Recovery process of rubidium and cesium from by-products of lithium extraction from lepidolite

Abstract

The present invention discloses a process for recovering rubidium and cesium from by-products of lithium extraction from lepidolite, comprising the following steps: S1. Take the mother liquor of lithium extraction, add concentrated sulfuric acid to adjust the pH to precipitate potassium sulfate crystals, and filter the supernatant; S2. Feed the supernatant into a multi-stage countercurrent extraction device for extraction; S3. Wash the extraction phase A with sodium hydroxide solution; S4. Back-extract the rubidium- and cesium-loaded organic phase with hydrochloric acid, and evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride; S5. Back-extract the cesium-loaded organic phase with hydrochloric acid, and evaporate and crystallize the cesium chloride solution to obtain cesium chloride; S6. Extract the rubidium-containing washing solution with 4-tert-butyl-2-(α-methylbenzyl)phenol solution; S7. Back-extract the extraction phase B with hydrochloric acid solution to obtain an organic phase and a rubidium chloride solution, and evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride. The present invention extracts rubidium and cesium in the alkali leaching solution from the mother liquor of lithium extraction with 4-tert-butyl-2-(α-methylbenzyl)phenol, and uses a multi-stage countercurrent extraction device to significantly improve the extraction efficiency and extraction effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of rubidium and cesium extraction, and particularly relates to a process for recovering rubidium and cesium from by-products of lithium extraction from lepidolite. Background Art

[0002] Due to their excellent photoelectric effect and special properties, rubidium and cesium and their compounds are widely used in fields such as phototubes and magnetohydrodynamic generators, and are extremely important strategic resources. Because of their active chemical properties, there are almost no separate minerals in nature, and they are usually associated with other minerals. Lepidolite is an important source of rubidium and cesium, accounting for 55% of the total domestic rubidium-containing ore resources. Since the sulfuric acid method has a very high leaching efficiency for lepidolite, it is widely used for lithium extraction. The mother liquor after lithium extraction from lepidolite ore contains abundant elements such as rubidium, cesium, potassium, and sodium, and it is of great significance to recover precious metals such as rubidium and cesium from it.

[0003] At present, solvent extraction is the most commonly used method for the separation of rubidium and cesium, which has the advantages of high separation efficiency, environmental friendliness, low cost, and easy continuous operation. In the process of solvent extraction of rubidium and cesium, extraction equipment is required for extraction or back-extraction. The three common typical equipment structures mainly include: 1. Multi-layer packed extraction tower; 2. Multi-stage stirred extraction tower; 3. Rotating disk extraction tower. Among them, the rotating disk extraction tower has a relatively simple structure, high mass transfer (extraction) efficiency, large production capacity, and strong adaptability to the system, and is widely used. However, the current rotating disk extraction tower has a short contact time between the heavy liquid and the light liquid, and the dispersion effect of the light liquid is not good, resulting in the need for multiple extractions to achieve the required extraction rate. Even so, the extraction rate of rubidium and cesium cannot be increased to more than 95%. Therefore, it is urgent to improve the existing rubidium and cesium recovery processes and equipment to improve the comprehensive utilization rate of the mother liquor of lithium extraction from lepidolite. Summary of the Invention

[0004] To solve the deficiencies mentioned in the above background art, the purpose of the present invention is to provide a process for recovering rubidium and cesium from by-products of lithium extraction from lepidolite, which extracts rubidium and cesium from the alkali leaching solution of the mother liquor of lithium extraction with 4-tert-butyl-2-(α-methylbenzyl)phenol, and significantly improves the extraction efficiency and extraction effect by using a countercurrent extraction device.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A process for recovering rubidium and cesium from by-products of lithium extraction from lepidolite, comprising the following steps:

[0007] S1. Take the mother liquor of lithium extraction, add concentrated sulfuric acid to adjust the pH to 9-10, cool down to 4-6 °C, and let it stand for 3-5 h to precipitate potassium sulfate crystals, and filter the supernatant;

[0008] S2. Adjust the pH of the supernatant to 12 - 13 with sodium hydroxide solution as the aqueous phase, dilute 4-tert-butyl-2-(α-methylbenzyl)phenol to 0.4 - 0.5 mol / L with an organic solvent as the organic phase, and then introduce the supernatant and 4-tert-butyl-2-(α-methylbenzyl)phenol solution into a multi-stage countercurrent extraction device in proportion for extraction. The extraction phase A and the raffinate phase A are obtained by extraction at 20 - 30 °C for 4 - 6 min;

[0009] S3. Introduce the extraction phase A obtained in step S2 and 0.4 - 0.6 mol / L sodium hydroxide solution into a multi-stage countercurrent extraction device in proportion for washing to remove the residual potassium ions in the extraction phase A, and obtain the organic phase loaded with rubidium and cesium and the rubidium-containing washing solution;

[0010] S4. Introduce the organic phase loaded with rubidium and cesium obtained in step S3 and 0.4 - 0.6 mmol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in proportion for selective back-extraction to obtain the organic phase loaded with cesium and rubidium chloride solution. Evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride;

[0011] S5. Introduce the organic phase loaded with cesium obtained in step S4 and 0.5 - 1.5 mol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in proportion for back-extraction to obtain the organic phase and cesium chloride solution. Evaporate and crystallize the cesium chloride solution to obtain cesium chloride;

[0012] S6. Use the rubidium-containing washing solution obtained in step S3 as the aqueous phase, dilute 4-tert-butyl-2-(α-methylbenzyl)phenol to 0.4 - 0.5 mol / L with an organic solvent as the organic phase, and then introduce the rubidium-containing washing solution and 4-tert-butyl-2-(α-methylbenzyl)phenol solution into a multi-stage countercurrent extraction device in proportion for extraction. The extraction phase B and the raffinate phase B are obtained by extraction at 20 - 30 °C for 4 - 6 min;

[0013] S7. Introduce the extraction phase B obtained in step S6 and 0.4 - 0.6 mmol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in proportion for selective back-extraction to obtain the organic phase and rubidium chloride solution. Evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride, and combine the rubidium chloride obtained in step S7 and step S4;

[0014] S8. Recycle and reuse the organic phases after back-extraction in step S5 and step S7. At the same time, evaporate and concentrate the raffinate phase A and the raffinate phase B and add them to the lithium extraction mother liquor, and repeat the separation and purification steps of S1 - S7.

[0015] Further preferably, the organic solvent in step S2 and step S6 is a mixture of sulfonated kerosene, xylene, and cyclohexane in a volume ratio of 2:1:1.

[0016] Further preferably, in step S2, the volume ratio of the supernatant to the 4-tert-butyl-2-(α-methylbenzyl)phenol solution is 1:1;

[0017] In step S3, the volume ratio of the extraction phase A to the sodium hydroxide solution is 1:5;

[0018] In step S4, the volume ratio of the rubidium and cesium-loaded organic phase to the hydrochloric acid solution is 1:2;

[0019] In step S5, the volume ratio of the cesium-loaded organic phase to the hydrochloric acid solution is 1:6;

[0020] In step S6, the volume ratio of the rubidium-containing washing solution to the 4-tert-butyl-2-(α-methylbenzyl)phenol solution is 1:1;

[0021] In step S7, the volume ratio of the extraction phase B to the hydrochloric acid solution is 1:2.

[0022] Further preferably, the countercurrent extraction device includes at least two rotating disk extraction columns, which are connected in series. The rotating disk extraction column includes a column body. A first feed pipe is fixedly installed on the side wall below the column body. One end of the first feed pipe passing through the column body is fixedly connected to a dispersion mechanism. The organic phase is broken up and dispersed into the water phase through the dispersion mechanism. A first drive shaft is arranged through the inside of the dispersion mechanism. The lower end of the first drive shaft passes through the column body, and the first drive shaft is rotationally connected to the column body in a sealed manner. The bottom end of the first drive shaft is fixedly connected to the output shaft of the first motor through a belt. At least three annular plates are fixedly arranged in the middle of the column body at equal intervals in the vertical direction. A second drive shaft is arranged through the middle of the annular plates. The upper end of the second drive shaft passes through the column body, and the second drive shaft is slidably connected to the column body in a sealed manner. Baffle plates are fixedly installed on the surface of the second drive shaft between the annular plates. The top end of the second drive shaft is connected to a drive mechanism. A weir plate assembly is fixedly installed above the column body. A second feed pipe is fixedly installed on the side wall of the column body between the weir plate assembly and the annular plates. A first discharge pipe is fixedly installed at the top of the column body, and a second discharge pipe is fixedly installed at the bottom of the column body.

[0023] Further preferably, the dispersion mechanism includes a first fixing plate and a second fixing plate. A mixing pipe is fixedly connected between the first fixing plate and the second fixing plate. Return holes arranged in an annular array are formed at the joints of the upper and lower ends of the mixing pipe with the first fixing plate and the second fixing plate. A turbine is arranged inside the mixing pipe. The turbine is fixedly installed at the top of the first drive shaft. The first feed pipe is fixedly connected to the middle of the first fixing plate above the mixing pipe. Through holes are formed on the outer circles of the first fixing plate and the second fixing plate.

[0024] Further preferably, the baffle plate is in an inverted funnel shape, and spoiler bars arranged in an annular array are fixedly installed at the bottom of the baffle plate.

