Method for recovering lithium from low-lithium multi-impurity complex solution and producing battery-grade lithium carbonate
Through the two-step liquid-liquid extraction process and carbonation reaction, the problems of long and high cost of traditional lithium recovery process are solved, and the efficient separation of lithium ions in complex solutions with low lithium multi-impact impurities are achieved, with the advantages of high recovery rate and low loss.
Patent Information
- Application Number
- CN202510326125.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-05-30
AI Technical Summary
The traditional lithium recycling process has a long process and high cost, and it is difficult to efficiently separate lithium ions in complex solutions with low lithium multiple impurities, resulting in large lithium loss.
Using a two-step liquid-liquid extraction process, I was first extracted by an organic relatively low lithium multi-imperfect solution containing extractant A to separate divalent or above impurity metal ions; then extracted II by an organic relative lithium-containing sodium raffinate containing synergistic extraction agent, and efficiently selectively extracted lithium ions, and finally prepared battery-grade lithium carbonate through carbonation reaction.
Efficient separation and deep removal of lithium ions in complex solutions of low lithium multi-impacts are achieved. The total recovery rate of lithium exceeds 99%, the lithium loss is less than 0.03%, and the process flow is greatly shortened and production costs are reduced.
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Figure CN120057958A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for recovering lithium from a complex lithium solution, and more particularly to a method for recovering lithium from a low-lithium and multi-impurity complex solution and producing battery-grade lithium carbonate, belonging to the technical field of lithium carbonate preparation. Background Art
[0002] Lithium is widely used in the electrochemical field due to its high electrochemical activity, low thermal expansion coefficient, and high specific heat capacity. In recent years, with the surge in lithium demand for electric vehicles, it is crucial to recover lithium from low-grade resources (such as LiF / Li 2 CO 3 / Li 3 PO 4 precipitation mother liquor, salt lake brine, raffinate from nickel recovery in ternary batteries, etc.) and prepare battery-grade lithium carbonate. Traditional impurity separation processes include two parts: preliminary impurity removal and deep impurity removal. In the first part, Fe, Al, and other trace heavy metals are removed by Na 2 CO 3 combined with Na 2 S, Mg is precipitated by Ca(OH) 2 , and Ca is precipitated by Na 2 CO 3 . These impurity removal operations are mainly based on the solubility deviation between impurities and lithium salts. However, chemical precipitation produces gel-like precipitates such as Fe(OH) 3 and Al(OH) 3 , resulting in a relatively high lithium entrainment rate, and repeated filtration and washing operations incur high equipment and operating costs. In the deep impurity removal part, mainly monovalent cation and anion impurities are removed. In the traditional concentration and evaporation process of low-lithium solutions, the enrichment of monovalent cations (especially Na) and anion impurities requires long and expensive purification steps. For the cooling crystallization of Na 2 SO 4 (for removing Na), due to the eutectics and entrainment of lithium-concentrated solutions, generally about 3% - 10% of lithium loss is caused. To deeply remove trace cations (Ca / Mg) and anion impurities (Cl - , F - , SO 4 2- ), industrially, methods such as carbonating Li 2 with CO 2 gas to form LiHCO 3 , chelating cations and ion exchange, and thermal decomposition are used to produce battery-grade Li 3 CO 2 CO 3However, cooling crystallization and carbonization-thermal decomposition respectively require large cooling systems, crystallization systems (for Na 2 SO 4 ·10H 2 O), heating recrystallization systems (to produce anhydrous Na 2 SO 4 ), and carbonization systems, ion exchange systems, thermal decomposition systems, mother liquor recovery / purification systems.
[0003] In summary, the traditional preparation method of battery-grade Li 2 CO 3 uses precipitates such as Fe / Al(OH) 3 , heavy metal sulfides, Mg(OH) 2 , CaCO 3 etc., cation exchange to precipitate trace amounts of Ca / Mg, and Li 2 CO 3 precipitation-CO 2 carbonization-cation exchange-anion exchange-thermal decomposition for further purification, resulting in a long process flow, large reagent consumption, high lithium loss, and high investment and operating costs. Summary of the Invention
[0004] Aiming at the problems faced by the existing lithium recovery process, the purpose of the present invention is to provide a method for recovering lithium from a low-lithium multi-impurity complex solution and producing battery-grade lithium carbonate. This method can efficiently separate and deeply remove impurities through a two-step extraction process, directly concentrate lithium from a low-lithium multi-impurity complex solution containing various impurities with the least loss, and prepare battery-grade lithium carbonate. This method has the advantages of short treatment time, high lithium recovery rate, and low production cost.
[0005] To achieve the above technical objectives, the present invention provides a method for recovering lithium from a low-lithium multi-impurity complex solution and producing battery-grade lithium carbonate, which includes the following steps:
[0006] 1) Perform extraction I on the low-lithium multi-impurity solution with an organic phase containing extractant A to obtain a lithium-sodium raffinate and an organic phase loaded with divalent or higher impurity metal ions;
[0007] The low-lithium multi-impurity solution contains sodium ions, divalent or higher impurity metal ions, and lithium ions;
[0008] The extractant A has the structure of formula 1:
[0009]
[0010] Wherein,
[0011] R 1 and R 2 are independently selected from C 3 ~C12 alkyl groups;
[0012] 2) Using an organic phase containing a synergistic extractant to perform extraction II on the lithium- and sodium-containing raffinate to obtain a lithium-loaded organic phase and a sodium raffinate; washing II and stripping II the lithium-loaded organic phase to obtain a lithium ion solution;
[0013] The synergistic extractant comprises extractant B and extractant C;
[0014] Extractant B has the structure of formula 2:
[0015]
[0016] Extractant C has the structure of formula 3:
[0017]
[0018] wherein,
[0019] R 3 is selected from C 1 to C 12 alkyl groups;
[0020] R 4 R 5 and R 6 are independently selected from C 3 to C 12 alkyl groups;
[0021] 3) Carbonating the lithium ion solution to obtain battery-grade lithium carbonate.
[0022] In view of the problems of long process flow and high cost in the traditional impurity separation process for complex solutions with low lithium and multiple impurities, the present invention innovatively proposes a method for efficiently separating metal ion impurities in complex solutions with low lithium and multiple impurities and obtaining a lithium-ion enriched solution through a two-step liquid-liquid extraction process. More specifically, the present invention preferentially selects extractant A to achieve the selective extraction and separation of high-valent metal ions such as calcium, magnesium, nickel, cobalt, and manganese from monovalent metal ions such as lithium and sodium, and then uses a synergistic extractant to achieve the selective extraction and separation of the two monovalent metal ions of lithium and sodium. Through the two-step liquid-liquid extraction separation, it is unexpectedly possible to achieve the highly selective separation of lithium ions in complex solutions with low lithium and multiple impurities, improving the extraction and recovery effect of lithium ions. For example, the total recovery rate of lithium exceeds 99%, and the lithium loss is less than 0.03%. More notably, through the two-step liquid-liquid extraction process, the efficient enrichment of lithium ions in complex solutions with low lithium and multiple impurities can be achieved, and the obtained lithium-rich solution can be directly used to prepare battery-grade lithium carbonate, greatly shortening the process flow for recovering lithium from solutions with low lithium and multiple impurities and saving production input costs. Compared with the evaporation-precipitation-evaporation process in the prior art, the present invention has the advantages of short process flow, high lithium recovery rate, and low production cost. This process has broad industrial applicability and great potential in the field of lithium recovery.
[0023] In the molecular structural formula of extractant A of the present invention, R 1 and R 2 are independently selected from alkyl groups of C 3 to C 12 . The alkyl group can be a straight-chain alkyl group or a branched-chain alkyl group, specifically such as propyl, heptyl, hexyl, isobutyl, etc.
[0024] In extractant B and extractant C of the present invention, R 3 is selected from alkyl groups of C 1 to C 12 . The alkyl group can be a straight-chain alkyl group, specifically such as methyl, ethyl, propyl, heptyl, hexyl, isobutyl, octyl, etc. When the number of carbon atoms exceeds 3, a branched-chain alkyl group can also be selected, such as isobutyl, isooctyl, etc. R 4 , R 5 and R 6 are independently selected from alkyl groups of C 3 to C 12 . The alkyl group can be a straight-chain alkyl group or a branched-chain alkyl group, specifically such as propyl, heptyl, hexyl, isobutyl, octyl, etc.
[0025] R 1 to R 6The length of the alkyl chain mainly affects the hydrophilic-lipophilic balance of the extractant. If the alkyl chain is too short, the hydrophilicity is too strong, and phase separation is difficult during subsequent extraction. If the alkyl chain is too long, the extractant is difficult to dissolve sufficiently in the organic phase, and its extraction effect cannot be effectively exerted. Therefore, the length of the alkyl chain should be controlled within an appropriate range.
[0026] As a preferred embodiment, the low-lithium multi-impurity solution contains 0.1 - 5 g / L of lithium, 0.1 - 100 g / L of sodium, and 0.1 - 10 g / L of metal cations with a valence of two or more. As a preferred embodiment, the metal cations with a valence of two or more include at least one of calcium ions, magnesium ions, nickel ions, cobalt ions, and manganese ions. There are many types of impurity metal ions in the low-lithium multi-impurity solution, which can simultaneously contain multiple metal cations with a valence of two or more and monovalent sodium ions, and the lithium ion concentration is low. Considering the type of the low-lithium multi-impurity complex solution as well as the recovery efficiency and value, in the low-lithium multi-impurity complex solution, the concentration ranges of various metal ions are preferably: 0.1 - 5 g / L of lithium, 0.1 - 100 g / L of sodium, and 0.1 - 10 g / L of total divalent metal cations.
[0027] As a preferred embodiment, the volume concentration of extractant A in the organic phase containing extractant A is 10 - 45%. The lower the concentration of extractant A in the organic phase, the more organic phase is required, and the lower the extraction efficiency. If the concentration of extractant A in the organic phase is too high, the extraction effect of the extractant cannot be effectively exerted. Therefore, the volume concentration of extractant A in the organic phase containing extractant A is further preferably 10% - 20%.
[0028] As a preferred embodiment, the organic phase containing extractant A contains a hydrophobic solvent.
[0029] As a preferred embodiment, the saponification degree of extractant A is 50 - 90%. Appropriate saponification can improve the coordination and chelation ability of the extractant to metal ions. The saponification degree of extractant A is further preferably 60% - 80%.
[0030] As a preferred embodiment, the hydrophobic solvent includes at least one of kerosene, sulfonated kerosene, D60 solvent oil, and 200# kerosene.
[0031] As a preferred embodiment, the conditions for extraction I are: pH is 0.5 - 7.0, the O / A ratio is 1:5 - 5:1, the extraction temperature is 25 - 40°C, and the extraction time is 5 - 10 min.
[0032] All ratios involved in the present invention are volume ratios.
[0033] As a preferred embodiment, the extraction I is carried out by at least one of single-stage extraction, multi-stage countercurrent extraction, multi-stage cocurrent extraction, multi-stage cross-flow extraction, and fractional extraction.
[0034] The low-lithium multi-impurity complex solution of the present invention undergoes extraction I. On the premise of selecting a preferred extractant, by optimizing conditions such as the solution pH and extractant concentration, high-efficiency and highly selective co-extraction of divalent metal ions such as calcium, magnesium, nickel, cobalt, and manganese can be achieved, and the extraction of monovalent metal ions such as lithium and sodium can be inhibited, thereby realizing the selective separation of divalent metal ions such as calcium, magnesium, nickel, cobalt, and manganese from monovalent metal ions such as lithium and sodium.
[0035] As a preferred embodiment, the organic phase loaded with divalent or higher impurity metal ions undergoes washing I and stripping I to obtain a solution of divalent or higher impurity metal ions.
[0036] As a preferred embodiment, at least one of nitric acid, sulfuric acid, and hydrochloric acid with a concentration lower than 2M is used as the detergent in the washing I.
[0037] As a preferred embodiment, the conditions for the washing I are: the O / A ratio is 1:2 to 8:1, and the temperature is 20 to 50°C.
[0038] As a preferred embodiment, the washing I is carried out by at least one of single-stage washing, multi-stage countercurrent washing, multi-stage cocurrent washing, and multi-stage cross-flow washing.
[0039] By optimizing the conditions for the washing I, the lithium ions carried in the organic phase loaded with divalent or higher impurity metal ions can be eluted and recovered.
[0040] As a preferred embodiment, at least one of nitric acid, sulfuric acid, and hydrochloric acid with a concentration of 2 to 8M is used as the stripping agent in the stripping I.
[0041] As a preferred embodiment, the conditions for the stripping I are: the O / A ratio is 1:2 to 8:1, and the temperature is 20 to 50°C.
[0042] As a preferred embodiment, the stripping I is carried out by at least one of single-stage stripping, multi-stage countercurrent stripping, multi-stage cocurrent stripping, and multi-stage cross-flow stripping.
[0043] By optimizing the conditions for the stripping I, the divalent or higher impurity metal ions extracted in the organic phase loaded with divalent or higher impurity metal ions can be desorbed, realizing the regeneration of the organic phase.
[0044] As a preferred embodiment, the co - extractant is composed of extractant B and extractant C in a volume ratio of 1:5 to 5:1. Due to the two - oxygen coordination site in its enol structure, extractant B can form a six - membered chelate ring with Li+. However, due to the small ionic radius and high hydration energy of Li+, when using extractant B alone, its chelating ability is insufficient, resulting in limited extraction efficiency, and the hydrophilicity caused by the remaining coordinated water molecules easily leads to emulsification of the organic phase. As a neutral ligand, extractant C can replace the coordinated water molecules in the chelate and form a hydrophobic extract, significantly improving the lithium extraction rate and the phase - separation effect of lithium extraction. Within a certain range, increasing extractant C can significantly improve the lithium extraction rate. When extractant C is in excess, its strong coordination ability leads to too high a coordination saturation of Li+, causing an increase in the steric hindrance of the complex and a decrease in the selectivity of extractant B for lithium. Therefore, the co - extractant is further preferably composed of extractant B and extractant C in a volume ratio of 1:3 to 2:1.
[0045] As a preferred embodiment, the volume content of the co - extractant in the organic phase containing the co - extractant is 5 - 45%. The lower the concentration of the co - extractant in the organic phase, the more organic phase is required, and the lower the extraction efficiency. If the concentration of the co - extractant in the organic phase is too high, the extraction effect of the extractant cannot be effectively exerted. Therefore, the volume concentration of the co - extractant in the organic phase containing the co - extractant is further preferably 10% - 30%.
[0046] As a preferred embodiment, the organic phase containing the co - extractant contains a hydrophobic solvent;
[0047] As a preferred embodiment, the hydrophobic solvent includes at least one of kerosene, sulfonated kerosene, D60 solvent oil, and 200# kerosene.
[0048] As a preferred embodiment, the conditions for extraction II are: pH is 7.0 - 13.0, the O / A ratio is 1:5 - 5:1, the extraction temperature is 25 - 40 °C, and the extraction time is 5 - 10 min. pH affects the ability of the co - extractant to chelate metal ions, and the further preferred pH is 8.0 - 12.0.
[0049] As a preferred embodiment, the extraction II method adopts at least one of single - stage extraction, multi - stage counter - current extraction, multi - stage co - current extraction, multi - stage cross - flow extraction, and fractional extraction.
[0050] The lithium-containing sodium raffinate of the present invention uses a preferred synergistic extractant and optimizes conditions such as the pH of extraction II, the concentration of the extractant, etc., and can efficiently and selectively extract lithium ions, inhibiting the co-extraction of sodium ions and other anionic impurities. In this way, it can unexpectedly achieve the efficient and highly selective separation of lithium ions and sodium ions. And based on this method, it helps to directly prepare high-quality battery-grade lithium carbonate from the obtained lithium-rich stripping solution.
[0051] As a preferred embodiment, at least one of nitric acid, sulfuric acid, and hydrochloric acid with a concentration lower than 2M is used as the detergent in the second washing.
[0052] As a preferred embodiment, the conditions for the second washing are: the O / A ratio is 1:2 to 20:1, and the temperature is 20 to 50 °C.
[0053] As a preferred embodiment, the method of the second washing adopts at least one of single-stage washing, multi-stage countercurrent washing, multi-stage cocurrent washing, and multi-stage cross-flow washing.
[0054] By optimizing the conditions of the second washing, the sodium ions carried in the lithium-loaded organic phase can be eluted, which is beneficial to obtaining a high-purity lithium ion solution.
[0055] As a preferred embodiment, at least one of nitric acid, sulfuric acid, and hydrochloric acid with a concentration of 2 to 10M is used as the stripping agent in the second stripping.
[0056] As a preferred embodiment, the conditions for the second stripping are: the O / A ratio is 1:2 to 20:1, and the temperature is 20 to 50 °C.
[0057] As a preferred embodiment, the method of the second stripping adopts at least one of single-stage stripping, multi-stage countercurrent stripping, multi-stage cocurrent stripping, and multi-stage cross-flow stripping.
[0058] As a preferred embodiment, a sodium carbonate solution with a concentration of 1 to 4M is used as the precipitant in the carbonation reaction.
[0059] As a preferred embodiment, the conditions for the carbonation reaction are: the addition amount of the sodium carbonate solution is measured by the lithium / sodium molar ratio of 1:2 to 2:1, the reaction temperature is 10 °C to 100 °C, and the reaction time is 30 to 300 min.
[0060] The lithium ion solution of the present invention is added with a saturated sodium carbonate solution for precipitation, and high-quality battery-grade lithium carbonate is directly obtained to realize the recovery of lithium. The prepared product is rod-shaped, with a smooth surface and good crystallinity, and can be directly used to prepare cathode materials for lithium ion batteries such as lithium cobaltate, lithium manganate, ternary materials, and lithium iron phosphate.
[0061] The beneficial technical effects brought by the present invention compared with the prior art:
[0062] Through a two-step liquid-liquid extraction process, the present invention can achieve efficient separation of lithium ions in a complex solution with low lithium and multiple impurities, obtaining a separation effect with a total lithium recovery rate exceeding 99% and a lithium loss of less than 0.03%. At the same time, through liquid-liquid extraction, a high-purity and relatively high-concentration lithium solution can be obtained, and battery-grade lithium carbonate can be directly prepared through a sodium carbonate precipitation process. BRIEF DESCRIPTION OF THE DRAWINGS
[0063] Figure 1 It is a process flow diagram of the present invention for recovering lithium from a complex solution with low lithium and multiple impurities and producing battery-grade lithium carbonate.
[0064] Figure 2 It is an XRD pattern of the product lithium carbonate obtained in the implementation case.
[0065] Figure 3 It is an SEM image of the product lithium carbonate obtained in the implementation case. DETAILED DESCRIPTION OF THE INVENTION
[0066] The following specific embodiments are intended to further illustrate the content of the present invention rather than limit the protection scope of the claims.
[0067] The chemical reagents involved in the following specific embodiments are all conventional commercially available products.
[0068] A method for recovering lithium from a solution with low lithium and multiple impurities and producing battery-grade lithium carbonate according to the present invention includes the following steps:
[0069] Step (1): The complex solution with low lithium and multiple impurities is first extracted with a first organic phase containing extractant A to selectively extract high-valent metal ions such as calcium, magnesium, nickel, cobalt, and manganese, obtaining a lithium-sodium raffinate and an organic phase loaded with metal ions such as calcium, magnesium, nickel, cobalt, and manganese. The organic phase is washed to recover a small amount of co-extracted lithium ions, and then the extractant A is recovered after back-extraction.
[0070] Step (2): The lithium-sodium raffinate obtained in step (1) is further extracted with a second organic phase containing a synergistic extractant to efficiently and selectively extract lithium ions, obtaining a sodium raffinate and an organic phase loaded with lithium ions. The obtained organic phase loaded with lithium ions is washed to remove a small amount of co-extracted sodium ions, and then a lithium-rich back-extract and the synergistic extractant are obtained after back-extraction.
[0071] Step (3): The lithium-rich back-extract after back-extracting lithium ions in step (2) is directly used to prepare battery-grade lithium carbonate by sodium carbonate precipitation.
[0072] Example 1
[0073] This embodiment provides a method for recovering lithium from a solution with low lithium and high impurity content to produce battery-grade lithium carbonate. The main components of the low-lithium and multi-impurity complex solution used in the embodiment are listed in Table 1, and the specific process schematic diagram can be seen Figure 1 , and the specific process is as follows:
[0074] Table 1 Composition of the solution with low lithium and high impurity content
[0075]
[0076] Step (1):
[0077] Use the first organic phase containing extractant A to perform the first extraction on the low-lithium and multi-impurity complex solution (raw material solution) to extract all calcium, magnesium, nickel, cobalt, manganese, etc. (divalent metal ions) in it. The first organic phase: 10v% A-1 (R 1 ~R 2 are all compounds of formula 1 with 2-ethylhexyl) + 90 vol% sulfonated kerosene. The extractant is saponified with 10 mol / L NaOH solution, and the saponification rate is 70%. After saponification, the extractant is subjected to three-stage countercurrent extraction at an O / A ratio of 1:2, an extraction temperature of 25 °C, and an extraction time of 5 min to obtain a lithium-sodium raffinate and an organic phase loaded with divalent metal ions such as calcium, magnesium, nickel, cobalt, and manganese. The calcium extraction rate is 99.89%, the magnesium extraction rate is 99.90%, the nickel extraction rate is 99.94%, the cobalt extraction rate is 100%, the manganese extraction rate is 99.97%, and the lithium and sodium extraction rates are both less than 2%. The residual concentrations of metal ions such as calcium, magnesium, nickel, cobalt, and manganese in the first-stage raffinate are 0.0005 g / L, 0.001 g / L, 0.0002 g / L, 0 g / L, and 0.0004 g / L respectively. The first-stage loaded organic phase is washed with 0.2 M hydrochloric acid to remove lithium ions in organic phase A. The washing method is single-stage washing, the washing O / A ratio is 6:1, the washing temperature is 25 °C, and the washing time is 5 min. The washing rate of lithium ions is 99.5%. Then, the loaded organic phase A is stripped with 2 M hydrochloric acid. The stripping method is two-stage countercurrent stripping, the stripping O / A ratio is 6:1, the stripping temperature is 25 °C, and the stripping time is 5 min. The stripping rates of valuable metal ions calcium, magnesium, nickel, cobalt, and manganese in the loaded organic phase are 99.98%, 99.93%, 99.97%, 99.96%, and 99.91% respectively.
[0078] Step (2):
[0079] Use the second organic phase containing a synergistic extractant to perform the second extraction on the first-stage raffinate. The second organic phase: 15 vol% B-1 (R 3 is n-heptyl of formula 2) + 15 vol% of formula C-1 (R 4 , R 5 , R6 3)+ 70 v% sulfonated kerosene with n-butyl, at an O / A ratio of 1:1, extraction temperature of 25 °C, extraction time of 10 min, equilibrium pH = 8.5. After four-stage countercurrent extraction, a sodium-rich raffinate and an organic phase loaded with lithium ions were obtained. The lithium extraction rate was 99.95%, and the sodium extraction rate was less than 1.5%. The sodium ions in the second-stage loaded organic phase were washed with 0.5 M sulfuric acid. Under the conditions of O / A = 8:1, temperature of 25 °C, and time of 10 min, two-stage countercurrent washing was carried out, and the sodium elution rate was 94.63%, and the lithium elution rate was 4.83%. Then, the loaded organic phase was stripped with 5 M sulfuric acid. The stripping method was two-stage countercurrent stripping, the stripping O / A ratio was 10:1, the stripping temperature was 25 °C, and the stripping time was 10 min. The lithium stripping rate in the loaded organic phase was 99.9%, and a lithium-rich stripping solution with a lithium content greater than 30 g / L was obtained.
[0080] Step (3):
[0081] The lithium-rich second-stage stripping solution was converted into lithium carbonate precipitate by adding 2.5 M sodium carbonate under the conditions of a lithium-to-sodium molar ratio of 1:1.1, temperature of 90 °C, and time of 60 min. After washing with boiling water 3 times and drying in an oven at 90 °C for 6 h, lithium carbonate solid was obtained. The product purity was 99.93%, and the yield was 75.93%, meeting the requirements of battery-grade lithium carbonate.
[0082] Example 2
[0083] Compared with Example 1, the difference is that the structures of extractant B and extractant C in the second extraction were changed. The experimental groups were:
[0084] A: Second extraction (second organic phase: 15 vol% B-1 (R 3 with n-pentyl of formula 2) + 15 vol% of formula C-1 (R 4 、R 5 、R 6 with n-butyl of formula 3) + 70 v% sulfonated kerosene, O / A = 1:1, four-stage countercurrent extraction, equilibrium pH = 8.5);
[0085] B: Second extraction (second organic phase: 15 vol% B-1 (R 3 with n-hexyl of formula 2) + 15 vol% of formula C-1 (R 4 、R 5 、R 6 with n-butyl of formula 3) + 70 v% sulfonated kerosene, O / A = 1:1, four-stage countercurrent extraction, equilibrium pH = 8.5);
[0086] C: Second extraction (second organic phase: 15 vol% B-1 (R 3Of formula 2) with n-heptyl + 15 vol% of formula C-1 (R 4 , R 5 , R 6 Of formula 3) with n-octyl + 70 v% sulfonated kerosene, O / A = 1:1, four-stage countercurrent extraction, equilibrium pH = 8.5);
[0087] The results are as follows:
[0088] A: In the second extraction, the lithium extraction rate is 99.85%, and the sodium extraction rate is less than 1.6%;
[0089] B: In the second extraction, the lithium extraction rate is 99.91%, and the sodium extraction rate is 2.04%;
[0090] C: In the second extraction, the lithium extraction rate is 99.89%, and the sodium extraction rate is 1.87%.
[0091] Example 3
[0092] Compared with Example 1, the difference is only that the organic components and saponification rate of the first extraction are changed. The experimental groups are:
[0093] A: The first extraction (the first organic phase: 15 vol% of formula A-1 + 85 vol% sulfonated kerosene, O / A = 1:2, three-stage countercurrent extraction, saponification rate 70%);
[0094] B: The first extraction (the first organic phase: 20 vol% of formula A-1 + 80 vol% sulfonated kerosene, O / A = 1:2, three-stage countercurrent extraction, saponification rate 70%);
[0095] Group C: Saponification rate 60%;
[0096] Group D: Saponification rate 80%;
[0097] The results are as follows:
[0098] A: In the first extraction, the calcium extraction rate is 99.92%, the magnesium extraction rate is 99.94%, the nickel extraction rate is 99.95%, the cobalt extraction rate is 100%, the manganese extraction rate is 99.99%, and the lithium extraction rate is 4.25%;
[0099] B: In the first extraction, the calcium extraction rate is 99.97%, the magnesium extraction rate is 99.96%, the nickel extraction rate is 99.98%, the cobalt extraction rate is 100%, the manganese extraction rate is 99.99%, and the lithium extraction rate is 6.64%;
[0100] C: In the first extraction, the calcium extraction rate is 98.43%, the magnesium extraction rate is 97.37%, the nickel extraction rate is 98.44%, the cobalt extraction rate is 99.27%, the manganese extraction rate is 96.98%, and the lithium extraction rate is 1.14%;
[0101] D: In the first extraction, the calcium extraction rate is 99.94%, the magnesium extraction rate is 99.97%, the nickel extraction rate is 99.89%, the cobalt extraction rate is 100%, the manganese extraction rate is 99.98%, and the lithium extraction rate is 2.34%.
[0102] Example 4
[0103] Compared with Example 1, the only difference is that the second extraction conditions are changed. The experimental groups are as follows:
[0104] A: Second extraction (second organic phase: 15 vol% B-1 + 20 v% formula C-1 + 65 vol% sulfonated kerosene, O / A = 1:1, four-stage countercurrent extraction, equilibrium pH = 8.5);
[0105] B: Second extraction (second organic phase: 15 vol% B-1 + 15 vol% formula C-1 + 70 vol% sulfonated kerosene, O / A = 1:1, four-stage countercurrent extraction, equilibrium pH = 11.8);
[0106] C: Second extraction (second organic phase: 20 vol% B-1 + 15 vol% formula C-1 + 65 vol% sulfonated kerosene, O / A = 1:1, four-stage countercurrent extraction, equilibrium pH = 10.6);
[0107] C: Second extraction (second organic phase: 15 vol% B-1 + 25 vol% formula C-1 + 60 vol% sulfonated kerosene, O / A = 1:1, four-stage countercurrent extraction, equilibrium pH = 9.7);
[0108] The results are as follows:
[0109] A: In the second extraction, the lithium extraction rate is 99.96%, and the sodium extraction rate is less than 1.5%;
[0110] B: In the second extraction, the lithium extraction rate is 99.99%, and the sodium extraction rate is 2.25%;
[0111] C: In the second extraction, the lithium extraction rate is 99.99%, and the sodium extraction rate is 1.98%;
[0112] D: In the second extraction, the lithium extraction rate is 99.98%, and the sodium extraction rate is less than 1.5%.
[0113] Example 5
[0114] Compared with Example 1, the only difference is that the carbon precipitation conditions are changed. The experimental groups are as follows:
[0115] A: Sodium carbonate precipitation (temperature 95 °C, time 60 min, lithium-sodium molar ratio: 1:1.1, Na 2 CO 3 : 2.75 M)
[0116] B: Sodium carbonate precipitation (temperature 90 °C, time 90 min, lithium-sodium molar ratio: 1:1, Na 2 CO 3 : 2.5 M)
[0117] The results are as follows:
[0118] A: The purity of the lithium carbonate product is 99.91%, and the yield is 74.85%;
[0119] B: The purity of the lithium carbonate product is 99.89%, and the yield is 75.81%.
[0120] Comparative Example 1
[0121] Compared with Example 1, the only difference is that the conditions of the first extraction are changed. The experimental groups are as follows:
[0122] A: First extraction (first organic phase: 5 vol% of formula A-1 + 95 vol% sulfonated kerosene, O / A = 1:2, three-stage countercurrent extraction, saponification rate 70%);
[0123] B: First extraction (first organic phase: 7.5 vol% of formula A-1 + 92.5 vol% sulfonated kerosene, O / A = 1:2, three-stage countercurrent extraction, saponification rate 70%);
[0124] Group C: Saponification rate 10%;
[0125] Group D: Saponification rate 30%;
[0126] The results are as follows:
[0127] A: In the first extraction, the calcium extraction rate is 85.26%, the magnesium extraction rate is 88.46%, the nickel extraction rate is 72.42%, the cobalt extraction rate is 92.53%, the manganese extraction rate is 93.92%, and the lithium extraction rate is 0.65%;
[0128] B: In the first extraction, the calcium extraction rate is 96.25%, the magnesium extraction rate is 93.10%, the nickel extraction rate is 82.55%, the cobalt extraction rate is 95.64%, the manganese extraction rate is 98.49%, and the lithium extraction rate is 1.05%;
[0129] C: In the first extraction, the calcium extraction rate is 52.28%, the magnesium extraction rate is 12.44%, the nickel extraction rate is 4.71%, the cobalt extraction rate is 14.25%, the manganese extraction rate is 61.03%, and the lithium extraction rate is 0.17%;
[0130] D: In the first extraction, the calcium extraction rate was 81.34%, the magnesium extraction rate was 43.36%, the nickel extraction rate was 24.62%, the cobalt extraction rate was 42.38%, the manganese extraction rate was 90.43%, and the lithium extraction rate was 0.34%.
[0131] Comparative Example 2
[0132] Compared with Example 1, the difference was only that the conditions of the second extraction organic components were changed. The experimental groups were as follows:
[0133] A: Organic phase B: 0 vol% B-1 + 15 vol% type C-1 + 85 vol% sulfonated kerosene, and other operations and parameters were the same as in Example 1;
[0134] B: Organic phase B: 15 vol% B-1 + 0 vol% type C-1 + 85 vol% sulfonated kerosene, and other operations and parameters were the same as in Example 1;
[0135] Group C: The equilibrium pH was 5.5;
[0136] Group D: The equilibrium pH was 6.5.
[0137] The specific results were as follows:
[0138] A: The result of the second extraction was that the lithium extraction rate was only 2.25%, and the sodium extraction rate was 1.61%, and effective separation of lithium and sodium could not be achieved;
[0139] B: The result of the second extraction was that the lithium extraction rate was only 79.43%, and the sodium extraction rate was 1.08%, and effective separation of lithium and sodium could not be achieved;
[0140] Group C: The result of the second extraction was that the lithium extraction rate was only 28.05%, and the sodium extraction rate < 1%, and high-efficiency extraction of lithium and sodium and effective separation of nickel and aluminum could not be achieved;
[0141] Group D: The result of the second extraction was that the lithium extraction rate was only 65.12%, and the sodium extraction rate < 1%, and effective separation of lithium and sodium could not be achieved.
[0142] Comparative Example 3
[0143] A: Sodium carbonate precipitation (temperature 95 °C, time 60 min, lithium-sodium molar ratio: 0.9:1, Na 2 CO 3 : 2 M)
[0144] B: Sodium carbonate precipitation (temperature 50 °C, time 90 min, lithium-sodium molar ratio: 1:1, Na 2 CO 3 : 2.5 M)
[0145] The results were as follows:
[0146] A: The purity of the lithium carbonate product is 99.83%, and the yield is 60.51%.
[0147] B: The purity of the lithium carbonate product is 99.86%, and the yield is 55.61%.
[0148] Finally, it should be noted that: the above various embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the operating conditions of the present invention; although the present invention has been described in detail with reference to the above various embodiments and comparative examples, for those of ordinary skill in the art, it should be understood that: they can still modify the technical solutions and technical conditions recorded in the above various embodiments, or perform relevant equivalent effect replacements on some or all of the technical solutions and technical conditions; and these modifications or replacements do not make the essence of the corresponding technical solutions and technical conditions deviate from the scope of the technical solutions and technical conditions of the various embodiments of the present invention, and these should also be regarded as the protection scope of the present invention.
Claims
1. A method for recovering lithium from a low-lithium, high-impurity complex solution and producing battery-grade lithium carbonate, characterized in that: The following steps are involved: 1) Extraction with an organic phase containing extractant A with low lithium and high impurity solution , obtaining a lithium-sodium raffinate and an organic phase loaded with divalent or higher impurity metal ions; The low-lithium and high-impurity solution contains sodium ions, divalent or higher impurity metal ions and lithium ions; The extractant A has a structure of formula 1: ； Formula 1 in, R1 and R2 are independently selected from C3 to C 12 The alkyl group; 2) Extraction of the sodium-lithium-containing raffinate using an organic phase containing a synergistic extractant , obtaining a lithium-loaded organic phase and a sodium raffinate; the lithium-loaded organic phase is washed and stripping , obtaining a lithium ion solution; The synergistic extractant comprises extractant B and extractant C; The extractant B has a structure of Formula 2: ； Formula 2 The extractant C has a structure of Formula 3: ； Formula 3 in, R3 is selected from C1~C 12 The alkyl group; R4, R5 and R6 are independently selected from C3 to C 12 The alkyl group; 3) subjecting the lithium ion solution to a carbonation reaction to obtain battery-grade lithium carbonate.
2. A method for recovering lithium from a low-lithium, high-impurity complex solution and producing battery-grade lithium carbonate according to claim 1, characterized in that: The low-lithium and high-impurity solution contains 0.1-5 g / L lithium, 0.1-100 g / L sodium, and 0.1-10 g / L divalent or higher metal cations; and / or, The divalent or higher metal cations include at least one of calcium ions, magnesium ions, nickel ions, cobalt ions, and manganese ions; The volume concentration of the extractant A in the organic phase containing the extractant A is 10 to 45%; and / or, The organic phase containing the extractant A comprises a hydrophobic solvent.
3. A method for recovering lithium from a low-lithium, high-impurity complex solution and producing battery-grade lithium carbonate according to claim 2, characterized in that: The saponification degree of the extractant A is 50-90%; and / or, The hydrophobic solvent includes at least one of kerosene, sulfonated kerosene, D60 solvent oil, and 200# kerosene.
4. A method for recovering lithium from a low-lithium, high-impurity complex solution and producing battery-grade lithium carbonate according to any one of claims 1 to 3, characterized in that: The extraction The conditions are: pH 0.5-7.0, O / A ratio 1:5-5:1, extraction temperature 25-40°C, extraction time 5-10 min; and / or, The extraction The extraction method adopts at least one of single-stage extraction, multi-stage countercurrent extraction, multi-stage parallel-current extraction, multi-stage cross-current extraction and fractional extraction.
5. The method of recovering lithium from a low-lithium and high-impurity complex solution and producing battery-grade lithium carbonate according to claim 1, characterized in that: The organic phase loaded with divalent or higher impurity metal ions is washed and stripping , obtaining a divalent or higher impurity metal ion solution; and / or, The washing Using at least one of nitric acid, sulfuric acid and hydrochloric acid with a concentration lower than 2M as a detergent; and / or, The washing The conditions are: O / A phase ratio is 1:2-8:1, temperature is 20-50℃; and / or, The washing The method adopts at least one of single-stage washing, multi-stage countercurrent washing, multi-stage parallel-current washing, and multi-stage cross-current washing; and / or, The stripping At least one of nitric acid, sulfuric acid and hydrochloric acid with a concentration of 2 to 8 M is used as a stripping agent; and / or, The stripping The conditions are: O / A phase ratio is 1:2-8:1, temperature is 20-50℃; and / or, The stripping The method adopts at least one of single-stage stripping, multi-stage countercurrent stripping, multi-stage parallel-current stripping and multi-stage cross-current stripping.
6. The method of claim 1 for recovering lithium from a low-lithium, high-impurity complex solution and producing battery-grade lithium carbonate, characterized in that: The synergistic extractant is composed of extractant B and extractant C in a volume ratio of 1:5 to 5:1; and / or, The volume content of the synergistic extractant in the organic phase containing the synergistic extractant is 5 to 45%; and / or, The organic phase containing the synergistic extractant comprises a hydrophobic solvent; and / or, The hydrophobic solvent includes at least one of kerosene, sulfonated kerosene, D60 solvent oil, and 200# kerosene.
7. A method for recovering lithium from a low-lithium, high-impurity complex solution and producing battery-grade lithium carbonate according to claim 1 or 6, characterized in that: The extraction The conditions are: pH 7.0-13.0, O / A ratio 1:5-5:1, extraction temperature 25-40°C, extraction time 5-10 min; and / or, The extraction The extraction method adopts at least one of single-stage extraction, multi-stage countercurrent extraction, multi-stage parallel-current extraction, multi-stage cross-current extraction and fractional extraction.
8. The method of claim 1 for recovering lithium from a low-lithium, high-impurity complex solution and producing battery-grade lithium carbonate, characterized in that: The washing Using at least one of nitric acid, sulfuric acid and hydrochloric acid with a concentration lower than 2M as a detergent; and / or, The washing The conditions are: O / A phase ratio is 1:2 to 20:1, temperature is 20 to 50°C; and / or, The washing The method adopts at least one of single-stage washing, multi-stage countercurrent washing, multi-stage parallel-current washing, and multi-stage cross-current washing; and / or, The stripping At least one of nitric acid, sulfuric acid and hydrochloric acid with a concentration of 2 to 10 M is used as a stripping agent; and / or, The stripping The conditions are: O / A phase ratio is 1:2 to 20:1, temperature is 20 to 50°C; and / or, The stripping The method adopts at least one of single-stage stripping, multi-stage countercurrent stripping, multi-stage parallel-current stripping and multi-stage cross-current stripping.
9. The method of claim 1 for recovering lithium from a low-lithium, high-impurity complex solution and producing battery-grade lithium carbonate, characterized in that: The carbonation reaction uses a sodium carbonate solution with a concentration of 1 to 4 M as a precipitant.
10. The method of claim 1 for recovering lithium from a low-lithium, high-impurity complex solution and producing battery-grade lithium carbonate, characterized in that: The conditions of the carbonation reaction are as follows: the amount of sodium carbonate solution added is measured at a lithium / sodium molar ratio of 1:2 to 2:1, the reaction temperature is 10° C. to 100° C., and the reaction time is 30 to 300 min.