CN116770068A - An efficient aluminum solvent extraction system - Google Patents

Abstract

The invention discloses an aluminum solvent extraction system, which includes a modified carboxylic acid extractant, a co-solvent and a diluent, wherein the modified carboxylic acid extractant has a structure of formula I, in which R is a linear or branched alkane. base chain; n represents the number of CH ₂ units connected to the carboxyl functional group, which is an integer of 0‑2,

Description

An efficient aluminum solvent extraction system

Technical field

The invention belongs to the field of metal extraction and relates to an aluminum solvent extraction system. Specifically, it relates to an efficient aluminum solvent extraction system based on a modified carboxylic acid extractant.

Background technique

The separation of aluminum elements is a key step in many production processes. For example, during the recycling of retired batteries and the mining of rare earth ores, aluminum is often leached together with other metals to form a mixture of aluminum, alkali metals (such as lithium, sodium, potassium, etc.), alkaline earth metals (such as magnesium, calcium, etc.), A mixed solution of transition metals (such as cobalt, nickel, iron, manganese, etc.) or rare earth metals (such as praseodymium, neodymium, etc.). In order to obtain high-purity high-value metals, such as rare earths, cobalt, nickel, lithium, etc., it is of great significance to separate aluminum elements in mixed solutions with high selectivity. In actual production, solvent extraction is a commonly used method to separate aluminum elements in solutions. Compared with other methods, such as precipitation, it has the advantages of low energy consumption, easy equipment operation, and high selectivity.

Currently, the more common aluminum extraction agent is a naphthenic acid extraction system (for example, disclosed in CN101979680A, CN103146921B, and CN103966441A). However, due to the high viscosity of naphthenic acid and its easy emulsification, the organic phase and the aqueous phase separate for a long time during the extraction process, and the phase separation interface is not clear. In actual use, it is easy to cause serious losses of the extraction agent and metal.

CN111944998A discloses an aluminum isodecanate extraction agent that achieves multi-stage continuous aluminum extraction. The extraction system has low viscosity, is not easy to emulsify, and has a short phase separation time between the organic phase and the water phase. However, isodecanic acid has poor selectivity for aluminum. In the presence of other metals, aluminum ions are easily extracted together with other metals, such as manganese, cobalt, nickel, etc.

CN112921176B discloses a phenoxy aluminum carboxylate extraction agent, which has high selectivity and high extraction rate for aluminum ions. However, the solubility of phenoxycarboxylic acid extractants in alkane solvents such as kerosene is small, and it is easy to emulsify after enriching aluminum ions, which increases the difficulty of separating the aqueous phase and the organic phase. Although phenoxycarboxylic acid has good solubility in aromatic hydrocarbon solvents such as toluene, the toxicity of toluene and other solvents limits its practical application.

In view of the problems existing in the existing technology, the present invention provides a low-toxic and cheap extraction system that has high selectivity for aluminum ions, high extraction rate, and is easily soluble in alkanes. It is suitable for a variety of production scenarios and can solve the problem of aluminum ions containing many It solves the problem of separating aluminum ions from a metal ion solution and avoids the waste of other metals, which has important application value.

Contents of the invention

The present invention aims to provide a modified carboxylic acid high-efficiency aluminum solvent extraction system with strong selectivity for aluminum ions, high extraction rate, and suitable for alkane solvents.

The invention relates to an efficient aluminum solvent extraction system, which contains a modified carboxylic acid extractant, a co-solvent and a diluent. Among them, the volume ratio of the modified carboxylic acid extractant is 0.5%-95%, preferably 10%-50%, the volume ratio of the co-solvent is 1-30%, preferably 10%-30%, and the balance is diluent to extract the system The total volume is based on the total volume.

Wherein, the modified carboxylic acid extractant is a compound containing a carboxyl functional group and an alkoxy chain functional group connected to the carboxyl functional group, and has structural formula (I)

Among them, R is a C4-C18 linear or branched alkyl group, and n represents the number of CH ₂ units connected to the carboxyl functional group, which is an integer from 0 to 2.

