阅读说明：本技术 用仲酰胺/烷烃复合溶剂从含钙卤水中分离钙提取锂的萃取体系、萃取方法和其应用 (Extraction system for separating calcium from calcium-containing brine by using secondary amide/alkane composite solvent to extract lithium, extraction method and application thereof ) 是由 杨立新 李海博 李聪 刘长 周钦耀 于 2019-11-08 设计创作，主要内容包括：本发明公开了用仲酰胺/烷烃复合溶剂从含钙卤水中分离钙提取锂的萃取体系、萃取方法和其应用。萃取体系中含有仲酰胺和烷烃分别由其单一化合物或两种以上的混合物组成,分子中碳原子总数分别为12～18和9～18,萃取体系的凝固点小于0℃。在有机相与卤水相体积比1～10:1、卤水密度为1.30～1.56g/cm<Sup>3</Sup>卤水pH值1～7和温度0～50℃下进行单级或多级逆流萃取,反萃取得到低钙锂比水相,经过浓缩、除杂与制备,分别得到氯化锂、碳酸锂和氢氧化锂。本发明的优异效果：仲酰胺萃取剂分子结构简单,容易生产,烷烃改进复合溶剂的粘度等性质；Li<Sup>+</Sup>多级萃取率高,锂钙分离系数大,用水反萃取酸碱消耗大大减少；萃取分离工艺流程短,萃取体系溶损小,适合于油田卤水开发。(The invention discloses an extraction system, an extraction method and application for separating calcium from calcium-containing brine by using a secondary amide/alkane composite solvent to extract lithium. The extraction system contains secondary amide and alkane which are respectively composed of single compounds or a mixture of more than two compounds, the total number of carbon atoms in molecules is respectively 12-18 and 9-18,the freezing point of the extraction system is less than 0 ℃. The volume ratio of the organic phase to the brine phase is 1-10: 1, and the brine density is 1.30-1.56 g/cm 3 Performing single-stage or multi-stage countercurrent extraction on the brine at the pH value of 1-7 and the temperature of 0-50 ℃, performing back extraction to obtain a low-calcium-lithium ratio water phase, and performing concentration, impurity removal and preparation to respectively obtain lithium chloride, lithium carbonate and lithium hydroxide. The excellent effects of the present invention: the secondary amide extractant has simple molecular structure, easy production and properties of alkane such as improved viscosity of the composite solvent; li + The multi-stage extraction rate is high, the lithium-calcium separation coefficient is large, and the consumption of acid and alkali by water back extraction is greatly reduced; the extraction and separation process flow is short, the dissolution loss of an extraction system is small, and the method is suitable for the development of oil field brine.)

1. An extraction system for separating calcium from calcium-containing brine by using a secondary amide/alkane composite solvent to extract lithium is characterized in that the extraction system contains A and B substances; wherein the A-type substance is a secondary amide and consists of a single compound or a mixture of more than two compounds; wherein the single compound has a structure as shown in formula (I):

wherein R is ₁Selected from C2-C12 alkyl or C3-C12 cycloalkyl containing single ring structure, R ₂Selected from C1-C11 alkyl or C3-C11 cycloalkyl containing single ring structure, and R ₁And R ₂The sum of the numbers of carbon atoms contained in the two groups is 11 to 17, wherein the alkyl or cycloalkyl group includes various isomers;

wherein the B-type substance is alkane composed of single compound or mixture of more than two compounds; wherein the single compound has a structure as shown in formula (II):

H-R ₃(Ⅱ)；

wherein R is ₃Alkyl selected from C9-C18, wherein the alkyl comprises various isomers which are linear or branched;

the freezing point of the extraction system containing the substances A and B is less than 0 ℃.

2. The extraction system for separating calcium and extracting lithium from calcium-containing brine by using a secondary amide/alkane composite solvent according to claim 1, wherein the extraction effect of the A-type substances accounts for 50-100% of the total volume of the organic phase, excluding 100%; the B-type substance accounts for 0-50% of the whole organic phase by volume percentage, excluding 0% of the end point, under the action of dilution.

