Regeneration method of extraction solvent

Abstract

The invention belongs to the technical field of solvent extraction, and particularly discloses a regeneration method of an extraction solvent. The method specifically comprises the following steps: mixing an extraction solvent with an adsorbent, and carrying out solid-liquid separation to obtain a regenerated extraction solvent and a to-be-treated adsorbent. The extraction solvent is a recovered extraction solvent after extraction operation, and the adsorbent comprises one or more of a zeolite molecular sieve, diatomite, kaolin, anhydrous magnesium sulfate and anhydrous sodium sulfate. The extraction solvent adsorbent used in the method has strong adsorption capacity, not only can adsorb water molecules entrained in the extraction solvent, but also has a very good removal effect on impurity elements enriched in the extraction solvent, and the treated extraction solvent has relatively short extraction phase separation time. The method is simple in process and low in energy consumption, the used adsorbent is low in price, adsorbed impurities can be removed at high temperature, then the adsorbent can be recycled continuously, no waste liquid is generated, and the method has remarkable environmental protection value and economic benefit.

Description

Technical Field

[0001] The invention relates to the technical field of solvent extraction, and in particular to a method for regenerating an extraction solvent. Background Art

[0002] The solvent extraction method has the advantages of high product purity, relatively simple production process and equipment, low energy consumption, less environmental pollution, easy automation and continuity of the production process, and conducive to the comprehensive utilization of resources. Therefore, it is widely used in the chemical and metallurgical industries.

[0003] The key to solvent extraction lies in the selection of extractants. The different extraction abilities of extraction solvents for different elements can be used to perform wet separation and purification of elements. However, during the extraction process, the extraction solvent is prone to poisoning and aging, which in turn leads to reduced extraction ability of the extraction solvent, reduced element separation ability, and slower phase separation speed.

[0004] At present, it is generally believed that the reduction in the extraction capacity of the extraction solvent is mainly because during the extraction process, some easily extracted metal ions form relatively stable complexes with the extraction solvent and are not easily stripped. These ions are gradually enriched in the extraction solvent and occupy organic extraction sites, thereby reducing the amount of organic extraction, worsening the phase separation effect, and even causing the extraction solvent to be "poisoned" or ineffective.

[0005] To this end, in the prior art, scholars have developed methods for regenerating extraction solvents, such as activated carbon regeneration, oxalic acid washing regeneration, vacuum distillation and alkali solution regeneration. The alkali solution regeneration method is currently the most commonly used. Some people use sodium hydroxide alkali solution to regenerate tributyl phosphate extractant, but this treatment technology produces severe emulsification and phase separation difficulties during the extraction process, and the extraction capacity of the regenerated extraction solvent can only be restored to about 80%.

[0006] Therefore, how to provide a method for regenerating an extraction solvent so that the extraction solvent can recover its initial effect, can be recycled, reduce the discharge of waste liquid, and ensure that the regeneration method is low in difficulty and cost is a difficult problem that needs to be solved urgently in this field. Summary of the invention

[0007] In view of this, the present invention provides a method for regenerating an extraction solvent, which can restore the extraction solvent to its original effect, make the extraction solvent recyclable, reduce the discharge of waste liquid, reduce environmental pollution, and reduce the difficulty of regenerating and recovering the extraction solvent, saving costs, and at the same time can accelerate the phase separation speed of the extraction process.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] A method for regenerating an extraction solvent, comprising mixing the extraction solvent with an adsorbent, and obtaining a regenerated extraction solvent and an adsorbent to be treated after solid-liquid separation;

[0010] The extraction solvent is a recovered extraction solvent after the extraction operation;

[0011] The adsorbent includes one or more of zeolite molecular sieve, diatomaceous earth, kaolin, anhydrous magnesium sulfate and anhydrous sodium sulfate.

[0012] Preferably, the mass ratio of the extraction solvent to the adsorbent is 100:10-50.

[0013] Preferably, the mixing temperature is 15 to 30° C., and the mixing time is 1 to 5 hours.

[0014] Preferably, the extraction solvent is a recovered extraction solvent in a wet crude phosphoric acid extraction system.

[0015] Preferably, the extraction solvent includes one or more of an organic phosphorus extractant, a ketone extractant, and a fatty alcohol extractant.

[0016] Preferably, the method for regenerating the extraction solvent further comprises calcining the adsorbent to be treated to obtain a regenerated adsorbent.

[0017] Preferably, the calcination temperature is 200-600° C., and the calcination time is 1-5 hours.

[0018] Current research generally believes that the reason why the extraction ability of the extraction solvent deteriorates when it is recycled is that the metal impurity elements are continuously enriched during the extraction process, resulting in "poisoning" of the extraction solvent, and a good extraction effect cannot be achieved after conventional extraction solvent regeneration. On this basis, the present invention innovatively discovered that the extraction ability of the extraction solvent deteriorates mainly because some water is entrained in the organic molecules during the extraction process, and this part of water cannot be completely removed due to bonding when the extraction system is clarified and stratified (it is not the same type of water as the water that can be clearly found), thus causing the extraction ability of the extraction solvent to be greatly reduced when it is recycled. The present invention utilizes an adsorbent to regenerate the recovered extraction solvent, which effectively removes the water in the extraction solvent, while also removing the impurity elements enriched in the extraction solvent, accelerating the phase separation rate of the extraction solvent, and allowing the extraction solvent to be recycled and regenerated.

