and

[0039] The scandium-rich organic phase is stripped to obtain a scandium-rich solution.

[0040] In the above embodiment, the red mud slurry is carbonized and de-alkalized, which can quickly convert the alkali in the red mud into NaHCO3 and Na2CO3, and while reducing the alkalinity of the red mud slurry to obtain the carbonized red mud slurry, the leaching aids NaHCO3 and Na2CO3 can be generated; the leaching agent and the extractant are added to the carbonized red mud slurry, and the leaching reaction and the extraction reaction are carried out simultaneously, and then the scandium-rich organic phase is separated; this step uses the leaching agent and the extractant to carry out one-step synergistic leaching and extraction, which can not only reduce the process flow, but also the scandium leached in the system can be quickly extracted by the extractant, maintaining the scandium concentration difference of the carbonized red mud slurry-leaching solution system, promoting the forward movement of the leaching chemical equilibrium, and improving the leaching efficiency. The scandium-rich organic phase is stripped to obtain a scandium-rich solution and an organic phase, wherein the organic phase can be recycled as an extractant again, and the scandium product can be obtained after the scandium-rich solution is precipitated and crystallized.

[0041] As an optional implementation, the extractant comprises, by mass fraction, 25% to 45% of an organic amine, 15% to 45% of an organic phosphonic acid, and 25% to 60% of a diluent.

[0042] In the above embodiment, the extractant is composed of an organic amine, an organic phosphonic acid and a diluent, wherein the diluent is used as a carrier for dissolving the organic amine and the organic phosphonic acid so that they can be evenly dispersed in the organic phase; the organic amine and the organic phosphonic acid can form complexes with certain metal ions, thereby promoting the transfer of metal ions from the aqueous phase to the organic phase. At the same time, the organic amine can also capture and adsorb the residual carbon dioxide in the first mixed slurry. When the extraction and leaching reaction is carried out, the carbon dioxide is slowly released as the temperature rises to maintain the carbon dioxide concentration in the reaction system, promote the slow reaction of carbon dioxide and the lattice base in the red mud, and can cooperate with the organic phosphoric acid and the diluent to extract the leached scandium.

[0043] As an optional embodiment, the organic amine includes at least one of the following: monoethanolamine, diethanolamine, diisopropanolamine, N-methyldiethanolamine, isopropanolamine, diethylamine, triethylamine, trioctylamine, triisooctylamine, n-dodecyl(trialkylmethyl)amine, trialkylmethylamine fluoride and trioctyldecyl tertiary amine;

[0044] The organic phosphate ester includes at least one of the following: tributyl phosphate, di(2-ethylhexyl)phosphoric acid, 2-ethylhexyl phosphate mono(2-ethylhexyl) ester, isopropyl monooctyl phosphate, di(2,4,4-trimethylpentyl)phosphonic acid and di(2-ethylhexyl)phosphinic acid.

[0045] As an optional implementation, the diluent is selected from kerosene, industrial white oil, light white oil, ethylene glycol dimethyl ether, resin diluent, propylene carbonate, diethylene glycol methyl ether and No. 260 solvent oil.

[0046] As an optional implementation manner, the volume ratio of the extractant to the first mixed slurry is 1:10 to 1:4.

[0047] In the above embodiment, controlling the volume ratio of the extractant to the first mixed slurry helps to control the amount of the extractant, thereby reducing the extraction cost while ensuring the extraction efficiency. For example, the volume ratio of the extractant to the first mixed slurry can be 1:10, 1:9, 1:8, 1:7, 1:6, 1:5 and 1:4.

[0048] As an optional embodiment, the leaching agent is a mixed solution of carbonate and / or bicarbonate, wherein the total content of the carbonate in the first mixed slurry is 4.16*10 -4 mol / L~15.5*10 -2 mol / L, the total content of bicarbonate in the first mixed slurry is 2.02*10 -3 mol / L~15.5*10 -2 mol / L.

[0049] In the above embodiment, the concentrations of carbonate and bicarbonate are controlled. The main reason is that the scandium leached from the red mud is mainly in the form of scandium hydroxide. In the carbonate solution and bicarbonate solution of the above concentration, the solubility of scandium hydroxide is relatively large, which is conducive to the leaching of scandium. Therefore, the concentrations of carbonate and bicarbonate need to be controlled.

[0050] As an optional embodiment, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, and then separated to obtain a scandium-rich organic phase, which specifically includes:

[0051] Using an ultrasonic-microwave composite field, the first mixed slurry is subjected to a leaching reaction and an extraction reaction simultaneously to obtain a second mixed slurry;

[0052] The second mixed slurry is subjected to extraction and separation to obtain a scandium-rich organic phase.

[0053] In the above implementation, an ultrasonic-microwave composite field is used, mainly using microwaves and ultrasound to extract scandium. Microwaves increase the vibration and friction of molecules in the reaction system through the dipole rotation or ion conduction of polar molecules, increase their activation energy, and promote the progress of chemical reactions; at the same time, the multiple effects of ultrasonic oscillation, dispersion, crushing, cavitation, stirring, etc. are used to disperse / crush particles, further reduce their particle size, accelerate the dissolution of solutes, improve reaction activity, and combine the advantages of the hydrothermal method to reduce the requirements for reaction temperature, overcome the crystal transformation, decomposition, and volatilization that cannot be overcome by certain high-temperature preparations, and can be uniformly doped, so that the activity of the reactants is changed and improved. Most importantly, microwaves can promote the separation of organic and inorganic phases in the reaction system through molecular rotation and vibration, avoid the occurrence of emulsification, and ensure and accelerate the stratification of the extractant in the reaction system.

[0054] As an optional implementation, the ultrasonic-microwave composite field meets the following parameters: ultrasonic power is 200W-1000W, and microwave power is 100W-500W.

[0055] In the above embodiment, the reason for controlling the ultrasonic power and microwave power is that different ultrasonic power and microwave power will have a significant impact on the extraction efficiency and product quality. Among them, ultrasonic assisted extraction uses the mechanical vibration effect generated by ultrasound to accelerate the penetration of solvent into the sample, thereby improving the extraction efficiency and shortening the extraction time. When the ultrasonic power is low, the mechanical vibration effect is small, resulting in poor extraction effect; when the ultrasonic power is high, the mechanical vibration effect is better and the extraction effect is better, but after the power reaches a certain level, increasing the power will not improve the extraction effect.

[0056] Microwave-assisted extraction is because microwaves can quickly heat the sample, accelerate the penetration of the extractant into the sample, and accelerate the formation of a complex between scandium hydroxide and the extractant, thereby improving the extraction efficiency and shortening the extraction time. However, if the power is too high, the reaction temperature will be too high, which may lead to the occurrence of side reactions during the extraction process.

[0057] As an optional implementation manner, the leaching reaction and the extraction reaction meet the following reaction parameters: the reaction temperature is 60° C. to 90° C., and the reaction time is 1 h to 3.5 h.

[0058] In the above embodiment, the reason for controlling the reaction temperature and time is that the reaction temperature is mainly to promote the release of carbon dioxide in the organic amine, increase the solubility of scandium hydroxide in the leaching solution, and make scandium combine with the extractant to form a complex, thereby improving the leaching rate and extraction rate. Exemplarily, the temperature of the leaching reaction and the extraction reaction can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C, and the reaction time is 1h, 1.5h, 2h, 2.5h, 3h or 3.5h.

[0059] As an optional implementation, the red mud slurry is carbonized and dealkalized to obtain carbonized red mud slurry, specifically including: activating the red mud slurry to obtain activated red mud slurry; carbonizing and dealkalizing the activated red mud slurry to obtain carbonized red mud slurry.

[0060] In the above embodiment, the red mud slurry is first activated, mainly to improve the extractability of elements such as scandium in the red mud. By changing the surface properties or structure of the red mud, it is easier to react with the reagents used subsequently. Common activation methods include chemical activation and thermal activation, both of which belong to the activation methods in this application, among which chemical activation may involve treating the red mud with acid, alkali or other chemical reagents to change its surface properties. Thermal activation changes the physical and chemical properties of the red mud by adding water and heating it, making it easier to react with subsequent reagents.

[0061] As an optional implementation, the specific steps of the activation treatment include: mixing red mud and water and then stirring and activating them, meeting the following parameters: a mass ratio of red mud to water of 1:8 to 1:4, an activation temperature of 60°C to 90°C, a stirring speed of 100r / min to 400r / min, and an activation time of 0.5h to 3h.

[0062] In the above embodiment, the mass ratio of red mud to water is controlled for the purpose of controlling the solid-liquid ratio of the red mud slurry. If the mass ratio of red mud to water is relatively low, the solid-liquid ratio of the red mud slurry is relatively small, the water content is relatively high, and subsequent treatments such as carbonization and dealkalization require more carbon dioxide; if the mass ratio of red mud slurry is relatively high, the solid-liquid ratio of the red mud slurry is relatively large, the red mud slurry is not easy to stir, and the subsequent reaction may not be sufficient. Therefore, the mass ratio of red mud to water can be 1:8, 1:7, 1:6, 1:5 or 1:4.

[0063] In the above embodiment, the activation temperature, stirring speed and activation time are controlled for the purpose of quickly mixing the red mud slurry and achieving better activation effect. The specific values ​​are not limited. For example, the activation temperature can be set to 60°C, 65°C, 70°C, 75°C, 80°C, 85°C and 90°C, the stirring speed can be 100r / min, 150r / min, 200r / min, 250r / min, 300r / min, 350r / min or 400r / min, and the activation time can be 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h or 4h according to the situation.

[0064] As an optional embodiment, the carbonization dealkalization process uses carbon dioxide to carry out the carbonization dealkalization reaction; wherein, during the carbonization dealkalization reaction process, the following reaction parameters are met: the carbon dioxide pressure is 0.6MPa to 1.5MPa, and the dealkalization reaction time is 0.5h to 2h.

[0065] In the above embodiment, by introducing carbon dioxide gas into the red mud slurry, and controlling the pressure and the dealkalization reaction time, CO2 is fully reacted with the alkaline substance (such as sodium hydroxide NaOH) in the red mud to generate carbonates and bicarbonates, thereby reducing the alkalinity in the slurry. The advantage of doing so is that the amount of acid required in the subsequent treatment process can be reduced, and it also helps to improve the extraction efficiency of scandium. Exemplarily, the pressure of carbon dioxide can be 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1.0MPa, 1.1MPa, 1.2MPa, 1.3MPa, 1.4MPa or 1.5MPa, and the dealkalization reaction time can be 0.5h, 1h, 1.5h or 2h.

[0066] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0067] The red mud used in the following examples and comparative examples is the same, and its chemical composition is shown in Table 1 below:

[0068] Table 1 Chemical composition of red mud

[0069]

[0070]

[0071] Example 1

[0072] This embodiment provides a method for extracting scandium from red mud. Figure 2 As shown, the following steps are included:

[0073] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:4, activating at 100 r / min for 0.5 h at a temperature of 60° C., and finally preparing red mud slurry;

[0074] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry, wherein the pressure of the carbon dioxide is 0.6 MPa and the duration is 0.5 h to obtain a carbonized red mud slurry;

[0075] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0076] The leaching agent is (NH4)2CO3, the total content of which in the first mixed slurry is 0.1 mol / L, the extractant is a mixture of 25% ethanolamine, 20% di(2-ethylhexyl)phosphoric acid and 55% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 10;

[0077] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, wherein the microwave power is adjusted to 200W, the ultrasonic power is adjusted to 200W, the temperature of the reaction system is maintained at 60°C for 1 hour, and the second mixed slurry is obtained.

[0078] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0079] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0080] Example 2

[0081] This embodiment provides a method for extracting scandium from red mud, comprising the following steps:

[0082] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0083] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0084] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0085] The leaching agent is (NH4)2CO3, the total content of which in the first mixed slurry is 0.1 mol / L, the extractant is a mixture of 25% ethanolamine, 20% di(2-ethylhexyl)phosphoric acid and 55% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 10;

[0086] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, wherein the microwave power is adjusted to 200W, the ultrasonic power is adjusted to 200W, the temperature of the reaction system is maintained at 60°C for 1 hour, and the second mixed slurry is obtained.

[0087] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0088] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0089] Example 3

[0090] This embodiment provides a method for extracting scandium from red mud, comprising the following steps:

[0091] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0092] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0093] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0094] The leaching agent is (NH4)2CO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is a mixture of 25% ethanolamine, 20% di(2-ethylhexyl)phosphoric acid and 55% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 10;

[0095] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, wherein the microwave power is adjusted to 400W, the ultrasonic power is adjusted to 500W, the temperature of the reaction system is maintained at 60°C for 1 hour, and the second mixed slurry is obtained.

[0096] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0097] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0098] Example 4

[0099] This embodiment provides a method for extracting scandium from red mud, comprising the following steps:

[0100] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0101] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0102] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0103] The leaching agent is (NH4)2CO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is a mixture of 25% ethanolamine, 20% di(2-ethylhexyl)phosphoric acid and 55% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 10;

[0104] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction at the same time. Carbon dioxide is introduced into the reaction process and the pressure is maintained at 0.6 mPa, wherein the microwave power is adjusted to 400 W and the ultrasonic power is adjusted to 500 W during the reaction process, and the microwave and ultrasonic powers are adjusted to maintain the temperature of the reaction system at 60° C. for 1 hour to obtain a second mixed slurry.

[0105] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0106] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0107] Example 5

[0108] This embodiment provides a method for extracting scandium from red mud, comprising the following steps:

[0109] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0110] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0111] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0112] The leaching agent is (NH4)2CO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is a mixture of 25% ethanolamine, 45% di(2-ethylhexyl)phosphoric acid and 35% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 10;

[0113] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, wherein the microwave power is adjusted to 100W, the ultrasonic power is adjusted to 900W, the temperature of the reaction system is maintained at 60°C for 1 hour, and the second mixed slurry is obtained.

[0114] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0115] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0116] Example 6

[0117] This embodiment provides a method for extracting scandium from red mud, comprising the following steps:

[0118] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0119] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0120] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0121] The leaching agent is (NH4)2CO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is 25% ethanolamine, 25% di(2-ethylhexyl)phosphoric acid, 20% isopropyl monooctyl phosphate and 35% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 10;

[0122] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, wherein the microwave power is adjusted to 400W, the ultrasonic power is adjusted to 500W, the temperature of the reaction system is maintained at 60°C for 1 hour, and the second mixed slurry is obtained.

[0123] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0124] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0125] Example 7

[0126] This embodiment provides a method for extracting scandium from red mud, comprising the following steps:

[0127] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0128] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0129] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0130] The leaching agent is (NH4)2CO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is 25% ethanolamine, 25% di(2-ethylhexyl)phosphoric acid, 20% isopropyl monooctyl phosphate and 35% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 4;

[0131] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, wherein the microwave power is adjusted to 400W, the ultrasonic power is adjusted to 500W, the temperature of the reaction system is maintained at 60°C for 1 hour, and the second mixed slurry is obtained.

[0132] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0133] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0134] Example 8

[0135] This embodiment provides a method for extracting scandium from red mud, comprising the following steps:

[0136] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0137] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0138] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0139] The leaching agent is (NH4)2CO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is 25% ethanolamine, 25% di(2-ethylhexyl)phosphoric acid, 20% isopropyl monooctyl phosphate and 35% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 4;

[0140] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, wherein the microwave power is adjusted to 400W, the ultrasonic power is adjusted to 500W, the temperature of the reaction system is maintained at 90°C for 3.5h, and the second mixed slurry is obtained.

[0141] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0142] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0143] Comparative Example 1

[0144] This comparative example provides a method for extracting scandium from red mud, comprising the following steps:

[0145] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:4 to obtain red mud slurry;

[0146] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry, wherein the pressure of the carbon dioxide is 0.6 MPa and the duration is 0.5 h to obtain a carbonized red mud slurry;

[0147] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0148] The leaching agent is (NH4)2CO3, the total content of which in the first mixed slurry is 0.1 mol / L, the extractant is a mixture of 25% ethanolamine, 20% di(2-ethylhexyl)phosphoric acid and 55% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 10;

[0149] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction at the same time. Carbon dioxide is introduced into the reaction process and the pressure is maintained at 0.6 MPa. The microwave power is adjusted to 200 W, the ultrasonic power is adjusted to 200 W, the temperature of the reaction system is maintained at 60° C. for 1 hour to obtain a second mixed slurry.

[0150] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0151] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is precipitated and crystallized to obtain a scandium product.

[0152] Comparative Example 2

[0153] This comparative example provides a method for extracting scandium from red mud, comprising the following steps:

[0154] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0155] S2, directly adding a leaching agent and an extracting agent into the red mud slurry to obtain a first mixed slurry;

[0156] The leaching agent is (NH4)2CO3 and NH4HCO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is 25% ethanolamine, 25% di(2-ethylhexyl)phosphoric acid, 20% isopropyl monooctyl phosphate and 35% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 4;

[0157] S3, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, wherein the microwave power is adjusted to 200W, the ultrasonic power is adjusted to 200W, the temperature of the reaction system is maintained at 90°C for 3.5h, and the second mixed slurry is obtained.

[0158] S4, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0159] S5, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced, which can be used as a building material.

[0160] Comparative Example 3

[0161] This embodiment provides a method for extracting scandium from red mud, comprising the following steps:

[0162] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0163] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0164] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0165] The leaching agent is (NH4)2CO3 and NH4HCO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is a mixture of 25% ether, 25% di(2-ethylhexyl)phosphoric acid, 20% isopropyl monooctyl phosphate and 35% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 4;

[0166] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, wherein the microwave power is adjusted to 500W, the ultrasonic power is adjusted to 800W, the temperature of the reaction system is maintained at 90°C for 3.5h, and the second mixed slurry is obtained.

[0167] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0168] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0169] Comparative Example 4

[0170] This comparative example provides a method for extracting scandium from red mud, comprising the following steps:

[0171] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0172] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0173] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0174] The leaching agent is (NH4)2CO3 and NH4HCO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is a mixture of 25% ethanolamine, 25% di(2-ethylhexyl)phosphoric acid, 20% isopropyl monooctyl phosphate and 35% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 4;

[0175] S4, using a stirred reactor to simultaneously perform leaching reaction and extraction reaction on the first mixed slurry, maintaining the temperature of the reaction system at 90° C. for 3.5 hours to obtain a second mixed slurry.

[0176] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0177] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0178] Comparative Example 5

[0179] This comparative example provides a method for extracting scandium from red mud, comprising the following steps:

[0180] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0181] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0182] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0183] The leaching agent is (NH4)2CO3 and NH4HCO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is a mixture of 25% ethanolamine, 25% di(2-ethylhexyl)phosphoric acid, 20% isopropyl monooctyl phosphate and 35% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 4;

[0184] S4, using microwaves to simultaneously perform leaching reaction and extraction reaction on the first mixed slurry, wherein the microwave power is adjusted to 200 W, the temperature of the reaction system is maintained at 90° C., and the reaction is carried out for 3.5 hours to obtain a second mixed slurry.

[0185] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0186] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0187] Comparative Example 6

[0188] This comparative example provides a method for extracting scandium from red mud, comprising the following steps:

[0189] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0190] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0191] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0192] The leaching agent is (NH4)2CO3 and NH4HCO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is a mixture of 25% ethanolamine, 25% di(2-ethylhexyl)phosphoric acid, 20% isopropyl monooctyl phosphate and 35% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 4;

[0193] S4, using ultrasonic wave to simultaneously perform leaching reaction and extraction reaction on the first mixed slurry, wherein the ultrasonic wave power is adjusted to 200W during the reaction process, and the temperature of the reaction system is maintained at 90°C for 3.5 hours to obtain a second mixed slurry.

[0194] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0195] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0196] Comparative Example 7

[0197] This comparative example provides a method for extracting scandium from red mud, comprising the following steps:

[0198] S1, preparing red mud slurry: mixing red mud and water in a mass ratio of 1:8, activating at 400 r / min for 3 h at a temperature of 90° C., and finally preparing red mud slurry;

[0199] S2, carbonizing and dealkalizing the red mud slurry: introducing carbon dioxide into the red mud slurry at a pressure of 1.5 MPa for 2 hours to obtain a carbonized red mud slurry;

[0200] S3, adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry;

[0201] The leaching agent is (NH4)2CO3 and NH4HCO3, the total content of which in the first mixed slurry is 0.15 mol / L, the extractant is a mixture of 25% ethanolamine, 25% di(2-ethylhexyl)phosphoric acid, 20% isopropyl monooctyl phosphate and 35% kerosene, and the volume ratio of the extractant to the first mixed slurry is 1 / 15;

[0202] S4, using microwave and ultrasonic synergistic effect, the first mixed slurry is subjected to leaching reaction and extraction reaction simultaneously, wherein the microwave power is adjusted to 200W, the ultrasonic power is adjusted to 200W, the temperature of the reaction system is maintained at 90°C for 3.5h, and the second mixed slurry is obtained.

[0203] S5, extracting and separating the second mixed slurry to obtain a second mixture and a scandium-rich organic phase;

[0204] S6, stripping the scandium-rich organic phase to obtain a scandium-rich solution and a residual organic phase, wherein the residual organic phase can be returned to the process and reused as an extractant, and the scandium-rich solution is subjected to precipitation and crystallization to obtain a scandium product; the second mixture is filtered to obtain a filtrate and a filter cake, wherein the filtrate can be returned to step S1 for preparing red mud slurry, and the alkali content in the filter cake is reduced and can be used as a building material.

[0205] The leaching extraction rate of scandium ions obtained by the scandium extraction methods provided in Examples 1 to 8 and Comparative Examples 1 to 7 and the final scandium recovery rate are calculated respectively, and the calculation method is as follows:

[0206] Among them, the calculation formula of the leaching extraction rate of scandium ions is as follows:

[0207]

[0208] Wherein, μ1 is the leaching extraction rate of scandium ions, c1 is the scandium ion concentration in the scandium-rich organic phase, v1 is the volume of the scandium-rich organic phase, w0 is the scandium element content in the red mud, and g0 is the original mass of the red mud.

[0209] The recovery rate of scandium ions is calculated as follows:

[0210]

[0211] In the formula, μ2 is the recovery rate of scandium ions, w2 is the scandium content in the scandium product, g2 is the mass of the scandium product, w0 is the scandium content in the red mud, and g0 is the mass of the red mud.

[0212] The test results obtained by statistics are shown in Table 2 below:

[0213] Table 2 Test results of Examples 1 to 8 and Comparative Examples 1 to 7

[0214] Leaching extraction rate / % Scandium recovery rate / % Example 1 70.9 54.3 Example 2 74.2 56.6 Example 3 78.4 59.1 Example 4 83.5 62.4 Example 5 85.6 63.5 Example 6 85.9 63.7 Example 7 88.6 67.8 Example 8 89.3 68.2 Comparative Example 1 58.4 45.8 Comparative Example 2 54.6 44.4 Comparative Example 3 55.7 44.8 Comparative Example 4 54.2 43.3 Comparative Example 5 51.5 49.6 Comparative Example 6 58.8 48.7 Comparative Example 7 51.1 40.2

[0215] As can be seen from the above table, the method for extracting scandium from red mud provided by the present application can be used to extract scandium from Bayer red mud. The method can achieve a one-step method for extracting scandium from Bayer red mud, and the leaching and extraction efficiency of scandium ions is ≥70%, and the final recovery rate of scandium in red mud is ≥50%, which is significantly higher than the experimental results in the comparative example. It can be seen that the scandium extraction method provided in the present invention has a high extraction efficiency for scandium in red mud. The specific reasons for the low extraction leaching rate and recovery rate of the product in the comparative example are as follows:

[0216] The Bayer red mud in Comparative Example 1 was not pre-activated, resulting in poor red mud dispersibility in the red mud slurry, low activity, and insufficient subsequent leaching, which affected the leaching extraction rate and recovery rate;

[0217] The Bayer red mud in Comparative Example 2 was not subjected to carbonization and dealkalization treatment, and the sodium alkali in the red mud was not replaced with sodium bicarbonate, which did not increase the solubility of scandium, and the leaching of metal scandium was not sufficient, which also affected the leaching extraction rate and recovery rate;

[0218] In Comparative Example 3, ether was used as the extractant instead of organic amine, which resulted in rapid overflow of carbon dioxide gas in the red mud slurry, insufficient carbon dioxide concentration in the first mixed solution, and the reaction efficiency was affected, resulting in a low leaching extraction rate;

[0219] In Comparative Example 4, no energy field was used, and the reaction was carried out only by heating and stirring. The dispersion, fragmentation, vibration and friction of the molecules in the reaction system were insufficient, and the reaction activation energy was insufficient, resulting in low leaching and extraction efficiency.

[0220] In Comparative Example 5, only microwaves were used, lacking the multiple effects of ultrasonic oscillation, dispersion, crushing, cavitation, stirring, etc., resulting in insufficient particle crushing size, insufficient solute dissolution, and insufficient reaction activity;

[0221] In Comparative Example 6, only ultrasound was used, the molecular vibration and friction in the reaction system were insufficient, the reaction efficiency was low, and the leaching extraction rate was low.

[0222] In Comparative Example 7, the content of the extractant is insufficient, and the leaching and extraction effect is not obvious.

[0223] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein 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 the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for extracting scandium from red mud, characterized in that: The red mud contains scandium, and the method comprises the following steps: Carbonizing and dealkalizing the red mud slurry prepared from the red mud to obtain carbonized red mud slurry; adding a leaching agent and an extracting agent into the carbonized red mud slurry to obtain a first mixed slurry; subjecting the first mixed slurry to a leaching reaction and an extraction reaction simultaneously to obtain a scandium-rich organic phase; and The scandium-rich organic phase is stripped to obtain a scandium-rich solution.

2. The method for extracting scandium from red mud according to claim 1, characterized in that: The extractant comprises, by mass fraction, 25% to 45% of an organic amine, 15% to 45% of an organic phosphonic acid and 25% to 60% of a diluent.

3. The method for extracting scandium from red mud according to claim 2, characterized in that: The organic amine comprises at least one of the following: monoethanolamine, diethanolamine, diisopropanolamine, N-methyldiethanolamine, isopropanolamine, diethylamine, triethylamine, trioctylamine, triisooctylamine, n-dodecyl(trialkylmethyl)amine, trialkylmethylamine fluoride and trioctyldecyl tertiary amine; and / or The organic phosphate ester includes at least one of the following: tributyl phosphate, di(2-ethylhexyl)phosphoric acid, 2-ethylhexyl phosphate mono(2-ethylhexyl) ester, isopropyl monooctyl phosphate, di(2,4,4-trimethylpentyl)phosphonic acid and di(2-ethylhexyl)phosphinic acid.

4. The method for extracting scandium from red mud according to claim 1, characterized in that: The volume ratio of the extractant to the first mixed slurry is 1:10 to 1:

4.

5. The method for extracting scandium from red mud according to claim 1, characterized in that: The leaching agent comprises a carbonate solution and / or a bicarbonate solution, wherein the molar content of the carbonate relative to the volume of the first mixed slurry is 4.16*10 -4 mol / L~15.5*10 -2 mol / L, the molar content of the bicarbonate relative to the volume of the first mixed slurry is 2.02*10 -3 mol / L~15.5*10 -2 mol / L.

6. The method for extracting scandium from red mud according to claim 1, characterized in that: The step of simultaneously subjecting the first mixed slurry to a leaching reaction and an extraction reaction to obtain a scandium-rich organic phase specifically comprises: Using an ultrasonic-microwave composite field, the first mixed slurry is subjected to a leaching reaction and an extraction reaction simultaneously, and a second mixed slurry is obtained after the reaction; The second mixed slurry is subjected to extraction and separation to obtain a scandium-rich organic phase.

7. The method for extracting scandium from red mud according to claim 6, characterized in that: The ultrasonic-microwave composite field meets the following parameters: ultrasonic power is 200W-1000W, and microwave power is 100W-500W.

8. The method for extracting scandium from red mud according to claim 6, characterized in that: The leaching reaction and the extraction reaction both meet the following reaction parameters: the reaction temperature is 60° C. to 90° C., and the reaction time is 1 h to 3.5 h.

9. The method for extracting scandium from red mud according to claim 1, characterized in that: The red mud slurry prepared from the red mud is subjected to carbonization and dealkalization to obtain carbonized red mud slurry, which specifically includes: activating the red mud slurry prepared from the red mud to obtain activated red mud slurry; The activated red mud slurry is carbonized and dealkalized to obtain carbonized red mud slurry.

10. The method for extracting scandium from red mud according to claim 1 or 9, characterized in that: The carbonization dealkalization adopts carbon dioxide to carry out the carbonization dealkalization reaction; wherein, the carbonization dealkalization reaction satisfies the following reaction parameters: the carbon dioxide pressure is 0.6MPa-1.5MPa, and the reaction time is 0.5h-2h.

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