The co-solvent is one or a mixture of phosphate ester and alkyl alcohol. The phosphate ester is a C4-C8 phosphate, such as tributyl phosphate, tripentyl phosphate, trihexyl phosphate, tripheptyl phosphate, and trioctyl phosphate. The alkyl alcohol is a C8-C12 alkyl alcohol, such as n-octanol, isooctyl alcohol, n-nonanol, 2-nonanol, undecyl alcohol, dodecanol, etc.

The diluent is selected from one or a mixture of several C6-C16 alkanes, such as kerosene, n-heptane, and octane, preferably kerosene.

The present invention further relates to a method for extracting aluminum from a mixed metal ion solution, wherein a modified carboxylic acid high-efficiency aluminum solvent extraction system according to the present invention is used, which includes the following steps:

(1) Mix the modified carboxylic acid extractant, co-solvent and diluent to configure the high-efficiency aluminum solvent extraction system of the present invention;

(2) Contact the solvent extraction system configured in step (1) with a certain amount of alkali to saponify the modified carboxylic acid extractant therein to obtain a saponified solvent extraction system;

(3) Pass the saponified solvent extraction system obtained in step (2) and the solution to be extracted into the extraction equipment to mix, and perform a single-stage extraction or multi-stage countercurrent extraction reaction to obtain an aluminum-loaded organic phase. The pH at which the extraction reaction is balanced The value range is 2.5-4.5;

(4) The aluminum-loaded organic phase obtained in step (3) is subjected to single-stage washing or multi-stage countercurrent washing with washing liquid to remove co-extracted impurity ions, and obtain the washed aluminum-loading organic phase;

(5) Perform single-stage back-extraction or multi-stage counter-current back-extraction on the washed organic phase obtained in step (4) with stripping liquid to obtain the stripped organic phase and high-purity aluminum salt solution;

(6) Return the stripped organic phase obtained in step (5) to the organic phase storage tank, saponify it again, and recycle it for aluminum extraction.

In step (1), the co-solvent is one or more of phosphate and alkyl alcohol, and the phosphate is C4-C8 phosphate, such as tributyl phosphate, tripentyl phosphate, trihexyl phosphate. ester, trioheptyl phosphate, trioctyl phosphate; the alkyl alcohol is a C8-C12 alkyl alcohol, such as n-octanol, isooctyl alcohol, n-nonanol, 2-nonanol, 1-undecanol, Dialkanol. The volume ratio of the modified carboxylic acid extractant is 0.5%-95%, and the volume ratio of the co-solvent is 1-30%, based on the total volume of the extraction system. The diluent is selected from one or a mixture of several C6-C16 alkanes, such as kerosene, n-heptane, and octane, preferably kerosene.

In step (2), the concentration of the carboxylic acid extractant in the solvent extraction system is determined based on the molar concentration of aluminum in the solution to be extracted. Furthermore, a certain amount of alkali is added to make the saponification rate of the extraction agent range from 5% to 100%. The base may be sodium hydroxide, potassium hydroxide, ammonia or any mixture thereof, with sodium hydroxide being preferred.

In step (3), the extraction equipment can use an extraction clarification tank, an extraction tower or a centrifugal extractor, the extraction levels of which are 1-20, and the volume ratio of the saponified solvent extraction system to the liquid to be extracted is 1 :50-50:1.

In step (4), the washing liquid is water, dilute hydrochloric acid or dilute sulfuric acid, and the concentration of the hydrochloric acid or sulfuric acid solution is 0.01-3.0 mol/L; the volume ratio of the organic phase and the washing liquid is 1:50-50:1 , the washing level is 0-20.

In step (5), the stripping liquid is hydrochloric acid solution or sulfuric acid solution, and its concentration is 0.1-12.0mol/L; the volume ratio of the organic phase and stripping liquid is 1:50-50:1, and the stripping stage Numbers are level 1-20.

The solvent extraction system of the present invention has strong selectivity for aluminum ions, and the single-stage extraction rate can reach more than 90%. For aqueous solutions containing complex metal ions, only one-stage reaction is needed to efficiently extract aluminum ions, and almost no extraction of other metal ions is required. .

The solvent extraction system of the present invention is suitable for the extraction and separation of aluminum in mixed solutions of metal ions such as alkali metals, alkaline earth metals, transition metals, rare earth metals, etc. The alkali metals include lithium, sodium, potassium, etc., the alkaline earth metals include magnesium, calcium, etc., the transition metals include cobalt, nickel, iron, manganese, etc., and the rare earth metals include praseodymium, neodymium, etc. In addition, the co-solvent in the system is beneficial to improving the solubility of the complex generated by the extraction reaction in the diluent, reducing the viscosity of the organic phase, thereby increasing the separation effect of the organic phase and the aqueous phase.

Therefore, the present invention further relates to the use of the solvent extraction system according to the present invention for extracting and separating aluminum ions from a mixed solution of metal ions, which is suitable for a variety of production scenarios, such as rare earth separation raw material liquid aluminum removal, decommissioned battery leachate aluminum recovery, coal slag Separation of aluminum, magnesium and lithium from leaching solution, separation of aluminum from laterite nickel ore, etc.

beneficial effects

The solvent extraction system of the present invention can solve the problem of separating aluminum ions from a solution containing multiple metal ions, avoids the waste of other metals, has low cost and low toxicity, and is suitable for industrial production. Compared with existing technology, the advantages are:

(1) It has higher selectivity and higher extraction efficiency for aluminum ions, and no or very little extraction of other metals in the mixed metal ion solution.

(2) In the present invention, by adding alkali to adjust the pH value after extraction equilibrium, or first saponifying the organic phase with alkali, the extraction of aluminum ions is completed at a lower pH value and avoids the precipitation of other metal ions at high pH values. Loss.

(3) The solvent extraction system of the present invention uses alkanes as diluents to avoid or reduce the use of aromatic hydrocarbon solvents such as toluene and S150. The production environment is less toxic, the solvent cost is low, and it is suitable for large-scale production.

(4) The co-solvent in the system can increase the solubility of the extraction agent loaded with aluminum ions in the alkane diluent, improve the fluidity of the organic phase after loading aluminum ions, and the separation effect from the water phase.

(5) After the organic phase of the solvent extraction system of the present invention is loaded with aluminum ions, it can be back-extracted with hydrochloric acid or sulfuric acid solution, thereby realizing recycling of the organic phase or continuous multi-stage extraction.

Description of drawings

Figure 1 shows the metal ion extraction results under different reaction equilibrium pH values in Example 1.

Detailed ways

The present invention is further described below with reference to specific examples, but the present invention is not limited by these examples. Within the technical concept of the present invention, those skilled in the art can make various modifications.

Example 1:

Single-stage extraction and separation of aluminum in lithium battery leachate. The types and contents of metals in the leachate are: aluminum 8.1g/L, manganese 13.8g/L, cobalt 9.1g/L, magnesium 2.2g/L, nickel 23.2g/L, and lithium 4.2g/L. The extraction agent is 2-(decyloxy)acetic acid, the co-solvent is TBP, and the diluent is kerosene.

Add 24mL of 2-(decyloxy)acetic acid (purity 95%, about 0.1mol) into a 100mL volumetric flask, add 20mL TBP (20% volume ratio), add kerosene to a constant volume of 100mL, and configure the extraction agent concentration to be about 1mol/ L aluminum extracts the organic phase. Take 3 mL of the organic phase, add 120 μL of 10 mol/L NaOH solution, and mix thoroughly for 30 min to saponify the extractant (saponification rate 40%). The saponified organic phase was mixed with 3 mL of the solution to be extracted and stirred for 30 minutes. After standing for phase separation, the aqueous phase of the lower raffinate was removed and analyzed. At this time, the pH value after the extraction reaction was balanced was about 4.3. Take 2 mL of the upper organic phase, add 2 mL of 1.5 mol/L HCl aqueous solution, and mix thoroughly for 30 minutes to perform back extraction. Let it stand for phase separation, and the organic phase after stripping can be reused. The lower aqueous phase was removed and analyzed, and the extraction rate of aluminum was calculated to be approximately 92%, while the extraction rate of other metals was <2% (see Figure 1, extraction results under different reaction equilibrium pH values).

Example 2:

Multi-stage extraction and separation of aluminum in lithium battery leachate. The types and contents of metals in the leachate are: aluminum 8.1g/L, manganese 13.8g/L, cobalt 9.1g/L, magnesium 2.2g/L, nickel 23.2g/L, and lithium 4.2g/L. The extraction agent is 2-(decyloxy)acetic acid, the co-solvent is TBP, and the diluent is kerosene.

Take 24 vol% 2-(decyloxy)acetic acid, 20 vol% TBP and 56 vol% kerosene to prepare the aluminum extraction organic phase. Add 4vol% 10mol/L NaOH solution to the organic phase and mix thoroughly for 30 minutes to saponify the extractant (saponification rate 40%). The saponified organic phase and aqueous phase were carried out in an extraction clarification tank at a volume ratio of 1:1 to carry out 4-stage continuous countercurrent extraction to obtain an aluminum-loaded organic phase. The extraction rate of aluminum was measured to be >98%. The pH after the extraction reaction was balanced. The value is approximately 4.3. Continue to wash the co-extracted manganese, cobalt and nickel ions with 1 mol/L hydrochloric acid in the extraction clarification tank at a volume ratio of 10:1 in the aluminum-loaded organic phase for 3 levels, and return the washing liquid to the inlet of the water phase. The washed organic phase continues to be back-extracted with 10 mol/L hydrochloric acid at a volume ratio of 10:1 in the extraction and clarification tank, and the back-extraction is performed in 3 stages to obtain chlorinated chlorine with an aluminum purity >99% and an aluminum concentration of 48-81g/L. aluminum solution. The organic phase after stripping is returned to the extraction section for recycling.

Example 3:

The system of the invention is used for separation of aluminum and magnesium from coal slag leaching liquid. The types and contents of metals in the leachate are: aluminum 1.5g/L, magnesium 0.5g/L. The extraction agent is 2-(decyloxy)acetic acid, the co-solvent is TBP, and the diluent is kerosene.

Take 4 vol% 2-(decyloxy)acetic acid, 4 vol% TBP and 92 vol% kerosene to prepare the aluminum extraction organic phase. Add 2vol% 4mol/L NaOH solution to the organic phase and mix thoroughly for 30 minutes to saponify the extractant (saponification rate 48%). The saponified organic phase and aqueous phase were subjected to 4-stage continuous countercurrent extraction in an extraction clarification tank at a volume ratio of 1:1 to obtain an aluminum-loaded organic phase. The measured extraction rate of aluminum was >99%, and the extraction rate of magnesium was 0. (No washing step required). The organic phase continues to be back-extracted with 3 mol/L hydrochloric acid at a volume ratio of 10:1 in the extraction and clarification tank, and the back-extraction is performed in 3 stages to obtain an aluminum chloride solution with an aluminum purity >99.5% and an aluminum concentration of 9-15g/L. The organic phase after stripping is returned to the extraction section for recycling.

Example 4:

The system of the invention is used for extraction and separation of aluminum in rare earth ore leachate. The types and contents of metals in the leachate are: aluminum 8.1g/L, neodymium 14.4g/L, and praseodymium 14g/L. The extraction agent is 2-(decyloxy)acetic acid, the co-solvent is TBP, and the diluent is kerosene.

Take 24 vol% 2-(decyloxy)acetic acid, 20 vol% TBP and 56 vol% kerosene to prepare the aluminum extraction organic phase. Add 2vol% 10mol/L NaOH solution to the organic phase and mix thoroughly for 30 minutes to saponify the extractant (saponification rate 20%). The saponified organic phase and aqueous phase were carried out in an extraction clarification tank at a volume ratio of 1:1 to carry out 4-stage continuous countercurrent extraction to obtain an aluminum-loaded organic phase. The extraction rate of aluminum was measured to be >99%. The pH after the extraction reaction was balanced. The value is about 3.6. Continue to wash the co-extracted neodymium and praseodymium ions with 1 mol/L hydrochloric acid in the extraction clarification tank at a volume ratio of 10:1 in the aluminum-loaded organic phase for 3 levels, and return the washing liquid to the inlet of the water phase. The organic phase continues to be back-extracted with 10 mol/L hydrochloric acid at a volume ratio of 10:1 in the extraction and clarification tank, and the back-extraction is performed in 3 stages to obtain an aluminum chloride solution with an aluminum purity >99% and an aluminum concentration of 48-81g/L. The organic phase after stripping is returned to the extraction section for recycling.

Example 5:

The system of the invention is used for extraction and separation of aluminum in laterite nickel ore leachate. The types and contents of metals in the leachate are: aluminum 5.4g/L, manganese 2.7g/L, cobalt 3.0g/L, magnesium 2.4g/L, and nickel 5.9g/L. The extraction agent is 2-(octyloxy)acetic acid, the co-solvent is n-octanol, and the diluent is kerosene.

Take 16.8 vol% 2-(octyloxy)acetic acid (purity 95%), 20 vol% n-octanol and 63.2 vol% kerosene to prepare the aluminum extraction organic phase. Add 2vol% 10mol/L NaOH solution to the organic phase and mix thoroughly for 30 minutes to saponify the extractant (saponification rate 25%). The saponified organic phase and aqueous phase were carried out in an extraction clarification tank at a volume ratio of 1:1 to carry out 4-stage continuous countercurrent extraction to obtain an aluminum-loaded organic phase. The extraction rate of aluminum was measured to be >98%. The pH after the extraction reaction was balanced. The value is approximately 4.2. Continue to wash the co-extracted manganese, cobalt and nickel ions with 1 mol/L hydrochloric acid in the extraction clarification tank at a volume ratio of 10:1 in the aluminum-loaded organic phase for 3 levels, and return the washing liquid to the inlet of the water phase. The washed organic phase continues to be back-extracted with 10 mol/L hydrochloric acid at a volume ratio of 10:1 in the extraction and clarification tank, and the back-extraction is performed in 3 stages to obtain chlorinated chlorine with an aluminum purity >99% and an aluminum concentration of 32-54g/L. aluminum solution. The organic phase after stripping is returned to the extraction section for recycling.

Claims (10)

1. An aluminum solvent extraction system, comprising a modified carboxylic acid extractant, a co-solvent and a diluent, wherein the modified carboxylic acid extractant has a structure of formula I, wherein R is a linear or branched chain of C4-C18 alkyl group; n represents the number of CH ₂ units connected to the carboxyl functional group, which is an integer from 0 to 2, 2. The aluminum solvent extraction system according to claim 1, characterized in that: the volume ratio of the modified carboxylic acid extractant is 0.5%-95%, the volume ratio of the co-solvent is 1-30%, and the balance is diluent. , based on the total volume of the extraction system. 3. The aluminum solvent extraction system according to claim 1, characterized in that: the co-solvent is one or a mixture of phosphate esters and alkyl alcohols; the diluent is one of C6-C16 alkanes. or a mixture of several. 4. A method for extracting aluminum in a mixed metal ion solution, wherein the aluminum solvent extraction system according to any one of claims 1-3 is used, including the following steps: (1) