Extraction system and lithium extraction method thereof

Abstract

The invention relates to the technical field of chemical synthesis, in particular to an extraction system and a lithium extraction method thereof. The extraction system comprises an extraction agent, a co-extraction agent and a diluent; wherein the extraction agent comprises HBTA, the co-extraction agent is TBP, and the diluent is 2-octanone. According to the novel synergistic extraction system provided by the invention, a proper amount of co-extraction agent is added into the TBP extraction agent, and the diluent is optimized, so that the use amount of TBP is reduced, the diluent is prevented from forming a polar complex with TBP and Li, the extraction efficiency of lithium is improved, and the phase separation time can be shortened.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to an extraction system and a method for extracting lithium therefrom. Background Art

[0003] Lithium in nature is mainly found in spodumene, lepidolite and lithium salt lakes. At present, the main methods for extracting lithium from lepidolite and ferrolithium mica ores are to pre-treat them by limestone sintering, sulfate method, pressure cooking method or chlorination roasting method, and then use stirring leaching to leach lithium and other valuable metals into the solution. For lithium salt lakes, the main methods for extracting lithium include adsorption method, sun-drying-precipitation method, electrodialysis method, electrochemical method and extraction method.

[0004] Extraction is one of the effective methods for lithium resource extraction, with the advantages of low economic cost and high recovery rate. Generally, the extraction system can be divided into four categories according to the type of extractant, namely, organic phosphate, ionic liquid, crown ether and β-diketone extractant. Organophosphorus tributyl phosphate (TBP)-FeCl3-kerosene is a commonly used extraction system, but it usually consumes a lot of acid and alkali in the stripping and regeneration process, corrodes the equipment, and causes Fe 3+ The loss of lithium ions affects the effective recovery of the extractant. In addition, for the TBP extraction system, the general extractant concentration must be as high as 60-90% to effectively separate lithium from other impurity metals and avoid the formation of the third phase, but the high concentration of TBP increases the viscosity of the organic phase and prolongs the phase separation time. Kerosene is a commonly used diluent with low water solubility and low cost, but it is a non-polar inert solvent and is easy to form polar complexes with Li, co-extractants and TBP, which may cause the formation of a third phase.

[0005] Therefore, a new extraction system is currently needed to efficiently recover lithium metal. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides an extraction system and a method for extracting lithium therefrom.

[0007] In a first aspect, the present invention provides a synergistic extraction system, which comprises an extractant, a co-extractant and a diluent; wherein the extractant comprises HBTA, the co-extractant is TBP, and the diluent is 2-octanone. The new synergistic extraction system provided by the present invention adds an appropriate amount of co-extractant to the TBP extractant and optimizes the diluent, thereby reducing the amount of TBP, avoiding the formation of polar complexes between the diluent and TBP and Li, thereby improving the extraction efficiency of lithium and improving the problem of long phase separation time.

[0008] Preferably, the molar ratio of the extractant, the co-extractant and the diluent is 0.5-1:0.5-1:1-2.

[0009] More preferably, the molar ratio of HBTA to TBP is 1:1; preferably, the molar ratio of HBTA, TBP and 2-octanone is 1:1:2.

[0010] In the present invention, by optimizing the ratio of the extractant, the co-extractant and the diluent, the separation effect of lithium and other valuable metals can be better exerted, and efficient extraction of lithium metal can be achieved.

[0011] In a second aspect, the present invention provides a method for extracting lithium metal from a leaching solution using an extraction system, comprising: S1. Adjusting pH: Using sodium hydroxide to adjust the pH of the leachate solution to obtain an alkaline leachate.

[0012] S2. Prepare an organic phase: Mix HBTA, TBP and 2-octanone to obtain an extraction system.

[0013] S3. Extraction: The alkaline leaching solution and the extraction system are mixed and then extracted to extract lithium.

[0014] S4. Clarification: Separating the extracted liquid into an organic phase and an aqueous phase to obtain an organic phase.

[0015] S5. Washing: washing the organic phase with a detergent.

[0016] S6. Reflux and stripping: The washed organic phase is mixed with a stripping agent and subjected to stripping treatment to strip the metallic lithium in the organic phase into the liquid phase.

[0017] Preferably, in step S3, the molar ratio of HBTA, TBP and 2-octanone is 0.5-1:0.5-1:1.5-2, preferably 1:1:2; preferably, the molar ratio of HBTA and TBP is 1:1.

[0018] In the present invention, sodium hydroxide solution is added to the leachate to adjust the leachate to alkalinity, and then HBTA extractant, TBP co-extractant and 2-octanone are used as the extraction system, which are fully mixed under a certain ratio of preferably 1:1:2, and subjected to extraction-washing-strip extraction steps, thereby achieving efficient extraction of lithium metal in the leachate, and achieving a lithium extraction rate of 99.7%, which has the characteristics of efficient lithium extraction.

[0019] Further preferably, in step S1, the pH of the alkaline leaching solution is 9-13, preferably 12-13.

[0020] Preferably, in the present invention, the leaching solution can be a lithium-containing solution after leaching of lithium-containing ore or a lithium precipitation mother liquor (the mother liquor after precipitation of lithium carbonate). The metal ions contained in the leaching solution include but are not limited to Li + 、Al3+ and Na + The present invention does not limit the ions and their specific concentrations in the leachate, and may also contain other ions such as Mg 2+ , Fe 3+ , K + , Ca 2+ Plasma.

[0021] Further preferably, in step S3, the volume ratio of the extraction system to the alkaline leaching solution is 1:3-5:1, preferably 1:1.

[0022] Further preferably, in step S5, the detergent is a 1-4 mol / L acidic lithium-containing solution, preferably a LiCl solution.

[0023] More preferably, step S4 further includes recovering and removing oil from the extracted liquid.

[0024] More preferably, step S5 further includes returning the washing liquid to step S3 for extraction.

[0025] Further preferably, in step S7, the stripping agent is 4-6 mol / L HCl or 2-3 mol / L H2SO4.

[0026] Further preferably, the method for extracting lithium metal in the leaching solution by the extraction system comprises: S1. Adjusting pH: Use sodium hydroxide to adjust the pH of the leachate to 9-13 to obtain an alkaline leachate.

[0027] S2. Preparing an organic phase: mixing HBTA, TBP and 2-octanone in a molar ratio of 0.5-1:0.5-1:1.5-2, preferably 1:1:2, to obtain an extraction system; S3. Extraction: The alkaline leaching solution and the extraction system are mixed and added into an extraction tank for extraction.

[0028] S4. Clarification: The extracted liquid is passed through a clarification chamber to separate the organic phase and the aqueous phase to obtain an organic phase, and the extracted liquid is recovered and deoiled.

[0029] S5. Washing: Using 1-4 mol / L acidic lithium-containing solution as a washing agent, the organic phase is washed to allow the impure metals in the organic phase to enter the aqueous phase.

[0030] S6. Reflux and stripping: The washed organic phase is mixed with a stripping agent and stripped to strip the metallic lithium in the organic phase into the liquid phase. The washed organic phase enters the stripping stage to extract the metal, and preferably the washed liquid is returned to the extraction stage to be extracted together with the lithium-containing solution, and 4-6 mol / L HCl or 2-3 mol / L H2SO4 is used as a stripping agent to strip the metallic lithium in the organic phase into the liquid phase, thereby achieving effective separation of lithium from other impurity metals.

[0031] The beneficial effects of the present invention are at least as follows: in view of the problem that TBP has increased viscosity and prolonged separation time at high concentrations, the present invention adds HTBA extractant and uses TBP as a co-extractant, effectively avoiding the problem of prolonged separation time. At the same time, in view of the problems that kerosene is prone to the appearance of a third phase and that the organic phase is prone to degradation when used as a diluent, 2-octanone is used as a diluent, effectively avoiding the problem of the appearance of a third phase. The present invention uses HBTA extractant, TBP co-extractant and 2-octanone as an extraction system, the lithium concentration in the raffinate can reach less than 10 ppm, the lithium concentration after extraction-washing-strip extraction increases, the extraction rate is higher than 99%, the concentration of impurity sodium ions is controlled at a relatively low level, lower than 100 ppm, and the separation of metallic lithium and sodium is effectively achieved. The present invention has the characteristics of high lithium extraction rate, efficient separation of lithium and sodium, and avoidance of long separation time. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0034] If no specific technology or conditions are specified in the examples of the present invention, the technology or conditions described in the literature in the field or the product instructions are used. If the manufacturer of the devices, instruments, reagents, etc. is not specified, they are all conventional products that can be purchased through regular channels. The experimental reagents and raw materials involved are all commercially available, and the reagents are all analytically pure products.

[0035] In the following examples, the raw materials involved are leached from lithium-containing ore, wherein Li + Content 2.48 g / L, Al 3+ Content: 10.78 g / L, Na + The content is 27.16 g / L; the mother liquor used for lithium precipitation is the mother liquor after lithium carbonate precipitation, in which Li + Content 1.25 g / L, Na + Content 95 g / L.

[0036] Example 1 This embodiment provides a synergistic extraction system, which specifically comprises HBTA, TBP and 2-octanone in a molar ratio of 1:1:2.

[0037] This embodiment also provides a method for extracting lithium metal from a leachate using an extraction system, and the specific steps are as follows: Step 1: HBTA, TBP and 2-octanone in a molar ratio of 1:1:1 were fully stirred and mixed to prepare an extraction system.

[0038] Step 2: Slowly drip 1 mol / L sodium hydroxide into the leaching solution and stir it thoroughly. Use a pH meter to detect in real time and adjust the pH to 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 12.5, 13, 13.5 respectively. After the pH is stable, set aside.

[0039] Step 3: Place the extraction system and the leaching solution in a volume ratio of 1:1 into a separatory funnel and use a shaker to fully mix for 1 minute. The experiment is carried out at room temperature and the shaker speed is 180 rpm. Then, the separatory funnel is left to stand, and the time is counted until the interface between the oil phase and the water phase is clear and no obvious emulsion layer appears. The phase separation time is recorded, and then the water phase is released.

[0040] Extraction test results: When the solution pH value is greater than 12, the lithium extraction rate can reach more than 85%.

[0041] Example 2 Step 1: Slowly drip 1 mol / L sodium hydroxide into the leaching solution and stir it thoroughly. Use a pH meter to detect in real time and adjust the pH to 13. After the pH is stable, set it aside.

[0042] Step 2: HBTA, TBP and 2-octanone in molar ratios of 3:1:1, 2:1:1, 1:1:1, 1:2:1 and 1:3:1 were fully stirred and mixed to prepare an extraction system.

[0043] Step 3: Place the extraction system and the leaching solution in a volume ratio of 1:1 into a separatory funnel and use a shaker to fully mix for 1 minute. The experiment is carried out at room temperature and the shaker speed is 180 rpm. Then, the separatory funnel is left to stand, and the time is counted until the interface between the oil phase and the water phase is clear and no obvious emulsion layer appears. The phase separation time is recorded, and then the water phase is released.

[0044] Extraction test results: When the molar ratio of HBTA to TBP is 1:1, the lithium extraction rate reaches more than 88%.

[0045] Example 3 Step 1: Slowly drip 1 mol / L sodium hydroxide into the leaching solution and stir it thoroughly. Use a pH meter to detect in real time and adjust the pH to 13. After the pH is stable, set it aside.

[0046] Step 2: HBTA, TBP and 2-octanone in molar ratios of 1:1:1, 1:1:1.5, 1:1:2 and 1:1:2.5 were fully stirred and mixed to prepare an extraction system.

[0047] Step 3: Place the extraction system and the leaching solution in a volume ratio of 1:1 into a separatory funnel and use a shaker to fully mix for 1 minute. The experiment is carried out at room temperature and the shaker speed is 180 rpm. Then, the separatory funnel is left to stand, and the time is counted until the interface between the oil phase and the water phase is clear and no obvious emulsion layer appears. The phase separation time is recorded, and then the water phase is released.

[0048] Extraction test results: When the molar ratio of HBTA, TBP and 2-octanone was 1:1:2, the lithium extraction rate reached more than 93%.

[0049] Example 4 Step 1: Slowly drip 1 mol / L sodium hydroxide into the leaching solution and stir it thoroughly. Use a pH meter to detect in real time and adjust the pH to 13. After the pH is stable, set it aside.

[0050] Step 2: HBTA, TBP and 2-octanone in a molar ratio of 1:1:2 were fully stirred and mixed to prepare an extraction system.

[0051] Step 3: The extraction system and the leaching solution were placed in a separatory funnel at a volume ratio of 1:1 and mixed thoroughly using a shaker. The experiment was conducted at room temperature, the shaker speed was 180 rpm, and the mixing time was set to 60s, 120s, 180s, 240s, 300s, 360s, 420s, 480s, 540s, and 600s. Subsequently, the separatory funnel was left to stand, and the timing was counted until the interface between the oil phase and the water phase was clear and no obvious emulsion layer appeared. The phase separation time was recorded, and then the water phase was released.

[0052] Extraction test results: When the extraction time is greater than 120s, the organic phase can completely extract the lithium metal in the leachate. However, when the extraction time is 180s, the lithium-sodium separation effect is better.

[0053] Example 5 Step 1: Slowly drip 1 mol / L sodium hydroxide into the leaching solution and stir it thoroughly. Use a pH meter to detect in real time and adjust the pH to 13. After the pH is stable, set it aside.

[0054] Step 2: HBTA, TBP and 2-octanone in a molar ratio of 1:1:2 were fully stirred and mixed to prepare an extraction system.

[0055] Step 3: The extraction system and the leaching solution were placed in a separatory funnel at a volume ratio of 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, and 5:1, and mixed thoroughly using a shaker. The experiment was conducted at room temperature, the shaker speed was 180 rpm, and the mixing time was set to 180 s. Subsequently, the separatory funnel was left to stand, and the timing was counted until the interface between the oil phase and the water phase was clear and no obvious emulsion layer appeared. The phase separation time was recorded, and then the water phase was released.

[0056] Extraction test results: When the volume ratio of the extraction system to the leaching solution is 1:1, the extraction rate of lithium is higher than 99%.

[0057] Example 6 Step 1: HBTA, TBP and 2-octanone in a molar ratio of 1:1:2 were fully stirred and mixed to prepare an extraction system.

[0058] Step 2: Adjust the pH of the lithium precipitation mother solution to 13.

[0059] Step 3: Place the extraction system and lithium precipitation mother liquor in a volume ratio of 2:1 into a separatory funnel and use a shaker to mix thoroughly. The experiment is carried out at room temperature, the shaker speed is 180rpm, and the mixing time is set to 180s. Then, the separatory funnel is left to stand, and the timing is counted until the interface between the oil phase and the water phase is clear, and no obvious emulsion layer appears. The phase separation time is recorded, and then the water phase is released.

[0060] Extraction test results: The separation effect of lithium and sodium is good, and the extraction rate of lithium is higher than 96%.

[0061] Comparative Example 1 This comparative example provides an extraction system and method for extracting lithium metal from the water extract of iron lithium mica concentrate, which is the same as Example 1, except that the extraction system is replaced by β-diketone extractant (M54-100), trialkylphosphine oxide mixture (Cyanex923) and sulfonated kerosene instead of HBTA, TBP and 2-octanone. The method is as follows: Step 1: Impurity removal: Add a certain amount of sodium hydroxide and sodium carbonate to the leaching solution to remove impurities, and filter after the reaction is balanced to obtain a de-impurity solution.

[0062] Step 2: Consume H + . Add a certain amount of sodium carbonate solution to the decontaminated solution to consume part of the H + , adjust the pH.

[0063] Step 3: A three-stage cascade extraction test was carried out with the decontaminated leaching solution and the extraction system at a volume ratio of O / A=1.5:1.

[0064] Extraction test results: After three-stage extraction, the extraction rates of Li and Na were 90.38% and 0.40%, respectively.

[0065] The above embodiments and comparative examples were subjected to verification of the effect of lithium extraction by leachate extraction. It can be seen from the results of lithium extraction in each embodiment and comparative example 1 that the lithium extraction rate of the embodiment of the present invention can reach more than 93%, and the highest can even reach more than 99%. The lithium extraction effect of the embodiment of the present invention is significantly better than the extraction rate of the comparative example, indicating that the technical scheme of the present invention and the extraction system can effectively improve the extraction of lithium metal in the leachate and improve the comprehensive recovery rate of lithium resources.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An extraction system, characterized in that: The extraction system comprises an extractant, a co-extractant and a diluent; wherein the extractant comprises HBTA, the co-extractant is TBP, and the diluent is 2-octanone.

2. The extraction system according to claim 1, characterized in that The molar ratio of the extractant, the co-extractant and the diluent is 0.5-1:0.5-1:1-2.

3. The extraction system according to claim 2, characterized in that The molar ratio of HBTA to TBP is 1:1; preferably, the molar ratio of HBTA, TBP and 2-octanone is 1:1:

2.

4. A method for extracting lithium from a leachate using an extraction system, characterized in that: include: S1. Adjusting pH: Using sodium hydroxide to adjust the pH of the leachate to obtain an alkaline leachate; S2. Preparing an organic phase: mixing HBTA, TBP and 2-octanone to obtain an extraction system; S3 extraction: the alkaline leachate and the extraction system are mixed and extracted to extract lithium; S4. Clarifying: separating the organic phase and the aqueous phase of the extracted liquid to obtain an organic phase; S5. Washing: washing the organic phase with a detergent; S6. Reflux and stripping: The washed organic phase is mixed with a stripping agent and subjected to stripping treatment to strip the metallic lithium in the organic phase into the liquid phase.

5. The method for extracting lithium from a leachate using the extraction system according to claim 4, characterized in that: In step S3, the molar ratio of HBTA, TBP and 2-octanone is 0.5-1:0.5-1:1.5-2, preferably 1:1:

2.

6. A method for extracting lithium from a leachate using the extraction system according to claim 4 or 5, characterized in that: In step S1, the pH of the alkaline leaching solution is 9-13, preferably 12-13.

7. A method for extracting lithium from a leachate using the extraction system according to any one of claims 4 to 6, characterized in that: In step S3, the volume ratio of the extraction system to the alkaline leaching solution is 1:3-5:1, preferably 1:

1.

8. A method for extracting lithium from a leachate using the extraction system according to any one of claims 4 to 7, characterized in that: In step S5, the detergent is a 1-4 mol / L acidic lithium-containing solution, preferably a LiCl solution.

9. A method for extracting lithium from a leachate using the extraction system according to any one of claims 4 to 8, characterized in that: In step S7, the stripping agent is 4-6 mol / L HCl or 2-3 mol / L H2SO4.

10. A method for extracting lithium from a leachate using the extraction system according to any one of claims 4 to 9, characterized in that: include: S1. Adjusting pH: Using sodium hydroxide to adjust the pH of the leachate to 9-13 to obtain an alkaline leachate; S2. Preparing an organic phase: mixing HBTA, TBP and 2-octanone in a molar ratio of 0.5-1:0.5-1:1.5-2, preferably 1:1:2, to obtain an extraction system; S3 extraction: the alkaline leachate and the extraction system are mixed and added to an extraction tank for extraction; S4. Clarification: The extracted liquid is passed through a clarification chamber to separate the organic phase and the aqueous phase to obtain an organic phase; S5 washing: 1-4 mol / L acidic lithium solution as a detergent, the organic phase is washed; S6. Reflux and stripping: The washed organic phase is mixed with a stripping agent and subjected to stripping treatment.