WO2019114815A1

WO2019114815A1 - Extraction solvent for lithium element and extraction method therefor

Info

Publication number: WO2019114815A1
Application number: PCT/CN2018/121094
Authority: WO
Inventors: 刘明彪; 韩道俊; 谢楠
Original assignee: 虔东稀土集团股份有限公司
Priority date: 2017-12-16
Filing date: 2018-12-14
Publication date: 2019-06-20
Also published as: CN109628758B; CN109628758A

Abstract

An extraction solvent for extracting and separating lithium element and a method for extracting and separating lithium element fall within the technical field of wet metal metallurgy. An extraction solvent comprising a neutral phosphorus-containing extractant, ferric chloride, and an auxiliary extractant is used to extract and separate lithium element in a lithium-containing solution so as to obtain a lithium element-containing solution. The present invention achieves the effects of not needing to use Ferric chloride as a synergistic extractant, the applicability being wide, the extractant being easy to obtain, requiring low investment and being low cost, being convenient to use, safety and reliability, being convenient for industrial production, recovering lithium element from production wastewater such as lithium carbonate, and also being used to extract lithium element from complex raw materials having high impurities such as brine having a high magnesium-lithium ratio. The present invention is especially applicable to extract lithium element from brine in China, being advantageous for improving the current status of lithium resources having low quality, being difficult to separate, having heavy pollution and having high cost in China.

Description

Extraction solvent of lithium element and extraction method thereof

Technical field

The invention relates to a lithium element extraction and separation method. It belongs to the field of wet metal metallurgy technology.

Background technique

With the rapid development and application of lithium batteries, lithium and its compounds are increasingly used in the chemical, pharmaceutical, electronics and other industrial fields. The amount of lithium is greatly increased. China's lithium resources mainly exist in salt lakes. After lithium enrichment, it has the characteristics of high magnesium-lithium ratio and many impurities. Since magnesium and lithium are similar in nature, they are not easily separated.

The Chinese Patent Application Publication No. CN 87103431 A, published on Nov. 4, 1987, discloses a method for extracting anhydrous lithium chloride from a lithium-containing brine. Using tributyl phosphate as an extractant, The mixture can be recycled in the extract. The lithium chloride can be directly extracted from the brine. The technical solution has achieved no pollution caused by the invention, and the economic benefit is remarkable. The profit per ton of lithium chloride can be 8,000 to 10,000 yuan. Left and right" technical effects.

The Chinese Patent Application Publication No. CN102275956A, published on Oct. 16, 2013, discloses a method for extracting lithium carbonate from high magnesium lithium than salt lake brine. The method is subjected to extraction, washing, and stripping steps. The stripping solution consisting of NaCl and LiCl or the stripping solution of NH4Cl and LiCl is obtained, and then the CO2 or Na2CO3 is added to control the pH and the kinetic conditions to obtain the nanometer or micron Li2CO3 product "technical solution, and obtained" The steps are simple, low requirements on equipment, wide source of raw materials, and suitable for industrial production.

The Chinese Patent Application Publication No. CN106521159A, published on March 22, 2017, discloses a method for extracting lithium in a brine based on an extraction system containing Fe(III) and recycling Fe(III). The Fe(III)-containing extraction system has problems such as high stripping acidity, difficulty in recovery of Fe(III), and poor multi-stage continuous extraction in the process of extracting lithium. The method supports Fe(III) in an organic extraction system, and then The Fe(III)-containing extraction system extracts lithium from the brine and uses the NaOH solution to strip the extracted lithium-rich organic phase. For the comprehensive recovery of Fe(III), the Fe(III) is completely converted. After being separated from Fe(OH)3, it is converted into Fe(III) solution by acid, and used for extracting lithium organic phase for extraction and recycling. The technical scheme is achieved, and the operation is simple, the organic phase extraction performance is stable, and It realizes the advantages of continuous multi-stage extraction, and successfully solves the problem of high acidity and recycling of Fe(III) in the traditional acid stripping process, and has broad application prospects.

In the above prior art, since the raffinate and the stripping solution obtained by the extraction and stripping process contain the +3 valent iron element to varying degrees, further separation and recovery of the +3 valent iron element is required, and it is necessary to continuously add the synergistic effect to the organic phase. The iron chloride and Fe(OH)3 are separated and recovered, and the defects are inconvenient.

Summary of the invention

It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art and to separate and efficiently recover lithium ions in an environmentally friendly manner.

The invention relates to a lithium element extraction solvent, comprising a neutral phosphorus-containing extracting agent and a synergistic agent ferric chloride and an auxiliary extracting agent, wherein the auxiliary extracting agent has the function of maintaining and stabilizing ferric chloride in an extraction solvent of lithium element. .

One of the preferred technical solutions for extracting a lithium element according to the present invention is that the neutral phosphorus-containing extracting agent is diamyl methylphosphonate, dimethyl heptyl methylphosphonate, tributyl phosphate, and trioctyl phosphate. Etc., and at least one of their isomers.

The invention further relates to an extraction solvent of a lithium element, which is an acidic phosphorus-containing extracting agent, an amine extracting agent, a chelate extracting agent, a neutral oxygen-containing extracting agent, and a neutral nitrogen-containing extracting agent. And replacing at least one of the amide extractants.

A further preferred embodiment of the lithium-based extraction solvent of the present invention, the amine-based extractant is a trialkylamine and/or trioctylamine and an isomer thereof; and the chelating agent is 8-hydroxyquinoline And/or 2-hydroxy-5-octylbenzophenone oxime (N510); the neutral oxygen-containing extractant is methyl isobutyl ketone; the neutral nitrogen-containing extractant is N, N- Di-n-alkylacetamide and/or N-phenyl-N-octylacetamide.

According to still another preferred embodiment of the lithium-based extraction solvent of the present invention, the acidic extractant is mono(2-ethylhexyl) phosphonate, di(2-ethylhexyl) phosphonate, 2-ethylphosphine. Acid mono(2-ethylhexyl) ester, phenylphosphonic acid (2-ethylhexyl) ester, di(2-ethylhexyl)phosphoric acid, bis(2,4,4-trimethylpentyl)phosphinic acid At least one of an acid, a naphthenic acid, and the like.

A further preferred embodiment of the lithium-based extraction solvent of the present invention further comprises a diluent which is at least one of kerosene, n-hexane and octanol.

A further preferred embodiment of the lithium solvent extraction solvent according to the invention is 0<(auxiliary extractant/neutral phosphorus-containing extractant) <40% by volume.

The invention further relates to a lithium solvent extraction solvent, wherein the molar ratio of the synergistic extracting agent in the extraction solvent is 0<(co-extractant/neutral phosphorus-containing extractant)≤0.5, preferably 0.1<( Co-extractor / neutral phosphorus extractant) <0.4.

A further preferred embodiment of the lithium-based extraction solvent of the present invention, wherein the concentration of the synergistic agent is 10-25 g/L.

The invention also provides a method for extracting lithium element, comprising the following steps,

Step one, extracting: mixing the lithium-containing solution with an extraction solvent of lithium to obtain a supported organic phase;

Step two, stripping: mixing the organic phase with the stripping agent to obtain an extraction solvent of lithium element and a solution containing lithium element;

The extraction solvent of the lithium element includes an extracting agent and a synergistic extracting agent, an auxiliary extracting agent, the extracting agent is a neutral phosphorus-containing extracting agent, the synergistic extracting agent is ferric chloride, and the auxiliary extracting agent is acidic phosphorus. At least one of an extractant, an amine extractant, a chelate extractant, a neutral oxygen-containing extractant, and a neutral nitrogen-containing extractant.

The present invention is one of the preferred technical solutions for the extraction method of lithium element, and the stripping agent is a water, acid and/or soluble salt solution.

A further preferred embodiment of the method for extracting lithium element according to the present invention further comprises the step of preparing an extraction solvent for lithium element before step one: mixing the extracting agent with the auxiliary extracting agent and the synergistic extracting agent to obtain an extraction solvent for lithium element.

A further preferred embodiment of the lithium element extraction process of the present invention further comprises the step of washing the supported organic phase with an acid and/or a stripping solution prior to step two.

A further preferred embodiment of the lithium element extraction method of the present invention further comprises the step of mixing the stripping solution with a precipitating agent to obtain a lithium element salt.

A further preferred embodiment of the lithium element extraction method of the present invention further comprises preparing the obtained lithium element salt into a metal lithium or other lithium element product.

In a preferred embodiment of the method for extracting and separating lithium element, the acid in the step of washing the supported organic phase with acid and/or stripping solution before step two is hydrochloric acid. At least one of sulfuric acid, oxalic acid, etc. may also be used depending on the difference in lithium salt obtained in the second step.

A preferred technical solution for extracting and separating a lithium element according to the present invention, wherein the lithium-containing solution further comprises an extraction salt, wherein the auxiliary extraction salt is at least a salt of calcium, magnesium, ferrous, cobalt, nickel, manganese, and rare earth elements. One.

The invention also provides a method for using a lithium-containing solution, which is prepared by using a lithium element-containing solution into a lithium element compound or other lithium element product such as lithium metal or lithium alloy, and the lithium element-containing solution is used for extraction and separation. A method for preparing a lithium element product by extracting a lithium element or extracting a lithium element by extraction.

One of the preferred technical solutions for using a lithium element-containing solution of the present invention is to prepare a lithium element-containing solution into a lithium battery.

The invention has the following advantages:

1 After the addition of the auxiliary extractant, the stability of the ferric chloride in the extraction solvent of lithium element is greatly improved. The iron chloride introduced by the iron in the stripping solution is less introduced by the ferric chloride, and the ferric chloride is recycled in the extraction system to save resources. Moreover, it avoids the introduction of new and other impurities into the extraction system by the addition of ferric chloride, which is beneficial to reducing impurities such as iron in the lithium product and improving the quality of the lithium product.

2 Lithium element extraction solvent and its extraction and separation method have wide applicability. It can recover lithium from production wastewater such as lithium carbonate, and can also be used to extract lithium from high impurities and complex raw materials such as high magnesium and lithium brine. It is especially suitable for extracting lithium from brine in China, which is conducive to solving the current situation of low lithium resource quality, difficult separation, heavy pollution and high cost. The extraction agent extracts lithium elements with high specificity.

3 can be directly applied in the existing lithium extraction production line, with low investment, low cost, fast phase separation, convenient use, safety, reliability and easy industrial production.

DRAWINGS

Figure 1 is a schematic view of the process flow of the present invention.

Detailed ways

The invention is illustrated in more detail below by way of examples.

Comparative example one

(1) Extraction of organic phase preparation: 160 mL of tributyl phosphate was mixed with 40 mL of sulfonated kerosene to obtain 200 ml of organic phase A, and then mixed with ferric chloride solution, and the aqueous phase was clarified to obtain an organic phase B in which Fe in the organic phase B The content of ³⁺ is 20 g/l.

(2) First extraction: 100 ml of a lithium-containing solution (in which LiCl = 7.29 g/L, NaCl = 141.41 g/L) was mixed with 200 ml of organic phase B, and the phases were allowed to stand to obtain 200 ml of the loaded organic phase C and 100 ml of the raffinate. Liquid A, detected in the raffinate A, Li ⁺ = 0.49 g / L, Fe ^{3 +} = 9.13 g / L, Na ⁺ = 50.69 g / L.

(3) The first counter-extraction:

1. Stripping with water: mixing 50 ml of water with 100 ml of supported organic phase C, statically clearing phase separation to obtain 100 ml of organic phase D1 and 50 ml of stripping solution A1, and Li ⁺ = 0.71 g/L in stripping solution A1, Fe ³⁺ = 26.22 g/L, Na ⁺ = 4.91 g/L, and the sodium to lithium ratio (mass ratio, the same below) was 6.92. The lithium element in the stripping solution is enriched relative to the lithium-containing solution, but the iron element impurities are also increased.

2. Stripping with acid: mixing 50 ml of 4.5 N hydrochloric acid instead of water and 100 ml of supported organic phase C, static clear phase separation to obtain 100 ml of organic phase D2 and 50 ml of stripping solution A2, and Li ⁺ = 0.71 g of stripping solution A2 L, Fe ³⁺ = 0.017 g/L, Na ⁺ = 4.90 g/L, and a sodium to lithium ratio of 6.9. The lithium element in the stripping solution is enriched relative to the lithium-containing solution. Although iron impurities are also added, the content of iron impurities is less than that of water.

After the first extraction and water stripping, the loss rate of iron in organic phase B was 88.38%.

After the first extraction and acid stripping, the loss rate of iron in the organic phase B was 22.87%.

(4) Second extraction and stripping:

1. 50 ml of the above lithium-containing solution was mixed with 100 ml of the organic phase D1, and after phase separation, 100 ml of the organic phase E1 and 50 ml of the raffinate B1 were obtained. It was detected that Li ⁺ = 1.18 g / L, Fe ^{3 +} = 1.23 g / L, and Na ⁺ = 53.7 g / L in the raffinate B1. Then, 50 ml of water is mixed with 100 ml of the supported organic phase E, and 100 ml of the organic phase F1 and 50 ml of the stripping solution B1 are obtained after phase separation. Li ⁺ = 0.018 g/L in the stripping solution B1, Fe ³⁺ = 2.56 g/L, Na ⁺ = 1.3g/L. Since the content of ferric chloride in the organic phase D1 is small, the lithium extraction rate is greatly reduced, and the sodium to lithium ratio in the stripping solution B1 is 72.2, which exceeds the sodium to lithium ratio of the lithium-containing solution. After extraction and stripping of the lithium-containing solution by the organic phase D1, the sodium ions in the lithium-containing solution are enriched in the organic phase and the stripping solution.

2. Mix 50 ml of the above lithium-containing solution with 100 ml of the organic phase D2, and obtain 100 ml of the loaded organic phase E2 and 50 ml of the raffinate B2 after phase separation. It was found that Li ⁺ = 0.89 g / L, Fe ^{3 +} = 7.13 g / L, and Na ⁺ = 53.11 g / L in the raffinate B2. Then, 50 ml of 4.5 N hydrochloric acid was mixed with 100 ml of the supported organic phase E2, and 100 ml of the organic phase F2 and 50 ml of the stripping solution B2 were obtained after phase separation. Li ⁺ = 0.31 g/L in the stripping solution B2, Fe ³⁺ = 0.015 g / L, Na ⁺ = 2.49 g/L. Since the content of ferric chloride in the organic phase D2 is small, the extraction rate of lithium is significantly decreased, but higher than that of the organic phase D1, and the ratio of sodium to lithium in the stripping solution B2 is 8.02.

The above test shows that when tributyl phosphate is used as an extractant alone and ferric chloride is used as a co-extractant to extract lithium, the ferric chloride in the organic phase easily enters the raffinate and the stripping solution and is largely lost, and with ferric chloride. The loss of organic phase extraction and separation capabilities and properties have changed significantly. On the other hand, the lithium element solution obtained after stripping contains a large amount of iron, and it is necessary to separately separate these iron elements in order to obtain a clean lithium element. Due to the low content of ferric chloride in the organic phases D1 and D2, the extraction efficiency of lithium is greatly reduced, and the ability of the organic phase D1 to extract and separate lithium ions is substantially lost. After the second extraction and stripping, the iron in the organic phase D1 lost 81.51% again; the iron in the organic phase D2 lost 23.16% again. In order to maintain the extraction efficiency of lithium, the organic phases D1 and D2 must be iron-added and then extracted again. The control level of the iron phase of the organic phase D1 and D2 is relatively high.

Embodiment 1

(1) Extraction solvent extraction of lithium element: 80 ml of tributyl phosphate was mixed with 32 ml of a trialkylamine, 20 ml of a sulfonated kerosene and a ferric chloride solution to obtain 132 ml of an extraction solvent (organic phase B) of a lithium element to be used. The content of Fe ³⁺ in the organic phase B was 15 g/l.

(2) First extraction: 50 ml of the lithium-containing solution of Comparative Example 1 was mixed with 132 ml of organic phase B. The phase was allowed to stand for 30 min to obtain a supported organic phase C and 50 ml of raffinate A. It was found that Li ⁺ = 0.58 g / L, Fe ^{3 +} = 0.52 g / L, and Na ⁺ = 51.93 g / L in the raffinate A.

(3) The first stripping: mixing 50 ml of water with the supported organic phase C, and clarifying the phase for 30 min to obtain the organic phase D and the stripping solution A. Li ⁺ = 0.62 g/L in the stripping solution A, Fe ³⁺ = 1.02 g/L, Na ⁺ = 3.67 g/L, and the sodium to lithium ratio was 5.92.

(4) Second extraction and stripping: 50 ml of the lithium-containing solution was mixed with the organic phase D, and the phase was allowed to stand for 30 min to obtain the supported organic phase E and 50 ml of the raffinate B, and the raffinate B was detected. Li ⁺ = 0.59 g / L, Fe ^{3 +} = 0.29 g / L, Na ⁺ = 53.17 g / L. Mix 50 ml of water with the supported organic phase E, and clarify the phase for 30 min to obtain 50 ml of organic phase F and stripping solution B. Li ⁺ = 0.61 g/L in the stripping solution B, Fe ³⁺ = 0.65 g/L, Na ⁺ =2.43g/L. When the organic phase D was not subjected to iron extraction, the lithium extraction ratio slightly decreased with respect to the organic phase B'. After the second extraction and stripping, the total loss of iron in the organic phase D was 2.44%. The sodium to lithium ratio in the stripping solution B was 3.98.

After adding the trialkylamine to the organic phase B of Comparative Example 1, the Fe ³⁺ loss rate in the organic phase after the first extraction and water stripping was 3.85%, and the separation efficiency of lithium and sodium was improved. The extraction rate was slightly decreased when the second extraction was carried out with the organic phase D, but the separation efficiency of lithium and sodium was further improved. Compared with the first ratio, after adding the trialkylamine to the comparative one extractant, on the one hand, the loss of ferric chloride in the extraction solvent of lithium element is greatly reduced, the ratio of sodium to lithium is decreased, and the separation efficiency of lithium and sodium is improved. On the other hand, the amount of iron in the lithium element solution obtained after stripping is greatly reduced.

Embodiment 2

(1) Extraction solvent extraction of lithium element: 32 ml of a trialkylamine in Example 1 was replaced with 16 ml each of 2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester and trialkylamine to obtain Fe. The organic phase B having a ³⁺ content of 15 g/l.

(2) Extraction: 50 ml of the lithium-containing solution of Comparative Example 1 was taken and mixed with 132 ml of organic phase B. The organic phase C and 50 ml raffinate were obtained by standing for 10 min, and the phase separation time was shorter than that of the first example. Li ⁺ = 0.56 g/L and Fe ³⁺ = 0.32 g/L were detected in the raffinate.

(3) Stripping: 10 ml of 5N hydrochloric acid was mixed with the supported organic phase C, and the phase separation was clarified for 10 min to obtain a blank organic phase D and a stripping solution. The lead extract was found to have Li ⁺ = 3.14 g/L, Fe ³⁺ = 0.035 g/L, and Na ⁺ = 11.3 g/L. The sodium to lithium ratio was 3.6.

After adding trialkylamine and 2-ethylhexyl monoethyl 2-ethylphosphonate to organic phase B of Comparative Example 1, the loss rate of Fe ³⁺ in the blank organic phase after one extraction and stripping was 0.82. %. Compared with Comparative Example 1 and Example 1, on the one hand, the loss of ferric chloride in the organic phase is further reduced. On the other hand, the lithium element solution obtained after stripping is less in iron, and the phase separation speed of the organic phase is obviously accelerated. Lithium and sodium separation is better. Acid stripping can reduce the loss of iron in the organic phase and the iron content of the impurities in the stripping solution.

Embodiment 3

(1) Preparation of extraction solvent for lithium element: 80 ml of tributyl phosphate was mixed with 32 ml of 2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester, 20 ml of sulfonated kerosene and ferric chloride solution to obtain 132 ml of Extraction solvent for lithium (organic phase B). The content of Fe ³⁺ in the organic phase B was 15 g/l.

(2) Extraction: 50 ml of a lithium-containing solution (in which LiCl = 7.89 g/L, NaCl = 154.14 g/L, MgCl ₂ = 7.84 g/L) was mixed with 132 ml of organic phase B. The phase was allowed to stand for 5 min to obtain the organic phase C and 50 ml of the raffinate. The detected raffinate Li ⁺ = 0.57 g / L, Fe ^{3 +} = 0.29 g / L, Mg ²⁺ = 1.96 g / L, Na ⁺ = 58 g / L.

(3) Stripping: 5N mixed 10 ml of hydrochloric acid with the supported organic phase C, and left to stand for 5 min to obtain a blank organic phase D and a stripping solution. Li ⁺ = 3.61 g/L in the stripping solution, Fe ³⁺ = 0.028 g /L, Mg ²⁺ = 0.018 g / L, Na ⁺ = 12.8 g / L. The sodium to lithium ratio was 3.54.

After the addition of 2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester in the organic phase B of Comparative Example 1, the Fe ³⁺ loss rate in the organic phase B' after one extraction and stripping was 0.739%. The ability to maintain and stabilize the iron chloride content in the organic phase is strong; the iron content in the stripping solution is low. The phase separation speed is fast.

The extraction solvent of the lithium element prepared in the present embodiment does not substantially extract magnesium, and the presence of magnesium element in the lithium-containing solution contributes to the improvement of the extraction and separation efficiency of the lithium element. The phase separation speed is fast.

Embodiment 4

(1) Extraction: 50 ml of a lithium-containing solution (in which LiCl = 7.89 g/L, NaCl = 154.14 g/L, MgCl ₂ = 110.75 g/L) was mixed with 132 ml of an organic phase prepared in Example 3. The phase was allowed to stand for 5 min to obtain the organic phase C and 50 ml of the raffinate. The detected raffinate Li ⁺ = 0.45 g / L, Fe ^{3 +} = 0.0685 g / L, Mg ²⁺ = 27.96 g / L, Na ⁺ = 57.86 g / L.

(2) Stripping: 5N mixed 10 ml of hydrochloric acid with the supported organic phase C, and left to stand for 5 min to obtain a blank organic phase D and a stripping solution. Li ⁺ = 4.23 g/L in the stripping solution, Fe ³⁺ = 0.014 g /L, Mg ²⁺ = 0.018 g / L, Na ⁺ = 13.8 g / L. The sodium to lithium ratio was 3.26.

With the increase of the concentration of magnesium ions in the lithium-containing solution, it helps to further reduce the iron loss rate in the organic phase, increase the extraction rate of lithium, the separation efficiency of lithium and sodium, reduce the impurities, reduce the loss of Fe ^{3+ in the} organic phase, and decrease the loss of Fe ^{3+ in the} organic phase. The Fe ³⁺ loss rate is 0.178%, and the ability to maintain and stabilize the ferric chloride content in the organic phase is strong; the iron content in the stripping solution is lower. The phase separation speed is fast. The magnesium ion in the lithium-containing solution is a helper salt, which serves to improve the extraction rate of lithium, the separation efficiency of lithium and sodium, and the iron content in the stable organic phase. Organic phase B does not substantially extract Mg ²⁺ .

The organic phase of the present embodiment does not substantially extract magnesium, and the concentration of divalent magnesium ions in the lithium-containing solution is increased, and the extraction effect is more remarkable. Therefore, the present embodiment is suitable for extracting and separating lithium elements from high-magnesium-lithium brines in China.

Embodiment 5

(1) Extraction: 50 ml of a lithium-containing solution (in which LiCl = 7.77 g/L, NaCl = 128.7 g/L, MgCl ₂ = 276.13 g/L) was mixed with 132 ml of an organic phase prepared in Example 3. The organic phase C and 50 ml of the raffinate were obtained by standing for 3 min. The detected raffinate Li ⁺ = 0.21 g / L, Fe ^{3 +} = < 0.001 g / L, Mg ²⁺ = 69.74 g / L, Na ⁺ = 47.57 g / L.

(3) Stripping: 5N mixed 10ml of hydrochloric acid with the supported organic phase C, and left to stand for 5min to obtain blank organic phase D and stripping solution. Li ⁺ =5.33g/L in the stripping solution, Fe ³⁺ =0.015g /L, Mg ²⁺ = 0.014 g / L, Na ⁺ = 15.1 g / L. The sodium to lithium ratio was 2.83.

With the increase of the concentration of magnesium ions in the lithium-containing solution, the extraction rate of lithium ions and the separation efficiency of lithium and sodium were significantly improved, and the concentration of lithium ions in the extract was correspondingly improved. The loss of ferric chloride in the extraction solvent of lithium was extremely small. Therefore, the present embodiment is particularly suitable for extracting and separating lithium elements from high-magnesium-lithium brines in China.

Embodiment 6

(1) Extraction: 50 ml of lithium-containing solution (LiCl=7.95 g/L, NaCl=151.59 g/L, FeCl ₂ = 105.3 g/L) was subjected to secondary extraction with the organic phase B132ml prepared in Example 3 to obtain a load. Organic phase C1 and C2. In the 50ml raffinate, Li ⁺ = 0.083g / L, Fe ^{3 +} = 0.13g / L, Na ⁺ = 55.57g / L, Fe ²⁺ = 46.21g / L.

(2) Stripping: 10 ml of 6N hydrochloric acid was mixed with the supporting organic phases C1 and C2, and the stationary phase was separated to obtain the blank organic phase C and the stripping solution. Li ⁺ = 5.89 g/L in the stripping solution, Fe ³⁺ = 0.02g / L, Fe ²⁺ = 0.6g / L, Na ⁺ = 20.1g / L, the content of Fe ^{3 + in the} stripping solution is low.

After the second extraction, the yield of lithium element is greatly increased. The presence of a certain amount of divalent iron ions in the lithium-containing solution also helps to reduce the iron loss rate in the organic phase and increase the extraction rate of lithium, as well as improve the separation efficiency of lithium and sodium, and play a role in helping the salt. In this embodiment, the organic relative to the divalent iron ions is substantially not extracted. Divalent iron ions also have a synergistic effect.

Example 7

(1) Preparation of extraction solvent for lithium element: tributyl phosphate by volume ratio: dimethylheptyl methyl phosphate: di(2-ethylhexyl) phosphonate: sulfonated kerosene: n-hexane = 20:20:12 : 5:5 and a ferric chloride solution were mixed to obtain an organic phase B having an iron content of 5.6 g/L.

(2) Extraction: 50 ml of lithium-containing solution (LiCl=8.2 g/L, NaCl=144.41 g/L, CoCl ₂ = 67.31 g/L, NiCl ₂ = 64.18 g/L, Mn Cl ₂ = 55.9 g/ L) 4 times of extraction with 100 ml of organic phase B, respectively, to obtain 4 parts of the loaded organic phase, after detecting 50 ml of raffinate, Li ⁺ <1 mg / L, Fe ^{3 +} = 0.11 g / L, Na ⁺ = 51 g / L , Co ²⁺ = 30.55 g / L, Ni ²⁺ = 29.13 g / L, Mn ²⁺ = 24.40 g / L. The yield of lithium is increased and the rate of iron loss in the organic phase is lowered, and the loss of Fe ³⁺ in the organic phase is small.

(3) Stripping: 10 ml of 5.5N hydrochloric acid was sequentially mixed with each supported organic phase, and the blank organic phase C and the stripping solution were obtained by phase separation. Li ⁺ = 6.62 g/L in the stripping solution, Na ⁺ = 22.51 g / L, Fe ³⁺ = 0.017 g / L, Co ²⁺ = 0.042 g / L, Ni ²⁺ = 0.029 g / L, Mn ²⁺ = 0.053 g / L. The total loss of iron in the organic phase is very low and the organic phase does not require iron. The Co ²⁺ , Ni ²⁺ , and Mn ²⁺ salts act as a salt-extracting salt.

In this embodiment, after replacing the tributyl phosphate with dimethylheptyl methyl phosphate, the extraction solvent of lithium element has higher extraction rate of lithium element, the total loss rate of iron in the organic phase is low, and the extraction solvent of lithium element does not need to be supplemented. Iron can be repeatedly extracted and separated from lithium ions, sodium ions, cobalt ions, nickel ions, manganese ions, and the like. The content of lithium in the stripping solution is high, and there are few impurities such as iron.

Example eight

(1) Preparation of extraction solvent for lithium element: 80 ml of tributyl phosphate was mixed with 4 ml of 2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester, 16 ml of sulfonated kerosene and ferric chloride solution to obtain 100 ml of Extraction solvent for lithium (organic phase B). The content of Fe ³⁺ in the organic phase B was 25 g/l.

(2) Extraction: 50 ml of a lithium-containing solution (in which LiCl=7.29 g/L, NaCl=141.41 g/L) was mixed with 100 ml of organic phase B, and the phase separation was carried out to obtain 100 ml of the loaded organic phase C and 100 ml of the raffinate A, It was detected that Li ⁺ = 0.51 g / L, Fe ^{3 +} = 7.39 g / L, and Na ⁺ = 50.78 g / L in the raffinate A.

(3) Stripping: 50 ml of 10% ammonium chloride solution was mixed with the supported organic phase C, and the phase was static and clear to obtain the organic phase D and the stripping solution A. Li ⁺ =0.60 g/L in the stripping solution A, Fe ^{3 +} =1.13 g/L, Na ⁺ = 3.57 g/L, and a sodium to lithium ratio of 5.95.

Example nine

(1) Preparation of extraction solvent for lithium element: 80 ml of tributyl phosphate was mixed with 34 ml of 2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester, 20 ml of sulfonated kerosene and ferric chloride solution to obtain 134 ml of Extraction solvent for lithium (organic phase B). The content of Fe ³⁺ in the organic phase B was 32.5 g/l.

(2) Extraction: 50 ml of a lithium-containing solution (in which LiCl=7.29 g/L, NaCl=141.41 g/L) was mixed with 134 ml of organic phase B, and the phase separation was carried out to obtain 154 ml of the loaded organic phase C and 100 ml of the raffinate A. It was detected that Li ⁺ = 0.53 g / L, Fe ^{3 +} = 0.18 g / L, and Na ⁺ = 50.67 g / L in the raffinate A.

(3) Stripping: Mix 50 ml of 10% ammonium chloride solution with the supported organic phase C, and clarify the phase by static to obtain organic phase D and stripping solution A. Li ⁺ = 0.59 g/L in the stripping solution A, Fe ^{3 +} = 0.93 g/L, Na ⁺ = 3.62 g/L, and the sodium to lithium ratio was 6.13.

Example ten

(1) Preparation of extraction solvent for lithium element: trioctyl tertiary amine by volume ratio: sulfonated kerosene: tributyl phosphate: trioctyl phosphate = 1:4:10:5 mixed with ferric chloride solution to obtain Fe-containing ³⁺ 8g/L extraction solvent.

(2) Extraction: extraction solvent according to flow ratio: lithium-containing solution=2:1 for 10-stage countercurrent extraction to obtain supported organic phase and raffinate; Li ⁺ =1.98 g/L, Mg ^{2+ in the} lithium-containing solution = 40.23 g / L, Na ⁺ = 107.94 g / L, K ⁺ = 18.17 g / L Cl ^- = 297.47.79 g / L, SO4 ^2- = 20.5 g / L;

(3) washing: according to the flow ratio of the organic phase: hydrochloric acid = 10:1 for 12 stages of countercurrent washing to obtain a purified organic phase, the hydrochloric acid concentration of 0.6N;

(4) Stripping: Purification of the organic phase by flow ratio: hydrochloric acid = 20:1, 6-stage countercurrent stripping to obtain a blank organic phase and a lithium chloride solution, the hydrochloric acid concentration being 3N.

(5) Precipitation: The lithium chloride solution was precipitated with sodium hydrogencarbonate to obtain lithium carbonate. The lithium carbonate content was 98.69% (weight, the same below), Fe<0.0002%, Ca=0.0007%, Cl=0.0011%, Na= 0.013%.

The lithium content in the raffinate was 0.079g/L, and the lithium content of the lithium chloride solution in the stripping solution was 19.4g/L, Mg ²⁺ =0.05g/L, K ⁺ =0.17g/L, Na ⁺ =0.11g /L, Fe = 0.017 g/L. The magnesium salt acts as a salt extracting aid.

Embodiment 11

(1) Extraction solvent extraction of lithium element: 2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester: sulfonated kerosene: tributyl phosphate = 4:5:20 to obtain a blank organic phase Then, it was mixed with a ferric chloride solution to obtain an extraction solvent containing 16 g/L of iron.

(2) Extraction: 10 stages of countercurrent extraction according to the flow ratio organic phase: lithium-containing brine=2:1, to obtain a supported organic phase and a raffinate; wherein the lithium-containing brine has Li ⁺ = 3.06 g/L, Mg ²⁺ =49.23g / L, Na ⁺ = 100.97g / L, K ⁺ = 24.74g / L Cl ^- = 310.79g / L, SO4 ^2- = 38.5g / L;

(3) Washing: according to the flow ratio of the loaded organic phase: the stripping solution = 25:1 for 6-stage countercurrent washing to obtain a purified organic phase;

(4) Stripping: Purification of the organic phase by flow ratio: sulfuric acid = 10:1 for 6-stage countercurrent stripping to obtain a blank organic phase and a lithium sulfate solution having a sulfuric acid concentration of 2N.

(5) Precipitation: The lithium sulfate solution was precipitated with sodium hydrogencarbonate to obtain lithium carbonate. The lithium carbonate content was 98.69% (weight, the same below), Fe<0.0002%, Ca=0.0005%, Na=0.015%, SO4 ^2- = 0.042%.

The magnesium salt in the lithium-containing brine is a helper salt.

Lithium chloride, lithium sulfate or lithium carbonate obtained after extraction and separation can be prepared into lithium compounds such as lithium oxide, lithium hydroxide, lithium iron phosphate and other lithium salts, and can be further prepared into a metal lithium or lithium battery.

The lithium content in the raffinate was detected to be 0.067 g/L. The content of the lithium sulfate solution was Li ⁺ = 9.26 g / L, Mg ²⁺ = 0.07 g / L, and K ⁺ = 0.19 g / L Na ⁺ = 0.13 g / L.

Finally, it should be noted that the above embodiments are only a few preferred modes listed in the present invention, and those skilled in the art should understand that the embodiments of the present invention are not limited to the above. Any equivalent transformation made on the basis of the present invention should fall within the scope of the present invention.

Claims

A lithium element extraction solvent, comprising a neutral phosphorus-containing extractant, ferric chloride, and an auxiliary extractant.
The extraction solvent for a lithium element according to claim 1, wherein the auxiliary extractant is an acidic phosphorus-containing extractant, an amine extractant, a chelate extractant, a neutral oxygen-containing extractant, and a neutral nitrogen-containing extract. At least one of an agent and a substituted amide extractant.
The extraction solvent for lithium element according to claim 1, wherein the acidic extractant is mono(2-ethylhexyl) phosphonate, di(2-ethylhexyl) phosphonate, 2-ethyl Phosphonic acid mono(2-ethylhexyl) ester, phenylphosphonic acid (2-ethylhexyl) ester, di(2-ethylhexyl)phosphoric acid, bis(2,4,4-trimethylpentyl) At least one of phosphonic acid and naphthenic acid; the amine extractant is a trialkylamine and/or trioctylamine; and the chelate extractant is 8-hydroxyquinoline and/or 2-hydroxy-5- Octyl benzophenone oxime (N510); the neutral oxygen-containing extractant is methyl isobutyl ketone; the neutral nitrogen-containing extractant is N,N-di-n-alkylacetamide and/or N -Phenyl-N-octylacetamide.
The extraction solvent for lithium element according to claim 1, characterized in that, by volume ratio, 0 < (auxiliary extractant / neutral phosphorus extractant) < 40%; molar ratio, synergistic agent in extraction solvent The ratio is 0 < (co-extraction agent / neutral phosphorus-containing extractant) < 0.35, preferably 0.1 < (co-extraction agent / neutral phosphorus-containing extractant) < 0.3.
The extraction solvent for lithium element according to claim 1, wherein the neutral phosphorus-containing extracting agent is diisoamyl methylphosphonate, dimethylheptyl methylphosphonate, tributyl phosphate, and phosphoric acid At least one of octyl ester and their isomers.
A method for extracting lithium elements, comprising the following steps,

Step one, extracting: mixing the lithium-containing solution with an extraction solvent of lithium to obtain a supported organic phase;

Step two, stripping: mixing the organic phase with the stripping agent to obtain an extraction solvent of lithium element and a solution containing lithium element;

The extraction solvent of the lithium element includes an extracting agent and a synergistic extracting agent, an auxiliary extracting agent, the extracting agent is a neutral phosphorus-containing extracting agent, the synergistic extracting agent is ferric chloride, and the auxiliary extracting agent is acidic phosphorus. At least one of an extractant, an amine extractant, a chelate extractant, a neutral oxygen-containing extractant, and a neutral nitrogen-containing extractant.
The method of extracting a lithium element according to claim 6, wherein the stripping agent is an acid and/or a soluble salt solution.
A method of extracting a lithium element according to claim 6, further comprising the step of washing the supported organic phase with an acid and/or a stripping solution before the second step.
The method for extracting a lithium element according to claim 6, wherein the lithium element-containing solution is prepared as a lithium element compound or a metal lithium, a lithium alloy, or a lithium battery.
The method for extracting lithium element according to claim 6, characterized in that the lithium-containing solution further comprises an extraction salt, which improves the extraction rate of lithium, the separation efficiency of lithium and sodium, and the iron content in the stable organic phase. The role.