3. The extraction system for separating calcium from calcium-containing brine and extracting lithium using secondary amide/alkane complex solvent as claimed in claim 1, further comprising C9-C18 cycloalkanes having a single ring structure in the molecule which also serves as a diluent, wherein said cycloalkanes comprise isomers consisting of a single compound or a mixture of two or more compounds.

4. The extraction system for separating calcium from calcium-containing brine and extracting lithium using secondary amide/alkane complex solvent as claimed in claim 3, wherein in said class B material, the alkane mixture is 200# solvent oil, 260# solvent oil, 300# solvent oil or sulfonated kerosene; among the cycloparaffins, the cycloparaffin mixture is 200# solvent oil produced by using a reformer raffinate.

5. An extraction method for separating calcium from calcium-containing brine by using a secondary amide/alkane composite solvent to extract lithium, which is characterized by comprising the following steps:

s1, taking calcium-containing brine as a brine phase before extraction; wherein, in the calcium-containing brine, the concentration of lithium ions is 0.09-24 g/L, the concentration of calcium ions is 145-277 g/L, the concentration of chloride ions is 271-511 g/L, the mass ratio of calcium to lithium is 7.5-1900: 1, and the brine density is 1.30-1.56 g/cm at 20 DEG C ³Adjusting the pH value of the brine to be 1-7 by using hydrochloric acid or sulfuric acid;

s2, using the extraction system of any one of claims 1 to 4 as a pre-extraction organic phase;

s3, mixing the organic phase before extraction and the brine phase before extraction according to the volume ratio of 1-10: 1, performing single-stage extraction or multi-stage countercurrent extraction, and separating the two phases to obtain a loaded organic phase and an extracted brine phase.

6. The extraction method for separating calcium from calcium-containing brine and extracting lithium using a secondary amide/alkane complex solvent according to claim 5, wherein the calcium-containing brine further contains one or more of sodium ion, potassium ion, magnesium ion, iron ion, ferrous ion, boric acid, and borate ion.

7. The extraction process of claim 5, wherein the calcium-containing brine comprises, but is not limited to, a lithium-containing oil field brine or a lithium-containing underground brine.

8. The extraction method for separating calcium from calcium-containing brine and extracting lithium by using a secondary amide/alkane complex solvent as claimed in claim 5, wherein in the step S3, the extraction temperature is 0-50 ℃; the mixing of the two phases is carried out by stirring, and the separation of the two phases after extraction is carried out by a centrifugal separation mode or a clarification and sedimentation mode.

9. The extraction process for separating calcium from calcium-containing brine and extracting lithium using secondary amide/alkane complex solvent as claimed in claim 5, further comprising the step of, after said step S3:

s4, taking water as a back extraction agent, carrying out single-stage back extraction or multi-stage counter-current back extraction on the loaded organic phase, wherein the volume ratio of the back extraction agent to the loaded organic phase is 1: 1-20, and carrying out two-phase separation to obtain a back-extracted organic phase and a back-extracted aqueous phase;

s5, returning the organic phase after back extraction to the step S2, and realizing the recycling of the extraction system.

10. The extraction method for separating calcium from calcium-containing brine and extracting lithium by using a secondary amide/alkane complex solvent as claimed in claim 9, wherein in the step S4, the back extraction temperature is 0-50 ℃; the two-phase mixing is carried out by a stirring mode, and the two-phase separation after back extraction is carried out by a centrifugal separation mode or a clarification and sedimentation mode.

11. Use of an extraction process for separating calcium from a calcium-containing brine using a secondary amide/alkane complex solvent to extract lithium in obtaining the lithium chloride product, characterized in that after said step S4, it further comprises the steps of:

s6, further removing oil, purifying and concentrating the back-extracted water phase, and then adding an impurity removing agent to remove residual calcium ions and a small amount of magnesium ions to obtain a lithium chloride solution after water phase refining; the impurity removing agent is one or more compounds of sodium sulfate, sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

s7, concentrating, crystallizing, separating and drying the refined lithium chloride solution to obtain the lithium chloride product.