[0025] Further preferably, the driving mechanism includes a guiding column and a driving wheel. The guiding column is fixedly installed at the top end of the second driving shaft. A closed bolt-shaped guiding groove is formed on the surface of the guiding column. A guiding rod is slidably arranged in the guiding groove. One end of the guiding rod away from the guiding column is fixed to the mounting frame. The driving wheel includes a fixing part and a driving part. The fixing part is rotatably connected to the mounting frame. The driving part is fixedly connected to the output shaft of the second motor through a belt. A driving hole penetrating through the fixing part and the driving part is formed in the middle of the driving wheel. A key strip is fixedly installed on the inner wall of the driving hole. The upper end of the second driving shaft penetrates through the driving hole, and a key groove is formed on the surface of the second driving shaft corresponding to the key strip.

[0026] Further preferably, the weir plate assembly includes a third fixing plate. A ring-shaped first weir plate is fixedly installed at the bottom of the third fixing plate. A funnel-shaped second weir plate is fixedly installed at the top of the third fixing plate. The diameter of the lower end of the second weir plate is the same as that of the first weir plate. Feeding holes are formed on the surface of the third fixing plate inside the first weir plate and the second weir plate. The lower end of the first discharge pipe is placed outside the second weir plate. The height of the lower end of the first discharge pipe is lower than that of the second weir plate. The height of the second feed pipe is higher than the bottom of the first weir plate.

[0027] Advantages of the present invention:

[0028] The present invention uses 4-tert-butyl-2-(α-methylbenzyl)phenol as an extractant, and dilutes the extractant with a mixed solvent of sulfonated kerosene, xylene, and cyclohexane. A multi-stage countercurrent extraction device is used to extract, separate, and enrich rubidium and cesium. The extraction rate of cesium can reach more than 99%, and the extraction rate of rubidium can reach more than 96%. In the multi-stage countercurrent extraction device, a dispersion mechanism is used in the rotary extraction column to break up and disperse the light liquid, thereby increasing the contact area between the light liquid and the heavy liquid. The baffle is in an inverted funnel shape and a flow disturbing strip is arranged at the bottom. While driving the baffle to rotate, it moves up and down reciprocally. The light liquid gathered at the bottom of the baffle is thrown to the periphery of the baffle by centrifugal force, increasing the rising stroke of the light liquid and improving the contact time between the light liquid and the heavy liquid, thereby improving the extraction efficiency and extraction effect. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0030] Figure 1 is a schematic structural diagram of the multi-stage countercurrent extraction device of the present invention;

[0031] Figure 2 is a cross-sectional view of the rotary extraction column of the present invention;

[0032] Figure 3It is a cross-sectional view of the dispersion mechanism of the rotary disk extraction column of the present invention;

[0033] Figure 4 It is a cross-sectional view of the annular plate and the baffle plate of the present invention;

[0034] Figure 5 It is the present invention Figure 4 Enlarged schematic diagram at position A;

[0035] Figure 6 It is a cross-sectional view of the weir plate assembly of the present invention.

[0036] In the figure: 1 - tower body, 2 - first feed pipe, 3 - first drive shaft, 4 - first motor, 5 - annular plate, 6 - second drive shaft, 7 - baffle plate, 8 - drive mechanism, 9 - weir plate assembly, 10 - second feed pipe, 11 - first discharge pipe, 12 - second discharge pipe, 13 - first fixing plate, 14 - second fixing plate, 15 - mixing pipe, 16 - reflux hole, 17 - turbine, 18 - turbulence strip, 19 - guiding column, 20 - driving wheel, 201 - fixing part, 202 - driving part, 203 - driving hole, 204 - key strip, 21 - guiding groove, 22 - guiding rod, 23 - mounting bracket, 24 - second motor, 25 - third fixing plate, 26 - first weir plate, 27 - second weir plate, 28 - dispersion mechanism. Detailed implementation mode

[0037] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0038] In the embodiment of the present invention, the mother liquor after roasting - water leaching and lithium extraction of lepidolite ore with a composite salt additive is used as the stock solution for rubidium and cesium extraction and separation. Among them, the concentration of Rb + is 11.24 g / L, the concentration of Cs + is 7.03 g / L, pH = 10.5, and the main chemical components in the mother liquor after lithium extraction are shown in Table 1.

[0039] Table 1 Content of main chemical components in the mother liquor after lithium extraction

[0040]

[0041] Example 1: A process for recovering rubidium and cesium from lithium - mica lithium - extraction by - products, comprising the following steps:

[0042] S1. Take the mother liquor after lithium extraction, adjust the pH to 9.5 with concentrated sulfuric acid, cool down to 5 °C, place for 4 h to precipitate potassium sulfate crystals, and filter the supernatant;

[0043] S2. Adjust the pH of the supernatant to 12.5 with sodium hydroxide solution as the aqueous phase. Dilute 4-tert-butyl-2-(α-methylbenzyl)phenol to 0.45 mol / L with an organic solvent mixture of sulfonated kerosene, xylene, and cyclohexane in a volume ratio of 2:1:1 as the organic phase. Then, introduce the supernatant and the 4-tert-butyl-2-(α-methylbenzyl)phenol solution into a multi-stage countercurrent extraction device in a volume ratio of 1:1 for extraction. The extraction phase A and the raffinate phase A are obtained after extraction at 25°C for 5 minutes.

[0044] S3. Introduce the extraction phase A obtained in step S2 and 0.5 mol / L sodium hydroxide solution into a multi-stage countercurrent extraction device in a volume ratio of 1:5 for washing to remove the residual potassium ions in the extraction phase A, obtaining an organic phase loaded with rubidium and cesium and a rubidium-containing washing solution.

[0045] S4. Introduce the organic phase loaded with rubidium and cesium obtained in step S3 and 0.5 mmol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in a volume ratio of 1:2 for selective back-extraction, obtaining an organic phase loaded with cesium and a rubidium chloride solution. Evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride.

[0046] S5. Introduce the organic phase loaded with cesium obtained in step S4 and 1 mol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in a volume ratio of 1:6 for back-extraction, obtaining an organic phase and a cesium chloride solution. Evaporate and crystallize the cesium chloride solution to obtain cesium chloride. The extraction rate of cesium is calculated to be 99.2%.

[0047] S6. Use the rubidium-containing washing solution obtained in step S3 as the aqueous phase. Dilute 4-tert-butyl-2-(α-methylbenzyl)phenol to 0.45 mol / L with an organic solvent mixture of sulfonated kerosene, xylene, and cyclohexane in a volume ratio of 2:1:1 as the organic phase. Then, introduce the rubidium-containing washing solution and the 4-tert-butyl-2-(α-methylbenzyl)phenol solution into a multi-stage countercurrent extraction device in a volume ratio of 1:1 for extraction. The extraction phase B and the raffinate phase B are obtained after extraction at 25°C for 5 minutes.

[0048] S7. Introduce the extraction phase B obtained in step S6 and 0.5 mmol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in a volume ratio of 1:2 for selective back-extraction, obtaining an organic phase and a rubidium chloride solution. Evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride. Combine the rubidium chloride obtained in step S7 and step S4, and the extraction rate of rubidium is calculated to be 96.6%.

[0049] S8. Recycle and reuse the organic phases after back-extraction in step S5 and step S7. At the same time, evaporate and concentrate the raffinate phase A and the raffinate phase B, add them to the mother liquor for lithium extraction, and repeat the separation and purification steps of S1~S7.

[0050] Example 2: A process for recovering rubidium and cesium from the by-products of lithium extraction from lepidolite, comprising the following steps:

[0051] S1. Take the mother liquor of lithium extraction, adjust the pH to 9 with concentrated sulfuric acid, cool it to 6 °C, let it stand for 3 h to precipitate potassium sulfate crystals, and filter the supernatant.

[0052] S2. Adjust the pH of the supernatant to 13 with sodium hydroxide solution as the aqueous phase. Dilute 4-tert-butyl-2-(α-methylbenzyl)phenol to 0.4 mol / L with an organic solvent mixture of sulfonated kerosene, xylene, and cyclohexane in a volume ratio of 2:1:1 as the organic phase. Then, introduce the supernatant and the 4-tert-butyl-2-(α-methylbenzyl)phenol solution into a multi-stage countercurrent extraction device in a volume ratio of 1:1 for extraction. The extraction phase A and the raffinate phase A are obtained after extraction at 30 °C for 4 min.

[0053] S3. Introduce the extraction phase A obtained in step S2 and 0.6 mol / L sodium hydroxide solution into a multi-stage countercurrent extraction device in a volume ratio of 1:5 for washing to remove the residual potassium ions in the extraction phase A, and obtain the rubidium- and cesium-loaded organic phase and the rubidium-containing washing solution.

[0054] S4. Introduce the rubidium- and cesium-loaded organic phase obtained in step S3 and 0.4 mmol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in a volume ratio of 1:2 for selective back-extraction to obtain the cesium-loaded organic phase and rubidium chloride solution. Evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride.

[0055] S5. Introduce the cesium-loaded organic phase obtained in step S4 and 1.5 mol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in a volume ratio of 1:6 for back-extraction to obtain the organic phase and cesium chloride solution. Evaporate and crystallize the cesium chloride solution to obtain cesium chloride. Calculate that the extraction rate of cesium is 99.5%.

[0056] S6. Take the rubidium-containing washing solution obtained in step S3 as the aqueous phase. Dilute 4-tert-butyl-2-(α-methylbenzyl)phenol to 0.4 mol / L with an organic solvent mixture of sulfonated kerosene, xylene, and cyclohexane in a volume ratio of 2:1:1 as the organic phase. Then, introduce the rubidium-containing washing solution and the 4-tert-butyl-2-(α-methylbenzyl)phenol solution into a multi-stage countercurrent extraction device in a volume ratio of 1:1 for extraction. The extraction phase B and the raffinate phase B are obtained after extraction at 30 °C for 4 min.

[0057] S7. Introduce the extraction phase B obtained in step S6 and 0.6 mmol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in a volume ratio of 1:2 for selective back-extraction to obtain the organic phase and rubidium chloride solution. Evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride. Combine the rubidium chloride obtained in step S7 and step S4, and calculate that the extraction rate of rubidium is 97.1%.

[0058] S8. Recycle and reuse the organic phase after back-extraction in steps S5 and S7. At the same time, evaporate and concentrate the raffinate phase A and raffinate phase B and add them to the mother liquor for lithium extraction, and repeat the separation and purification steps of S1 - S7.

[0059] Example 3: A process for recovering rubidium and cesium from by-products of lithium extraction from lepidolite, comprising the following steps:

[0060] S1. Take the mother liquor for lithium extraction, adjust the pH to 10 with concentrated sulfuric acid, cool down to 4°C, place for 5 h to precipitate potassium sulfate crystals, and filter the supernatant.

[0061] S2. Adjust the pH of the supernatant to 12 with sodium hydroxide solution as the aqueous phase. Dilute 4-tert-butyl-2-(α-methylbenzyl)phenol to 0.5 mol / L with an organic solvent mixture of sulfonated kerosene, xylene, and cyclohexane in a volume ratio of 2:1:1 as the organic phase. Then, introduce the supernatant and 4-tert-butyl-2-(α-methylbenzyl)phenol solution into a multi-stage countercurrent extraction device in a volume ratio of 1:1 for extraction. The extraction phase A and raffinate phase A are obtained after extraction at 20°C for 6 min.

[0062] S3. Introduce the extraction phase A obtained in step S2 and 0.4 mol / L sodium hydroxide solution into a multi-stage countercurrent extraction device in a volume ratio of 1:5 for washing to remove the residual potassium ions in the extraction phase A, and obtain the rubidium-cesium-loaded organic phase and the rubidium-containing washing solution.

[0063] S4. Introduce the rubidium-cesium-loaded organic phase obtained in step S3 and 0.6 mmol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in a volume ratio of 1:2 for selective back-extraction to obtain the cesium-loaded organic phase and rubidium chloride solution. Evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride.

[0064] S5. Introduce the cesium-loaded organic phase obtained in step S4 and 0.5 mol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in a volume ratio of 1:6 for back-extraction to obtain the organic phase and cesium chloride solution. Evaporate and crystallize the cesium chloride solution to obtain cesium chloride, and calculate the extraction rate of cesium to be 99.3%.

[0065] S6. Take the rubidium-containing washing solution obtained in step S3 as the aqueous phase. Dilute 4-tert-butyl-2-(α-methylbenzyl)phenol to 0.5 mol / L with an organic solvent mixture of sulfonated kerosene, xylene, and cyclohexane in a volume ratio of 2:1:1 as the organic phase. Then, introduce the rubidium-containing washing solution and 4-tert-butyl-2-(α-methylbenzyl)phenol solution into a multi-stage countercurrent extraction device in a volume ratio of 1:1 for extraction. The extraction phase B and raffinate phase B are obtained after extraction at 20°C for 6 min.

[0066] S7. The extraction phase B obtained in step S6 and the 0.4 mmol / L hydrochloric acid solution are introduced into a multi-stage countercurrent extraction device according to a volume ratio of 1:2 for selective back-extraction to obtain an organic phase and a rubidium chloride solution. The rubidium chloride solution is evaporated and crystallized to obtain rubidium chloride. The rubidium chloride obtained in step S7 and step S4 is combined, and the extraction rate of rubidium is calculated to be 96.8%;

[0067] S8. The organic phase after back-extraction in step S5 and step S7 is recycled and reused. At the same time, the raffinate phase A and the raffinate phase B are evaporated and concentrated and then added to the mother liquor for lithium extraction, and the separation and purification steps of S1-S7 are repeated.

[0068] The above multi-stage countercurrent extraction device includes at least two rotating disk extraction columns, which are connected in series. The rotating disk extraction column includes a column body 1. A first feed pipe 2 is fixedly installed on the side wall below the column body 1. One end of the first feed pipe 2 passing through the column body 1 is fixedly connected to a dispersion mechanism 28. The organic phase is dispersed and dispersed into the aqueous phase through the dispersion mechanism 28. A first drive shaft 3 is arranged through the inside of the dispersion mechanism 28. The lower end of the first drive shaft 3 passes through the column body 1, and the first drive shaft 3 is hermetically and rotatably connected to the column body 1. The bottom end of the first drive shaft 3 is fixedly connected to the output shaft of the first motor 4 through a belt. At least three annular plates 5 are fixedly arranged in the middle of the column body 1 at equal intervals in the vertical direction. A second drive shaft 6 is arranged through the middle of the annular plate 5. The upper end of the second drive shaft 6 passes through the column body 1, and the second drive shaft 6 is hermetically and slidably connected to the column body 1. Baffle plates 7 are fixedly installed on the surface of the second drive shaft 6 between the annular plates 5. The top end of the second drive shaft 6 is connected to a drive mechanism 8. A weir plate assembly 9 is fixedly installed above the column body 1. A second feed pipe 10 is fixedly installed on the side wall of the column body 1 between the weir plate assembly 9 and the annular plate 5. A first discharge pipe 11 is fixedly installed at the top of the column body 1. A second discharge pipe 12 is fixedly installed at the bottom of the column body 1.

[0069] The dispersion mechanism 28 includes a first fixing plate 13 and a second fixing plate 14. A mixing pipe 15 is fixedly connected between the first fixing plate 13 and the second fixing plate 14. Return holes 16 arranged in an annular array are opened at the joints of the upper and lower ends of the mixing pipe 15 with the first fixing plate 13 and the second fixing plate 14. A turbine 17 is arranged inside the mixing pipe 15. The turbine 17 is fixedly installed at the top of the first drive shaft 3. The first feed pipe 2 is fixedly connected to the middle of the first fixing plate 13 above the mixing pipe 15. Through holes are opened on the outer rings of the first fixing plate 13 and the second fixing plate 14. The turbine 17 is driven by the first drive shaft 3 to rotate, so that the liquid inside the column body 1 enters the mixing tank through the return holes 16 at the upper end of the mixing pipe 15, is mixed with the light liquid entering from the first feed pipe 2 in the middle of the top of the mixing pipe 15, and after being sheared and broken by the turbine 17, the light liquid is dispersed and flows out through the return holes 16 at the lower end of the mixing pipe 15 and then flows upward along the outer ring of the mixing pipe 15 and flows to the annular plate 5 through the through holes on the first fixing plate 13.

[0070] The baffle plate 7 is in an inverted funnel shape, and the bottom of the baffle plate 7 is fixedly installed with spoiler bars 18 arranged in an annular array. The driving mechanism 8 includes a guide post 19 and a driving wheel 20. The guide post 19 is fixedly installed at the top end of the second driving shaft 6. A closed bolt-shaped guide groove 21 is formed on the surface of the guide post 19. A guide rod 22 is slidably arranged in the guide groove 21. One end of the guide rod 22 away from the guide post 19 is fixed to the mounting frame 23. The driving wheel 20 includes a fixed part 201 and a driving part 202. The fixed part 201 is rotatably connected to the mounting frame 23. The driving part 202 is fixedly connected to the output shaft of the second motor 24 through a belt. A driving hole 203 penetrating through the fixed part 201 and the driving part 202 is formed in the middle of the driving wheel 20. A key bar 204 is fixedly installed on the inner wall of the driving hole 203. The upper end of the second driving shaft 6 penetrates through the driving hole 203. A key groove 61 is formed on the surface of the second driving shaft 6 corresponding to the key bar 204. When the light liquid passes through the annular plate 5 and the baffle plate 7, the driving wheel 20 drives the second driving shaft 6 and the baffle plate 7 to rotate. Through the cooperation of the guide post 19 and the guide rod 22, the second driving shaft 6 and the baffle plate 7 rotate and reciprocate up and down at the same time, so as to extend the area where the light liquid passes through the annular plate 5 and increase the contact time between the light liquid and the heavy liquid.

[0071] The weir plate assembly 9 includes a third fixing plate 25. The bottom of the third fixing plate 25 is fixedly installed with a first weir plate 26 in an annular shape. The top of the third fixing plate 25 is fixedly installed with a second weir plate 27 in a funnel shape. The diameter of the lower end of the second weir plate 27 is the same as the diameter of the first weir plate 26. Feeding holes are formed on the surface of the third fixing plate 25 inside the first weir plate 26 and the second weir plate 27. The lower end of the first discharge pipe 11 is placed outside the second weir plate 27. The height of the lower end of the first discharge pipe 11 is lower than that of the second weir plate 27. The height of the second feed pipe 10 is higher than the bottom of the first weir plate 26. The weir plate assembly 9 blocks the heavy liquid entering from the second feed pipe 10 through the first weir plate 26, so as to ensure that the heavy liquid and the light liquid on the upper layer of the tower body 1 can be stably stratified, facilitating the separation of the light liquid. When the height of the light liquid on the upper layer exceeds the second weir plate 27, it overflows into the area between the second weir plate 27 and the tower body 1, and then the light liquid is discharged through the first discharge pipe 11.

[0072] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A recovery process for rubidium and cesium in the by-products of lithium extraction from lepidolite, characterized in that, It includes the following steps: S1. Take the lithium extraction mother liquor, add concentrated sulfuric acid to adjust the pH to 9 - 10, cool down to 4 - 6 °C, let it stand for 3 - 5 h to precipitate potassium sulfate crystals, and filter the supernatant; S2. Adjust the pH of the supernatant to 12 - 13 with sodium hydroxide solution as the aqueous phase, dilute 4-tert-butyl-2-(α-methylbenzyl)phenol to 0.4 - 0.5 mol / L with an organic solvent as the organic phase, then introduce the supernatant and the 4-tert-butyl-2-(α-methylbenzyl)phenol solution into a multi-stage countercurrent extraction device in proportion for extraction, and perform extraction at 20 - 30 °C for 4 - 6 min to obtain the extraction phase A and the raffinate phase A; S3. Introduce the extraction phase A obtained in step S2 and a 0.4 - 0.6 mol / L sodium hydroxide solution into a multi-stage countercurrent extraction device in proportion for washing to remove the residual potassium ions in the extraction phase A, and obtain the rubidium and cesium-loaded organic phase and the rubidium-containing washing solution; S4. Introduce the rubidium and cesium-loaded organic phase obtained in step S3 and a 0.4 - 0.6 mmol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in proportion for selective back-extraction to obtain the cesium-loaded organic phase and rubidium chloride solution, and evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride; S5. Introduce the cesium-loaded organic phase obtained in step S4 and a 0.5 - 1.5 mol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in proportion for back-extraction to obtain the organic phase and cesium chloride solution, and evaporate and crystallize the cesium chloride solution to obtain cesium chloride; S6. Take the rubidium-containing washing solution obtained in step S3 as the aqueous phase, dilute 4-tert-butyl-2-(α-methylbenzyl)phenol to 0.4 - 0.5 mol / L with an organic solvent as the organic phase, then introduce the rubidium-containing washing solution and the 4-tert-butyl-2-(α-methylbenzyl)phenol solution into a multi-stage countercurrent extraction device in proportion for extraction, and perform extraction at 20 - 30 °C for 4 - 6 min to obtain the extraction phase B and the raffinate phase B; S7. Introduce the extraction phase B obtained in step S6 and a 0.4 - 0.6 mmol / L hydrochloric acid solution into a multi-stage countercurrent extraction device in proportion for selective back-extraction to obtain the organic phase and rubidium chloride solution, evaporate and crystallize the rubidium chloride solution to obtain rubidium chloride, and combine the rubidium chloride obtained in step S7 and step S4; S8. Recycle and reuse the organic phase after back-extraction in step S5 and step S7, and at the same time, evaporate and concentrate the raffinate phase A and the raffinate phase B and add them to the lithium extraction mother liquor, and repeat the separation and purification steps of S1 - S7; The multi-stage countercurrent extraction device includes at least two rotating disk extraction towers, which are connected in series between the rotating disk extraction towers. The rotating disk extraction tower includes: A dispersion mechanism (28), which disperses and breaks up the organic phase into the aqueous phase through the dispersion mechanism; An annular plate (5), which divides the rotating disk extraction tower into multiple extraction zones through the annular plate, and a baffle plate is arranged below the annular plate. The baffle plate is in an inverted funnel shape and a spoiler bar is arranged at the bottom; A driving mechanism (8), which drives the baffle plate to rotate and move up and down reciprocally at the same time; A weir plate assembly (9), which enables the heavy liquid and the light liquid to be smoothly stratified to facilitate the separation of the light liquid; A tower body (1), and the dispersion mechanism, the annular plate, the driving mechanism and the weir plate assembly are all integrated on the tower body; A first feed pipe (2) is fixedly installed on the side wall below the tower body (1). One end of the first feed pipe (2) penetrates through the tower body (1) and is fixedly connected to a dispersion mechanism (28). The dispersion mechanism (28) includes a first fixing plate (13) and a second fixing plate (14). A mixing pipe (15) is fixedly connected between the first fixing plate (13) and the second fixing plate (14). Return holes (16) arranged in an annular array are formed at the joints of the upper and lower ends of the mixing pipe (15) with the first fixing plate (13) and the second fixing plate (14). A turbine (17) is arranged inside the mixing pipe (15). A first driving shaft (3) penetrates through the inside of the dispersion mechanism (28). The turbine (17) is fixedly installed at the top of the first driving shaft (3). The first feed pipe (2) is fixedly connected to the middle of the first fixing plate (13) above the mixing pipe (15). Through holes are formed in the outer circles of the first fixing plate (13) and the second fixing plate (14).

2. The recovery process of rubidium and cesium from the by-products of lithium extraction from lepidolite according to claim 1, characterized in that, In the steps S2 and S6, the organic solvent is a mixture of sulfonated kerosene, xylene, and cyclohexane in a volume ratio of 2:1:

1.

3. The recovery process of rubidium and cesium from the by-products of lithium extraction from lepidolite according to claim 1, characterized in that, In the step S2, the volume ratio of the supernatant to the 4-tert-butyl-2-(α-methylbenzyl)phenol solution is 1:

1. In the step S3, the volume ratio of the extraction phase A to the sodium hydroxide solution is 1:

5. In the step S4, the volume ratio of the organic phase loaded with rubidium and cesium to the hydrochloric acid solution is 1:

2. In the step S5, the volume ratio of the organic phase loaded with cesium to the hydrochloric acid solution is 1:

6. In the step S6, the volume ratio of the rubidium-containing washing liquid to the 4-tert-butyl-2-(α-methylbenzyl)phenol solution is 1:

1. In the step S7, the volume ratio of the extraction phase B to the hydrochloric acid solution is 1:

2.

4. The recovery process of rubidium and cesium from the by-products of extracting lithium from lepidolite according to claim 1, characterized in that, The lower end of the first driving shaft (3) penetrates through the tower body (1). The first driving shaft (3) is in sealed rotational connection with the tower body (1). The bottom end of the first driving shaft (3) is fixedly connected to the output shaft of a first motor (4) through a belt. At least three annular plates (5) are fixedly installed in the middle of the tower body (1) at equal intervals in the vertical direction. A second driving shaft (6) penetrates through the middle of the annular plates (5). The upper end of the second driving shaft (6) penetrates through the tower body (1). The second driving shaft (6) is in sealed sliding connection with the tower body (1). Baffle plates (7) are fixedly installed on the surface of the second driving shaft (6) between the annular plates (5). The top end of the second driving shaft (6) is connected to a driving mechanism (8). A weir plate assembly (9) is fixedly installed above the tower body (1). A second feed pipe (10) is fixedly installed on the side wall of the tower body (1) between the weir plate assembly (9) and the annular plates (5). A first discharge pipe (11) is fixedly installed at the top of the tower body (1). A second discharge pipe (12) is fixedly installed at the bottom of the tower body (1).

5. The recovery process of rubidium and cesium in the by-products of lithium extraction from lepidolite according to claim 4, characterized in that, The baffle plate (7) is in an inverted funnel shape. Turbulence strips (18) arranged in an annular array are fixedly installed at the bottom of the baffle plate (7).

6. The recovery process of rubidium and cesium in the by-products of lithium extraction from lepidolite according to claim 4, characterized in that, The driving mechanism (8) includes a guide post (19) and a driving wheel (20). The guide post (19) is fixedly installed at the top end of the second driving shaft (6). A closed bolt-shaped guide groove (21) is formed on the surface of the guide post (19). A guide rod (22) is slidably arranged in the guide groove (21). One end of the guide rod (22) away from the guide post (19) is fixed to the mounting frame (23). The driving wheel (20) includes a fixing part (201) and a driving part (202). The fixing part (201) is rotatably connected to the mounting frame (23). The driving part (202) is fixedly connected to the output shaft of the second motor (24) through a belt. A driving hole (203) penetrating through the fixing part (201) and the driving part (202) is formed in the middle of the driving wheel (20). A key strip (204) is fixedly installed on the inner wall of the driving hole (203). The upper end of the second driving shaft (6) penetrates through the driving hole (203). A key groove (61) is formed on the surface of the second driving shaft (6) corresponding to the key strip (204).

7. The recovery process of rubidium and cesium from the by-products of lithium extraction from lepidolite according to claim 4, characterized in that, The weir plate assembly (9) includes a third fixing plate (25). A ring-shaped first weir plate (26) is fixedly installed at the bottom of the third fixing plate (25). A funnel-shaped second weir plate (27) is fixedly installed at the top of the third fixing plate (25). The diameter of the lower end of the second weir plate (27) is the same as that of the first weir plate (26). Feeding holes are formed on the surface of the third fixing plate (25) inside the first weir plate (26) and the second weir plate (27). The lower end of the first discharge pipe (11) is placed outside the second weir plate (27). The height of the lower end of the first discharge pipe (11) is lower than that of the second weir plate (27). The height of the second feeding pipe (10) is higher than the bottom of the first weir plate (26).

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