WO2021088285A1 - Extraction system and extraction method for extracting lithium and boron by separating calcium from calcium-containing brine with secondary amide/alkyl alcohol composite solvent, and use of extraction method - Google Patents

Abstract

Disclosed are an extraction system and extraction method for extracting lithium and boron by separating calcium from a calcium-containing brine with a secondary amide/alkyl alcohol composite solvent and the use of the extraction method. In the extraction system, a secondary amide and an alkyl alcohol are contained and used as extractants for extracting lithium and boron, respectively, and composed of a single compound or a mixture of two or more compounds. The total number of carbon atoms in the molecules is 12-18 and 8-20, respectively. The freezing point of the extraction system is less than 0ºC. A single-stage or multi-stage countercurrent extraction is conducted under the conditions that the volume ratio of an organic phase to a brine phase is 1-10 : 1, the density of the brine is 1.30 to 1.56 g/cm³, the pH value of the brine is 0 to 7 and the temperature is 0 to 50℃, an aqueous phase with a low calcium-lithium ratio is obtained through back extraction, and lithium chloride, lithium carbonate, lithium hydroxide and boric acid are respectively obtained through concentration, impurity removal and preparation. The secondary amide of the present invention has a simple molecular structure, and the composite solvent improved by an alkyl alcohol can extract lithium and boron simultaneously. The multi-stage extraction rate is high, the back extraction is carried out with water, and the acid and alkali consumption is greatly reduced. The extraction separation flow is shortened, and the extraction system has little solution loss and is suitable for development of oilfield brine.

Description

Extraction system, extraction method and application for separating calcium and extracting lithium and boron from calcium-containing brine by using secondary amide/alkyl alcohol composite solvent Technical field

The invention relates to a method for extracting lithium and boron from calcium-containing brine, in particular to an extraction system, an extraction method and its application for separating calcium from calcium-containing brine using a composite solvent to extract lithium and boron.

Background technique

There are abundant oilfield underground brines in the Nanyishan area in the western part of Qaidam Basin, Qinghai, my country. Its resource reserves are comparable to those of salt lakes in the Qaidam Basin. It is a rare multi-element coexisting super large deposit in the world and has great industrial development value. . Among them, potassium, boron, lithium, iodine and other useful components are many and high in content, and the resource occurrence state is quite different from the types of developed salt lake resources. It belongs to the calcium chloride type brine in the Surin classification, showing high salinity, high calcium, Low-magnesium and low-sulfate characteristics, the calcium chloride content is as high as 30.8-43.0% after being concentrated by the salt field in the sun.

At present, the research on the simultaneous extraction of the valuable elements lithium and boron from high calcium lithium ratio brine is still in the initial stage. The main work involved is: (1) Cui Xiangmei et al. evaporated the Nanyishan high calcium boron brine system and found that boron was among them. The behavior of boron is quite different from the previously reported high-magnesium boron-containing brine systems. The special crystallization behavior of boron is restricted by the pH value and ion composition of the system [Acta Inorganic Chemistry, 2009, 25(8), 1434–1438]. (2) Yu Xiaoping first adopts acid method to precipitate boron and adopts extraction or adsorption method to deeply recover boron, then uses sodium carbonate to precipitate calcium and most of magnesium, and separates and recovers sodium chloride and/ by evaporative crystallization and/or cooling crystallization. Or potassium chloride, lithium-containing concentrated solution adopts sodium carbonate precipitation method to recover lithium carbonate (CN108264064A). (3) Peng Shili et al. comprehensively utilize the process flow of extracting boron removal from the Sijing gas field in Pingluo, western Sichuan, removing calcium from Glauber's salt, precipitating magnesium with caustic soda, and extracting lithium with soda ash precipitation [Guangdong Chemical Industry, 2010, 37(7), 24 –25]. (4) Zheng Mianping used lime milk and Glauber's salt to remove the magnesium and calcium in the potassium extraction mother liquor, added hydrochloric acid or sulfuric acid to obtain crude boric acid. The lithium-containing mother liquor was purified by chelation or adsorption to remove impurities, and then added alkali precipitation in the refined lithium-rich mother liquor. , Wash to obtain crude lithium carbonate (CN108584995A). It can be seen from the above methods that the process of simultaneously extracting lithium and boron from brine is actually carried out separately according to different technical characteristics, and the process flow is long. The traditional method of removing calcium and magnesium has always had a large amount of precipitation treatment and poor atomic economic utilization. High-level shortcomings affect the production cost and market competitiveness of the product.

However, among many technical methods, the solvent extraction method is considered to be the most promising method for extracting lithium from salt lake brine with high magnesium-lithium ratio [Song JF, Nghiem LD, Li XM, He T..Environ.Sci.:Water Res.Technol .,2017,3(4),593–597], this method may also be applied to high calcium-to-lithium ratio oilfield brines. The development of new extractants that simultaneously extract lithium and boron from it is very important. Alkyl alcohol, as an effective neutral solvent for extracting boron from brine, may be combined with other effective ingredients to form a new high-efficiency extraction system. After the high-calcium-lithium ratio brine is converted into low-calcium-lithium ratio brine, the basic chemical products such as lithium carbonate, lithium chloride and lithium hydroxide can be produced, and the brine can also be purified and enriched. Boron elements produce boric acid products.

Summary of the invention

The purpose of the present invention is to provide an economical and effective extraction system, extraction method and application for extracting lithium and boron from calcium-containing brine by using a secondary amide/alkyl alcohol composite solvent to solve the deficiencies in the prior art methods. .

The technical scheme and technological process provided by the present invention are as follows:

1. An extraction system for separating calcium from calcium-containing brine with a secondary amide/alkyl alcohol composite solvent to extract lithium and boron. The extraction system contains two types of substances A and B; the type A substance is a single compound or two secondary amides. It is composed of a mixture of more than one species; wherein, a single compound has a structure as shown in formula (I):

Wherein, R _{1 is} selected from a C1-C12 alkyl group or a C3-C12 cycloalkyl group containing a monocyclic structure, and R _{2 is} selected from a C1-C11 alkyl group or a C3-C11 cycloalkyl group containing a monocyclic structure, And the _{sum of the number of carbon atoms contained in the two groups R 1} and R ₂ is 11-17, where alkyl or cycloalkyl includes various isomers (because R ₁ and R ₂ can be changed, when When R ₁ and R _{2 are} uniquely determined, the Type A substance is a single compound, and the mixture refers to a substance formed by mixing two or more compounds produced with the change _{of R 1} and R _{2 );}

Among them, type B substances are alkyl alcohols consisting of a single compound or a mixture of two or more; among them, a single compound has a structure as shown in formula (II):

R ₃ -OH (Ⅱ);

Among them, R _{3 is} selected from C8 to C20 alkyl groups, where the alkyl groups include linear or branched various isomers (because R ₃ can be changed, when R _{3 is} uniquely determined, B The class substance is a single compound, and the mixture refers to a substance formed by mixing two or more compounds produced with the change _{of R 3);}

The freezing point of an extraction system containing two types of substances A and B is less than 0°C (the freezing point of a single component constituting the extraction system may be less than, equal to, or greater than 0°C. When the freezing point of a single component is less than 0°C, it can meet the requirements of the present invention The conditions of the extraction system; when the freezing point of a single component is greater than or equal to 0°C, it may be mixed with other components with a freezing point less than 0°C, dissolve and finally form a mixture with a freezing point less than 0°C).

In the extraction system, the type A substance mainly plays the role of extracting lithium. The volume percentage in the entire organic phase is 0-100%, excluding the two endpoints (when the volume percentage of the type A substance is high, there is Facilitate the extraction of lithium from calcium-containing brine); in the extraction system, the B-type substances mainly play the role of extracting boron. The volume percentage in the entire organic phase is 0-100%, excluding the two endpoints (when B When the volume percentage of such substances is high, it is beneficial to extract boron from calcium-containing brine).

In the extraction system, when the extraction system is conducive to the simultaneous extraction of lithium and boron, the volume percentage of the A substance in the entire organic phase is 50-90%, and the B substance in the entire organic phase The volume percentage is 10-50% (when the volume percentages of the two types of substances A and B are relatively large, it is beneficial to extract lithium and boron from the calcium-containing brine at the same time).

In the extraction system, the diluent 260# solvent oil, 300# solvent oil or sulfonated kerosene is also included.

2. The extraction method for separating calcium from calcium-containing brine with a secondary amide/alkyl alcohol composite solvent to extract lithium and boron includes the following steps:

S1. The calcium-containing brine is used as the pre-extraction brine phase; wherein, in the calcium-containing brine, the concentration of lithium ions is 0.09-24g/L, the concentration of calcium ions is 145-277g/L, and the concentration of chloride ions is 271 ～517g/L, the mass ratio of calcium to lithium is 7.5～1900:1, the _{total concentration of boric acid and its borate ion is 0.5～17g/L based on B 2} O ₃ , and the brine density is 1.30～1.56g/cm at 20℃ ^3. Use hydrochloric acid or sulfuric acid to adjust the pH value of brine between 0-7;

S2, using the extraction system described in 1 above as the organic phase before extraction;

S3. Mix the pre-extraction organic phase and the pre-extraction brine phase in a volume ratio of 1-10:1, perform single-stage extraction or multi-stage countercurrent extraction, and obtain a loaded organic phase and a post-extraction brine phase after the two phases are separated .

The calcium-containing brine also contains one or more of sodium ion, potassium ion, magnesium ion, iron ion or ferrous ion.

The calcium-containing brine includes oilfield brine or underground brine containing lithium and boron, but is not limited to this kind of brine.

Further, in the step S3, the extraction temperature is 0-50°C; the two-phase mixing is performed by stirring, and the two-phase separation after extraction is performed by centrifugal separation or clarification and sedimentation.

Further, after the step S3, the method further includes the following steps:

S4. Using water as the stripping agent, single-stage stripping or multi-stage countercurrent stripping is performed on the loaded organic phase. The stripping ratio, that is, the ratio of the stripping agent to the volume of the loaded organic phase is 1:1-20. After phase separation, a back-extracted organic phase and a back-extracted aqueous phase are obtained;

S5. Return the organic phase after the stripping to step S2 to realize the recycling use of the extraction system.

Further, in the step S4, the stripping temperature is 0-50°C; the two-phase mixing is carried out by stirring, and the two-phase separation after stripping is carried out by centrifugal separation or clarification and sedimentation.

3. The application of the extraction method for separating calcium and extracting lithium and boron from calcium-containing brine with a secondary amide/alkyl alcohol composite solvent in obtaining boron product boric acid, after the step S4, further includes the following steps:

S6. The water phase after the stripping is further deoiled and purified, concentrated, the pH value of the water phase is adjusted with hydrochloric acid or sulfuric acid, boric acid is precipitated from the solution, and the boric acid product is obtained after washing and drying.

4. The application of the extraction method for separating calcium from calcium-containing brine with a secondary amide/alkyl alcohol compound solvent to extract lithium and boron in obtaining the lithium product lithium chloride, after the step S4, further includes the following steps:

S6. The water phase after the stripping is further deoiled and purified, concentrated, the pH value of the water phase is adjusted with hydrochloric acid or sulfuric acid, boric acid is precipitated from the solution, and the boric acid product is obtained after washing and drying;

S7. In the lithium-containing solution after the boric acid is precipitated, an impurity removing agent is added to remove the remaining calcium ions and a small amount of magnesium ions, to obtain a lithium chloride solution refined from the lithium-containing solution; the impurity removing agent used is sodium sulfate, One or more than two compounds of sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

S8. The refined lithium chloride solution is concentrated, crystallized, separated and dried to obtain a lithium chloride product.

5. The application of the extraction method for separating calcium from calcium-containing brine with a secondary amide/alkyl alcohol composite solvent to extract lithium and boron in obtaining the lithium product lithium carbonate, after the step S4, further includes the following steps:

S6. The water phase after the stripping is further deoiled and purified, concentrated, the pH value of the water phase is adjusted with hydrochloric acid or sulfuric acid, boric acid is precipitated from the solution, and the boric acid product is obtained after washing and drying;

S7. In the lithium-containing solution after the boric acid is precipitated, an impurity removing agent is added to remove the remaining calcium ions and a small amount of magnesium ions, to obtain a lithium chloride solution refined from the lithium-containing solution; the impurity removing agent used is sodium sulfate, One or more than two compounds of sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

S9, adding sodium carbonate to the refined lithium chloride solution to obtain a lithium carbonate precipitate, and performing separation and drying processes on the lithium carbonate precipitate to obtain a lithium carbonate product.

6. The application of the extraction method for separating calcium from calcium-containing brine with a secondary amide/alkyl alcohol composite solvent to extract lithium and boron in obtaining the lithium product lithium hydroxide, after the step S4, the method further includes the following steps:

S6. The water phase after the stripping is further deoiled and purified, concentrated, the pH value of the water phase is adjusted with hydrochloric acid or sulfuric acid, boric acid is precipitated from the solution, and the boric acid product is obtained after washing and drying;

S7. In the lithium-containing solution after the boric acid is precipitated, an impurity removing agent is added to remove the remaining calcium ions and a small amount of magnesium ions, to obtain a lithium chloride solution refined from the lithium-containing solution; the impurity removing agent used is sodium sulfate, One or more than two compounds of sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

S10, electrolyzing the refined lithium chloride solution to obtain a lithium hydroxide product, and at the same time by-produce hydrogen and chlorine, which can be used to produce hydrochloric acid;

Or after the step S7, the method further includes the following steps:

S9, adding sodium carbonate to the refined lithium chloride solution to obtain a lithium carbonate precipitate, and performing separation and drying processes on the lithium carbonate precipitate to obtain a lithium carbonate product;

S11. Adding a calcium hydroxide emulsion to the prepared lithium carbonate, performing a solid-liquid reaction, and obtaining a lithium hydroxide solution after separation, which is subjected to the processes of concentration, crystallization and drying to obtain a lithium hydroxide product.

The source of the secondary amide compound used in the examples of the present invention is synthesized by reacting organic acid chlorides or acid anhydrides with primary amines in a stoichiometric ratio, and then washed with water and purified by vacuum distillation, using the Agilent 7890A/5975C GC/MS instrument. Test evaluation is obtained. The source of the alkyl alcohol compound used in the examples of the present invention is purchased from a chemical product company on the market.

Compared with the prior art, the present invention has found that a secondary amide/alkyl alcohol composite solvent composed of compounds represented by formula (I) and formula (II) is used as a new extraction system, thereby obtaining a new extraction system for The extraction method of separating calcium from calcium brine to extract lithium and boron and its application have achieved unexpected results. There is no literature report on the use of a mixture of secondary amide and alkyl alcohol as a brine extraction system for lithium extraction, which is the current high calcium The development of brine lithium resources in Libi oilfield provides new technologies. The invention has the following advantages:

1) The secondary amide as the A substance in the extraction system has a simple molecular structure, easy to obtain and easy to produce. It is used as an extractant for lithium. It is a new type of special component for separating calcium and extracting lithium from calcium-containing brine. The secondary amide functional group It is the key part of lithium-calcium separation and extraction of lithium. The hydrogen atom on N–H shifts to a low field in the ¹ H NMR spectrum before and after extraction, which plays a key role in the extraction ^{of Li +.} Alkyl alcohol as the B substance in the extraction system is used as an extractant for boron in brine, which can effectively improve the physical properties of the composite solvent such as the viscosity and freezing point, increase the mixing entropy of the system, and produce a synergistic co-extraction effect.

2) Under ^{the premise of ensuring a certain level of single-stage extraction capacity of Li +} , the loaded organic phase is easy to back-extract with water directly, without the need to use acid to strengthen ^{the back-extraction of Li +} , and there is no need to use alkali to neutralize the previous acid to restore organic The extraction capacity of the phase and the acidity and alkalinity of the water phase, the consumption of acid and alkali is small, and the two-way balance of the extraction and stripping process is realized. It is easy to carry out the stripping of lithium and boron while extracting lithium and boron. After the calcium-containing brine is subjected to multi-stage countercurrent extraction, the lithium-calcium separation coefficient is large, and the calcium-lithium mass ratio in the water phase after the stripping is significantly reduced.

3) The entire extraction and separation process is simple, the organic phase is directly recycled, the degree of equipment corrosion is small, and the production process is easy to control. The low density of the organic phase is suitable for the separation of the two phases when the organic phase is loaded by back extraction with water. By adjusting the molecular structure and composition of the extraction system, the solubility of the preferred extraction system in water is significantly reduced compared to the solubility of TBP.

Attached table description

Fig. 1 is an extraction system, an extraction method and a process flow diagram of its application for separating calcium from calcium-containing brine by using a secondary amide/alkyl alcohol composite solvent to extract lithium and boron according to the present invention.

Table 19 shows the common names, corresponding standardized names and codes of the secondary amides of substance A involved in the examples of the present invention.

Table 20 shows the common names, corresponding normative names and CAS numbers of substance B alkyl alcohols involved in the examples of the present invention.

Detailed ways

In the following, the present invention will be further described in conjunction with the embodiments:

Example 1

A calcium brines _{^{Li +, Ca 2+ B 2 O}} 3 content are 2.92,169.11 and 9.41g / L, Ca mass ratio of lithium is 57.91: 1, wherein the Na ^+, K ^+, Mg ²⁺ and Cl ^- in The content is 4.13, 14.46, 9.27 and 361.31g/L, the density of the brine is 1.39g/cm ³ , the pH value of the brine is adjusted to 1.7, and the ion concentration in the brine is prepared according to the composition of the brine from an oilfield in Nanyishan, Qaidam Basin, Qinghai. The brine is degreasing in advance with an oil-water separator. Take 5mL of this kind of brine in a 100mL conical flask, and then add 20mL of N-isooctylisohexanamide and 5mL of 3,5,5-trimethylhexanol as the extractant, and the alkyl alcohol accounts for the volume of the organic phase. The volume ratio of organic phase to brine is 5:1. Put the magnet in the Erlenmeyer flask, insert the matching air condenser at the mouth of the flask to prevent the liquid from splashing out, put it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir, and extract at 20°C for 30 minutes. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged at 4000r/min for 10min in an LD5-10 benchtop centrifuge. The two-phase interface was clear. After phase separation, the extracted organic phase and the remaining brine phase were obtained. Transfer the loaded organic phase to another 100 mL conical flask, add deionized water according to the volume ratio of 1:5 to the organic phase, and place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 30 min. Then transfer the mixed liquid to a 100mL plastic test tube, and centrifuge at 4000r/min for 10min in an LD5-10 benchtop centrifuge to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ content, the extraction rate E, the stripping rate S, the distribution ratio D and the lithium-calcium separation coefficient β are calculated, and the results are shown in Table 1.

Table 1 The two-phase separation ^{of Li +} , Ca ²⁺ and B ₂ O ₃ in a calcium-containing brine by the composite solvent of N-isooctylisohexanamide and 3,5,5-trimethylhexanol ^*

^* The meanings of the symbols are respectively designated as ^a : organic relative water phase volume ratio, ^b : Li ⁺ extraction rate, ^c : Ca ²⁺ extraction rate, ^d : Li ⁺ distribution ratio, ^e : Ca ²⁺ distribution ratio, ^f : lithium calcium Separation coefficient, ^g : mass ratio of calcium to lithium in the organic phase after extraction, ^h : mass ratio of calcium to lithium in the brine after extraction, ⁱ : extraction rate of _{B 2} O ₃ ^{; j} : volume ratio of water to organic phase, ^k : Li ⁺ back extraction Rate, ^l : Ca ²⁺ back-extraction rate, ^m : Li ⁺ back-extraction distribution ratio, ⁿ : Ca ²⁺ back-extraction distribution ratio, ^o : lithium-calcium back-extraction separation coefficient, ^p : quality of calcium and lithium in the organic phase after back-extraction Ratio, ^q : mass ratio of calcium to lithium in the aqueous phase after stripping, ^r : _{stripping rate of B 2} O ₃ ; the meanings of the symbols in Table 2 to Table 18 below are also the same.

It can be seen from Table 1 that the single-stage extraction rate of ^{Li + is 36.20%, the single-stage extraction rate of Ca 2+} is 4.44%, and the lithium-calcium separation coefficient is 12.22. The Li ⁺ single-stage stripping rate was 70.32%, the Ca ²⁺ single-stage stripping rate was 84.57%, the lithium-calcium separation coefficient after the stripping was 0.43, and the calcium-lithium mass ratio in the water phase dropped to 8.54. The single-stage extraction rate of _{B 2} O ₃ is 47.42%, and the single-stage back extraction rate of _{B 2} O _{3 is 68.80%.}

Example 2

Take 24mL of N-pentylisononylamide and 6mL of 2-propylheptanol as extractants in a 100mL conical flask. Alkyl alcohol accounts for 20% of the volume of the organic phase, and then add 3mL of Example 1 For calcium-containing brine, the volume ratio of organic phase to calcium-containing brine is 10:1. Put the magnet in the conical flask, insert the matching air condenser at the mouth of the flask to prevent the liquid from splashing out, put it in the DF-101S heat-collecting thermostatic heating magnetic stirrer, mix, stir, and extract at 20°C for 25min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged at 4000r/min for 10min in an LD5-10 benchtop centrifuge. The two-phase interface was clear. After phase separation, the extracted organic phase and the remaining brine phase were obtained. Transfer the loaded organic phase to another 100 mL conical flask with ground mouth, add deionized water at a volume ratio of 1:10 to the organic phase, and place it in a DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 25 min. Then transfer the mixed liquid to a 100mL plastic test tube, and centrifuge at 4000r/min for 10min in an LD5-10 benchtop centrifuge to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ content, the calculated experimental results are shown in Table 2.

Table 2 The two-phase separation ^{of Li +} , Ca ²⁺ and B ₂ O ₃ in a calcium-containing brine by the composite solvent of N-pentylisononylamide and 2-propylheptanol

It can be seen from Table 2 that the single-stage extraction rate of ^{Li + is 43.82%, the single-stage extraction rate of Ca 2+} is 3.45%, and the lithium-calcium separation coefficient is 21.81. The Li ⁺ single-stage back-extraction rate was 88.04%, and the Ca ²⁺ single-stage back-extraction rate was 89.34%. After the back-extraction, the lithium-calcium separation coefficient was 0.92, and the calcium-lithium mass ratio in the water phase dropped to 4.63. The single-stage extraction rate of _{B 2} O ₃ is 53.14%, and the single-stage back extraction rate of _{B 2} O _{3 is 87.72%.}

Example 3

Take 10mL N-isobutylisononylamide (liquid after heating), 10mL N-isooctylpentanoamide and 5mL 2-hexyldecanol as the extractant in a 100mL conical flask. Alkyl alcohol accounts for 20% of the volume of the organic phase. %, and then add 5 mL of the calcium-containing brine in Example 1 to it, and the volume ratio of the organic phase to the calcium-containing brine is 5:1. Put the magnet in the Erlenmeyer flask, insert the matching air condenser at the mouth of the flask to prevent the liquid from splashing out, put it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir, and extract at 20°C for 30 minutes. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged at 4000r/min for 10min in an LD5-10 benchtop centrifuge. The two-phase interface was clear. After phase separation, the extracted organic phase and the remaining brine phase were obtained. Transfer the loaded organic phase to another 100 mL conical flask, add deionized water according to the volume ratio of 1:5 to the organic phase, and place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 30 min. Then transfer the mixed liquid to a 100mL plastic test tube, and centrifuge at 4000r/min for 10min in an LD5-10 benchtop centrifuge to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 3.

Table 3 The two-phase separation ^{of Li +} , Ca ²⁺ and B ₂ O ₃ in a calcium-containing brine by the composite solvent of N-isobutylisononylamide, N-isooctylpentanamide and 2-hexyldecanol

It can be seen from Table 3 that the single-stage extraction rate of ^{Li + is 36.16%, the single-stage extraction rate of Ca 2+} is 4.78%, and the separation coefficient of lithium and calcium is 11.28. The Li ⁺ single-stage stripping rate was 70.61%, and the Ca ²⁺ single-stage stripping rate was 95.38%. After the stripping, the lithium-calcium separation coefficient was 0.12, and the calcium-lithium mass ratio dropped to 10.35. The single-stage extraction rate of _{B 2} O ₃ is 41.32%, and the single-stage back extraction rate of _{B 2} O _{3 is 93.23%.}

Example 4

Take 10mL of N-isobutylisononylamide (liquid after heating), 10mL of N-pentylisononylamide and 5mL of 2-butyloctanol as the extractant in a 100mL conical flask. Alkyl alcohol accounts for a fraction of the volume of the organic phase. 20%, and then add 5 mL of the calcium-containing brine in Example 1 into it, and the volume ratio of the organic phase to the calcium-containing brine is 5:1. Put the magnet in the Erlenmeyer flask, insert the matching air condenser at the mouth of the flask to prevent the liquid from splashing out, put it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir, and extract at 20°C for 30 minutes. Then the mixed liquid was transferred to a 100mL plastic test tube, centrifuged at 4000r/min for 15min in an LD5-10 benchtop centrifuge. The two-phase interface was clear. After phase separation, the extracted organic phase and the remaining brine phase were obtained. Transfer the loaded organic phase to another 100 mL conical flask, add deionized water according to the volume ratio of 1:5 to the organic phase, and place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 30 min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 benchtop centrifuge at 4000r/min for 15min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 4.

Table 4 The two-phase separation ^{of Li +} , Ca ²⁺ and B ₂ O ₃ in a calcium-containing brine by the composite solvent of N-isobutylisononylamide, N-pentylisononylamide and 2-butyloctanol

It can be seen from Table 4 that the single-stage extraction rate of ^{Li + is 33.16%, the single-stage extraction rate of Ca 2+} is 4.02%, and the lithium-calcium separation coefficient is 11.84. The Li ⁺ single-stage stripping rate was 95.25%, the Ca ²⁺ single-stage stripping rate was 89.99%, the lithium-calcium separation coefficient after the stripping was 2.23, and the calcium-lithium mass ratio in the water phase dropped to 6.63. The single-stage extraction rate of _{B 2} O ₃ was 44.89%, and the single-stage back extraction rate of _{B 2} O _{3 was 92.42%.}

Example 5

Take 20mL of N-pentylisononylamide, 2.5mL of 2-propylheptanol, 2.5mL of 3,5,5-trimethylhexanol as the extractant in a 100mL conical flask. Alkyl alcohol occupies the organic phase. 20% of the volume, and then add 5 mL of the calcium-containing brine in Example 1 into it, and the volume ratio of the organic phase to the calcium-containing brine is 5:1. Put the magnet in the Erlenmeyer flask, insert the matching air condenser at the mouth of the flask to prevent the liquid from splashing out, place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir, and extract at 0°C for 30 minutes. Then transfer the mixed liquid to a 100mL plastic test tube, centrifuge at 4000r/min for 8min in an LD5-10 benchtop centrifuge. The two-phase interface is clear. After phase separation, the extracted organic phase and the remaining brine phase are obtained. Transfer the loaded organic phase to another 100mL conical flask with a ground mouth, add water according to the volume ratio of 1:5 to the organic phase, and place it in a DF-101S type heat-collecting thermostatic heating magnetic stirrer at 0℃ Perform back extraction and mix the two phases for 30 minutes. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 tabletop centrifuge at 4000r/min for 8min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 5.

Table 5 N-pentylisononylamide and 2-propylheptanol, 3,5,5-trimethylhexanol composite solvent for the two phases ^{of Li +} , Ca ²⁺ and B ₂ O _{3 in a calcium-containing brine} Separation situation

It can be seen from Table 5 that the single-stage extraction rate of ^{Li + is 39.60%, the single-stage extraction rate of Ca 2+} is 5.37%, and the lithium-calcium separation coefficient is 11.56. The Li ⁺ single-stage stripping rate was 80.19%, the Ca ²⁺ single-stage stripping rate was 94.99%, the lithium-calcium separation coefficient after the stripping was 0.21, and the calcium-lithium mass ratio in the water phase dropped to 9.30. The single-stage extraction rate of _{B 2} O ₃ is 50.29%, and the single-stage back extraction rate of _{B 2} O _{3 is 92.05%.}

Example 6

Take 5mL of the calcium-containing brine in Example 1 into a 100mL conical flask, and then add 0.56g of 99% pure ferric trichloride hexahydrate, dissolve it, and then add 20mL N-pentylisonon Amide and 5mL 2-butyloctanol are used as extractants. Alkyl alcohol accounts for 20% of the volume of the organic phase. The volume ratio of the organic phase to the calcium-containing brine is 5:1. Put the magnet in the Erlenmeyer flask, insert the matching air condenser at the mouth of the flask to prevent the liquid from splashing out, put it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir, and extract at 20°C for 30 minutes. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged at 4000r/min for 10min in an LD5-10 benchtop centrifuge. The two-phase interface was clear. After phase separation, the extracted organic phase and the remaining brine phase were obtained. Transfer the loaded organic phase to another 100 mL conical flask with a ground mouth, add water according to the volume ratio of 1:5 to the organic phase, and place it in a DF-101S type heat-collecting thermostatic heating magnetic stirrer at 20°C Perform back extraction and mix the two phases for 30 minutes. Then transfer the mixed liquid to a 100mL plastic test tube, and centrifuge at 4000r/min for 10min in an LD5-10 benchtop centrifuge to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 6.

Table 6 The two-phase separation of Li ⁺ , Ca ²⁺ and B ₂ O ₃ ^{in a Fe 3+} brine containing N-pentylisononylamide and 2-butyloctanol composite solvent

It can be seen from Table 6 that the single-stage extraction rate of ^{Li + is 42.71%, the single-stage extraction rate of Ca 2+} is 3.90%, and the separation coefficient of lithium and calcium is 18.35. The Li ⁺ single-stage stripping rate was 89.06%, and the Ca ²⁺ single-stage stripping rate was 92.31%. After the stripping, the lithium-calcium separation coefficient was 0.68, and the calcium-lithium mass ratio in the water phase dropped to 5.48. The single-stage extraction rate of _{B 2} O ₃ is 37.60%, and the single-stage back extraction rate of _{B 2} O _{3 is 92.75%.}

Example 7

Take 24.55mL N-pentylisononylamide, 0.20mL N-hexyl-3-cyclopentylpropionamide and 0.25mL 2-propylheptanol as the extractant in a 100mL conical flask, where the secondary amide accounts for the organic 99% of the volume of the phase and 1% of the volume of the organic phase. Then add 5 mL of calcium-containing brine, and the volume ratio of organic phase to brine is 5:1. ^{The contents of Li +} , Ca ²⁺ , Cl ^- and B ₂ O _{3 in} the calcium-containing brine are 0.26, 210.54, 374.11 and 0.91g/L, respectively, the mass ratio of calcium to lithium is 825.65:1, and the brine density is 1.41g/cm ³ , The pH of brine is 2.0. Put the magnet in the Erlenmeyer flask, place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir and extract at 25°C for 25 minutes. Then, the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 benchtop centrifuge at 4300r/min for 15min to obtain the extracted organic phase and the remaining brine phase. Transfer the loaded organic phase to another 100 mL conical flask with a ground mouth, add deionized water at a volume ratio of 1:5 to the organic phase, and place it in a DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 25 min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 benchtop centrifuge at 4300r/min for 15min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 7.

Table 7 N-pentylisononylamide, N-hexyl-3-cyclopentylpropionamide and 2-propylheptanol composite solvent for the two phases ^{of Li +} , Ca ²⁺ and B ₂ O _{3 in a calcium-containing brine} Separation situation

It can be seen from Table 7 that the single-stage extraction rate of ^{Li + is 47.71%, the single-stage extraction rate of Ca 2+} is 7.59%, and the lithium-calcium separation coefficient is 11.11. The Li ⁺ single-stage back extraction rate was 63.27%, the Ca ²⁺ single-stage back extraction rate was 93.15%, the lithium-calcium separation coefficient after the back-extraction was 0.13, and the calcium-lithium mass ratio in the water phase dropped to 193.43. The single-stage extraction rate of _{B 2} O ₃ is 31.73%, and the single-stage back extraction rate of _{B 2} O _{3 is 79.72%.} When the volume ratio of the secondary amide extractant in the organic phase is high, it is more conducive to ^{the extraction of Li +} from the brine.

Example 8

Take 0.25mL N-isooctylheptanamide and 24.75mL 2-propylheptanol as extractants in a 100mL conical flask with a ground mouth. The secondary amide accounts for 1% of the volume of the organic phase and the alkyl alcohol accounts for 99% of the volume of the organic phase. . Then, 5 mL of the calcium-containing brine in Example 1 was added thereto, and the volume ratio of the extractant to the calcium-containing brine was 5:1. Put the magnet in the Erlenmeyer flask, insert the matching air condenser at the mouth of the flask to prevent the liquid from splashing out, put it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir, and extract at 20°C for 30 minutes. Then the mixed liquid was transferred to a 100mL plastic test tube, centrifuged in a LD5-10 benchtop centrifuge at 4000r/min for 5 minutes, the two-phase interface was clear, and the extracted organic phase and the remaining brine phase were obtained after phase separation. Transfer the loaded organic phase to another 100 mL conical flask, add deionized water according to the volume ratio of 1:5 to the organic phase, and place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 30 min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 tabletop centrifuge at 4000r/min for 5min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 8.

Table 8 The two-phase separation ^{of Li +} , Ca ²⁺ and B ₂ O ₃ in a calcium-containing brine by the composite solvent of N-isooctylheptanamide and 2-propylheptanol

It can be seen from Table 8 that the single-stage extraction rate of ^{Li + is 6.50%, the single-stage extraction rate of Ca 2+} is 1.91%, and the separation coefficient of lithium and calcium is 3.57. The Li ⁺ single-stage back extraction rate was 48.99%, the Ca ²⁺ single-stage back extraction rate was 23.35%, the lithium-calcium separation coefficient after the back-extraction was 3.15, and the calcium-lithium mass ratio in the water phase dropped to 8.11. The single-stage extraction rate of _{B 2} O ₃ is 91.26%, and the single-stage back extraction rate of _{B 2} O _{3 is 48.29%.} When the volume ratio of the alkyl alcohol extractant in the organic phase is high, it is more conducive to _{the extraction of B 2} O ₃ from the brine.

Example 9

Take 14.7mL N-pentylisononylamide, 0.2mL N-cyclopropyldecamide (liquid after heating), 0.1mL N-(4-tert-butylcyclohexyl)octamide, 3mL 2-octyldodecanol and 12mL 260 #Solvent oil (provided by Shanghai Youta Chemical Technology Co., Ltd., the same below) is used as the extractant and diluent in a 100mL conical flask with a grinding mouth. Alkyl alcohol and diluent account for 10% and 40% of the volume of the organic phase, respectively. Then, 3 mL of the calcium-containing brine in Example 7 was added thereto, and the volume ratio of the organic phase to the calcium-containing brine was 10:1. Put the magnet in the Erlenmeyer flask, place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir and extract at 25°C for 25 minutes. Then, the mixed liquid was transferred to a 100 mL plastic test tube, and centrifuged at 4200 r/min in an LD5-10 benchtop centrifuge for 8 minutes to obtain the extracted organic phase and the remaining brine phase. Transfer the loaded organic phase to another 100 mL conical flask with a ground mouth, add deionized water at a volume ratio of 1:20 to the organic phase, and place it in a DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 25 min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 benchtop centrifuge at 4200r/min for 8min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 9.

Table 9 The effect of N-pentylisononylamide, N-cyclopropyl decanamide, N-(4-tert-butylcyclohexyl) octylamide, 2-octyldodecanol and 260# solvent oil composite system on Li in a calcium-containing brine ⁺ , Ca ²⁺ and B ₂ O ₃ phase separation

It can be seen from Table 9 that the single-stage extraction rate of ^{Li + is 30.75%, the single-stage extraction rate of Ca 2+} is 2.37%, and the separation coefficient of lithium and calcium is 18.32. The Li ⁺ single-stage stripping rate was 94.15%, the Ca ²⁺ single-stage stripping rate was 92.24%, the lithium-calcium separation coefficient after the stripping was 1.35, and the calcium-lithium mass ratio in the water phase dropped to 62.27. The single-stage extraction rate of _{B 2} O ₃ was 42.65%, and the single-stage back extraction rate of _{B 2} O _{3 was 75.51%.}

Example 10

Take 14.4mL N-pentylisononylamide, 0.5mL N-isooctyl-1-cyclopropylformamide, 0.1g N-cyclododecylacetamide, 14.85mL 2-propylheptanol and 0.15mL 260# Solvent oil is used as an extractant and a diluent in a 100 mL conical flask with a ground mouth. Alkyl alcohol and diluent account for 49.5% and 0.5% of the volume of the organic phase, respectively. Then, 3 mL of the calcium-containing brine of Example 7 was added to it, wherein the _{content of B 2} O _{3 was} adjusted to 14.30 g/L, the pH of the brine was 0.0 after the addition of boric acid, and the volume ratio of the organic phase to the calcium-containing brine was 10:1. Insert a polytetrafluoroethylene stirring rod into the conical flask, mix, stir, and extract with a DW-1-60 DC constant speed stirrer at 50°C for 25 minutes. Then, the mixed liquid is naturally clarified and settled for 60 minutes, and the two phases are separated to obtain the loaded organic phase and the remaining brine phase after extraction. Transfer the loaded organic phase to another 100 mL conical flask with a ground mouth, add deionized water at a volume ratio of 1:20 to the organic phase, insert a PTFE stirring rod, and use DW-1-60 DC constant speed The stirrer performs back extraction at 50°C, and the two phases are mixed for 25 minutes. Then, the mixed liquid is allowed to naturally clarify and settle for 60 minutes, and the organic phase and the water phase after the back extraction are obtained after the two phases are separated.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 10.

Table 10 The effect of N-pentylisononylamide, N-isooctyl-1-cyclopropylformamide, N-cyclododecylacetamide, 2-propylheptanol and 260# solvent oil composite system on a calcium-containing brine The two-phase separation of Li ⁺ , Ca ²⁺ and B ₂ O ₃

It can be seen from Table 10 that the single-stage extraction rate of ^{Li + is 32.88%, the single-stage extraction rate of Ca 2+} is 1.75%, and the separation coefficient of lithium and calcium is 27.53. The Li ⁺ single-stage back extraction rate was 88.87%, the Ca ²⁺ single-stage back extraction rate was 94.48%, the lithium-calcium separation coefficient after the back-extraction was 0.47, and the calcium-lithium mass ratio in the water phase dropped to 46.69. The single-stage extraction rate of _{B 2} O ₃ is 87.23%, and the single-stage back extraction rate of _{B 2} O _{3 is 25.97%.}

Example 11

Take 13.5mL N-pentylisononylamide, 1mL N-isooctylneodecylamide, 0.5mL N-dodecylacetamide (liquid after heating) and 15mL 3-octanol as extractant in a 100mL grinding cone In the bottle, the alkyl alcohol accounts for 50% of the volume of the organic phase, and then 3 mL of calcium-containing brine is added to the bottle, and the volume ratio of the organic phase to the brine is 10:1. ^{The content of Li +} , Ca ²⁺ , Cl ^- and B ₂ O _{3 in} the calcium-containing brine are 3.99, 274.10, 514.18 and 2.01g/L, respectively, the mass ratio of calcium to lithium is 68.70:1, and the brine density is 1.55g/cm ³ , The brine pH is 0.6. Put the magnet in the Erlenmeyer flask, place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix and stir at 20℃, and extract for 25min. Then, the mixed liquid was transferred to a 100 mL plastic test tube, and centrifuged in an LD5-10 tabletop centrifuge at 4200 r/min for 8 minutes to obtain the extracted organic phase and the remaining brine phase. Transfer the loaded organic phase to another 100 mL conical flask with ground mouth, add deionized water at a volume ratio of 1:10 to the organic phase, and place it in a DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 25 min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 benchtop centrifuge at 4200r/min for 8min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 11.

Table 11 The effects of N-pentylisononylamide, N-isooctylneodecylamide, N-dodecylacetamide and 3-octanol composite solvent on Li ⁺ , Ca ²⁺ and B ₂ O _{3 in a calcium-containing brine} The two-phase separation

It can be seen from Table 11 that the single-stage extraction rate of ^{Li + is 36.90%, the single-stage extraction rate of Ca 2+} is 7.51%, and the separation coefficient of lithium and calcium is 7.21. The Li ⁺ single-stage stripping rate was 95.64%, and the Ca ²⁺ single-stage stripping rate was 83.01%. After the stripping, the lithium-calcium separation coefficient was 4.49, and the calcium-lithium mass ratio in the water phase dropped to 12.14. The single-stage extraction rate of _{B 2} O ₃ was 85.05%, and the single-stage back extraction rate of _{B 2} O _{3 was 77.92%.}

Example 12

Take 23.5mL N-pentylisononylamide, 0.5mL N-ethyl-1-(4-pentylcyclohexyl)formamide and 6mL 2-butyloctanol as the extractant in a 100mL conical flask with a ground mouth. Alkyl alcohol accounts for 20% of the volume of the organic phase, and then 3 mL of calcium-containing brine is added to it, and the volume ratio of the organic phase to the brine is 10:1. ^{The contents of Li +} , Ca ²⁺ , Cl ^- and B ₂ O _{3 in} the calcium-containing brine are 23.87, 179.61, 439.81 and 0.50g/L, respectively, the mass ratio of calcium to lithium is 7.52:1, and the density of the brine is 1.40g/cm ³ , Its pH value is adjusted to 2.4 with concentrated hydrochloric acid. Put the magnet in the Erlenmeyer flask, place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir, and extract at 20°C for 30 minutes. Then, the mixed liquid was transferred to a 100 mL plastic test tube, and centrifuged in an LD5-10 tabletop centrifuge at 4200 r/min for 8 minutes to obtain the extracted organic phase and the remaining brine phase. Transfer the loaded organic phase to another 100 mL conical flask with ground mouth, add deionized water at a volume ratio of 1:10 to the organic phase, and place it in a DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 30 min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 benchtop centrifuge at 4200r/min for 8min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 12.

Table 12 The effects of N-pentylisononylamide, N-ethyl-1-(4-pentylcyclohexyl)formamide and 2-butyloctanol composite solvent on Li ⁺ , Ca ²⁺ and B in a calcium-containing brine Two-phase separation of ₂ O ₃

It can be seen from Table 12 that the single-stage extraction rate of ^{Li + is 40.83%, the single-stage extraction rate of Ca 2+} is 6.16%, and the separation coefficient of lithium and calcium is 10.52. The Li ⁺ single-stage stripping rate was 70.83%, and the Ca ²⁺ single-stage stripping rate was 84.22%. After the stripping, the lithium-calcium separation coefficient was 0.46, and the calcium-lithium mass ratio in the water phase dropped to 1.36. The single-stage extraction rate of _{B 2} O ₃ is 50.41%, and the single-stage back extraction rate of _{B 2} O _{3 is 89.29%.}

Example 13

Take 25.5mL N-pentylisononylamide, 1mL N-isooctylbutanamide, 0.45g N-ethyl lauramide, 2.85mL 2-hexyldecanol and 0.15mL 260# solvent oil as extractant and diluent in 100mL In the ground conical flask, the alkyl alcohol and the diluent accounted for 9.5% and 0.5% of the volume of the organic phase respectively, and then 3 mL of calcium-containing brine was added into it, and the volume ratio of the organic phase to the brine was 10:1. ^{The contents of Li +} , Ca ²⁺ , Cl ^- and B ₂ O _{3 in} the calcium-containing brine are 2.51, 147.61, 274.31 and 2.48g/L, respectively, the mass ratio of calcium to lithium is 58.80:1, and the density of the brine is 1.30g/cm ³ , The pH of brine is 2.0. Put the magnet in the Erlenmeyer flask, place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix and stir at 20℃, and extract for 25min. Then, the mixed liquid was transferred to a 100 mL plastic test tube, and centrifuged in an LD5-10 tabletop centrifuge at 4200 r/min for 8 minutes to obtain the extracted organic phase and the remaining brine phase. Transfer the loaded organic phase to another 100 mL conical flask with ground mouth, add deionized water at a volume ratio of 1:10 to the organic phase, and place it in a DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 25 min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 benchtop centrifuge at 4200r/min for 8min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 13.

Table 13 The effects of N-isooctylbutanamide, N-ethyl lauramide, N-pentylisononylamide, 2-hexyldecanol and 260# solvent oil composite system on Li ⁺ , Ca ²⁺ and B in a calcium-containing brine Two-phase separation of ₂ O ₃

It can be seen from Table 13 that the single-stage extraction rate of ^{Li + is 38.11%, the single-stage extraction rate of Ca 2+} is 5.03%, and the separation coefficient of lithium and calcium is 11.62. The Li ⁺ single-stage stripping rate was 76.74%, the Ca ²⁺ single-stage stripping rate was 87.96%, the lithium-calcium separation coefficient after the stripping was 0.45, and the calcium-lithium mass ratio in the water phase dropped to 8.91. The single-stage extraction rate of _{B 2} O ₃ is 35.06%, and the single-stage back extraction rate of _{B 2} O _{3 is 79.20%.}

Example 14

Take 18mL of N-pentylisononylamide and 2mL of 2-propylheptanol as extractants in a 100mL conical flask with a ground mouth. The secondary amide accounts for 90% of the volume of the organic phase and the alkyl alcohol accounts for 10% of the volume of the organic phase. . Then add 10 mL of calcium-containing brine, and the volume ratio of organic phase to brine is 2:1. ^{The content of Li +} , Ca ²⁺ , Cl ^- and B ₂ O _{3 in} the calcium-containing brine is 0.21, 210.79, 374.33 and 1.35g/L, respectively, the mass ratio of calcium to lithium is 1003.76:1, and the density of brine is 1.41g/cm ³ , Its pH value is adjusted to 2.0 with concentrated hydrochloric acid. Put the magnet in the Erlenmeyer flask, place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix and stir at 20℃, and extract for 25min. Then, the mixed liquid was transferred to a 100 mL plastic test tube, and centrifuged in an LD5-10 tabletop centrifuge at 4200 r/min for 8 minutes to obtain the extracted organic phase and the remaining brine phase. Transfer the loaded organic phase to another 100 mL conical flask with ground mouth, add deionized water at a volume ratio of 1:2 to the organic phase, and place it in a DF-101S heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 25 min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 benchtop centrifuge at 4200r/min for 8min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 14.

Table 14 The two-phase separation ^{of Li +} , Ca ²⁺ and B ₂ O ₃ in a calcium-containing brine by the composite solvent of N-pentylisononylamide and 2-propylheptanol

It can be seen from Table 14 that the single-stage extraction rate of ^{Li + is 29.39%, the single-stage extraction rate of Ca 2+} is 8.68%, and the lithium-calcium separation coefficient is 4.38. The Li ⁺ single-stage stripping rate was 82.76%, and the Ca ²⁺ single-stage stripping rate was 81.09%. After the stripping, the lithium-calcium separation coefficient was 1.13, and the calcium-lithium mass ratio in the water phase dropped to 290.47. The single-stage extraction rate of _{B 2} O ₃ was 23.14%, and the single-stage back extraction rate of _{B 2} O _{3 was 94.61%.}

Example 15

Take 21mL of N-pentylisononylamide and 9mL of 2-propylheptanol as extractants in a 100mL conical flask, where the secondary amide accounts for 70% of the volume of the organic phase, and the alkyl alcohol accounts for 30% of the volume of the organic phase. , And then add 3mL calcium-containing brine, the volume ratio of organic phase to brine is 10:1. ^{The contents of Li +} , Ca ²⁺ , Cl ^- and B ₂ O _{3 in} the calcium-containing brine are 0.094, 178.60, 316.43 and 1.01g/L, respectively, the mass ratio of calcium to lithium is 1900.00:1, and the brine density is 1.36g/cm ³ , Its pH value is adjusted to 7.0 with concentrated ammonia water. Put the magnet in the Erlenmeyer flask, place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix and stir at 20℃, and extract for 25min. Then, the mixed liquid was transferred to a 100 mL plastic test tube, and centrifuged in an LD5-10 tabletop centrifuge at 4200 r/min for 8 minutes to obtain the extracted organic phase and the remaining brine phase. Transfer the loaded organic phase to another 100 mL conical flask with ground mouth, add deionized water at a volume ratio of 1:10 to the organic phase, and place it in a DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 25 min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 benchtop centrifuge at 4200r/min for 8min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 15.

Table 15 The two-phase separation ^{of Li +} , Ca ²⁺ and B ₂ O ₃ in a calcium-containing brine by the composite solvent of N-pentylisononylamide and 2-propylheptanol

It can be seen from Table 15 that the single-stage extraction rate of ^{Li + is 42.68%, the single-stage extraction rate of Ca 2+} is 3.70%, and the lithium-calcium separation coefficient is 19.33. The Li ⁺ single-stage stripping rate was 92.13%, the Ca ²⁺ single-stage stripping rate was 89.55%, the lithium-calcium separation coefficient after the stripping was 1.37, and the calcium-lithium mass ratio in the water phase dropped to 160.10. The single-stage extraction rate of _{B 2} O ₃ is 58.51%, and the single-stage back extraction rate of _{B 2} O _{3 is 92.54%.}

Example 16

Take 9.5 mL of N-pentylisononylamide and 0.5 mL of 2-propylheptanol as extractants in a 100 mL conical flask. The secondary amide accounts for 95% of the volume of the organic phase, and the alkyl alcohol accounts for 95% of the volume of the organic phase. 5%. Then, 10 mL of the calcium-containing brine in Example 7 was added thereto, and the volume ratio of the organic phase to the calcium-containing brine was 1:1. Put the magnet in the Erlenmeyer flask, place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix and stir at 20℃, and extract for 25min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 benchtop centrifuge at 4200r/min for 15min to obtain the extracted organic phase and the remaining brine phase. Transfer the loaded organic phase to another 100 mL conical flask, add deionized water at a volume ratio of 1:1 to the organic phase, and place it in a DF-101S type heat-collecting thermostatic heating magnetic stirrer. Perform back extraction at ℃ and mix the two phases for 25 min. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged at 4200r/min for 15min in an LD5-10 benchtop centrifuge to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 16.

Table 16 The two-phase separation ^{of Li +} , Ca ²⁺ and B ₂ O ₃ in a calcium-containing brine by the composite solvent of N-pentylisononylamide and 2-propylheptanol

It can be seen from Table 16 that the single-stage extraction rate of ^{Li + is 32.70%, the single-stage extraction rate of Ca 2+} is 4.67%, and the lithium-calcium separation coefficient is 9.72. The Li ⁺ single-stage stripping rate was 72.14%, the Ca ²⁺ single-stage stripping rate was 89.10%, the lithium-calcium separation coefficient after the stripping was 0.32, and the calcium-lithium mass ratio in the water phase dropped to 145.64. The single-stage extraction rate of _{B 2} O ₃ was 15.38%, and the single-stage back extraction rate of _{B 2} O _{3 was 92.26%.}

Example 17

Take 20mL of N-pentylisononylamide and 5mL of 2-propylheptanol as extractants in a 100mL conical flask with a ground mouth. Alkyl alcohol accounts for 20% of the volume of the organic phase, and then add 5mL of Example 1 For calcium-containing brine, the volume ratio of organic phase to calcium-containing brine is 5:1. Put the magnet in the Erlenmeyer flask, insert the matching air condenser at the mouth of the flask to prevent the liquid from splashing out, place it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir, and extract at 20°C for 20 minutes. Then transfer the mixed liquid to a 100mL plastic test tube, centrifuge at 4000r/min for 8min in an LD5-10 benchtop centrifuge. The two-phase interface is clear. After phase separation, the extracted organic phase and the remaining brine phase are obtained. Then, perform three-stage countercurrent extraction according to the extraction cascade crossover operation steps to obtain the loaded organic phase and the remaining brine phase after the three-stage countercurrent extraction.

Transfer the loaded organic phase after the three-stage countercurrent extraction to another 100mL conical flask with ground mouth, add deionized water according to the volume ratio of 1:5 to the organic phase, and place it in the DF-101S type heat-collecting thermostatic heating magnetic force In the stirrer, single-stage back extraction and two-phase mixing were carried out at 20°C for 20 minutes. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 tabletop centrifuge at 4000r/min for 8min to obtain the organic phase and the water phase after the stripping.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 17.

Table 17 The three-stage countercurrent extraction and single-stage back extraction ^{of Li +} , Ca ²⁺ and B ₂ O ₃ in a calcium-containing brine by the composite solvent of N-pentylisononylamide and 2-propylheptanol

It can be seen from Table 17 that after the three-stage countercurrent extraction of brine, the ^{extraction rate of Li +} is 54.62%, the ^{extraction rate of Ca 2+} is 6.14%, and the separation coefficient of lithium and calcium reaches 18.40. Li ⁺ single stage inverse extraction rate 72.28%, Ca ²⁺ single stage inverse extraction rate 58.12%, lithium, calcium separation factor 1.88 back extracted the aqueous phase mass ratio of lithium, calcium decreased to 5.23, and Li ⁺ in the brine Ca ²⁺ achieves effective separation. Among them, the extraction rate _{of B 2} O ₃ was 79.48% after three-stage countercurrent of brine _{, and the single-stage back-extraction rate of B 2} O ₃ was 92.50%, indicating that the extraction system can extract Li ⁺ and also effectively extract B ₂ O ₃ . The more multi-stage counter-current extraction stages, the higher the extraction rate of lithium and boron in the brine, and the greater the lithium-calcium separation coefficient. In the case of reducing the amount of water phase, the more multi-stage counter-current extraction stages are more beneficial to the reaction. The concentration of ^{Li +} and B ₂ O _{3 in the} aqueous phase increased after extraction. Further increase the countercurrent extraction and countercurrent stripping stages, the extraction rate and stripping rate of ^{Li +} and B ₂ O ₃ ^{are further improved, while the extraction rate of Ca 2+} is basically unchanged, and the extraction rate of ^{Mg 2+ is not large.}

The organic phase after the stripping is returned and remixed with the brine phase before the extraction to realize the recycling of the extractant.

Then the water phase solution obtained after the back extraction is degreasing, and after two-effect evaporation is concentrated to a Li ⁺ concentration of 30g/L, sodium sulfate and sodium carbonate solutions are respectively added to completely precipitate and remove Ca ²⁺ , and chlorination is added separately The barium and sodium hydroxide solution are completely precipitated to remove the sulfate radical and Mg ²⁺ , and then the remaining solution is evaporated and concentrated, cooled and crystallized, filtered and dried to obtain anhydrous lithium chloride product.

The lithium chloride concentrate obtained after purification and purification is placed in an ion-exchange membrane electrolyzer for electrolysis, a lithium hydroxide solution with a mass concentration of 12% is obtained at the cathode, and lithium hydroxide monohydrate is obtained after concentration and crystallization. After washing and drying, an anhydrous lithium hydroxide product is prepared. At the same time, hydrogen and chlorine are by-produced, and hydrogen and chlorine are further reacted to produce hydrochloric acid.

Example 18

Take 10mL N-isobutylisononylamide (liquid after heating), 10mL N-isooctylisovaleramide and 5mL 2-octyldodecanol as extractants in a 100mL ground-mouth Erlenmeyer flask. Alkyl alcohol accounts for the organic phase. 20% of the volume, and then add 5 mL of the calcium-containing brine in Example 1 into it, the pH value of which is adjusted to 0.9 by adding concentrated hydrochloric acid, and the volume ratio of the organic phase to the calcium-containing brine is 5:1. Put the magnet in the Erlenmeyer flask, insert the matching air condenser at the mouth of the flask to prevent the liquid from splashing out, put it in the DF-101S type heat-collecting thermostatic heating magnetic stirrer, mix, stir, and extract at 20°C for 30 minutes. Then transfer the mixed liquid to a 100mL plastic test tube, centrifuge at 4000r/min for 8min in an LD5-10 benchtop centrifuge. The two-phase interface is clear. After phase separation, the extracted organic phase and the remaining brine phase are obtained. Then, three-stage countercurrent extraction is performed according to the extraction cascade crossover operation steps to obtain the loaded organic phase and the remaining brine phase after the three-stage countercurrent extraction.

Transfer the loaded organic phase after the three-stage countercurrent extraction to another 100mL conical flask with ground mouth, add deionized water according to the volume ratio of 1:5 to the organic phase, and place it in the DF-101S type heat-collecting thermostatic heating magnetic force In the stirrer, single-stage back extraction and two-phase mixing were carried out at 20°C for 30 minutes. Then the mixed liquid was transferred to a 100mL plastic test tube, and centrifuged in an LD5-10 tabletop centrifuge at 4000r/min for 8min to obtain the organic phase and the water phase after the stripping. Then, the secondary countercurrent back extraction is performed according to the cascade crossover operation steps to obtain the organic phase and the water phase after the second countercurrent back extraction.

The standard addition method of Japan Shimadzu AA-7000 atomic absorption spectrophotometer, EDTA titration method and mannitol method were used to determine the volume of the brine phase and the water phase in the extraction and stripping process, prepare the analysis solution, and sample and analyze the Li ⁺ , Ca ²⁺ and B ₂ O ₃ contents, calculated experimental results are shown in Table 18.

Table 18 The three-stage countercurrent extraction and extraction ^{of Li +} , Ca ²⁺ and B ₂ O ₃ in a calcium-containing brine by the composite solvent of N-isobutylisononylamide, N-isooctylisovaleramide and 2-octyldodecanol Secondary countercurrent extraction situation

It can be seen from Table 18 that after the three-stage countercurrent extraction of brine, the ^{extraction rate of Li +} is 45.37%, the ^{extraction rate of Ca 2+} is 3.98%, and the separation coefficient of lithium and calcium reaches 20.04. After the loaded organic phase is subjected to secondary countercurrent stripping, the Li ⁺ stripping rate is 86.81%, the Ca ²⁺ stripping rate is 89.47%, the lithium-calcium separation coefficient after stripping is 0.77, and the calcium-lithium mass ratio in the water phase drops to 5.24. ^{Li +} and Ca ^{2+ in} brine are effectively separated. Among them, the extraction rate of B 2 O ₃ was 56.41% after the brine was subjected to three-stage countercurrent, and the _{second- stage counter-current extraction rate of B 2} O ₃ was 96.14%, indicating that the extraction system can extract Li ⁺ while also effectively extracting B ₂ O ₃ . Further increase the countercurrent extraction and countercurrent stripping stages, the extraction rate and stripping rate of ^{Li +} and B ₂ O ₃ ^{are further improved, while the extraction rate of Ca 2+} is basically unchanged, and the extraction rate of ^{Mg 2+ is not large.}

Then the water phase solution obtained after the back extraction is degreasing, and after two-effect evaporation is concentrated to a Li ⁺ concentration of 20g/L, sodium sulfate and sodium carbonate solutions are respectively added to completely precipitate and remove Ca ²⁺ , and chlorination is added separately The barium and sodium hydroxide solutions are completely precipitated to remove sulfate radicals and Mg ^{2+ in them} , and a refined solution of lithium chloride is obtained. Then, a sodium carbonate solution with a concentration of 250 g/L was added to it at 1.1 times the theoretical amount to produce a lithium carbonate precipitate, which was filtered and dried to obtain a lithium carbonate product.

Add calcium hydroxide emulsion to the obtained lithium carbonate, heat and vigorously stir for solid-liquid reaction to produce lithium hydroxide solution and calcium carbonate precipitate, after the two phases are separated, the lithium hydroxide solution is obtained, which is concentrated under reduced pressure, crystallized and After drying at 130-140°C, monohydrate lithium hydroxide is prepared, and then heated under reduced pressure at 150-180°C to prepare anhydrous lithium hydroxide product.

The above are only part of the implementation cases selected and provided by the present invention, and the implementation of the present invention is not limited by the foregoing embodiments. For those skilled in the art, the present invention can have various modifications and changes. Any modifications, equivalent substitutions, combinations and improvements made within the spirit and principle of the present invention, as well as various changes in form and details made accordingly, fall within the protection scope of this technical invention.

Table 19: Common names, corresponding standard names and codes of the secondary amides of substance A involved in the Examples

Serial number	Common names of secondary amides of part A substances	Part A substance secondary amide corresponding to the standard name	Codename
1	N-Isooctyl Butanamide	N-(2-ethylhexyl) n-butanamide	Z842
2	N-isobutylisononylamide	N-(2-methylpropyl)-3,5,5-trimethylhexanamide	Z494

3	N-isooctyl valeramide	N-(2-ethylhexyl) n-pentanoamide	Z852
4	N-Isooctyl Isovaleramide	N-(2-ethylhexyl)-3-methylbutanamide	Z854
5	N-ethyl lauramide	N-ethyl n-dodecamide	Z2121
6	N-Pentylisononamide	N-pentyl-3,5,5-trimethylhexanamide	Z593
7	N-Dodecylacetamide	N-Dodecylacetamide	Z1221
8	N-isooctylisohexanamide	N-(2-ethylhexyl)-4-methylpentanamide	Z864
9	N-Isooctylheptanamide	N-(2-Ethylhexyl) n-heptanamide	Z872
10	N-Isooctyl Neodecylamide	N-(2-Ethylhexyl)-7,7-Dimethyloctylamide	Z8104
11	N-isooctyl-1-cyclopropylformamide	N-(2-ethylhexyl)-1-cyclopropylformamide	Z84h2
12	N-cyclopropyl decanamide	N-Cyclopropyl-n-decylamide	Z3h101
13	N-ethyl-1-(4-pentylcyclohexyl)formamide	N-ethyl-1-(4-n-pentylcyclohexyl)formamide	Z212h1
14	N-Cyclododecylacetamide	N-Cyclododecylacetamide	Z12h21
15	N-hexyl-3-cyclopentyl propionamide	N-hexyl-3-cyclopentyl propionamide	Z68h1
16	N-(4-tert-butylcyclohexyl)octylamide	N-(4-tert-butylcyclohexyl) n-octylamide	Z10h82

Table 20: Common names, corresponding normative names and CAS numbers of substance B alkyl alcohols involved in the examples ^*

Serial number	Common Names of Part B Alkyl Alcohols	Part B Alkyl Alcohol Corresponding Specification Name	CAS number
1	3-octanol	3-octanol	589-98-0
2	3,5,5-Trimethylhexanol	3,5,5-Trimethyl-1-hexanol	3452-97-9
3	2-propylheptanol	2-n-propyl-1-heptanol	10042-59-8
4	2-Butyloctanol	2-n-Butyl-1-octanol	3913-02-8
5	2-hexyldecanol	2-n-hexyl-1-decanol	2425-77-6
6	2-octyldodecanol	2-n-octyl-1-dodecanol	5333-42-6

^* CAS number is the American Chemical Abstract Service registration number.

Claims (14)

1. A secondary amide/alkyl alcohol composite solvent is used to separate calcium from calcium-containing brine to extract lithium and boron. The extraction system is characterized in that the extraction system contains two types of substances A and B; wherein the type A substance is a secondary amide compound or It is composed of a mixture of two or more; wherein, a single compound has a structure as shown in formula (I):

   

   Wherein, R _{1 is} selected from a C1-C12 alkyl group or a C3-C12 cycloalkyl group containing a monocyclic structure, and R _{2 is} selected from a C1-C11 alkyl group or a C3-C11 cycloalkyl group containing a monocyclic structure, And the sum of the number of carbon atoms contained in the two groups _{R 1} and R _{2 is 11-17, wherein alkyl or cycloalkyl includes various isomers;}

   Among them, type B substances are alkyl alcohols consisting of a single compound or a mixture of two or more; among them, a single compound has a structure as shown in formula (II):

   R ₃ ——OH (Ⅱ);

   Wherein, R _{3 is} selected from C8 to C20 alkyl groups, where the alkyl groups include linear or branched isomers;

   The freezing point of the extraction system containing two types of substances A and B is less than 0°C.
2. The extraction system for separating calcium and extracting lithium and boron from calcium-containing brine using a secondary amide/alkyl alcohol composite solvent according to claim 1, wherein the type A substance mainly functions to extract lithium in the entire organic phase. The volume percentage in the organic phase is 0-100%, excluding the two endpoints; the B-type substance mainly functions to extract boron, and the volume percentage in the entire organic phase is 0-100%, excluding the two Endpoint value.
3. The extraction system for extracting lithium and boron from calcium-containing brine by using a secondary amide/alkyl alcohol composite solvent according to claim 1, wherein the extraction system facilitates simultaneous extraction of lithium and boron. The volume percentage of the substance in the entire organic phase is 50-90%, and the volume percentage of the B-type substance in the entire organic phase is 10-50%.
4. The extraction system for separating calcium and extracting lithium and boron from calcium-containing brine using a secondary amide/alkyl alcohol composite solvent according to claim 1, characterized in that it also contains a diluent 260# solvent oil, 300 #Solvent oil or sulfonated kerosene.
5. The extraction method for separating calcium from calcium-containing brine by using a secondary amide/alkyl alcohol composite solvent to extract lithium and boron is characterized in that it comprises the following steps:

   S1. The calcium-containing brine is used as the pre-extraction brine phase; wherein, in the calcium-containing brine, the concentration of lithium ions is 0.09-24g/L, the concentration of calcium ions is 145-277g/L, and the concentration of chloride ions is 271 ～517g/L, the mass ratio of calcium to lithium is 7.5～1900:1, the concentration of boric acid and its borate ions _{is 0.5～17g/L based on B 2} O ₃ , and the brine density is 1.30～1.56g/cm at 20℃ ^3. Use hydrochloric acid or sulfuric acid to adjust the pH value of brine between 0-7;

   S2, using the extraction system of any one of claims 1 to 4 as the organic phase before extraction;

   S3. Mix the pre-extraction organic phase and the pre-extraction brine phase in a volume ratio of 1-10:1, perform single-stage extraction or multi-stage countercurrent extraction, and obtain a loaded organic phase and a post-extraction brine phase after the two phases are separated .
6. The extraction method for separating calcium and extracting lithium and boron from calcium-containing brine using a secondary amide/alkyl alcohol composite solvent according to claim 5, wherein the calcium-containing brine also contains sodium ions and potassium ions. , Magnesium ion, iron ion or ferrous ion one or more than two kinds.
7. The extraction method for separating calcium and extracting lithium and boron from calcium-containing brine by using a secondary amide/alkyl alcohol composite solvent according to claim 5, wherein the calcium-containing brine comprises lithium and boron-containing oilfield brine or Underground brine, but not limited to this kind of brine.
8. The extraction method for separating calcium and extracting lithium and boron from calcium-containing brine by using a secondary amide/alkyl alcohol composite solvent according to claim 5, wherein, in the step S3, the extraction temperature is 0-50°C; The two-phase mixing is carried out by stirring, and the two-phase separation after extraction is carried out by centrifugal separation or clarification and sedimentation.
9. The extraction method for separating calcium and extracting lithium and boron from calcium-containing brine by using a secondary amide/alkyl alcohol composite solvent according to claim 5, characterized in that, after the step S3, the method further comprises:

   S4. Using water as the stripping agent, single-stage stripping or multi-stage countercurrent stripping is performed on the loaded organic phase. The stripping ratio, that is, the ratio of the stripping agent to the volume of the loaded organic phase is 1:1-20. After phase separation, a back-extracted organic phase and a back-extracted aqueous phase are obtained;

   S5. Return the organic phase after the stripping to step S2 to realize the recycling use of the extraction system.
10. The extraction method for separating calcium and extracting lithium and boron from calcium-containing brine using a secondary amide/alkyl alcohol composite solvent according to claim 9, characterized in that, in the step S4, the stripping temperature is 0-50°C ；

    The two-phase mixing is carried out by stirring, and the two-phase separation after back extraction is carried out by centrifugal separation or clarification sedimentation.
11. The application of the extraction method for extracting lithium and boron from calcium-containing brine with a secondary amide/alkyl alcohol composite solvent in obtaining boron product boric acid is characterized in that, after the step S4, the method further includes the following steps:

    S6. The water phase after the stripping is further deoiled and purified, concentrated, the pH value of the water phase is adjusted with hydrochloric acid or sulfuric acid, boric acid is precipitated from the solution, and the boric acid product is obtained after washing and drying.
12. The application of the extraction method for extracting lithium and boron from calcium-containing brine with a secondary amide/alkyl alcohol composite solvent in obtaining the lithium product lithium chloride is characterized in that, after the step S4, the method further includes the following steps:

    S6. The water phase after the stripping is further deoiled and purified, concentrated, the pH value of the water phase is adjusted with hydrochloric acid or sulfuric acid, boric acid is precipitated from the solution, and the boric acid product is obtained after washing and drying;

    S7. In the lithium-containing solution after the boric acid is precipitated, an impurity removing agent is added to remove the remaining calcium ions and a small amount of magnesium ions, to obtain a lithium chloride solution refined from the lithium-containing solution; the impurity removing agent used is sodium sulfate, One or more than two compounds of sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

    S8. The refined lithium chloride solution is concentrated, crystallized, separated and dried to obtain a lithium chloride product.
13. The application of the extraction method for extracting lithium and boron from calcium-containing brine with a secondary amide/alkyl alcohol composite solvent in obtaining the lithium product lithium carbonate is characterized in that, after the step S4, the method further comprises the following steps:

    S6. The water phase after the stripping is further deoiled and purified, concentrated, the pH value of the water phase is adjusted with hydrochloric acid or sulfuric acid, boric acid is precipitated from the solution, and the boric acid product is obtained after washing and drying;

    S7. In the lithium-containing solution after the boric acid is precipitated, an impurity removing agent is added to remove the remaining calcium ions and a small amount of magnesium ions, to obtain a lithium chloride solution refined from the lithium-containing solution; the impurity removing agent used is sodium sulfate, One or more than two compounds of sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

    S9, adding sodium carbonate to the refined lithium chloride solution to obtain a lithium carbonate precipitate, and performing separation and drying processes on the lithium carbonate precipitate to obtain a lithium carbonate product.
14. The application of the extraction method for extracting lithium and boron from calcium-containing brine with a secondary amide/alkyl alcohol composite solvent in obtaining the lithium product lithium hydroxide is characterized in that, after the step S4, the method further includes the following steps:

    S6. The water phase after the stripping is further deoiled and purified, concentrated, the pH value of the water phase is adjusted with hydrochloric acid or sulfuric acid, boric acid is precipitated from the solution, and the boric acid product is obtained after washing and drying;

    S7. In the lithium-containing solution after the boric acid is precipitated, an impurity removing agent is added to remove the remaining calcium ions and a small amount of magnesium ions, to obtain a lithium chloride solution refined from the lithium-containing solution; the impurity removing agent used is sodium sulfate, One or more than two compounds of sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

    S10, electrolyzing the refined lithium chloride solution to obtain a lithium hydroxide product, and at the same time by-produce hydrogen and chlorine, which can be used to produce hydrochloric acid;

    Or after the step S7, the method further includes the following steps:

    S9, adding sodium carbonate to the refined lithium chloride solution to obtain a lithium carbonate precipitate, and performing a separation and drying process on the lithium carbonate precipitate to obtain a lithium carbonate product;

    S11. Adding a calcium hydroxide emulsion to the prepared lithium carbonate, performing a solid-liquid reaction, and obtaining a lithium hydroxide solution after separation, which is subjected to the processes of concentration, crystallization and drying to obtain a lithium hydroxide product.

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