[0019] It can be seen from the above technical solutions that, compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention finds that the deterioration of the extraction capacity of the recovered extraction solvent is mainly due to the fact that some water is entrained in the organic molecules during the extraction process. This water cannot be completely removed due to bonding when the extraction system is clarified and stratified, thus causing the extraction capacity of the extraction solvent to be greatly reduced during circulation, which is different from the existing view.

[0021] (2) The extraction solvent adsorbent used in the present invention has a strong adsorption capacity, which can not only adsorb water molecules entrained in the extraction solvent, but also has a good removal effect on the impurity elements enriched in the extraction solvent, and can also shorten the extraction phase separation time.

[0022] (3) The method of the present invention has a simple process and low energy consumption. The extraction solvent can be regenerated in only one step. The adsorbent used is inexpensive. The adsorbed impurities can be removed by high temperature and then recycled. No waste liquid is generated. The cost is low and it has significant environmental value and economic benefits. DETAILED DESCRIPTION

[0023] The invention provides a method for regenerating an extraction solvent, which comprises mixing the extraction solvent with an adsorbent, and performing solid-liquid separation to obtain a regenerated extraction solvent and an adsorbent to be treated.

[0024] In the present invention, the extraction solvent is a recovered extraction solvent after the extraction operation.

[0025] In the present invention, the adsorbent includes one or more of zeolite molecular sieve, diatomaceous earth, kaolin, anhydrous magnesium sulfate and anhydrous sodium sulfate.

[0026] In the present invention, the mass ratio of the extraction solvent to the adsorbent is 100:10-50, preferably 100:20-40, and more preferably 100:30.

[0027] In the present invention, the mixing temperature is 15-30°C, specifically 16°C, 18°C, 20°C, 22°C, 24°C, 25°C, 26°C, 28°C; the mixing time is 1-5h, specifically 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h.

[0028] In the present invention, the extraction solvent is a recovered extraction solvent in a wet crude phosphoric acid extraction system.

[0029] In the present invention, the extraction solvent includes one or more of an organic phosphorus extractant, a ketone extractant, and a fatty alcohol extractant; specifically, it can be a tributyl phosphate extractant, a methyl isobutyl ketone extractant, a n-butanol extractant, a tri-isooctanol phosphate extractant, and an isopropanol extractant.

[0030] In the present invention, the method for regenerating the extraction solvent further comprises calcining the adsorbent to be treated to obtain a regenerated adsorbent.

[0031] In the present invention, the calcination temperature is 200-600°C, specifically 250°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C; the calcination time is 1-5h, specifically 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h.

[0032] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Example 1

[0034] (1) Take 1L of the extraction solvent (60% tributyl phosphate + 40% methyl isobutyl ketone) recovered from the wet crude phosphoric acid impurity removal extraction line, add 30% of the total weight of 4A type zeolite molecular sieve, and mix and stir at 25°C for 3h;

[0035] (2) performing solid-liquid separation in step (1), and reusing the extraction solvent in a single-stage extraction experiment of wet crude phosphoric acid, the extraction conditions being: 25° C., 45% wet crude phosphoric acid solution (in terms of P2O5), and extraction phase ratio O / A=4:1;

[0036] (3) calcining the 4A zeolite molecular sieve used in step (2) at 400° C. for 4 h to regenerate the molecular sieve.

[0037] Embodiment 2:

[0038] (1) Take 1L of the extraction solvent (80% tributyl phosphate + 20% n-butanol) recovered from the wet crude phosphoric acid impurity removal extraction line, add 20% of the total mass of diatomaceous earth, and mix and stir at 25°C for 2h;

[0039] (2) performing solid-liquid separation in step (1), and reusing the extraction solvent in a single-stage extraction experiment of wet crude phosphoric acid, the extraction conditions being: 25° C., 45% wet crude phosphoric acid solution (in terms of P2O5), and extraction phase ratio O / A=4:1;

[0040] (3) calcining the diatomaceous earth used in step (2) at 350° C. for 3 h to regenerate the molecular sieve.

[0041] Embodiment 3:

[0042] (1) Take 1L of the extraction solvent (60% tributyl phosphate + 40% methyl isobutyl ketone) recovered from the wet crude phosphoric acid impurity removal extraction line, add 50% of the total mass of anhydrous magnesium sulfate, and mix and stir at 15°C for 1h;

[0043] (2) performing solid-liquid separation in step (1), and reusing the extraction solvent in a single-stage extraction experiment of wet crude phosphoric acid, the extraction conditions being: 25° C., 45% wet crude phosphoric acid solution (in terms of P2O5), and extraction phase ratio O / A=4:1;

[0044] (3) calcining the magnesium sulfate used in step (2) at 200° C. for 1 h to regenerate the molecular sieve.

[0045] Embodiment 4:

[0046] (1) Take 1L of the extraction solvent (80% tributyl phosphate + 20% n-butanol) recovered from the wet crude phosphoric acid impurity removal extraction line, add 10% of the total mass of kaolin, and mix and stir at 30°C for 5h;

[0047] (2) performing solid-liquid separation in step (1), and reusing the extraction solvent in a single-stage extraction experiment of wet crude phosphoric acid, the extraction conditions being: 25° C., 45% wet crude phosphoric acid solution (in terms of P2O5), and extraction phase ratio O / A=4:1;

[0048] (3) calcining the diatomaceous earth used in step (2) at 600° C. for 2 h to regenerate the molecular sieve.

[0049] Comparative Example 1:

[0050] The extraction solvent (60% tributyl phosphate + 40% methyl isobutyl ketone) recovered from the wet crude phosphoric acid impurity removal extraction line was directly used in the single-stage extraction experiment of wet crude phosphoric acid. The extraction conditions were: 25°C, 45% wet crude phosphoric acid solution (calculated as P2O5), and extraction phase ratio O / A = 4:1.

[0051] Comparative Example 2:

[0052] (1) Take 1L of the extraction solvent (60% tributyl phosphate + 40% methyl isobutyl ketone) recovered from the wet crude phosphoric acid impurity removal extraction line and add 0.5 mol / L NaOH solution in a volume ratio of 1:1, stir at 25°C for 30 minutes, and let stand for 10 minutes to separate into layers;

[0053] (2) The upper layer of the extraction solvent in step (1) was reused in a single-stage extraction experiment of wet crude phosphoric acid, and the extraction conditions were: 25° C., 45% wet crude phosphoric acid solution (calculated as P2O5), and extraction phase ratio O / A=4:1.

[0054] The extraction performance comparison results of Examples 1-2, Comparative Examples 1-2 and a fresh organic extraction solvent (60% tributyl phosphate + 40% methyl isobutyl ketone, the extraction conditions are the same as those of Example 1) are shown in Table 1.

[0055] Table 1 Extraction performance comparison results

[0056] name Extraction capacity of P (%) Phase separation time Example 1 73.34 20s Example 2 70.13 20s Comparative Example 1 56.97 300s Comparative Example 2 61.77 300s Fresh and organic 72.34 20s

[0057] As can be seen from Table 1, both zeolite molecular sieve and diatomaceous earth can be used to regenerate the extraction solvent, and the extraction capacity can be restored to the initial capacity; while the extraction solvent that has not been regenerated (Comparative Example 1) has an extraction capacity of only about 79% of the initial capacity, indicating that the extraction solvent after use has partially "aged" due to the presence of impurities, and the extraction phase separation time is prolonged, so the extraction solvent needs to be regenerated and activated; the extraction solvent regenerated by adding alkali in the traditional way (Comparative Example 2) has an extraction capacity of about 85% of the initial capacity, indicating that the addition of alkali has some regeneration effect, but the regeneration is not complete. Comprehensively considered, the deactivation of the extraction solvent is mostly due to the water molecules entrained in the organic, and a small part is due to the enrichment of impurity elements. The regeneration method provided by the present invention can not only remove the water molecules entrained in the extraction solvent, but also has a good removal effect on the impurity elements enriched in the extraction solvent, and can also shorten the extraction phase separation time.

[0058] It can be seen from the above embodiments that the method of the present invention has a simple process flow, low cost, good economic and environmental benefits, and broad application prospects.

[0059] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0060] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for regenerating an extraction solvent, characterized in that: The extraction solvent and the adsorbent are mixed, and after solid-liquid separation, a regenerated extraction solvent and an adsorbent to be treated are obtained; The extraction solvent is a recovered extraction solvent after the extraction operation; The adsorbent includes one or more of zeolite molecular sieve, diatomaceous earth, kaolin, anhydrous magnesium sulfate and anhydrous sodium sulfate.

2. The method for regenerating an extraction solvent according to claim 1, characterized in that: The mass ratio of the extraction solvent to the adsorbent is 100:10-50.

3. The method for regenerating an extraction solvent according to claim 2, characterized in that: The mixing temperature is 15-30° C., and the mixing time is 1-5 hours.

4. A method for regenerating an extraction solvent according to any one of claims 1 to 3, characterized in that: The extraction solvent is a recovered extraction solvent in a wet crude phosphoric acid extraction system.

5. The method for regenerating an extraction solvent according to claim 4, characterized in that: The extraction solvent includes one or more of an organic phosphorus extractant, a ketone extractant, and a fatty alcohol extractant.

6. The method for regenerating an extraction solvent according to claim 5, characterized in that: The method for regenerating the extraction solvent further comprises calcining the adsorbent to be treated to obtain a regenerated adsorbent.

7. The method for regenerating an extraction solvent according to claim 6, characterized in that: The calcination temperature is 200-600° C., and the calcination time is 1-5 hours.