12. Use of an extraction process for separating calcium from a calcium-containing brine using a secondary amide/alkane complex solvent to extract lithium in the production of lithium carbonate as a lithium product, characterized in that after said step S4, it further comprises the steps of:

s6, further removing oil, purifying and concentrating the back-extracted water phase, and then adding an impurity removing agent to remove residual calcium ions and a small amount of magnesium ions to obtain a lithium chloride solution after water phase refining; the impurity removing agent is one or more compounds of sodium sulfate, sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

and S8, adding sodium carbonate into the refined lithium chloride solution to obtain lithium carbonate precipitate, and separating and drying the lithium carbonate precipitate to obtain a lithium carbonate product.

13. Use of an extraction process for separating calcium from a calcium-containing brine using a secondary amide/alkane complex solvent to extract lithium in obtaining the lithium product lithium hydroxide, characterized in that after said step S4, it further comprises the steps of:

s6, further removing oil, purifying and concentrating the back-extracted water phase, and then adding an impurity removing agent to remove residual calcium ions and a small amount of magnesium ions to obtain a lithium chloride solution after water phase refining; the impurity removing agent is one or more compounds of sodium sulfate, sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

s9, electrolyzing the refined lithium chloride solution to obtain a lithium hydroxide product, and simultaneously by-producing hydrogen and chlorine, wherein the hydrogen and chlorine can be used for producing hydrochloric acid;

or after the step S6, the method further includes the steps of:

s8, adding sodium carbonate into the refined lithium chloride solution to obtain lithium carbonate precipitate, and separating and drying the lithium carbonate precipitate to obtain a lithium carbonate product;

and S10, adding calcium hydroxide emulsion into the prepared lithium carbonate, carrying out solid-liquid reaction, separating to obtain a lithium hydroxide solution, and concentrating, crystallizing and drying the lithium hydroxide solution to obtain a lithium hydroxide product.

Technical Field

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

Background

The method has abundant oil field underground brine in the south wing mountain area in the west of the Qinghai firewood basin in China, the resource storage capacity of the method can be comparable to that of the salt lake in the Qinghai firewood basin, and the method is a rare multi-element coexistence extra-large mineral deposit in the world and has great industrial development value. The potassium, boron, lithium, iodine and other useful components are abundant and high in content, the resource occurrence state is greatly different from the developed salt lake resource types, the calcium chloride type brine in the Sulin classification has the characteristics of high salinity, high calcium, low magnesium and low sulfate radical, and the calcium chloride content is up to 30.8-43.0% after the calcium chloride type brine is subjected to solarization and concentration in a salt field.

In recent years, valuable element lithium is extracted from brine with high calcium-lithium ratio and is valued, the separation of calcium and lithium is a technical key, and the existing calcium-lithium separation methods mainly comprise two methods: (1) the bittern admission method is to mix mirabilite or bittern containing sulfate radical with calcium containing bittern to eliminate calcium sulfate precipitate and separate calcium from lithium. The Gaoyangyuan and the like react with a calcium source in high-calcium old brine by utilizing a sodium sulfate resource of a salt lake or nearby sodium sulfate resource to carry out old brine decalcification (CN104817096B), and the method can generate a large amount of calcium sulfate precipitation and has serious lithium ion entrainment loss. (2) The freeze crystallization method is to precipitate calcium salt in brine at low temperature by utilizing the change of calcium chloride solubility with temperature. Plum ice and the like evaporate oil field water to a specific gravity of 1.40-1.54, and freeze the oil field water at 0-30 ℃ for 3-15 days to obtain lithium-rich brine (CN103508472A), wherein the method has long time and the reduction degree of the calcium-lithium mass ratio is limited.

In other methods for separating calcium from brine, the methods of removing divalent or more metal cations (CN108840354A) in a lithium-containing solution by adopting a chelating cation exchange resin column at a pH value of 10-12 (Qinxing et al), removing calcium and magnesium impurities (CN106048218A) in a high-salt lithium chloride mixed solution by adopting a nanofiltration device (Guodingjiang et al) and removing calcium and magnesium ions (CN105712383A) in a lithium-rich solution by adopting an extraction method and P204 as an extraction agent and sulfonated kerosene as a slow release agent (Ningming et al) are only suitable for deep purification treatment of low-concentration calcium and magnesium-containing brine. At present, few documents relating to research on high-calcium-lithium-ratio oil field brine are available, and particularly, no document is reported for calcium-lithium separation of high-calcium-lithium-ratio brine by using solvent extraction method, which is attributed to Ca ²⁺The valence layer has empty 3d orbit, strong coordination ability, ion hardness and Mg ²⁺In a significant difference, the fact that separation of high calcium-lithium ratio brines is more difficult than separation of high magnesium-lithium ratio brines has led to the development of lithium resources in oil field brines that has not been realized to date.

However, the solvent extraction method achieves the purpose of separating lithium calcium or lithium magnesium by utilizing the specific extraction performance of an organic solvent on lithium ions, is considered as the most promising lithium extraction method for the salt lake brine with high magnesium-lithium ratio, and can also be applied to the oil field brine with high calcium-lithium ratio, and the advantages and disadvantages of the extractant and the discovery of a new extractant are the key points of the technical process. The alkane is used as a neutral solvent with low density, small viscosity and environmental protection, is beneficial to two-phase separation, and can form a new extraction system by combining with other effective components. After the high-calcium lithium ratio brine is converted into the low-calcium lithium ratio brine through the lithium-calcium separation, basic chemical products such as lithium chloride, lithium carbonate and lithium hydroxide which are particularly needed in the market can be prepared.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides an economical and effective extraction system for separating calcium from calcium-containing brine by using a secondary amide/alkane composite solvent to extract lithium, an extraction method and application thereof.

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

1. an extraction system for separating calcium from calcium-containing brine by using a secondary amide/alkane composite solvent to extract lithium, wherein the extraction system contains A and B substances; wherein the A-type substance is a secondary amide and consists of a single compound or a mixture of more than two compounds; wherein the single compound has a structure as shown in formula (I):

wherein R is ₁Selected from C2-C12 alkyl or C3-C12 cycloalkyl containing single ring structure, R ₂Selected from C1-C11 alkyl or C3-C11 cycloalkyl containing single ring structure, and R ₁And R ₂The sum of the number of carbon atoms contained in the two groups being 11 to 17, wherein the alkyl or cycloalkyl group includes various isomers (due to R) ₁、R ₂Is variable when R ₁、R ₂When uniquely identified, class A is a single compound, and mixtures thereof refer to compounds that follow R ₁、R ₂A mixture of two or more compounds produced by the change of (1);

wherein the B-type substance is alkane composed of single compound or mixture of more than two compounds; wherein the single compound has a structure as shown in formula (II):

H-R ₃(Ⅱ)；

wherein R is ₃Selected from C9-C18 alkyl, wherein the alkyl comprises various isomers (due to R) which are linear or branched ₃Is variable when R ₃When uniquely identified, class B is a single compound, and mixtures thereof refer to compounds that follow R ₃A mixture of two or more compounds produced by the change of (1);

the freezing point of the extraction system containing the substances A and B is less than 0 deg.C (the freezing point of a single component constituting the extraction system may be less than, equal to or greater than 0 deg.C, the conditions for the extraction system of the present invention can be satisfied when the freezing point of the single component is less than 0 deg.C, and when the freezing point of the single component is greater than or equal to 0 deg.C, the single component may be mixed with other components having freezing points less than 0 deg.C, and dissolved to finally form a mixture having a freezing point less than 0 deg.C).

In the extraction system, the volume percentage of the A-type substances in the whole organic phase for extraction is 50-100%, and the end value is not 100%; the volume percentage of the B-type substance in the whole organic phase for dilution is 0-50%, and the end value is not 0%.

The extraction system comprising the substances A and B also comprises naphthenic hydrocarbon of C9-C18 with single ring structure in the molecule which also has the function of dilution, and the naphthenic hydrocarbon comprises isomers which are composed of single compounds or a mixture of more than two compounds.

In the B-type substances, the alkane mixture is 200# solvent oil (composed of alkanes), 260# solvent oil, 300# solvent oil or sulfonated kerosene; among the cycloparaffins, the cycloparaffin mixture is 200# solvent oil (composed of cycloparaffins) produced by using a reformer raffinate.

2. An extraction process for separating calcium from calcium-containing brine using a secondary amide/alkane complex solvent to extract lithium, comprising the steps of:

s1, taking calcium-containing brine as a brine phase before extraction; wherein, in the calcium-containing brine, the concentration of lithium ions is 0.09-24 g/L, the concentration of calcium ions is 145-277 g/L, the concentration of chloride ions is 271-511 g/L, the mass ratio of calcium to lithium is 7.5-1900: 1, and the brine density is 1.30-1.56 g/cm at 20 DEG C ³Adjusting the pH value of the brine to be 1-7 by using hydrochloric acid or sulfuric acid;

s2, taking the extraction system in the step 1 as an organic phase before extraction;

s3, mixing the organic phase before extraction and the brine phase before extraction according to the volume ratio of 1-10: 1, performing single-stage extraction or multi-stage countercurrent extraction, and separating the two phases to obtain a loaded organic phase and an extracted brine phase.

The calcium-containing brine also contains one or more of sodium ions, potassium ions, magnesium ions, iron ions, ferrous ions, boric acid or borate ions.

The calcium-containing brine includes, but is not limited to, lithium-containing oil field brine or lithium-containing underground brine.

Further, in the step S3, the extraction temperature is 0-50 ℃; the mixing of the two phases is carried out by stirring, and the separation of the two phases after extraction is carried out by a centrifugal separation mode or a clarification and sedimentation mode.

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

s4, taking water as a back extraction agent, carrying out single-stage back extraction or multi-stage counter-current back extraction on the loaded organic phase, wherein the volume ratio of the back extraction agent to the loaded organic phase is 1: 1-20, and carrying out two-phase separation to obtain a back-extracted organic phase and a back-extracted aqueous phase;

s5, returning the organic phase after back extraction to the step S2, and realizing the recycling of the extraction system.

Further, in the step S4, the back extraction temperature is 0-50 ℃; the two-phase mixing is carried out by a stirring mode, and the two-phase separation after back extraction is carried out by a centrifugal separation mode or a clarification and sedimentation mode.

3. The application of the extraction method for separating calcium from calcium-containing brine by using a secondary amide/alkane composite solvent to extract lithium in the preparation of lithium chloride products further comprises the following steps after the step S4:

s6, further removing oil, purifying and concentrating the back-extracted water phase, and then adding an impurity removing agent to remove residual calcium ions and a small amount of magnesium ions to obtain a lithium chloride solution after water phase refining; the impurity removing agent is one or more compounds of sodium sulfate, sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

s7, concentrating, crystallizing, separating and drying the refined lithium chloride solution to obtain the lithium chloride product.

4. The use of an extraction method for extracting lithium by separating calcium from a calcium-containing brine with a secondary amide/alkane complex solvent to obtain lithium carbonate as a lithium product, further comprising the steps of, after said step S4:

s6, further removing oil, purifying and concentrating the back-extracted water phase, and then adding an impurity removing agent to remove residual calcium ions and a small amount of magnesium ions to obtain a lithium chloride solution after water phase refining; the impurity removing agent is one or more compounds of sodium sulfate, sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

and S8, adding sodium carbonate into the refined lithium chloride solution to obtain lithium carbonate precipitate, and separating and drying the lithium carbonate precipitate to obtain a lithium carbonate product.

5. The use of an extraction method for separating calcium from a calcium-containing brine using a secondary amide/alkane complex solvent to extract lithium in order to obtain a lithium product, lithium hydroxide, further comprising the steps of, after said step S4:

s6, further removing oil, purifying and concentrating the back-extracted water phase, and then adding an impurity removing agent to remove residual calcium ions and a small amount of magnesium ions to obtain a lithium chloride solution after water phase refining; the impurity removing agent is one or more compounds of sodium sulfate, sodium carbonate, sodium oxalate, barium chloride or sodium hydroxide;

s9, electrolyzing the refined lithium chloride solution to obtain a lithium hydroxide product, and simultaneously by-producing hydrogen and chlorine, wherein the hydrogen and chlorine can be used for producing hydrochloric acid;

or after the step S6, the method further includes the steps of:

s8, adding sodium carbonate into the refined lithium chloride solution to obtain lithium carbonate precipitate, and separating and drying the lithium carbonate precipitate to obtain a lithium carbonate product;

and S10, adding calcium hydroxide emulsion into the prepared lithium carbonate, carrying out solid-liquid reaction, separating to obtain a lithium hydroxide solution, and concentrating, crystallizing and drying the lithium hydroxide solution to obtain a lithium hydroxide product.

The secondary amide type compound is synthesized by reacting organic acyl chloride or anhydride with primary amine according to a stoichiometric ratio, purified by water washing and reduced pressure distillation, and detected and evaluated by an American Agilent 7890A/5975C gas chromatograph-mass spectrometer. The source of the alkane-type compounds in the present invention is purchased from chemical products companies on the market.

Compared with the prior art, the invention has the advantages that a secondary amide/alkane composite solvent composed of the compounds shown in the formula (I) and the formula (II) is used as a new extraction system, so that a new extraction method for separating calcium from calcium-containing brine and extracting lithium and application thereof are obtained, unexpected effects are achieved, a document report that a solvent composed of a mixture of secondary amide and alkane is used as a brine lithium extraction system is not seen, and a new technology is provided for the development of the current high-calcium-lithium-ratio oil field brine lithium resource. The invention has the following advantages:

1) the secondary amide as the substance A in the extraction system has simple molecular structure, easily obtained source, easy production and extraction effect, is a novel special-effect component for separating calcium from calcium-containing brine and extracting lithium, wherein the secondary amide functional group is a key part for separating and extracting lithium from lithium and calcium, and hydrogen atoms on N-H are arranged before and after extraction ¹Shift of H NMR spectrum to low field, for Li ⁺Plays a key role in the extraction. The alkane is used as the B substance in the extraction system, is easy to obtain from petroleum refining and organic synthesis, has low price, can effectively improve the physical properties of the composite solvent such as viscosity, density, freezing point and the like, increases the mixing entropy of the system and generates synergistic effect.

2) In ensuring Li ⁺On the premise of single-stage extraction capacity with a certain size, the loaded organic phase is compatible and easy to be directly back-extracted by water, and acid does not need to be used for strengthening Li ⁺The back extraction does not need to use alkali to neutralize the acid in the front to restore the extraction capacity of the organic phase and the acid-base property of the aqueous phase, the acid-base consumption is low, the bidirectional balance of the extraction and back extraction processes is realized, and the Li is extracted ⁺While also facilitating Li ⁺Back extraction of (4). After the calcium-containing brine is subjected to multi-stage countercurrent extraction, the lithium-calcium separation coefficient is large, and the mass ratio of calcium to lithium in the water phase after back extraction is obviously reduced.

3) The whole extraction and separation process is simple, the organic phase is directly recycled, the corrosion degree of equipment is low, and the production process is easy to control. The low density of the organic phase is suitable for the two-phase separation when the loaded organic phase is back-extracted 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.

Description of the figures

FIG. 1 is a block diagram of the process flow for the separation of calcium from calcium-containing brine to extract lithium using a secondary amide/alkane complex solvent of the present invention.

Table 22 shows the common names, corresponding canonical names and code numbers of the secondary amides of substance A referred to in the examples of the present invention.

Table 23 shows the common names, corresponding canonical names and CAS numbers of the alkanes and cycloalkanes of the B species referred to in the examples of the present invention.

Detailed Description

The invention is further illustrated by the following examples: