Method for extracting cesium from salt lake brine

Abstract

The invention discloses a method for extracting cesium from salt lake brine. The method comprises the following steps: step 1, carrying out saponification reaction, and centrifugally standing for layering; step 2, adjusting the pH value of the salt lake brine, and putting the salt lake brine into a reaction container for extraction; step 3, washing until the concentration of the organic solution containing the cesium element is less than 0.01 g / L; step 4, carrying out back extraction; and 5, impurity removal is conducted on a cesium-containing reverse extraction phase obtained after reverse extraction. The method has the advantages that the salt lake brine is extracted through the saponified organic phase, the alkali liquor consumption is very small and can be recycled, meanwhile, addition of a large amount of strongly alkaline substances into the organic phase is avoided, environment pollution caused by generation of a large amount of waste alkali liquor is avoided, the production cost and the treatment cost are reduced, the treatment capacity is large, the process and equipment are simple, investment is small, and the method is suitable for industrial production. And continuous production is easy to realize.

Description

Technical Field

[0001] The invention relates to the technical field of extraction and recovery of cesium, and in particular to a method for extracting cesium from salt lake brine. Background Art

[0002] In modern industry and scientific research, cesium is an extremely important rare and precious metal resource, and it has great economic and strategic significance. It has good ductility, good electrical and thermal conductivity, strong chemical activity and excellent photoelectric effect performance. It is a high-performance industrial metal. Cesium is used in photocells, photomultiplier tubes, infrared spectrometers, catalysts for various organic reactions, scintillation counters, and magnetohydrodynamic power generation. In addition, cesium also plays an important role in high-tech fields such as fission products, ion rockets, and atomic clocks. It is a rare resource required for the development of high-tech industries. As an important rare metal element, cesium has unique physical and chemical properties and is widely used in many fields such as optoelectronics, atomic clocks, catalysts, and medicine. However, the distribution of cesium in nature is relatively scattered, and salt lake brine is one of the important sources of cesium.

[0003] Traditional methods of obtaining cesium face many challenges when dealing with complex systems such as salt lake brine. Salt lake brine has a complex composition and usually contains a variety of alkali metal and alkaline earth metal ions, such as sodium, potassium, magnesium, calcium, etc. The presence of these ions will interfere with the cesium extraction process. For example, in some existing extraction methods, due to the poor selectivity for cesium ions, a large number of other ions are extracted at the same time during the extraction process, which reduces the purity and extraction efficiency of cesium. In addition, impurities in salt lake brine may react adversely with the extractant, affecting the service life of the extractant and the extraction effect. Therefore, there is an urgent need for a method for extracting cesium from salt lake brine to improve the extraction rate of cesium.

[0004] In addition, some existing extraction technologies may require complex equipment and high costs, which is not conducive to large-scale industrial applications. In the current situation of growing industrial demand, there is an urgent need for a cesium extraction method that is efficient, highly selective, low-cost and can adapt to the complex environment of salt lake brine to meet the market demand for cesium resources. Therefore, it is of great practical significance to develop a method for extracting cesium from salt lake brine. In order to solve the above problems, the present invention proposes a method for extracting cesium from salt lake brine. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for extracting cesium from salt lake brine which is simple in construction, reliable in use, easy to clean, strong in damage resistance and low in cost.

[0006] In order to solve the above technical problems, the present invention is solved by the following technical solutions: A method for extracting cesium from salt lake brine, comprising the following steps:

[0007] Step 1: Mix the organic phosphorus compound with the mixing agent to obtain an organic phase, then add an alkaline solution to the organic phase for saponification reaction, and centrifuge and stand to separate the layers.

[0008] Step 2, adjusting the pH of the salt lake brine, then placing the saponified organic phase and the salt lake brine containing the cesium element into a reaction container for extraction, and adding a diluent with a volume ratio of 0.5 to 2 and an organic phosphorus compound with a concentration of 1.5 mol / L to 2 mol / L to obtain an organic solution containing the cesium element;

[0009] Step 3: Mix the organic solution containing cesium element obtained in step 2 with an acidic washing solution for washing until the concentration of the organic solution containing cesium element is less than 0.01 g / L.

[0010] Step 4: Mix the organic solution containing cesium element obtained in step 3 with a stripping agent and perform stripping to obtain a stripping phase containing cesium and a blank phase.

[0011] Step 5: removing impurities from the cesium-containing stripping phase obtained after stripping in step 4, and treating the resulting effluent as waste liquid. The cesium-containing stripping phase that flows out can be recycled.

[0012] In step 1, the ratio of the organophosphorus compound to the mixed agent is 2-6:3-5, and the ratio of the alkaline solution to the organic phase is 2.5-4:2-3.5.

[0013] In step 1, the organophosphorus compound is one of TBP, TOPO, DAMP, BEAP or D2EHP, and the mixed agent is a mixture of a composite extractant and a diluent.

[0014] The composite extractant includes crown ethers and calixarene, wherein the crown ether includes one or a mixture of two or more of 4,4',5,5'-tetra-tert-butyl-2,2'-biphenyl-18-crown-6 (t-Bu-B18C6), dibenzo-18-crown-6 (DB18C6), DCH18C6, anisole-18-crown-6 and B15C5,

[0015] The calixarene includes one or a mixture of two or more of t-Bu-C[4], a disubstituted ester derivative of t-Bu-C[4], and a disubstituted hydrazide derivative of t-Bu-C[4];

[0016] In step 2, the diluent is one or a mixture of two or more of pentane, cyclopentane, 1,4-dioxane, chloroform, ether, xylene, toluene, heptane and cyclohexane.

[0017] In step 2, the pH of the salt lake brine is adjusted by using one of NaOH solution or KOH solution, and the pH is maintained at 12-13, for example, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9 or 13, and specific point values ​​between the above values. Due to space limitations and for the sake of simplicity, the present invention will no longer list them exhaustively. The pH value can be measured by an online pH meter;

[0018] The pH value of salt lake brine is to increase the extraction rate of cesium.

[0019] The acidic washing solution in step 3 is one of sulfuric acid solution, hydrochloric acid solution, and acetic acid solution, or a mixture of two or more thereof, wherein when two or more mixtures are used, the concentration after mixing is 1.5 mol / L to 2 mol / L.

[0020] First, an alkaline solution is used to saponify the organic phase. After alkaline washing and saponification, part of the phenolic hydroxyl hydrogen in the organic phase has been replaced by Na(+) and is in an ionized state, and part of it is converted into a sodium salt form.

[0021] During extraction, Na(+) can be efficiently separated from impurity elements such as Cs(I), Rb(I) and K(I) in neutral salt lake brine. The extraction method has a large processing capacity, simple process and equipment, low investment, and is easy to realize continuous production.

[0022] The stripping agent in step 4 is pure water and a mixture of one or two or more of sulfuric acid, hydrochloric acid, nitric acid, acetic acid, and perchloric acid with a concentration of 5 mol / L to 20 mol / L.

[0023] The impurity remover in step 5 is an aqueous solution containing 1 mol / L to 3 mol / L nitric acid (or one or two of barium chloride solution, copper sulfate solution, sodium hydroxide solution, hydrochloric acid or sulfuric acid) as an impurity remover,

[0024] In step 2, the volume ratio of the saponified organic phase to the salt lake brine containing cesium is 2-4:3-6.

[0025] In step 3, the volume ratio of the acidic washing solution to the organic solution containing the cesium element is 1.5-3:3-6.

[0026] In step 4, the volume ratio of the stripping agent to the organic solution containing the cesium element is 1-2.5:3-6.

[0027] The extraction equipment is an extraction tank or a centrifugal extractor, and the stripping equipment is a stripping tank.

[0028] The extraction temperature is controlled at 20-30°C.

[0029] The extraction time is controlled at 30-100 min.

[0030] The stripping temperature is controlled at 20-50°C.

[0031] The temperature control of the extraction and the back extraction is carried out by water bath heating.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The organic phase after saponification is extracted with salt lake brine, and the alkali solution consumption is very small and can be recycled. At the same time, it avoids adding a large amount of strong alkaline substances to the organic phase, avoids the generation of a large amount of waste alkali solution to pollute the environment, and reduces production costs and treatment costs;

[0034] 2. By optimizing the extractant formula and extraction conditions, a large amount of cesium can be extracted in a relatively short time, that is, no strong alkaline substances are added to the salt lake brine system. This method is suitable for neutral or weakly alkaline salt lake brine systems, suitable for industrial promotion, and has good application prospects;

[0035] 3. The method for extracting cesium from salt lake brine provided by the present invention has a large processing capacity, simple process and equipment, small investment, and is easy to realize continuous production. DETAILED DESCRIPTION

[0036] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be used for other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0037] Embodiment A method for extracting cesium from salt lake brine comprises the following steps:

[0038] Step 1: Salt lake brine sampling and preliminary analysis:

[0039] Step 1: Mix the organophosphorus compound with the mixing agent to obtain an organic phase, the concentration of the organic phase after mixing is 1.5 mol / L, then add an alkaline solution to the organic phase for saponification reaction, and shake for 1 hour, centrifuge and stand to separate layers to obtain an upper liquid and a lower liquid.

[0040] Step 2, adjusting the pH of the salt lake brine to 12, then placing the saponified organic phase and the salt lake brine containing the cesium element into a reaction vessel for extraction, controlling the temperature at 20° C., and adding a diluent and an organic phosphorus compound with a concentration of 1.5 mol / L to obtain an organic solution containing the cesium element;

[0041] Step 3: The organic solution containing cesium element obtained in step 2 is mixed with an acidic washing liquid for washing, and the concentration after mixing is 1.5 mol / L.

[0042] Step 4: Mix the organic solution containing cesium element obtained in step 3 with a stripping agent at a concentration of 5 mol / L, control the temperature at 25° C., and perform stripping for 30 min to obtain a stripping phase containing cesium and a blank phase.

[0043] Step 5: removing impurities from the cesium-containing stripping phase obtained after stripping in step 4 by using an aqueous solution containing 1 mol / L nitric acid as an impurity remover, and treating the resulting effluent as waste liquid. The cesium-containing stripping phase that flows out can be recycled.

[0044] The purification rate of cesium in the salt lake brine in Example 1 of the present invention was measured by mass spectrometry to be 84%.

[0045] Embodiment 2 A method for extracting cesium from salt lake brine comprises the following steps:

[0046] Step 1: Mix the organophosphorus compound with the mixing agent to obtain an organic phase, the concentration of the organic phase after mixing is 1.5 mol / L, then add an alkaline solution to the organic phase for saponification reaction, and shake for 1.5 hours, centrifuge and stand to separate layers to obtain an upper liquid and a lower liquid.

[0047] Step 2, adjusting the pH of the salt lake brine to 12.5, then placing the saponified organic phase and the salt lake brine containing the cesium element into a reaction vessel for extraction, controlling the temperature at 25° C., and adding a diluent and an organic phosphorus compound with a concentration of 1.7 mol / L to obtain an organic solution containing the cesium element;

[0048] Step 3: The organic solution containing cesium element obtained in step 2 is mixed with an acidic washing liquid for washing, and the concentration after mixing is 1.7 mol / L.

[0049] Step 4: Mix the organic solution containing cesium element obtained in step 3 with a stripping agent at a concentration of 10 mol / L, control the temperature at 25° C., and perform stripping for 40 min to obtain a stripping phase containing cesium and a blank phase.

[0050] Step 5: removing impurities from the cesium-containing stripping phase obtained after stripping in step 4 by using an aqueous solution containing 1.5 mol / L nitric acid as an impurity remover, and treating the resulting effluent as waste liquid. The cesium-containing stripping phase that flows out can be recycled.

[0051] The purification rate of cesium in the salt lake brine in Example 2 of the present invention was measured by mass spectrometry to be 89%.

[0052] Embodiment A method for extracting cesium from salt lake brine comprises the following steps:

[0053] Step 1: Mix the organophosphorus compound with the mixing agent to obtain an organic phase, the concentration of the organic phase after mixing is 2 mol / L, then add an alkaline solution to the organic phase for saponification reaction, oscillate for h, centrifuge and stand to separate layers, and obtain an upper liquid and a lower liquid.

[0054] Step 2, adjusting the pH of the salt lake brine to 13, then placing the saponified organic phase and the salt lake brine containing the cesium element into a reaction vessel for extraction, controlling the temperature at 30° C., and adding a diluent and an organic phosphorus compound with a concentration of 2 mol / L to obtain an organic solution containing the cesium element;

[0055] Step 3: The organic solution containing cesium element obtained in step 2 is mixed with an acidic washing liquid for washing, and the concentration after mixing is 2 mol / L.

[0056] Step 4: Mix the organic solution containing cesium element obtained in step 3 with a stripping agent at a concentration of 20 mol / L, control the temperature at 30° C., and perform stripping for 50 min to obtain a stripping phase containing cesium and a blank phase.

[0057] Step 5: removing impurities from the cesium-containing stripping phase obtained after stripping in step 4 by using an aqueous solution containing 2 mol / L nitric acid as an impurity remover, and treating the resulting effluent as waste liquid. The cesium-containing stripping phase that flows out can be recycled.

[0058] The purification rate of cesium in the salt lake brine in Example 2 of the present invention was measured by mass spectrometry and was found to be 93%.

[0059] It should be understood by those skilled in the art that the embodiments of the present invention described above are only examples and do not limit the present invention. The purpose of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments. Without departing from the principles, the embodiments of the present invention may be subject to any changes or modifications. Although the embodiments of the present invention have been shown and described, it is understood by those of ordinary skill in the art that various changes, modifications, substitutions and deformations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the attached claims and their equivalents. This specific embodiment is merely an explanation of the present application, and it is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without creative contributions as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for extracting cesium from salt lake brine, comprising at least the following steps: Step 1: Mix the organic phosphorus compound with the mixing agent to obtain an organic phase, then add an alkaline solution to the organic phase for saponification reaction, and centrifuge and stand to separate the layers. Step 2, adjusting the pH of the salt lake brine, then placing the saponified organic phase and the salt lake brine containing the cesium element into a reaction container for extraction, and adding a diluent with a volume ratio of 0.5 to 2 and an organic phosphorus compound with a concentration of 1.5 mol / L to 2 mol / L to obtain an organic solution containing the cesium element; Step 3: Mix the organic solution containing cesium element obtained in step 2 with an acidic washing solution for washing until the concentration of the organic solution containing cesium element is less than 0.01 g / L. Step 4: Mix the organic solution containing cesium element obtained in step 3 with a stripping agent and perform stripping to obtain a stripping phase containing cesium and a blank phase. Step 5: removing impurities from the cesium-containing stripping phase obtained after stripping in step 4, and treating the resulting effluent as waste liquid. The cesium-containing stripping phase that flows out can be recycled.

2. The method for extracting cesium from salt lake brine according to claim 1, characterized in that: In step 1, the ratio of the organophosphorus compound to the mixed agent is 2-6:3-5, and the ratio of the alkaline solution to the organic phase is 2.5-4:2-3.

5.

3. The method for extracting cesium from salt lake brine according to claim 1, characterized in that: In step 1, the organophosphorus compound is one of TBP, TOPO, DAMP, BEAP or D2EHP, and the mixed agent is a mixture of a composite extractant and a diluent.

4. The method for extracting cesium from salt lake brine according to claim 1, characterized in that: The composite extractant includes crown ethers and calixarene.

5. The method for extracting cesium from salt lake brine according to claim 1, characterized in that: In step 2, the diluent is one or a mixture of two or more of pentane, cyclopentane, 1,4-dioxane, chloroform, ether, xylene, toluene, heptane and cyclohexane.

6. The method for extracting cesium from salt lake brine according to claim 1, characterized in that: In step 2, the pH value of the salt lake brine is adjusted by using a NaOH solution or a KOH solution.

7. The method for extracting cesium from salt lake brine according to claim 1, characterized in that: The acidic washing solution in step 3 is one or a mixture of two or more of sulfuric acid solution, hydrochloric acid solution and acetic acid solution.

8. The method for extracting cesium from salt lake brine according to claim 1, characterized in that: The stripping agent in step 4 is pure water and one or a mixture of two or more of sulfuric acid, hydrochloric acid, nitric acid, acetic acid, and perchloric acid with a concentration of 5 mol / L to 20 mol / L.

9. The method for extracting cesium from salt lake brine according to claim 1, characterized in that: The impurity remover in step 5 is an aqueous solution containing 1 mol / L to 3 mol / L nitric acid.

10. The method for extracting cesium from salt lake brine according to claim 1, characterized in that: The extraction equipment is an extraction tank or a centrifugal extractor, the back-extraction equipment is a back-extraction tank, and the temperature control of the extraction and back-extraction both adopts a water bath heating method.