Method for efficiently leaching Sc, Al and Fe from red mud by using eutectic solvent

Abstract

The invention relates to a method for efficiently leaching Sc, Al and Fe from red mud by using a deep eutectic solvent, and belongs to the technical field of red mud resource utilization. The preparation method comprises the following steps: carrying out heat treatment on red mud at 500-800 DEG C for 0.5-2 hours, and carrying out ball milling to obtain red mud powder; the preparation method comprises the following steps: by taking DL-carnitine hydrochloride as a hydrogen bond acceptor and ascorbic acid as a hydrogen bond donor, dissolving the DL-carnitine hydrochloride and the ascorbic acid into deionized water, heating and stirring for 30-120 minutes at the temperature of 60-90 DEG C, and cooling to room temperature to obtain the eutectic solvent; the method comprises the following steps: adding red mud powder into a deep eutectic solvent, and stirring and leaching for 60-120 minutes at the temperature of 100-130 DEG C to obtain a leachate containing Sc, Al and Fe; according to the method, Sc, Al and Fe can be efficiently leached from the red mud in an extremely short time by utilizing the eutectic solvent, and the leaching efficiency of Sc, Al and Fe can reach 99% or above.

Description

TECHNICAL FIELD

[0001] The application relates to a method for efficiently leaching Sc, Al and Fe from red mud by using a eutectic solvent, and belongs to the technical field of red mud resource utilization. BACKGROUND

[0002] Red mud (RM) is the main waste residue discharged in the production process of alumina. It is named because of its high iron oxide content, reddish-brown appearance and similarity to red soil. Untreated RM is difficult to utilize due to its fine particle size, complex mineral phase composition and strong alkalinity which is corrosive. RM contains a large amount of valuable metal elements such as iron, titanium, aluminum, scandium, etc. Now these useful elements cannot be recovered due to the accumulation of RM, causing serious resource waste. In particular, high-iron RM has a high iron content, mainly in the form of Fe2O3, FeOOH and FeTiO3, which can be used as a potential iron resource for recycling.

[0003] From the composition, red mud is rich in a large amount of valuable metal oxides such as Fe2O3, Al2O3, TiO2 and rare metal oxides. Generally speaking, since the iron oxide content in red mud can exceed 50%, the recovery of iron will be one of the hottest issues. In addition to extracting iron, it is also difficult to extract alumina from red mud because it usually exists in the form of gibbsite, boehmite and red limestone. The alkali sintering method for extracting Al2O3 from red mud is the most mature method. It is usually sintered with Na2CO3 and CaO at high temperature to generate water-soluble sodium aluminate, and then the aluminate is leached with an alkaline solution to extract alumina. Under the best conditions, the alkali sintering method can obtain a high recovery rate of alumina; but its high energy consumption limits its large-scale application. In recent years, in order to further reduce the cost, some other methods have also been proposed, such as the sub-molten salt method and the acid leaching technology for extracting alumina from red mud. However, due to the excessive use of alkali and acid agents, a large amount of acid-containing waste residue or alkali-containing waste residue is generated.

[0004] Therefore, developing a technology for reducing acid and alkali consumption, realizing high-purity leaching of valuable metals in red mud and sustainable treatment of large quantities of solid waste is an effective way to practice circular economy and promote sustainable development, and has positive significance in solving the problem of resource recycling and environmental pollution. SUMMARY

[0005] In view of the problems of high energy consumption, excessive use of acid and alkali reagents, and low leaching recovery efficiency in the current recovery of valuable metals in red mud, the application provides a method for efficiently leaching Sc, Al and Fe from red mud by using a eutectic solvent. The eutectic solvent is configured by using DL-carnitine hydrochloride as a hydrogen bond acceptor and ascorbic acid as a hydrogen bond donor. The eutectic solvent can efficiently leach Sc, Al and Fe from red mud, and the leaching efficiency of Sc, Al and Fe can reach more than 99% within 60 minutes.

[0006] A method for efficiently leaching Sc, Al and Fe from red mud by using a eutectic solvent, the specific steps are as follows: (1) The red mud is placed at a temperature of 500-800℃ for heat treatment for 0.5-2h, and ball milling is performed to obtain red mud powder; (2) DL-carnitine hydrochloride is used as a hydrogen bond acceptor, and ascorbic acid is used as a hydrogen bond donor, the DL-carnitine hydrochloride and ascorbic acid are dissolved in deionized water, heated and stirred at a temperature of 60-90℃ for 30-120min, and cooled to room temperature to obtain a eutectic solvent; (3) The red mud powder is added to the eutectic solvent, and stirred and leached at a temperature of 100-130℃ for 60-120min to obtain a leaching solution containing Sc, Al and Fe.

[0007] Preferably, the particle size of the red mud powder in step (1) is 0.471-13.7μm.

[0008] Preferably, the molar ratio of DL-carnitine hydrochloride to ascorbic acid in step (2) is 2:1-1:4.

[0009] Preferably, the mass content of deionized water in the eutectic solvent in step (2) is 20-60%.

[0010] Preferably, the solid-liquid ratio g:L of the red mud powder to the eutectic solvent in step (2) is 10:1-50:1.

[0011] The leaching rate calculation formula (1) of Sc, Al and Fe in the red mud powder of the present application is as follows: (1) In the formula, is the leaching efficiency of Sc, Al and Fe, is the concentration (mg / L) of metal ions (M=Sc, Al and Fe) in the leaching solution, V is the volume (L) of the leaching solution, and m is the mass (g) of the red mud powder added to the eutectic solvent; is the mass fraction (wt%) of Sc, Al and Fe in the red mud.

[0012] The principle of using a eutectic solvent to efficiently leach Sc, Al and Fe from red mud in the present application is as follows: (1) In the eutectic solvent, the hydrogen ions ionized from ascorbic acid combine with the oxygen in the metal-oxygen bonds of Sc2O3, Al2O3 and Fe2O3 in the red mud, resulting in the dissolution of the metal oxides; (2) The high-valence metal ions of Sc 3+ , Al 3+ and Fe 3+ in the red mud are reduced to Sc 2+Sc, Al and Fe 2+ Sc, Al and Fe 2+ low valence metal ions; (3) The low valence metal ions after reduction form a complex with the chloride ions in the DL-carnitine hydrochloride. Due to the presence of water, partial hydrolysis of the complex of the chloride ions occurs to generate a complex of the hydrated metal ions, thereby finally realizing the leaching of Sc, Al and Fe.

[0013] The present application has the following advantages: (1) The present application uses DL-carnitine hydrochloride as a hydrogen bond acceptor and ascorbic acid as a hydrogen bond donor to configure a deep eutectic solvent. The deep eutectic solvent is used to efficiently leach Sc, Al and Fe from red mud. The process can be shortened to 60 min, and the leaching rates of Sc, Al and Fe are all above 99%. (2) The present application uses the deep eutectic solvent to efficiently leach Sc, Al and Fe from red mud. The use of toxic solvents, strong acids or strong bases can be avoided. Moreover, both DL-carnitine hydrochloride and ascorbic acid can be naturally degraded, thereby reducing the harm to the environment. (3) The process of the present application has the advantages of simple operation, low reaction temperature, short leaching time and high leaching efficiency in the whole selective precipitation separation process. DETAILED DESCRIPTION

[0014] The present application will be further described in detail below in conjunction with specific embodiments, but the scope of protection of the present application is not limited to the content described.

[0015] Example 1: The content of metal oxides contained in the red mud in the present embodiment is shown in Table 1 in terms of mass percentage. Table 1 Chemical composition of red mud

[0016] A method for efficiently leaching Sc, Al and Fe from red mud by using a deep eutectic solvent, the specific steps are as follows: (1) The red mud is heat-treated at a temperature of 500℃ for 1h, and then ball-milled to obtain red mud powder. The average particle size of the red mud powder is 5.39μm; (2) DL-carnitine hydrochloride is used as a hydrogen bond acceptor, and ascorbic acid is used as a hydrogen bond donor. The DL-carnitine hydrochloride and the ascorbic acid are dissolved in deionized water. The solution is heated and stirred at a temperature of 60℃ for 30min, and then cooled to room temperature to obtain a deep eutectic solvent. The molar ratio of the DL-carnitine hydrochloride to the ascorbic acid is 2:1. The mass content of deionized water in the deep eutectic solvent is 20%; (3) The red mud powder is added to the deep eutectic solvent, and then stirred and leached at a temperature of 100℃ for 60min to obtain a leaching solution containing Sc, Al and Fe. The solid-liquid ratio g:L of the red mud powder to the deep eutectic solvent is 10:1. Sc 2+ , Al 2+ and Fe 2 leaching rates were 99.11%, 99.14% and 99.41%, respectively.

[0017] Example 2: In this example, the red mud is the same as that in Example 1; A method for efficiently leaching Sc, Al and Fe from red mud by using a deep eutectic solvent, the specific steps are as follows: (1) The red mud is heated at a temperature of 500°C for 1h, and then ball milled to obtain a red mud powder, the average particle size of the red mud powder is 5.39μm; (2) DL-carnitine hydrochloride is used as a hydrogen bond acceptor, and ascorbic acid is used as a hydrogen bond donor, the DL-carnitine hydrochloride and ascorbic acid are dissolved in deionized water, heated and stirred at a temperature of 60°C for 30min, and then cooled to room temperature to obtain a deep eutectic solvent; the molar ratio of the DL-carnitine hydrochloride to the ascorbic acid is 3:1, and the mass content of deionized water in the deep eutectic solvent is 20%; (3) The red mud powder is added to the deep eutectic solvent, and stirred and leached at a temperature of 100°C for 90min to obtain a leaching solution containing Sc, Al and Fe; the solid-liquid ratio g:L of the red mud powder to the deep eutectic solvent is 10:1; Sc 2+ , Al 2+ and Fe 2 leaching rates were 99.25%, 99.71% and 99.98%, respectively.

[0018] Example 3: In this example, the red mud is the same as that in Example 1; A method for efficiently leaching Sc, Al and Fe from red mud by using a deep eutectic solvent, the specific steps are as follows: (1) The red mud is heated at a temperature of 750°C for 1.5h, and then ball milled to obtain a red mud powder, the average particle size of the red mud powder is 5.39μm; (2) DL-carnitine hydrochloride is used as a hydrogen bond acceptor, and ascorbic acid is used as a hydrogen bond donor, the DL-carnitine hydrochloride and ascorbic acid are dissolved in deionized water, heated and stirred at a temperature of 75°C for 1h, and then cooled to room temperature to obtain a deep eutectic solvent; the molar ratio of the DL-carnitine hydrochloride to the ascorbic acid is 1:2, and the mass content of deionized water in the deep eutectic solvent is 40%; (3) The red mud powder is added to the deep eutectic solvent, and stirred and leached at a temperature of 120°C for 90min to obtain a leaching solution containing Sc, Al and Fe; the solid-liquid ratio g:L of the red mud powder to the deep eutectic solvent is 30:1; Sc 2+ , Al 2+ and Fe 2The leaching rates of Sc, Al and Fe are 99.94%, 99.99% and 99.98%, respectively.

[0019] In this embodiment, the red mud is the same as that in Embodiment 1. A method for efficiently leaching Sc, Al and Fe from red mud by using a deep eutectic solvent, the specific steps are as follows: (1) The red mud is heated at a temperature of 750°C for 1.5 h, and then ball-milled to obtain a red mud powder, the average particle size of the red mud powder being 5.39 μm; (2) DL-carnitine hydrochloride is used as a hydrogen bond acceptor, and ascorbic acid is used as a hydrogen bond donor, the DL-carnitine hydrochloride and the ascorbic acid are dissolved in deionized water, heated and stirred at a temperature of 75°C for 1 h, and then cooled to room temperature to obtain a deep eutectic solvent; the molar ratio of the DL-carnitine hydrochloride to the ascorbic acid is 1:3, and the mass content of deionized water in the deep eutectic solvent is 40%; (3) The red mud powder is added into the deep eutectic solvent, and then stirred and leached at a temperature of 120°C for 90 min to obtain a leaching solution containing Sc, Al and Fe; the solid-liquid ratio g:L of the red mud powder to the deep eutectic solvent is 30:1; It is determined that the leaching rates of Sc 2+ , Al 2+ and Fe 2 are 99.94%, 99.99% and 99.98%, respectively.

[0020] In this embodiment, the red mud is the same as that in Embodiment 1. A method for efficiently leaching Sc, Al and Fe from red mud by using a deep eutectic solvent, the specific steps are as follows: (1) The red mud is heated at a temperature of 800°C for 2 h, and then ball-milled to obtain a red mud powder, the average particle size of the red mud powder being 5.39 μm; (2) DL-carnitine hydrochloride is used as a hydrogen bond acceptor, and ascorbic acid is used as a hydrogen bond donor, the DL-carnitine hydrochloride and the ascorbic acid are dissolved in deionized water, heated and stirred at a temperature of 90°C for 120 min, and then cooled to room temperature to obtain a deep eutectic solvent; the molar ratio of the DL-carnitine hydrochloride to the ascorbic acid is 1:3, and the mass content of deionized water in the deep eutectic solvent is 50%; (3) The red mud powder is added into the deep eutectic solvent, and then stirred and leached at a temperature of 130°C for 120 min to obtain a leaching solution containing Sc, Al and Fe; the solid-liquid ratio g:L of the red mud powder to the deep eutectic solvent is 50:1; It is determined that the leaching rates of Sc 2+ , Al 2+ and Fe 2 are 99.89%, 99.99% and 99.99%, respectively.

[0021] Embodiment 6: In this embodiment, the red mud is the same as that in Embodiment 1; A method for efficiently leaching Sc, Al and Fe from red mud by using a eutectic solvent, the specific steps are as follows: (1) The red mud is heat treated at a temperature ℃ for h, and then ball milled to obtain a red mud powder, wherein the average particle size of the red mud powder is (2) DL-carnitine hydrochloride is used as a hydrogen bond acceptor, and ascorbic acid is used as a hydrogen bond donor, and the DL-carnitine hydrochloride and the ascorbic acid are dissolved in deionized water, heated and stirred at a temperature of 90℃ for 120 min, and then cooled to room temperature to obtain a eutectic solvent; the molar ratio of the DL-carnitine hydrochloride to the ascorbic acid is 1:4, and the mass content of deionized water in the eutectic solvent is 50%; (3) The red mud powder is added into the eutectic solvent, and then stirred and leached at a temperature of 130℃ for 120 min to obtain a leaching solution containing Sc, Al and Fe; the solid-liquid ratio g:L of the red mud powder to the eutectic solvent is 50:1; It is determined that the leaching rates of Sc 2+ , Al 2+ and Fe 2 are 99.86%, 99.89% and 99.99%, respectively.

[0022] The specific embodiments of the present application are described in detail above, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application.

Claims

1. A method for efficient leaching of Sc, Al and Fe from red mud using a deep eutectic solvent, characterized in that, The specific steps are as follows: (1) the red mud is placed at a temperature of 500-800℃ for heat treatment for 0.5-2h, and ball milling is performed to obtain red mud powder; (2) taking DL-carnitine hydrochloride as a hydrogen bond acceptor and ascorbic acid as a hydrogen bond donor, the DL-carnitine hydrochloride and the ascorbic acid are dissolved in deionized water, heated and stirred at a temperature of 60-90℃ for 30-120min, and cooled to room temperature to obtain a deep eutectic solvent; (3) the red mud powder is added to the deep eutectic solvent, and stirring leaching is performed at a temperature of 90-130℃ for 60-120min to obtain a leaching solution containing Sc, Al and Fe.

2. The method for efficiently leaching Sc, Al and Fe from red mud by using a deep eutectic solvent according to claim 1, characterized in that: The particle size of the red mud powder in step (1) is 0.471-13.7μm.

3. The method for efficiently leaching Sc, Al and Fe from red mud by using a deep eutectic solvent according to claim 1, characterized in that: The molar ratio of DL-carnitine hydrochloride to ascorbic acid in step (2) is 2:1-1:

4.

4. The method for efficiently leaching Sc, Al and Fe from red mud by using a deep eutectic solvent according to claim 1, characterized in that: The mass content of deionized water in the deep eutectic solvent in step (2) is 20-60%.

5. The method for efficiently leaching Sc, Al and Fe from red mud by using a deep eutectic solvent according to claim 1, characterized in that: The solid-liquid ratio g:L of the red mud powder to the deep eutectic solvent in step (2) is 10:1-50:1.

Images