Method for recycling organic phase in a stable emulsion layer of rare earth extraction

Abstract

The application discloses a method for recycling organic phase in a rare earth extraction stable emulsion layer. The method mainly comprises the following steps: performing primary centrifugal separation on the extraction stable emulsion layer mixture, collecting the upper organic phase and the lower concentrated solid residue; mixing and heating the concentrated solid residue with a mixed acid of hydrochloric acid and glacial acetic acid and stirring to react, and separating an acid-soluble organic phase containing impurities; contacting the organic phase with a feed liquid containing cheap metal ions, so that the impurities are combined to form a third phase rich in impurities; and finally performing secondary centrifugal separation on the mixed system to separate and collect the purified organic phase. The application mainly uses physical centrifugation and mild acid dissolution, and cooperates with impurity transfer technology, avoids degradation of the extractant caused by high temperature, and has a total organic phase recovery rate of more than 85%, realizes deep purification and maximized recycling of the organic phase, greatly reduces the production cost, and guarantees stable operation of the equipment.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, specifically to a method for recovering the organic phase in a rare earth extraction stabilized emulsion layer. Background Technology

[0002] In industrial solvent extraction, acidic phosphorus extractants are the most commonly used choice. However, due to factors such as fluctuations in feed acidity, accumulation of impurity ions, and aging and degradation of the organic phase, a stable emulsion layer (intermediate phase contaminant) often forms at the interface between the two phases in the extraction tank. This emulsion layer extensively coats the effective extractant and diluent, leading to increased loss of the extracted organic phase, decreased extraction efficiency, slower phase separation, and easy equipment blockage. This necessitates frequent production line shutdowns for tank cleaning, severely impacting continuous production and economic efficiency.

[0003] In existing technologies for emulsion layer treatment and organic recovery: Patent CN101629239A discloses a method for treating the third phase of a copper extraction system, which uses centrifugal separation combined with activated clay adsorption. First, solid particles are removed by centrifugation, then activated clay is added to adsorb impurities and emulsion components, and the organic phase is recovered after clarification. However, this method is only a single physical separation and adsorption treatment, and cannot release and recover the large amount of effective organic matter encapsulated in the three-phase slag, resulting in a low organic recovery rate. Furthermore, it relies on activated clay adsorption, which is prone to saturation and requires frequent replacement, leading to high operating costs. It also has limited effectiveness in stabilizing the emulsion layer, and the regenerated organic matter easily leads to the formation of a new emulsion layer.

[0004] Patent CN120290882A describes a method for recycling the organic phase by adding P204 extractant to the transition phase material, heating and stirring, followed by acid back-extraction. However, this method suffers from poor selectivity, severe co-extraction of iron, rare earth elements, and aluminum, high subsequent material purification costs, and poor recycling efficiency of the organic phase.

[0005] Patent CN111118313B discloses a method for removing impurities and recovering organic phases from rare earth extraction emulsions, including separation of the organic phase, hydrochloric acid back-extraction, acid washing, and water washing. This method mainly relies on long-term static separation and uses hydrochloric acid back-extraction and mixed acid washing to remove impurities. The process is lengthy, and the recovery rate of the organic phase still needs to be improved.

[0006] In summary, existing technologies generally suffer from low organic recovery rates, complex processes, high reagent costs, and a tendency to cause organic phase degradation or incomplete regeneration. They cannot achieve efficient and maximized recovery of the organic phase from the extraction-stabilized emulsion layer under low-cost and mild conditions. Therefore, developing a simple, high-recovery, low-cost, and widely applicable method for efficient recovery of the organic phase from the extraction-stabilized emulsion layer is of great significance for the stable operation of industrial extraction systems and for reducing production costs. Summary of the Invention

[0007] The purpose of this invention is to provide a method for recovering the organic phase in a rare earth extraction stabilized emulsion layer, so as to solve the problems of low organic recovery rate, complex process, high reagent cost, and easy degradation or incomplete regeneration of organic phase in the prior art.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] A method for recovering the organic phase from a rare earth extraction stabilized emulsion includes the following steps:

[0010] S1. Centrifuge the mixture of extraction-stabilized emulsion layer produced by rare earth extraction at a speed of 1000-4000 rpm for 10-30 min to separate and collect the upper organic phase A and the lower concentrated solid residue B.

[0011] S2. The concentrated solid residue B obtained in step S1 is mixed with hydrochloric acid-glacial acetic acid mixed acid, and stirred at 70-90℃ for 0.5-1.5h. After the reaction is completed, the mixture is allowed to stand and separate into layers. The upper acid-soluble organic phase C and the lower rare earth acid solution are separated and collected. The hydrochloric acid-glacial acetic acid mixed acid is made by mixing 4-6 mol / L hydrochloric acid and glacial acetic acid at a mass ratio of 80-95:5-20.

[0012] S3. The acid-soluble organic phase C obtained in step S2 is contacted and mixed with a 40-50 g / L solution of inexpensive metal ions. The mixture is stirred at 20-60°C for 5-15 minutes to allow impurities in the organic phase to combine with the inexpensive metal ions to form a mixed system D containing a third phase rich in impurities. The inexpensive metal ions are selected from Ca... 2+ Mg 2+ La 3+ One or more of the following;

[0013] S4. Centrifuge the mixture D containing the third phase after the reaction in step S3 at a speed of 1000-4000 rpm for 20-40 min. After separating and collecting the upper layer, the purified organic phase E can be reused.

[0014] Furthermore, in step S2, the hydrochloric acid-glacial acetic acid mixed acid is made by mixing 4.5-5.5 mol / L hydrochloric acid and glacial acetic acid at a mass ratio of 85-92:8-15; the solid-liquid ratio of the concentrated solid residue B to the hydrochloric acid-glacial acetic acid mixed acid is 1 g:1-4 mL.

[0015] Furthermore, in step S3, the inexpensive metal ion solution is a lanthanum chloride solution with a concentration of 42-48 g / L.

[0016] Furthermore, in step S3, the volume ratio of the acid-soluble organic phase C to the inexpensive metal ion solution is 1:0.8-1.2.

[0017] Furthermore, the process also includes returning the upper organic phase A collected in step S1 to the main extraction process after acid washing, water washing, and saponification; and combining the purified upper organic phase E collected in step S4 with the upper organic phase collected in step S1 or reusing it separately after acid washing, water washing, and acidity adjustment.

[0018] Furthermore, the impurity-rich solid third-phase slag obtained from the lower layer after centrifugation in step S4 is returned to step S2 and combined with the concentrated solid slag B for cyclic acid dissolution treatment or directly treated as solid waste for resource recovery.

[0019] Furthermore, the organic phase in the extraction-stabilized emulsion mixture comprises an acidic phosphorus extractant and a diluent, wherein the acidic phosphorus extractant is P204 or P507, and the diluent is sulfonated kerosene or No. 260 solvent oil.

[0020] The acid dissolution reaction mechanism in step S2 is as follows: the concentrated solid slag contains metallic impurities (mainly Fe). 3+ Al 3+ Oxides and hydroxides of metals (such as zinc oxide, acetic acid, etc.) dissolve into the aqueous phase under the action of mixed acids, while simultaneously disrupting the colloidal structure of the emulsion layer and releasing the encapsulated organic phase. During this process, glacial acetic acid forms soluble complexes with some metal ions through coordination, promoting the transfer of impurities from the organic phase to the aqueous phase, thereby reducing the processing load of subsequent organic phase purification steps.

[0021] The impurity transfer mechanism in step S3 is as follows: A large number of impurities accumulate in the acid-soluble organic phase obtained from the acid dissolution of solid acid-dissolved residue. These impurities easily form emulsions when the organic phase undergoes an extraction reaction with metal ions. A solution of inexpensive metal ions is added to this acid-soluble organic phase, and an extraction reaction is carried out. The impurities inside the organic phase interact with the inexpensive metal ions to form an emulsion phase. After centrifugation, the impurities are enriched and transferred to the newly formed third phase. The upper organic phase is the purified organic phase after impurity removal, achieving directional transfer and separation of impurities and obtaining a reusable effective organic phase.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. High organic phase recovery rate: approximately 55% of the organic phase is recovered in one centrifugation separation, and more than 30% is recovered in a second centrifugation separation, with a total organic phase recovery rate of no less than 85%, which is significantly better than the single physical separation recovery rate of existing technologies.

[0024] 2. The extractant does not degrade: This method mainly uses room temperature centrifugation and mild acid dissolution, avoiding high temperature strong alkali or carbonate treatment. The extractant does not degrade and has stable performance. The regenerated organic phase can be directly reused after simple treatment.

[0025] 3. Deep purification of the organic phase: Utilizing a low-cost metal ion impurity transfer mechanism, residual Fe in the organic phase is removed.3+ Al 3 + Impurities are transferred to the newly formed third phase, achieving deep purification of the organic phase and preventing the accumulation of impurities during recycling.

[0026] 4. Low cost and simple process: The hydrochloric acid, glacial acetic acid and inexpensive metal ion chloride used in this method are all inexpensive and readily available chemicals. The process is short (completed in four steps) and requires low-level equipment (a conventional centrifuge is sufficient), making it suitable for industrial application.

[0027] 5. Wide applicability: This method is applicable to stable emulsion layers produced by different acidic phosphorus extractant systems such as P204 and P507, and can also be extended to the treatment of emulsion layers in other solvent extraction systems such as copper extraction and nickel-cobalt extraction. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of a method for recovering the organic phase in a rare earth extraction stabilized emulsion layer, provided in an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] This invention provides a method for recovering the organic phase (85-95% organic phase, 4-14% rare earth phase, and the remainder being entrained aqueous phase) from a rare earth extraction stabilized emulsion. The method achieves efficient resource recovery and impurity separation through four steps: primary physical centrifugation, concentrated solid slag mixed with acid for dissolution, acid dissolution of the organic phase from the solid slag followed by extraction with inexpensive metal ions for impurity removal, secondary centrifugation, and recovery. The specific process flow is as follows: Figure 1 As shown. The above composition ratios are typical ranges of mass percentages of the stable emulsion mixture in the extraction tank during actual production, based on sampling and analysis. The organic phase is calculated as a mixture of acidic phosphorus extractant and diluent; rare earth is calculated as REO (rare earth oxides); and the entrained aqueous phase is the residual aqueous solution after the extractant is emulsified and encapsulated.

[0031] Example 1

[0032] This embodiment provides a method for recovering the organic phase in a rare earth extraction stabilized emulsion layer, and the specific steps are as follows.

[0033] S1. Primary Physical Centrifugal Separation: Take 1000 g of the extraction-stabilized emulsion mixture (86% organic phase, 9.6% rare earth, and the remainder being entrained aqueous phase) generated in the rare earth extraction tank and place it in a centrifuge. Centrifuge at 3000 rpm for 20 min. After centrifugation, the system separates into layers. Collect the upper clear, directly reusable normal organic phase A, and the lower concentrated solid residue B, which is rich in impurities and residual organic phase. Organic phase A is directly returned to the extraction production line after acid washing, water washing, and saponification. The acid solution is precipitated to recover 18.94 g of rare earth.

[0034] S2. Acid Dissolution with Mixed Acid: Prepare a 5 mol / L hydrochloric acid and glacial acetic acid mixture at a mass ratio of 90:10 to obtain a hydrochloric acid-glacial acetic acid mixed acid. Mix the concentrated solid residue B obtained in step S1 with the mixed acid at a solid-liquid ratio of 1 g:2 mL, and stir at 300 rpm for 1 h at 80℃. After the reaction is complete, allow it to stand and separate into layers. Separate the upper layer, which contains impurities, into the concentrated solid residue acid-dissolved organic phase C, and the lower layer, which is a solution containing rare earth acid (75.89 g of rare earth was recovered through precipitation). Collect the solution for later use.

[0035] S3. Extraction and removal of inexpensive metal ions: A 42 g / L lanthanum chloride solution was mixed with the acid-soluble organic phase C obtained in step S2 at a volume ratio of 1:1. The mixture was stirred at 200 rpm for 10 min at 40 °C. Impurities in the organic phase and La... 3+ The mixture combines to form a new mixed system D containing a third phase, which is rich in impurities and contains a large amount of normal organic phase, while the upper organic phase is purified.

[0036] S4. Secondary Centrifugation and Recovery: The mixed system D containing the third phase after the reaction in step S3 is centrifuged again at 2000 rpm for 30 min. After separation, the upper layer, purified organic phase E, can be reused, while the lower layer is concentrated solid third phase slag. The upper organic phase E is collected, and after acid washing, water washing, and acidity adjustment, it is combined with the upper organic phase collected in step S1 or reused separately. The solid third phase slag is returned to step S2 and combined with the concentrated solid slag B for recycling acid dissolution treatment or directly treated as solid waste for resource recovery.

[0037] Example 2

[0038] The difference between this embodiment and Example 1 is that in S2, 4 mol / L hydrochloric acid and glacial acetic acid are mixed at a mass ratio of 80:20 to obtain a hydrochloric acid-glacial acetic acid mixed acid. The concentrated solid residue B obtained in step S1 is mixed with the mixed acid at a solid-liquid ratio of 1 g:2 mL, and the mixture is stirred at 300 rpm for 1.5 h at 70 °C.

[0039] The remaining parameters in this embodiment are the same as those in Embodiment 1.

[0040] Example 3

[0041] The difference between this embodiment and Example 1 is that in S2, 6 mol / L hydrochloric acid and glacial acetic acid are mixed at a mass ratio of 95:5 to obtain a hydrochloric acid-glacial acetic acid mixed acid. The concentrated solid residue B obtained in step S1 is mixed with the mixed acid at a solid-liquid ratio of 1 g: 2 mL, and stirred at 300 rpm for 0.5 h at 90 °C.

[0042] The remaining parameters in this embodiment are the same as those in Embodiment 1.

[0043] Example 4

[0044] The difference between this embodiment and embodiment 1 is that in step S3, a 42 g / L magnesium chloride solution is used to mix with the acid-soluble organic phase C obtained in step S2 at a volume ratio of 1:1, and the mixture is stirred at 200 rpm for 10 min at 40°C.

[0045] The remaining parameters in this embodiment are the same as those in Embodiment 1.

[0046] Example 5

[0047] The difference between this embodiment and embodiment 1 is that in step S3, a 42 g / L calcium chloride solution is used to mix with the acid-soluble organic phase C obtained in step S2 at a volume ratio of 1:1, and the mixture is stirred at 200 rpm for 10 min at 40°C.

[0048] The remaining parameters in this embodiment are the same as those in Embodiment 1.

[0049] Comparative Example 1

[0050] This embodiment provides a method for recovering the organic phase in a rare earth extraction stabilized emulsion layer, and the specific steps are as follows.

[0051] S1, Same as Example 1.

[0052] S2, Acid Dissolution: The concentrated solid slag B obtained in step S1 was mixed with 6 mol / L acetic acid at a solid-liquid ratio of 1 g: 2 mL and stirred at 80 °C for 1 h. After the reaction was complete, the mixture was allowed to stand and separate into layers. Acid washing and back-extraction were then performed by stirring at 25 °C for 1 h. After the reaction was complete, the mixture was allowed to stand and separate into phases for 2 h. The solid slag could not be completely dissolved, resulting in a three-phase interface consisting of a small amount of organic phase on top, a solid slag layer in the middle, and an aqueous phase at the bottom, leading to a significant decrease in the recovery rate of the organic phase.

[0053] S3 cannot be carried out: Because the solid slag in S2 failed to dissolve and separate into phases effectively, the acid-soluble organic phase C that can be used in S3 cannot be separated, so S3 cannot be carried out.

[0054] Comparative Example 2

[0055] The difference between this comparative example and Example 1 is that: in step S3, a cheap metal ion feed solution is not added (i.e., the impurity transfer and secondary three-phase generation steps are missing). Instead, an equal volume of 6 mol / L acetic acid is added to the acid-soluble organic phase C obtained in step S2, and acid washing and back-extraction are performed by stirring at 25°C for 1 hour. After the reaction is completed, the mixture is allowed to stand for phase separation for 2 hours. The solid slag cannot be completely dissolved, resulting in a three-phase interface with a small amount of organic phase on the top, solid slag in the middle, and aqueous phase at the bottom, leading to a significant decrease in the organic phase recovery rate.

[0056] Performance testing

[0057] The performance test results of the examples and comparative examples are shown in Table 1.

[0058] Table 1 Performance test results in the examples and comparative examples

[0059]

[0060] As can be seen from the experimental results in Table 1, by adopting the technical solution of this invention, the invention achieves efficient recovery of the organic phase in the extraction stabilized emulsion layer. Through four steps—primary physical centrifugation separation, concentrated solid slag mixed acid dissolution, solid slag acid dissolution of organic phase through extraction of inexpensive metal ions for impurity removal, secondary centrifugation separation, and recovery—efficient resource recovery and impurity separation are achieved. The total organic phase recovery rate reaches over 85%, and the rare earth recovery rate reaches over 98%. Moreover, the process flow is short, the chemical treatment is mild, and the degradation of the extractant caused by high temperature is effectively avoided, ensuring the performance stability of the regenerated organic phase and the long-term continuous and stable operation of the extraction system.

[0061] The foregoing descriptions have outlined some exemplary embodiments of the present invention. It is understood that these embodiments are merely illustrative and do not constitute a limitation on the scope of protection of the present invention. Features in these embodiments can be rearranged in suitable ways, and the resulting solutions remain within the scope of protection claimed by the present invention. All other embodiments obtained by those skilled in the art based on the foregoing embodiments without inventive effort, i.e., all modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, fall within the scope of protection claimed by the present invention.

Claims

1. A method for recovering the organic phase from a rare earth extraction stabilized emulsion layer, characterized in that, Includes the following steps: S1. Centrifuge the mixture of extraction-stabilized emulsion layer produced by rare earth extraction at a speed of 1000-4000 rpm for 10-30 min to separate and collect the upper organic phase A and the lower concentrated solid residue B. S2. The concentrated solid residue B obtained in step S1 is mixed with hydrochloric acid-glacial acetic acid mixed acid, and stirred at 70-90℃ for 0.5-1.5h. After the reaction is completed, the mixture is allowed to stand and separate into layers. The upper acid-soluble organic phase C and the lower rare earth acid solution are separated and collected. The hydrochloric acid-glacial acetic acid mixed acid is made by mixing 4-6 mol / L hydrochloric acid and glacial acetic acid at a mass ratio of 80-95:5-20. S3. The acid-soluble organic phase C obtained in step S2 is contacted and mixed with a 40-50 g / L solution of inexpensive metal ions. The mixture is stirred at 20-60°C for 5-15 minutes to allow impurities in the organic phase to combine with the inexpensive metal ions to form a mixed system D containing a third phase rich in impurities. The inexpensive metal ions are selected from Ca... 2+ Mg 2+ La 3+ One or more of the following; S4. Centrifuge the mixed system D containing the third phase after the reaction in step S3 at a speed of 1000-4000 rpm for 20-40 min. After separating and collecting the upper layer, the purified organic phase E can be reused.

2. The method for recovering the organic phase in a rare earth extraction stabilized emulsion layer according to claim 1, characterized in that, In step S2, the hydrochloric acid-glacial acetic acid mixed acid is made by mixing 4.5-5.5 mol / L hydrochloric acid and glacial acetic acid at a mass ratio of 85-92:8-15; the solid-liquid ratio of the concentrated solid residue B to the hydrochloric acid-glacial acetic acid mixed acid is 1 g:1-4 mL.

3. The method for recovering the organic phase in a rare earth extraction stabilized emulsion layer according to claim 1, characterized in that, In step S3, the inexpensive metal ion solution is a lanthanum chloride solution with a concentration of 42-48 g / L.

4. The method for recovering the organic phase in a rare earth extraction stabilized emulsion layer according to claim 3, characterized in that, In step S3, the volume ratio of the acid-soluble organic phase C to the inexpensive metal ion solution is 1:0.8-1.

2.

5. The method for recovering the organic phase in a rare earth extraction stabilized emulsion layer according to claim 1, characterized in that, It also includes returning the upper organic phase A collected in step S1 to the main extraction process after acid washing, water washing, and saponification; and combining the purified upper organic phase E collected in step S4 with the upper organic phase collected in step S1 or reusing it separately after acid washing, water washing, and acidity adjustment.

6. The method for recovering the organic phase in a rare earth extraction stabilized emulsion layer according to claim 1, characterized in that, The impurity-rich solid third-phase slag obtained from the lower layer after centrifugation in step S4 is returned to step S2 and combined with the concentrated solid slag B for cyclic acid dissolution treatment or directly treated as solid waste for resource recovery.

7. The method for recovering the organic phase in a rare earth extraction stabilized emulsion layer according to claim 1, characterized in that, The organic phase in the extract-stabilized emulsion mixture comprises an acidic phosphorus extractant and a diluent, wherein the acidic phosphorus extractant is P204 or P507, and the diluent is sulfonated kerosene or No. 260 solvent oil.

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