A method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate

Abstract

The present invention belongs to the technical field of extraction and separation, and provides a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate. The method includes: (1) an extraction process, (2) a washing or oil-water separation process, (3) a first stripping process, (4) a second stripping process, and (5) a re-washing or oil-water separation process. The first stripping agent used in the first stripping process is prepared from a sulfate, an acid, and water or / and a first crystallization mother liquor. In the first stripping agent, the concentration of the sulfate is 20 wt% to 50 wt%, and the concentration of the acid is 1 wt% to 15 wt%. The second stripping agent used in the second stripping process is prepared from an acid and water or / and a second crystallization mother liquor. In the second stripping agent, the concentration of the acid is 10 wt% to 60 wt%. The method of the present invention can streamline the extraction and separation process of extracting rubidium and cesium on the basis of ensuring a high recovery rate of rubidium and cesium, and effectively reduce the cost of extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate.

Description

Technical Field

[0001] The present invention belongs to the technical field of extraction and separation, and relates to a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate. Background Art

[0002] Lithium is an important metallic element and is widely used in fields such as batteries, alloys, and ceramics. Preparing lithium carbonate from ores and brines is one of the ways to obtain lithium. In addition to lithium, ores and brines also contain other metal elements such as sodium, potassium, rubidium, and cesium.

[0003] As important scarce alkali metal resources, rubidium and cesium have unique physical and chemical properties and have important application values in strategic emerging industrial fields such as aerospace, national defense, and information technology. Due to the special scarcity of rubidium and cesium resources, the methods for their development and utilization are relatively complex. Currently, the global rubidium and cesium resources are mainly concentrated in a few countries and regions. Moreover, the industrial production processes of rubidium and cesium are complex, with high separation costs and large energy consumption, resulting in expensive rubidium and cesium products. How to efficiently and low-costly separate high-purity rubidium and cesium products from the crystallization mother liquor of lithium carbonate formed during the production of lithium carbonate and achieve efficient resource utilization is one of the current challenges in this field.

[0004] The main components of the crystallization mother liquor of lithium carbonate are sulfates of lithium, sodium, potassium, rubidium, and cesium. Among them, the sodium content is the highest, followed by the potassium and lithium contents, while the rubidium and cesium contents are relatively low. In the prior art, usually, the crystallization mother liquor of lithium carbonate obtained after lithium extraction is recycled by evaporative concentration and other means to recover the sulfates therein. However, with the increase in the number of cycles, elements such as rubidium and cesium accumulate continuously, which will not only have a negative impact on the quality of lithium carbonate products, but also the rubidium and cesium therein are not utilized, resulting in waste of rubidium and cesium resources. Since the chemical properties of rubidium and cesium are similar to those of lithium, sodium, and potassium, it is relatively difficult to separate rubidium and cesium from the crystallization mother liquor after lithium extraction.

[0005] Common methods for separating alkali metals mainly include: organic solvent extraction method, chemical precipitation method, ion exchange method, and membrane separation method. The impurity removal efficiency of the chemical precipitation method is low, and impurity ions will be introduced, causing difficulties in subsequent separation. The resin consumption of the ion exchange method is large, and the cost of resin regeneration and utilization is high. The cost of the membrane separation method is relatively high. The organic solvent extraction method has low energy consumption, good separation effect, high recovery rate, high purity of the obtained products, and can be continuously applied, becoming the mainstream process for separating metal ions. Currently, domestic and foreign researchers have conducted a large number of studies on the extraction of rubidium and cesium metal ions by the organic solvent extraction method. Most of them extract rubidium and cesium from resources such as salt lakes, lepidolite, and feldspar, and there are still problems such as low recovery rates of rubidium and cesium, complex processes, numerous steps, and classification difficulties.

[0006] For example, CN115180640A discloses a method for extracting rubidium and cesium salts from the mother liquor of lithium extraction from lepidolite. This method uses the solution after lithium extraction from lepidolite as the raw material. First, the impurity elements of potassium and sodium are removed by a freezing impurity removal and purification process. Then, the solution after freezing to remove potassium and sodium is extracted under alkaline conditions. Then, the obtained rubidium- and cesium-containing organic extraction phase solution is subjected to multi-stage water washing under alkaline conditions. Finally, the obtained rubidium- and cesium-containing organic extraction phase solution is subjected to back extraction under the condition of filling high-purity carbon dioxide gas to form a weak acid environment to obtain an aqueous solution containing rubidium and cesium. After filtration and drying, rubidium carbonate and cesium carbonate are obtained. This method requires the solution after lithium extraction from lepidolite to be cooled by freezing until potassium and sodium crystallize out, and then the crystallized potassium and sodium are removed by centrifugation to increase the concentration of rubidium and cesium in the solution. However, the energy consumption of the freezing and cooling process is relatively high, which is not conducive to reducing the production cost. In the whole process of this method, the pH value of the system needs to be adjusted multiple times. For example, the pH value needs to be controlled at 12-14 in the extraction stage, the pH value of the organic phase feed liquid needs to be controlled at 7-10 in the multi-stage water washing stage, and the pH value needs to be controlled at 5-6 in the back extraction stage. Adjusting the pH value of the system multiple times will increase the complexity of the operation. The operation of extracting rubidium and cesium by this method is not concise enough and the process flow is long, which will also lead to an increase in production cost and is not conducive to large-scale industrial production.

[0007] Therefore, there is an urgent need to develop a more efficient and concise process for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate, to streamline the extraction and separation process of rubidium and cesium on the basis of ensuring a high recovery rate of rubidium and cesium, and to reduce the difficulty and cost of extracting and separating rubidium and cesium. Summary of the Invention

[0008] Aiming at the problems of long process flow, cumbersome and complex process, and high production cost existing in the existing organic solvent extraction method for extracting rubidium and cesium from the crystallization mother liquor of lithium carbonate, the present invention provides a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate, so as to streamline the extraction and separation process of rubidium and cesium on the basis of ensuring a high recovery rate of rubidium and cesium, and to reduce the cost of extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate.

[0009] To achieve the above invention purpose, the technical solution adopted by the present invention is as follows:

[0010] A method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate, comprising the following steps:

[0011] (1) Extraction process

[0012] Extract the alkali metal ions in the crystallization mother liquor of lithium carbonate with an extractant; the extractant consists of a main extractant and a diluent, and the volume ratio of the main extractant to the diluent is (0.1~1):1; during extraction, control the extraction temperature at 20~85 °C and the phase ratio at (1~10):1;

[0013] (2) Washing or oil-water separation process

[0014] Wash the extraction phase obtained in step (1) with a first detergent to obtain a washed extraction phase and a first washing residue liquid, and use the obtained first washing residue liquid as the first detergent for recycling; the first detergent is water or / and the first washing residue liquid; or, perform oil-water separation on the extraction phase obtained in step (1) through a separation device to remove the entrained aqueous phase in the extraction phase and obtain the extraction phase after separating the aqueous phase;

[0015] (3) First stripping process

[0016] Strip the washed extraction phase or the extraction phase after separating the aqueous phase obtained in step (2) with a first stripping agent to obtain a first organic phase and a first stripping liquid enriched with Cs + ; perform evaporation concentration, cooling crystallization, and separation on the first stripping liquid to obtain a double salt crystal of cesium and a first crystallization mother liquor, and use the first crystallization mother liquor to prepare the first stripping agent;

[0017] The first stripping agent is prepared from sulfate, acid and water or / and the first crystallization mother liquor. In the first stripping agent, the concentration of sulfate is 20 wt%~50 wt% and the concentration of acid is 1 wt%~15 wt%; during stripping, control the stripping temperature at 20~85 °C and the phase ratio at (1~10):1;

[0018] (4) Second stripping process

[0019] Strip the first organic phase obtained in step (3) with a second stripping agent to obtain a second organic phase and a second stripping liquid enriched with Rb + ; add sulfate to the second stripping liquid until the concentration of sulfate reaches 20 wt%~50 wt%, cool and crystallize, and separate to obtain a double salt crystal of rubidium and a second crystallization mother liquor, and use the second crystallization mother liquor to prepare the second stripping agent;

[0020] The second stripping agent is prepared from acid and water or / and the second crystallization mother liquor. In the second stripping agent, the concentration of acid is 10 wt%~60 wt%; during stripping, control the stripping temperature at 25~65 °C and the phase ratio at (1~10):1;

[0021] (5) Re-washing or oil-water separation process

[0022] The second organic phase obtained in step (4) is washed with a second detergent to obtain a regenerated extractant and a second washing residue solution, and the obtained second washing residue solution is used to prepare the second detergent; the second detergent is prepared from an acid and water or / and the second washing residue solution, and the concentration of the acid in the second detergent is 1 wt% to 10 wt%.

[0023] Alternatively, the second organic phase obtained in step (4) is subjected to oil-water separation by a separation device to remove the aqueous phase entrained in the second organic phase, and a regenerated extractant is obtained; the regenerated extractant is returned to step (1) for recycling.

[0024] In steps (3) to (4) of the above technical solution, the sulfate is ferric sulfate, ferrous sulfate, manganese sulfate, ammonium sulfate, aluminum sulfate or magnesium sulfate.

[0025] In steps (3) to (5) of the above technical solution, the acid includes at least one of sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, phosphoric acid, acetic acid and citric acid.

[0026] In step (3) of the above technical solution, the double salt crystal of cesium is a double salt crystal of cesium sulfate, and the specific type of the double salt of cesium sulfate varies according to the type of the sulfate selected in step (3). For example, the double salt crystal of cesium can be cesium aluminum sulfate crystal, cesium magnesium sulfate crystal, cesium manganese sulfate crystal, etc.

[0027] In step (4) of the above technical solution, the double salt crystal of rubidium is a double salt crystal of rubidium sulfate, and the specific type of the double salt of rubidium sulfate varies according to the type of the sulfate selected in step (4). For example, the double salt crystal of rubidium can be rubidium aluminum sulfate crystal, rubidium magnesium sulfate crystal, rubidium manganese sulfate crystal, etc.

[0028] In step (3) of the above technical solution, at the beginning of the reaction operation, no first crystallization mother liquor is produced, and the first stripping agent is prepared from a sulfate, an acid and water. After the first crystallization mother liquor is produced during the reaction operation, the first stripping agent is prepared from a sulfate, an acid and the first crystallization mother liquor, or the first stripping agent is prepared from a sulfate, an acid, the first crystallization mother liquor and water.

[0029] In step (4) of the above technical solution, at the beginning of the reaction operation, no second crystallization mother liquor is produced, and the second stripping agent is prepared from an acid and water. After the second crystallization mother liquor is produced during the reaction operation, the second stripping agent is prepared from an acid and the second crystallization mother liquor, or the second stripping agent is prepared from an acid, the second crystallization mother liquor and water.

[0030] In step (5) of the above technical solution, when the second organic phase obtained in step (4) is washed with the second detergent, no second washing residue liquid is produced at the beginning of the reaction. The second detergent is prepared from an acid and water. After the reaction proceeds to produce the second washing residue liquid, the second detergent is prepared from an acid and the second washing residue liquid, or the second detergent is prepared from an acid, the second washing residue liquid and water.

[0031] In step (1) of the above technical solution, the main extractant and diluent used can be determined with reference to the prior art. Generally, the main extractant is 4-tert-butyl-2-(α-methylbenzyl)phenol, bis(2-ethylhexyl) phosphate, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, bis(2,4,4-trimethylpentyl) phosphinic acid, dinonylnaphthalenesulfonic acid, naphthenic acid or neo-acid. Generally, the diluent is at least one of sulfonated kerosene, n-hexane, octane, cyclohexane, decane, nonane, n-heptane, dodecane, solvent oil, xylene, diethylbenzene, carbon tetrachloride, benzene and petroleum ether.

[0032] In step (1) of the above technical solution, the extraction method used is countercurrent extraction in several stages and several stages. Further, the number of stages of the countercurrent extraction in several stages and several stages is 1 to 5 stages, and the number of stages in each stage is 1 to 5 stages. In practical applications, the number of stages and the number of stages used in the countercurrent extraction are determined according to the composition and content of the lithium carbonate crystallization mother liquor. Further, the number of stages of the countercurrent extraction in several stages and several stages is preferably 3 stages, and the number of stages in each stage is preferably 3 stages.

[0033] In steps (3) to (4) of the above technical solution, the stripping method used is countercurrent stripping in several stages and several stages. The number of stages of the countercurrent stripping in several stages and several stages is 1 to 5 stages, and the number of stages in each stage is 1 to 5 stages. The number of stages and the number of stages used in the countercurrent stripping can be determined according to the actual application requirements. Preferably, the number of stages of the countercurrent stripping in several stages and several stages is preferably 3 stages, and the number of stages in each stage is preferably 3 stages.

[0034] In steps (2) and (5) of the above technical solution, when an oil-water separation device is used for oil-water separation, the separation device used is a commonly used oil-water separation device in the field of extraction separation, including but not limited to coalescing separators, disc centrifuges, etc. When using the separation device for oil-water separation, the operating parameters can be determined with reference to the prior art according to actual application requirements. For example, when using a coalescing separator for oil-water separation, the separation temperature can be controlled at 20-40 °C, the flow rate of the coalescing separator can be controlled at 200-500 m³ / h, the working pressure of the coalescing separator can be controlled at 0.4-0.7 MPa, and the working pressure difference can be 0.15 MPa. Another example is that when using a disc centrifuge for oil-water separation, the centrifugation temperature can be controlled at 20-35 °C, the rotation speed of the disc centrifuge can be controlled at 300-2000 r / min, and the separation time can be 1-10 min.

[0035] In the above technical solution, when the extraction phase obtained in step (1) is washed with the first detergent in step (2), the washing temperature is controlled at 20-85 °C and the phase ratio is (1-10):1. When the second organic phase obtained in step (4) is washed with the second detergent in step (5), the washing temperature is controlled at 25-65 °C and the phase ratio is (1-10):1.

[0036] In the above technical solution, during the washing in steps (2) and (5), the washing method used is multi-stage and multi-stage countercurrent washing. Further, the number of stages of the multi-stage and multi-stage countercurrent washing is 1-3 stages, and the number of stages in each stage is 1-3 stages.

[0037] In steps (3) and (4) of the above technical solution, during cooling crystallization, the solution to be crystallized can usually be cooled to 5-30 °C for crystallization, and the crystallization time can be controlled within 1-3 h.

[0038] Compared with the prior art, the technical solution provided by the present invention has the following beneficial technical effects:

[0039] 1. The present invention provides a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate. The method includes extraction, washing or oil-water separation, first stripping, second stripping, and again washing or oil-water separation processes. The key of this method is that in the first stripping process, sulfate and acid are combined as the first stripping agent in an appropriate ratio and concentration. In a solution environment containing a high concentration of sulfate, only a small amount of cesium ions can cause cesium ions to precipitate in the form of cesium sulfate double salt crystals, thereby improving the stripping effect on cesium ions. At the same time, in the first stripping process, the acid with an appropriate concentration in the first stripping agent can strip out the impurity ions in the washed extraction phase or the extraction phase after separating the water phase, so as to reduce the content of impurity ions in the first organic phase. After stripping the first organic phase with the second stripping agent, the acid in the second stripping agent can further strip out the impurity ions in the first organic phase, further reducing the content of impurity ions in the subsequent regenerated extractant and improving the recycling performance of the extractant. Since the first stripping process improves the stripping effect on cesium ions and strips out as many cesium ions as possible, the stripping difficulty of rubidium ions in the second stripping process is reduced. On this basis, through the cooperation of process operations and process parameters in each process, the method of the present invention effectively improves the extraction and separation effect of cesium and rubidium under a more concise process than the prior art. Compared with the existing organic extraction process for extracting rubidium and cesium from the crystallization mother liquor of lithium carbonate, the process of the method of the present invention is simpler, the process flow is shorter, there is no need to adjust the pH value of the reaction system in different processes multiple times or specifically, and there is no need for high-energy-consuming operations such as freezing, which can effectively reduce the difficulty and cost of cascade classification and recovery of cesium and rubidium from the crystallization mother liquor of lithium carbonate and is beneficial to popularization and application in engineering practice.

[0040] 2. The present invention has been experimentally verified that after continuous operation for 1 day, the extraction rate, stripping rate, and recovery rate of cesium and rubidium by the method of the present invention are all above 98%. At the same time, the purities of the cesium double salt crystals and rubidium double salt crystals obtained in Examples 1 to 8 are all above 98%. And, when Examples 1 to 8 are continuously operated for 1 day, the extraction rate, stripping rate, and recovery rate of cesium and rubidium, and the purities of the rubidium double salt crystals and cesium double salt crystals obtained are all about 10% higher than the data of Comparative Example 1 continuously operated for 10 h. This shows that the method of the present invention has more excellent long-term operation stability, and the method of the present invention realizes the efficient resource utilization of the crystallization mother liquor of lithium carbonate through a simpler process. Detailed implementation mode

[0041] The following further illustrates the method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate provided by the present invention through examples.

[0042] In the following embodiments, taking the case of using 4-tert-butyl-2-(α-methylbenzyl)phenol (t-BAMBP) as the main extractant as an example, the extraction process of the present invention will be described. In practical applications, the selection of the main extractant is not limited to t-BAMBP, and other main extractants used in the extraction of rubidium and cesium by the organic solvent extraction method according to the prior art can also be referred to.

[0043] In the following examples and comparative examples, the phase ratio (O / A) refers to the ratio of the volume of the organic phase (Organic phase volume) to the volume of the aqueous phase (Aqueous phase volume).

[0044] In the following examples and comparative examples, the crystallization mother liquor of lithium carbonate is derived from the crystallization mother liquor after extracting lithium from ore, and the metal ions contained therein are mainly Na + , K + , Li + , Rb + , Cs + , Ca 2+ , Fe 3+ , and the anions contained therein are mainly SO 4 2- and Cl - . The element contents of the crystallization mother liquor of lithium carbonate are shown in Table 1:

[0045] Table 1 Element contents of the crystallization mother liquor of lithium carbonate

[0046] Element Na K Rb Cs Mg Ca Fe Content (g / L) 107 30.99 2.53 0.93 0.0031 0.87 0.33 Element B Li Zn Cu <![CDATA[SO 4 2- > <![CDATA[Cl - > Content (g / L) 5.83 9.14 0.0012 0.0028 220 41.35

[0047] Example 1

[0048] In this example, a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate is provided, and the steps are as follows:

[0049] (1) Extraction process

[0050] Add the extractant and the crystallization mother liquor of lithium carbonate into a centrifugal extractor, and perform five-stage three-stage countercurrent extraction on the alkali metal ions in the crystallization mother liquor of lithium carbonate to transfer the alkali metal ions in the crystallization mother liquor of lithium carbonate into the extractant, obtaining an extraction phase and a raffinate phase.

[0051] The extractant is composed of a main extractant and a diluent. The main extractant is t-BAMBP, and the diluent is sulfonated kerosene. The volume ratio of the main extractant to the diluent is 0.3:1; during extraction, the extraction temperature of each stage is controlled at 60 °C, and the phase ratio (O / A) is 4:1.

[0052] (2) Oil-water separation process

[0053] The extraction phase obtained in step (1) is subjected to oil-water separation by a coalescing separator to remove the aqueous phase entrained in the extraction phase, and the extraction phase after separating the aqueous phase is obtained. During the oil-water separation, the separation temperature is controlled at 20 °C, and the flow rate of the coalescing separator is controlled at 200 m³ / h, the working pressure is 0.4 MPa, and the working pressure difference is 0.15 MPa.

[0054] (3) First stripping process

[0055] The first stripping agent and the extraction phase after separating the aqueous phase obtained in step (2) are added to a centrifugal extractor for two-stage three-stage countercurrent stripping to obtain a first organic phase and an enriched Cs + first stripping solution; the first stripping solution is evaporated and concentrated to a saturated state, then cooled to 30 °C, crystallized for 3 h, and separated to obtain cesium magnesium sulfate crystals and a first crystallization mother liquor, and the first crystallization mother liquor is used to prepare the first stripping agent.

[0056] When the reaction starts to run, no first crystallization mother liquor is produced. The first stripping agent is prepared from magnesium sulfate, sulfuric acid and deionized water. After the first crystallization mother liquor is produced during the reaction, the first stripping agent is prepared from magnesium sulfate, sulfuric acid and the first crystallization mother liquor, or the first stripping agent is prepared from magnesium sulfate, sulfuric acid, the first crystallization mother liquor and deionized water. In the first stripping agent, the concentration of magnesium sulfate is 35 wt% and the concentration of sulfuric acid is 1 wt%; during stripping, the stripping temperature of each stage is controlled at 30 °C and the phase ratio (O / A) is 1:1.

[0057] (4) Second stripping process

[0058] The second stripping agent and the first organic phase obtained in step (3) are added to a centrifugal extractor for three-stage three-stage countercurrent stripping to obtain a second organic phase and an enriched Rb + second stripping solution; aluminum sulfate is added to the second stripping solution and fully dissolved to make the concentration of aluminum sulfate 30 wt%, then cooled to 30 °C, crystallized for 3 h, and separated to obtain rubidium aluminum sulfate crystals and a second crystallization mother liquor, and the second crystallization mother liquor is used to prepare the second stripping agent.

[0059] When the reaction starts to run, no second crystallization mother liquor is produced. The second stripping agent is prepared from sulfuric acid and deionized water. After the second crystallization mother liquor is produced during the reaction, the second stripping agent is prepared from sulfuric acid and the second crystallization mother liquor, or the second stripping agent is prepared from sulfuric acid, the second crystallization mother liquor and deionized water. In the second stripping agent, the concentration of sulfuric acid is 30 wt%; during stripping, the stripping temperature of each stage is controlled at 30 °C and the phase ratio (O / A) is 1:1.

[0060] (5) Washing process

[0061] Add the second detergent and the second organic phase obtained in step (4) to a centrifugal extractor, and perform a one-stage two-stage countercurrent washing on the second organic phase to obtain a regenerated extractant and a second washing residue solution. Use the obtained second washing residue solution to prepare the second detergent. Return the regenerated extractant to step (1) for recycling.

[0062] At the beginning of the reaction operation, no second washing residue solution is produced. The second detergent is prepared from sulfuric acid and deionized water. After the second washing residue solution is produced during the reaction operation, the second detergent is prepared from sulfuric acid and the second washing residue solution, or the second detergent is prepared from sulfuric acid, the second washing residue solution and deionized water. The concentration of sulfuric acid in the second detergent is 6 wt%. During washing, control the washing temperature at 30 °C and the phase ratio (O / A) at 1:1.

[0063] Example 2

[0064] In this example, a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate is provided, and the steps are as follows:

[0065] (1) Extraction process

[0066] Add the extractant and the crystallization mother liquor of lithium carbonate to a centrifugal extractor, and perform a one-stage three-stage countercurrent extraction on the alkali metal ions in the crystallization mother liquor of lithium carbonate to transfer the alkali metal ions in the crystallization mother liquor of lithium carbonate to the extractant, obtaining an extraction phase and a raffinate phase.

[0067] The extractant consists of a main extractant and a diluent. The main extractant is t-BAMBP, and the diluent is xylene. The volume ratio of the main extractant to the diluent is 1:1; during extraction, control the extraction temperature at 85 °C and the phase ratio (O / A) at 6:1.

[0068] (2) Oil-water separation process

[0069] Perform oil-water separation on the extraction phase obtained in step (1) through a disc centrifuge to remove the entrained aqueous phase in the extraction phase, obtaining the extraction phase after separating the aqueous phase. During oil-water separation, control the separation temperature at 35 °C, the rotation speed of the disc centrifuge at 300 r / min, and the separation time at 10 min.

[0070] (3) First stripping process

[0071] Add the first stripping agent and the extraction phase after separating the aqueous phase obtained in step (2) to a centrifugal extractor for a one-stage three-stage countercurrent stripping to obtain a first organic phase and a Cs + enriched first stripping solution; evaporate and concentrate the first stripping solution to a saturated state, then cool it to 20 °C, crystallize for 3 h, and separate to obtain cesium aluminum sulfate crystals and a first crystallization mother liquor. Use the first crystallization mother liquor to prepare the first stripping agent.

[0072] At the beginning of the reaction operation, no first crystallization mother liquor is produced. The first stripping agent is prepared from aluminum sulfate, sulfuric acid, and deionized water. After the reaction operation produces the first crystallization mother liquor, the first stripping agent is prepared from aluminum sulfate, sulfuric acid, and the first crystallization mother liquor, or the first stripping agent is prepared from aluminum sulfate, sulfuric acid, the first crystallization mother liquor, and deionized water. In the first stripping agent, the concentration of aluminum sulfate is 50 wt% and the concentration of sulfuric acid is 10 wt%. During stripping, the stripping temperature is controlled at 50 °C and the phase ratio (O / A) is 3:1.

[0073] (4)Second stripping process

[0074] Add the second stripping agent and the first organic phase obtained in step (3) into a centrifugal extractor for one-stage three-stage countercurrent stripping to obtain a second organic phase and a second stripping solution enriched with Rb + Add ferric sulfate to the second stripping solution and dissolve it fully so that the concentration of ferric sulfate is 20 wt%. Then cool it to 25 °C, crystallize for 1 h, and separate to obtain rubidium ferric sulfate crystals and a second crystallization mother liquor. The second crystallization mother liquor is used to prepare the second stripping agent.

[0075] At the beginning of the reaction operation, no second crystallization mother liquor is produced. The second stripping agent is prepared from sulfuric acid and deionized water. After the reaction operation produces the second crystallization mother liquor, the second stripping agent is prepared from sulfuric acid and the second crystallization mother liquor, or the second stripping agent is prepared from sulfuric acid, the second crystallization mother liquor, and deionized water. In the second stripping agent, the concentration of sulfuric acid is 40 wt%. During stripping, the stripping temperature is controlled at 65 °C and the phase ratio (O / A) is 6:1.

[0076] (5)Washing process

[0077] Add the second detergent and the second organic phase obtained in step (4) into a centrifugal extractor to perform one-stage two-stage countercurrent washing on the second organic phase to obtain a regenerated extractant and a second washing residue solution. The obtained second washing residue solution is used to prepare the second detergent. The regenerated extractant is returned to step (1) for recycling.

[0078] At the beginning of the reaction operation, no second washing residue solution is produced. The second detergent is prepared from sulfuric acid and deionized water. After the reaction operation produces the second washing residue solution, the second detergent is prepared from sulfuric acid and the second washing residue solution, or the second detergent is prepared from sulfuric acid, the second washing residue solution, and deionized water. In the second detergent, the concentration of sulfuric acid is 6 wt%. During washing, the washing temperature is controlled at 25 °C and the phase ratio (O / A) is 4:1.

[0079] Example 3

[0080] In this embodiment, a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate is provided, and the steps are as follows:

[0081] (1) Extraction process

[0082] Add the extractant and the crystallization mother liquor of lithium carbonate into a centrifugal extractor, and perform a two-stage and three-stage countercurrent extraction on the alkali metal ions in the crystallization mother liquor of lithium carbonate to transfer the alkali metal ions in the crystallization mother liquor of lithium carbonate into the extractant, obtaining an extract phase and a raffinate phase.

[0083] The extractant is composed of a main extractant and a diluent. The main extractant is t-BAMBP, the diluent is dodecane, and the volume ratio of the main extractant to the diluent is 0.1:1; during extraction, control the extraction temperature of each stage to be 55 °C and the phase ratio (O / A) to be 10:1.

[0084] (2) Washing process

[0085] Add the first washing agent and the extract phase obtained in step (1) into a centrifugal extractor, and perform a one-stage and three-stage countercurrent washing on the extract phase to obtain a washed extract phase and a first washing raffinate. Use the obtained first washing raffinate as the first washing agent for recycling. The first washing agent is deionized water or / and the first washing raffinate. During washing, control the washing temperature to be 85 °C and the phase ratio (O / A) to be 5:1.

[0086] (3) First stripping process

[0087] Add the first stripping agent and the washed extract phase obtained in step (2) into a centrifugal extractor for two-stage and three-stage countercurrent stripping to obtain a first organic phase and a Cs + enriched first stripping solution; evaporate and concentrate the first stripping solution to a saturated state, then cool it to 20 °C, crystallize for 2 h, and separate to obtain cesium sulfate magnesium crystals and a first crystallization mother liquor. Use the first crystallization mother liquor to prepare the first stripping agent.

[0088] At the beginning of the reaction operation, no first crystallization mother liquor is produced. The first stripping agent is prepared from magnesium sulfate, sulfuric acid, and deionized water. After the first crystallization mother liquor is produced during the reaction operation, the first stripping agent is prepared from magnesium sulfate, sulfuric acid, and the first crystallization mother liquor, or the first stripping agent is prepared from magnesium sulfate, sulfuric acid, the first crystallization mother liquor, and deionized water. In the first stripping agent, the concentration of magnesium sulfate is 20 wt% and the concentration of sulfuric acid is 5 wt%; during stripping, control the stripping temperature of each stage to be 85 °C and the phase ratio (O / A) to be 3:1.

[0089] (4)Second stripping process

[0090] Add the second stripping agent and the first organic phase obtained in step (3) to a centrifugal extractor for two-stage three-stage countercurrent stripping to obtain a second organic phase and a second stripping solution enriched with Rb + ; Add aluminum sulfate to the second stripping solution and dissolve it fully until the concentration of aluminum sulfate reaches 35 wt%, then cool it to 25 °C, crystallize for 2 h, separate to obtain rubidium aluminum sulfate crystals and a second crystallization mother liquor, and use the second crystallization mother liquor to prepare the second stripping agent.

[0091] At the beginning of the reaction operation, no second crystallization mother liquor is produced, and the second stripping agent is prepared from sulfuric acid and deionized water. After the second crystallization mother liquor is produced during the reaction operation, the second stripping agent is prepared from sulfuric acid and the second crystallization mother liquor, or the second stripping agent is prepared from sulfuric acid, the second crystallization mother liquor and deionized water, and the concentration of sulfuric acid in the second stripping agent is 40 wt%; during stripping, control the stripping temperature of each stage to be 40 °C and the phase ratio (O / A) to be 2:1.

[0092] (5) Re-washing process

[0093] Add the second detergent and the second organic phase obtained in step (4) to a centrifugal extractor, and perform three-stage two-stage countercurrent washing on the second organic phase to obtain a regenerated extractant and a second washing residue solution, and use the obtained second washing residue solution to prepare the second detergent. Return the regenerated extractant to step (1) for recycling.

[0094] At the beginning of the reaction operation, no second washing residue solution is produced, and the second detergent is prepared from sulfuric acid and deionized water. After the second washing residue solution is produced during the reaction operation, the second detergent is prepared from sulfuric acid and the second washing residue solution, or the second detergent is prepared from sulfuric acid, the second washing residue solution and deionized water, and the concentration of sulfuric acid in the second detergent is 10 wt%. During washing, control the washing temperature of each stage to be 25 °C and the phase ratio (O / A) to be 10:1.

[0095] Example 4

[0096] In this example, a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate is provided, and the steps are as follows:

[0097] (1) Extraction process

[0098] Add the extractant and the crystallization mother liquor of lithium carbonate to a centrifugal extractor, and perform three-stage three-stage countercurrent extraction on the alkali metal ions in the crystallization mother liquor of lithium carbonate to transfer the alkali metal ions in the crystallization mother liquor of lithium carbonate to the extractant to obtain an extraction phase and a raffinate phase.

[0099] The extractant consists of a main extractant and a diluent, the main extractant is t-BAMBP, the diluent is n-hexane, and the volume ratio of the main extractant to the diluent is 0.7:1; during extraction, the extraction temperature of each section is controlled to be 45°C and the phase ratio (O / A) is 4:1.

[0100] (2) Washing process

[0101] The first detergent and the extract phase obtained in step (1) are added to a centrifugal extractor, and the extract phase is subjected to three-stage three-stage countercurrent washing to obtain the washed extract phase and the first washing residual liquid, and the obtained first washing residual liquid is recycled as the first detergent, wherein the first detergent is deionized water or / and the first washing residual liquid. During washing, the washing temperature of each stage is controlled to be 20°C, and the phase ratio (O / A) is 10:1.

[0102] (3) First stripping step

[0103] The first stripping agent and the washed extract phase obtained in step (2) are added to a centrifugal extractor for three-stage three-stage countercurrent stripping to obtain a first organic phase and a Cs-enriched phase. + The first stripping solution; the first stripping solution is evaporated and concentrated to a saturated state, then cooled to 15°C, crystallized for 2 hours, separated, and cesium aluminum sulfate crystals and a first crystallization mother liquor are obtained, and the first crystallization mother liquor is used to prepare a first stripping agent.

[0104] When the reaction just starts running, no first crystallization mother liquor is produced, and the first stripping agent is prepared from aluminum sulfate, sulfuric acid and deionized water. After the reaction runs until the first crystallization mother liquor is produced, the first stripping agent is prepared from aluminum sulfate, sulfuric acid and the first crystallization mother liquor, or the first stripping agent is prepared from aluminum sulfate, sulfuric acid, the first crystallization mother liquor and deionized water, in which the concentration of aluminum sulfate and the concentration of sulfuric acid are 40 wt% and 15 wt% respectively. During stripping, the stripping temperature of each section is controlled to be 20°C and the phase ratio (O / A) is 5:1.

[0105] (4) Second stripping process

[0106] The second stripping agent and the first organic phase obtained in step (3) are added to a centrifugal extractor for two-stage three-stage countercurrent stripping to obtain a second organic phase and Rb-enriched + to the second stripping solution; adding manganese sulfate to the second stripping solution and fully dissolving it to make the concentration of manganese sulfate 40 wt%, then cooling to 15 ° C, crystallizing for 2 h, separating, obtaining manganese sulfate rubidium crystals and a second crystallization mother liquor, and using the second crystallization mother liquor to prepare a second stripping agent.

[0107] At the beginning of the reaction operation, no second crystallization mother liquor is produced. The second stripping agent is prepared from sulfuric acid and deionized water. After the reaction operation produces the second crystallization mother liquor, the second stripping agent is prepared from sulfuric acid and the second crystallization mother liquor, or the second stripping agent is prepared from sulfuric acid, the second crystallization mother liquor and deionized water. The concentration of sulfuric acid in the second stripping agent is 60 wt%. During stripping, the stripping temperature of each stage is controlled at 40 °C and the phase ratio (O / A) is 8:1.

[0108] (5)Re-washing process

[0109] Add the second detergent and the second organic phase obtained in step (4) into a centrifugal extractor, and perform one-stage two-stage countercurrent washing on the second organic phase to obtain a regenerated extractant and second washing residue liquid. The obtained second washing residue liquid is used to prepare the second detergent. The regenerated extractant is returned to step (1) for recycling.

[0110] At the beginning of the reaction operation, no second washing residue liquid is produced. The second detergent is prepared from sulfuric acid and deionized water. After the reaction operation produces the second washing residue liquid, the second detergent is prepared from sulfuric acid and the second washing residue liquid, or the second detergent is prepared from sulfuric acid, the second washing residue liquid and deionized water. The concentration of sulfuric acid in the second detergent is 1 wt%. During washing, the washing temperature is controlled at 65 °C and the phase ratio (O / A) is 6:1.

[0111] Example 5

[0112] In this example, a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate is provided, and the steps are as follows:

[0113] (1)Extraction process

[0114] Add the extractant and the crystallization mother liquor of lithium carbonate into a centrifugal extractor, and perform three-stage three-stage countercurrent extraction on the alkali metal ions in the crystallization mother liquor of lithium carbonate to transfer the alkali metal ions in the crystallization mother liquor of lithium carbonate to the extractant to obtain an extraction phase and a raffinate phase.

[0115] The extractant is composed of a main extractant and a diluent. The main extractant is t-BAMBP and the diluent is cyclohexane. The volume ratio of the main extractant to the diluent is 0.4:1. During extraction, the extraction temperature of each stage is controlled at 20 °C and the phase ratio (O / A) is 2:1.

[0116] (2)Washing process

[0117] The first detergent and the extract phase obtained in step (1) are added to a centrifugal extractor, and the extract phase is subjected to three-stage three-stage countercurrent washing to obtain the washed extract phase and the first washing residual liquid, and the obtained first washing residual liquid is recycled as the first detergent, wherein the first detergent is deionized water or / and the first washing residual liquid. During washing, the washing temperature of each stage is controlled to be 30°C, and the phase ratio (O / A) is 4:1.

[0118] (3) First stripping step

[0119] The first stripping agent and the washed extract phase obtained in step (2) are added to a centrifugal extractor for two-stage three-stage countercurrent stripping to obtain a first organic phase and a Cs-enriched phase. + The first stripping solution is evaporated and concentrated to a saturated state, then cooled to 10°C, crystallized for 2 hours, separated, and magnesium cesium sulfate crystals and a first crystallization mother liquor are obtained, and the first crystallization mother liquor is used to prepare a first stripping agent.

[0120] When the reaction just starts running, no first crystallization mother liquor is produced, and the first stripping agent is prepared from magnesium sulfate, sulfuric acid and deionized water. After the reaction runs until the first crystallization mother liquor is produced, the first stripping agent is prepared from magnesium sulfate, sulfuric acid and the first crystallization mother liquor, or the first stripping agent is prepared from magnesium sulfate, sulfuric acid, the first crystallization mother liquor and deionized water, in which the concentration of magnesium sulfate and the concentration of sulfuric acid are 45 wt% and 10 wt% respectively. During stripping, the stripping temperature of each section is controlled to be 40°C and the phase ratio (O / A) is 10:1.

[0121] (4) Second stripping process

[0122] The second stripping agent and the first organic phase obtained in step (3) are added to a centrifugal extractor for two-stage three-stage countercurrent stripping to obtain a second organic phase and Rb-enriched + A second stripping solution is prepared; aluminum sulfate is added to the second stripping solution and fully dissolved to make the concentration of aluminum sulfate 50 wt%, then cooled to 5 ° C, crystallized for 2 h, separated, and aluminum sulfate rubidium crystals and a second crystallization mother liquor are obtained, and the second crystallization mother liquor is used to prepare a second stripping agent.

[0123] When the reaction just starts running, no second crystallization mother liquor is produced, and the second stripping agent is prepared from sulfuric acid and deionized water. After the reaction runs until the second crystallization mother liquor is produced, the second stripping agent is prepared from sulfuric acid and the second crystallization mother liquor, or the second stripping agent is prepared from sulfuric acid, the second crystallization mother liquor and deionized water, and the concentration of sulfuric acid in the second stripping agent is 25 wt%; during stripping, the stripping temperature of each section is controlled to be 25°C and the phase ratio (O / A) is 4:1.

[0124] (5) Oil-water separation process

[0125] The second organic phase obtained in step (4) is subjected to oil-water separation by a disc centrifuge to remove the entrained aqueous phase in the second organic phase, and a regenerated extractant is obtained. The regenerated extractant is returned to step (1) for recycling. During the oil-water separation, the separation temperature is controlled at 25 °C, the rotation speed of the disc centrifuge is controlled at 300 r / min, and the separation time is 5 min.

[0126] Example 6

[0127] In this example, a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate is provided, and the steps are as follows:

[0128] (1) Extraction process

[0129] The extractant and the crystallization mother liquor of lithium carbonate are added to a centrifugal extractor, and the alkali metal ions in the crystallization mother liquor of lithium carbonate are subjected to three-stage and three-stage countercurrent extraction, and the alkali metal ions in the crystallization mother liquor of lithium carbonate are transferred to the extractant to obtain an extraction phase and a raffinate phase.

[0130] The extractant is composed of a main extractant and a diluent. The main extractant is t-BAMBP, and the diluent is sulfonated kerosene. The volume ratio of the main extractant to the diluent is 0.3:1; during extraction, the extraction temperature of each stage is controlled at 55 °C, and the phase ratio (O / A) is 3:1.

[0131] (2) Washing process

[0132] The first detergent and the extraction phase obtained in step (1) are added to a centrifugal extractor, and the extraction phase is subjected to three-stage and three-stage countercurrent washing to obtain a washed extraction phase and a first washing raffinate. The obtained first washing raffinate is recycled as the first detergent. The first detergent is deionized water or / and the first washing raffinate. During washing, the washing temperature of each stage is controlled at 40 °C, and the phase ratio (O / A) is 1:1.

[0133] (3) First stripping process

[0134] The first stripping agent and the washed extraction phase obtained in step (2) are added to a centrifugal extractor for two-stage and three-stage countercurrent stripping to obtain a first organic phase and a Cs + enriched first stripping solution; the first stripping solution is evaporated and concentrated to a saturated state, then cooled to 10 °C, crystallized for 2 h, separated to obtain cesium magnesium sulfate crystals and a first crystallization mother liquor, and the first crystallization mother liquor is used to prepare the first stripping agent.

[0135] At the beginning of the reaction operation, no first crystallization mother liquor is produced. The first stripping agent is prepared from magnesium sulfate, sulfuric acid, and deionized water. After the reaction operation produces the first crystallization mother liquor, the first stripping agent is prepared from magnesium sulfate, sulfuric acid, and the first crystallization mother liquor, or the first stripping agent is prepared from magnesium sulfate, sulfuric acid, the first crystallization mother liquor, and deionized water. In the first stripping agent, the concentration of magnesium sulfate is 40 wt% and the concentration of sulfuric acid is 5 wt%. During stripping, the stripping temperature of each stage is controlled at 40 °C and the phase ratio (O / A) is 10:1.

[0136] (4)Second stripping process

[0137] Add the second stripping agent and the first organic phase obtained in step (3) to a centrifugal extractor for two-stage three-stage countercurrent stripping to obtain a second organic phase and a second stripping solution enriched with Rb + Add magnesium sulfate to the second stripping solution and dissolve it fully so that the concentration of magnesium sulfate is 35 wt%. Then cool it to 5 °C, crystallize for 2 h, and separate to obtain rubidium magnesium sulfate crystals and a second crystallization mother liquor. The second crystallization mother liquor is used to prepare the second stripping agent.

[0138] At the beginning of the reaction operation, no second crystallization mother liquor is produced. The second stripping agent is prepared from sulfuric acid and deionized water. After the reaction operation produces the second crystallization mother liquor, the second stripping agent is prepared from sulfuric acid and the second crystallization mother liquor, or the second stripping agent is prepared from sulfuric acid, the second crystallization mother liquor, and deionized water. The concentration of sulfuric acid in the second stripping agent is 45 wt%. During stripping, the stripping temperature of each stage is controlled at 45 °C and the phase ratio (O / A) is 10:1.

[0139] (5)Oil-water separation process

[0140] Perform oil-water separation on the second organic phase obtained in step (4) through a coalescing separator to remove the aqueous phase entrained in the second organic phase and obtain a regenerated extractant. The regenerated extractant is returned to step (1) for recycling. During oil-water separation, the separation temperature is controlled at 40 °C, the flow rate of the coalescing separator is controlled at 200 m³ / h, the working pressure is 0.7 MPa, and the working pressure difference is 0.15 MPa.

[0141] Example 7

[0142] In this example, a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate is provided, and the steps are as follows:

[0143] (1)Extraction process

[0144] Add the extractant and the crystallization mother liquor of lithium carbonate into a centrifugal extractor, and perform three-stage and three-stage countercurrent extraction on the alkali metal ions in the crystallization mother liquor of lithium carbonate to transfer the alkali metal ions in the crystallization mother liquor of lithium carbonate into the extractant, obtaining an extraction phase and a raffinate phase.

[0145] The extractant consists of a main extractant and a diluent. The main extractant is t-BAMBP, and the diluent is sulfonated kerosene. The volume ratio of the main extractant to the diluent is 0.7:1. During extraction, control the extraction temperature of each stage to be 75 °C and the phase ratio (O / A) to be 1:1.

[0146] (2) Washing process

[0147] Add the first detergent and the extraction phase obtained in step (1) into a centrifugal extractor, and perform one-stage and three-stage countercurrent washing on the extraction phase to obtain the washed extraction phase and the first washing residue liquid. Use the obtained first washing residue liquid as the first detergent for recycling. The first detergent is deionized water or / and the first washing residue liquid. During washing, control the washing temperature to be 60 °C and the phase ratio (O / A) to be 7:1.

[0148] (3) First stripping process

[0149] Add the first stripping agent and the washed extraction phase obtained in step (2) into a centrifugal extractor for two-stage and three-stage countercurrent stripping to obtain the first organic phase and the Cs + enriched first stripping liquid; Evaporate and concentrate the first stripping liquid to a saturated state, then cool it to 10 °C, crystallize for 2 h, and separate to obtain cesium sulfate magnesium crystals and the first crystallization mother liquor. Use the first crystallization mother liquor to prepare the first stripping agent.

[0150] At the beginning of the reaction operation, no first crystallization mother liquor is produced. The first stripping agent is prepared from magnesium sulfate, sulfuric acid, and deionized water. After the reaction operation produces the first crystallization mother liquor, the first stripping agent is prepared from magnesium sulfate, sulfuric acid, and the first crystallization mother liquor, or the first stripping agent is prepared from magnesium sulfate, sulfuric acid, the first crystallization mother liquor, and deionized water. In the first stripping agent, the concentration of magnesium sulfate is 40 wt% and the concentration of sulfuric acid is 8 wt%. During stripping, control the stripping temperature of each stage to be 35 °C and the phase ratio (O / A) to be 5:1.

[0151] (4) Second stripping process

[0152] Add the second stripping agent and the first organic phase obtained in step (3) into a centrifugal extractor for three-stage and three-stage countercurrent stripping to obtain the second organic phase and the Rb +The second stripping solution; aluminum sulfate is added to the second stripping solution and fully dissolved to make the concentration of aluminum sulfate 40 wt%, then it is cooled to 5 °C and crystallized for 2 h, and separated to obtain rubidium aluminum sulfate crystals and a second mother liquor, and the second mother liquor is used to prepare the second stripping agent.

[0153] When the reaction just starts to run, no second mother liquor is produced, and the second stripping agent is prepared from sulfuric acid and deionized water. After the second mother liquor is produced during the reaction, the second stripping agent is prepared from sulfuric acid and the second mother liquor, or the second stripping agent is prepared from sulfuric acid, the second mother liquor and deionized water, and the concentration of sulfuric acid in the second stripping agent is 50 wt%; during stripping, the stripping temperature of each stage is controlled to be 60 °C and the phase ratio (O / A) is 6:1.

[0154] (5)Re-washing process

[0155] The second detergent and the second organic phase obtained in step (4) are added to a centrifugal extractor, and the second organic phase is subjected to two-stage three-stage countercurrent washing to obtain a regenerated extractant and a second washing residue, and the obtained second washing residue is used to prepare the second detergent. The regenerated extractant is returned to step (1) for recycling.

[0156] When the reaction just starts to run, no second washing residue is produced, and the second detergent is prepared from hydrochloric acid and deionized water. After the second washing residue is produced during the reaction, the second detergent is prepared from hydrochloric acid and the second washing residue, or the second detergent is prepared from hydrochloric acid, the second washing residue and deionized water, and the concentration of hydrochloric acid in the second detergent is 1 wt%. During washing, the washing temperature of each stage is controlled to be 55 °C and the phase ratio (O / A) is 3:1.

[0157] Example 8

[0158] In this example, a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate is provided, and the steps are as follows:

[0159] (1)Extraction process

[0160] The extractant and the crystallization mother liquor of lithium carbonate are added to a centrifugal extractor, and the alkali metal ions in the crystallization mother liquor of lithium carbonate are subjected to three-stage three-stage countercurrent extraction, and the alkali metal ions in the crystallization mother liquor of lithium carbonate are transferred to the extractant to obtain an extraction phase and a raffinate phase.

[0161] The extractant is composed of a main extractant and a diluent. The main extractant is t-BAMBP, the diluent is sulfonated kerosene, and the volume ratio of the main extractant to the diluent is 0.2:1; during extraction, the extraction temperature of each stage is controlled to be 75 °C and the phase ratio (O / A) is 4:1.

[0162] (2)Oil-water separation process

[0163] The extraction phase obtained in step (1) is subjected to oil-water separation by a coalescing separator to remove the aqueous phase entrained in the extraction phase, and the extraction phase after separating the aqueous phase is obtained. During the oil-water separation, the separation temperature is controlled at 40 °C, and the flow rate of the coalescing separator is controlled at 500 m³ / h, the working pressure is 0.7 MPa, and the working pressure difference is 0.15 MPa.

[0164] (3) First stripping process

[0165] The first stripping agent and the extraction phase after separating the aqueous phase obtained in step (2) are added to a centrifugal extractor for five-stage three-stage countercurrent stripping to obtain a first organic phase and an enriched Cs + first stripping solution; the first stripping solution is evaporated and concentrated to a saturated state, then cooled to 10 °C, crystallized for 2 h, and separated to obtain cesium magnesium sulfate crystals and a first crystallization mother liquor, and the first crystallization mother liquor is used to prepare the first stripping agent.

[0166] At the beginning of the reaction operation, no first crystallization mother liquor is produced. The first stripping agent is prepared from magnesium sulfate, sulfuric acid and deionized water. After the first crystallization mother liquor is produced during the reaction operation, the first stripping agent is prepared from magnesium sulfate, sulfuric acid and the first crystallization mother liquor, or the first stripping agent is prepared from magnesium sulfate, sulfuric acid, the first crystallization mother liquor and deionized water. In the first stripping agent, the concentration of magnesium sulfate is 45 wt% and the concentration of sulfuric acid is 1 wt%; during stripping, the stripping temperature of each stage is controlled at 30 °C and the phase ratio (O / A) is 3:1.

[0167] (4) Second stripping process

[0168] The second stripping agent and the first organic phase obtained in step (3) are added to a centrifugal extractor for five-stage three-stage countercurrent stripping to obtain a second organic phase and an enriched Rb + second stripping solution; aluminum sulfate is added to the second stripping solution and dissolved fully to make the concentration of aluminum sulfate 40 wt%, then cooled to 5 °C, crystallized for 2 h, and separated to obtain rubidium aluminum sulfate crystals and a second crystallization mother liquor, and the second crystallization mother liquor is used to prepare the second stripping agent.

[0169] At the beginning of the reaction operation, no second crystallization mother liquor is produced. The second stripping agent is prepared from sulfuric acid and deionized water. After the second crystallization mother liquor is produced during the reaction operation, the second stripping agent is prepared from sulfuric acid and the second crystallization mother liquor, or the second stripping agent is prepared from sulfuric acid, the second crystallization mother liquor and deionized water. In the second stripping agent, the concentration of sulfuric acid is 40 wt%; during stripping, the stripping temperature of each stage is controlled at 45 °C and the phase ratio (O / A) is 2:1.

[0170] (5) Washing process

[0171] Add the second detergent and the second organic phase obtained in step (4) into a centrifugal extractor, and perform a one-stage two-stage countercurrent washing on the second organic phase to obtain a regenerated extractant and a second washing residue solution. Use the obtained second washing residue solution to prepare the second detergent. Return the regenerated extractant to step (1) for recycling.

[0172] At the beginning of the reaction operation, no second washing residue solution is produced. The second detergent is prepared from nitric acid and deionized water. After the reaction runs to produce the second washing residue solution, the second detergent is prepared from nitric acid and the second washing residue solution, or the second detergent is prepared from nitric acid, the second washing residue solution and deionized water. The concentration of nitric acid in the second detergent is 5 wt%. During washing, control the washing temperature at 55 °C and the phase ratio (O / A) at 3:1.

[0173] Comparative Example 1

[0174] In this comparative example, a method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate is provided, and the steps are as follows:

[0175] (1) Extraction process

[0176] The operation of the extraction process is the same as that of step (1) in Example 1.

[0177] (2) Oil-water separation process

[0178] The operation of the oil-water separation process is the same as that of step (2) in Example 1.

[0179] (3) First stripping process

[0180] Add the first stripping agent and the extract phase after separating the aqueous phase obtained in step (2) into a centrifugal extractor for two-stage three-stage countercurrent stripping to obtain a first organic phase and a Cs + enriched first stripping solution; evaporate and concentrate the first stripping solution to a saturated state, then cool it to 30 °C, crystallize for 3 h, and separate to obtain cesium magnesium sulfate crystals and a first crystallization mother liquor. Use the first crystallization mother liquor to prepare the first stripping agent.

[0181] At the beginning of the reaction operation, no first crystallization mother liquor is produced. The first stripping agent is prepared from magnesium sulfate and deionized water. After the reaction runs to produce the first crystallization mother liquor, the first stripping agent is prepared from magnesium sulfate and the first crystallization mother liquor, or the first stripping agent is prepared from magnesium sulfate, the first crystallization mother liquor and deionized water. The concentration of magnesium sulfate in the first stripping agent is 35 wt% magnesium sulfate; during stripping, control the stripping temperature of each stage at 30 °C and the phase ratio (O / A) at 1:1.

[0182] (4)Second stripping process

[0183] The operation of the second stripping process is the same as that of step (4) in Example 1.

[0184] (5) Washing process

[0185] The operation of the washing process is the same as that of step (5) in Example 1.

[0186] During the continuous operation of Examples 1 to 8 and Comparative Example 1, samples were taken and tested at regular intervals to calculate the extraction rates of cesium and rubidium, the stripping rates of cesium and rubidium, and the recovery rates of cesium and rubidium for each example and Comparative Example 1, and the purities of the double salt crystals of cesium and the double salt crystals of rubidium obtained in Examples 1 to 8 and Comparative Example 1 were tested. Tables 2 to 4 show the extraction rates, stripping rates, recovery rates, and product purities after continuous operation for 1 day in Examples 1 to 8 and continuous operation for 10 h in Comparative Example 1.

[0187] The calculation method of the extraction rate is: the mass of cesium or rubidium extracted into the extraction phase, divided by the mass of cesium or rubidium in the crystallization mother liquor of lithium carbonate.

[0188] The calculation method of the stripping rate is: the mass of cesium or rubidium in the double salt of cesium or rubidium obtained after the stripping operation, divided by the mass of cesium or rubidium in the extraction phase.

[0189] The calculation method of the recovery rate is: the mass of cesium or rubidium in the double salt of cesium or rubidium obtained after the stripping operation, divided by the mass of cesium or rubidium in the crystallization mother liquor of lithium carbonate.

[0190] Table 2 Extraction rates, stripping rates, recovery rates, and product purities of metal ions in Example 1 and Comparative Example 1

[0191]

[0192] Table 3 Extraction rates, stripping rates, recovery rates, and product purities of metal ions in Examples 2 to 5

[0193]

[0194] Table 4 Extraction rates, stripping rates, recovery rates, and product purities of metal ions in Examples 6 to 8

[0195]

[0196] After continuously operating for 10 h in Comparative Example 1, the extraction rate, stripping rate, recovery rate of cesium and rubidium, and the purity of the double salt crystals of cesium and rubidium obtained showed a relatively obvious decline compared with the initial operation. Therefore, the continuous operation in Comparative Example 1 was stopped after 10 h of continuous operation. After continuously operating for 1 day in Example 1, the extraction rate, stripping rate, recovery rate of cesium and rubidium, and the purity of the double salt crystals of cesium and rubidium obtained were still good. As shown in Table 2, after continuously operating for 10 h in Comparative Example 1 and for 1 day in Example 1, there were obvious differences in the extraction rate, stripping rate, recovery rate of cesium and rubidium, and the purity of the double salt crystals of cesium and rubidium obtained between Example 1 and Comparative Example 1. The main difference between Example 1 and Comparative Example 1 is that the compositions of the first stripping agents used in the first stripping process are different. Sulfuric acid was not added to the first stripping agent used in the first stripping process of Comparative Example 1. This shows that in the first stripping process of the method of the present invention, when a sulfate and an acid are combined as the first stripping agent in an appropriate ratio and concentration level, the extraction rate, stripping rate, and recovery rate of cesium and rubidium after long-term continuous operation of the process can be effectively improved, and the purity of the double salt crystals of cesium and rubidium obtained can also be improved. This is mainly because: in the first stripping process of the method of the present invention, a solution containing a high concentration of sulfate and an acid is used as the first stripping agent. In a solution environment containing a high concentration of sulfate, only a small amount of cesium ions can cause the cesium ions to precipitate in the form of double salt crystals of cesium sulfate, thereby serving as the outlet of cesium ions in the whole process and improving the stripping effect on cesium ions; at the same time, in the first stripping process, the impurity ions in the washed extraction phase or the extraction phase after separating the aqueous phase can be stripped out by the appropriate concentration of acid in the first stripping agent, thereby reducing the content of impurity ions in the first organic phase. After stripping the first organic phase with the second stripping agent, the acid in the second stripping agent can further strip out the impurity ions in the first organic phase, further reducing the content of impurity ions in the subsequent regenerated extractant, thereby improving the recycling performance of the extractant; since the first stripping process improves the stripping effect on cesium ions and strips out as many cesium ions as possible, the stripping difficulty of rubidium ions in the second stripping process is reduced, and the extraction and separation effect of cesium and rubidium in the process is improved; the reduction of the content of impurity ions in the regenerated extractant can improve the recycling performance of the extractant, and the improvement of the recycling performance of the extractant is beneficial to improving the extraction effect of cesium and rubidium in the whole process during long-term operation.

[0197] As can be seen from Tables 2 to 4, after continuously operating for 1 day, the extraction rates of cesium and rubidium, the stripping rates of cesium and rubidium, and the recovery rates of cesium and rubidium in Examples 1 to 8 were all above 98%. At the same time, the purities of the double salt crystals of cesium and rubidium obtained in Examples 1 to 8 were all above 98%. This shows that the method of the present invention has more excellent long-term operation stability.

[0198] The above embodiments are only partial embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can make equivalent substitutions or non-essential adjustments such as changes according to the technical concept and technical solution of the present invention. All equivalent substitutions and non-essential adjustments shall be included within the protection scope of the present invention.

Claims

1. A method for extracting and separating rubidium and cesium from a crystallization mother liquor of lithium carbonate, characterized in that: The following steps are involved: (1) Extraction process The alkali metal ions in the crystallization mother liquor of lithium carbonate are extracted by using an extractant; the extractant is composed of a main extractant and a diluent, the volume ratio of the main extractant to the diluent is (0.1-1): 1, and the main extractant is 4-tert-butyl-2-(α-methylbenzyl)phenol, di(2-ethylhexyl)phosphate, 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, di(2,4,4-trimethylpentyl) hypophosphorous acid, dinonylnaphthalenesulfonic acid, cycloalkane acid or tert-carbonic acid; during the extraction, the extraction temperature is controlled to be 20-85°C, and the phase ratio is (1-10): 1; (2) Washing or oil-water separation process The extract phase obtained in step (1) is washed with a first detergent to obtain a washed extract phase and a first washing residual liquid, and the obtained first washing residual liquid is recycled as a first detergent, wherein the first detergent is water and / or the first washing residual liquid; Alternatively, the extract phase obtained in step (1) is subjected to oil-water separation by a separation device, and the water phase entrained in the extract phase is removed to obtain an extract phase after the water phase is separated; (3) First stripping step The first stripping agent is used to strip the washed extract phase obtained in step (2) or the extract phase after separation of the aqueous phase to obtain a first organic phase and a Cs-enriched phase. + first stripping solution; evaporating and concentrating the first stripping solution, cooling and crystallizing, and separating to obtain cesium double salt crystals and a first crystallization mother liquor, and using the first crystallization mother liquor to prepare a first stripping agent; The first stripping agent is prepared from sulfate, sulfuric acid and water or / and the first crystallization mother liquor. In the first stripping agent, the concentration of sulfate is 20 wt%~50 wt%, and the concentration of sulfuric acid is 1 wt%~15 wt%. During stripping, the stripping temperature is controlled to be 20~85°C, and the ratio is (1~10):

1. (4) Second stripping process The first organic phase obtained in step (3) is stripped with a second stripping agent to obtain a second organic phase and Rb-enriched + adding sulfate to the second stripping solution until the concentration of sulfate is 20 wt% to 50 wt%, cooling and crystallizing, separating, obtaining rubidium double salt crystals and a second crystallization mother liquor, and using the second crystallization mother liquor to prepare a second stripping agent; The second stripping agent is prepared from sulfuric acid and water or / and the second crystallization mother liquor, and the concentration of sulfuric acid in the second stripping agent is 10 wt%~60 wt%; during stripping, the stripping temperature is controlled to be 25~65 °C, and the ratio is (1~10): 1; (5) Second washing or oil-water separation process The second organic phase obtained in step (4) is washed with a second washing agent to obtain a regenerated extractant and a second washing residual liquid, and the obtained second washing residual liquid is used to prepare a second washing agent; the second washing agent is prepared from an acid and water or / and the second washing residual liquid, and the concentration of the acid in the second washing agent is 1 wt% to 10 wt%; Alternatively, the second organic phase obtained in step (4) is subjected to oil-water separation by a separation device, and the water phase entrained in the second organic phase is removed to obtain a regenerated extractant; the regenerated extractant is returned to step (1) for recycling; The sulfate in step (3) to step (4) is ferric sulfate, ferrous sulfate, manganese sulfate, ammonium sulfate, aluminum sulfate or magnesium sulfate.

2. The method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate according to claim 1, characterized in that: The acid in step (5) includes at least one of sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, phosphoric acid, acetic acid and citric acid.

3. The method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate according to claim 1, characterized in that: The diluent in step (1) is at least one of sulfonated kerosene, n-hexane, octane, cyclohexane, decane, nonane, n-heptane, dodecane, solvent oil, xylene, diethylbenzene, carbon tetrachloride, benzene and petroleum ether.

4. The method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate according to any one of claims 1 to 3, characterized in that: The extraction method adopted in step (1) is a multi-stage countercurrent extraction, and the stripping method adopted in steps (3) to (4) is a multi-stage countercurrent stripping.

5. The method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate according to claim 4, characterized in that: The number of sections of the multi-section and multi-stage countercurrent extraction is 1 to 5 sections, and the number of levels of each section is 1 to 5 levels. The number of sections of the multi-section and multi-stage countercurrent stripping is 1 to 5 sections, and the number of levels of each section is 1 to 5 levels.

6. The method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate according to any one of claims 1 to 3, wherein when the first detergent is used to wash the extract phase obtained in step (1) in step (2), the washing temperature is controlled to be 20-85°C and the phase ratio is (1-10): 1; when the second detergent is used to wash the second organic phase obtained in step (4) in step (5), the washing temperature is controlled to be 25-65°C and the phase ratio is (1-10):

1.

7. The method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate according to any one of claims 1 to 3, characterized in that: During the washing in step (2) and step (5), the washing method adopted is a multi-stage countercurrent washing.

8. The method for extracting and separating rubidium and cesium from the crystallization mother liquor of lithium carbonate according to claim 7, characterized in that: The number of sections and stages of countercurrent washing is 1 to 3, and the number of stages in each section is 1 to 3.

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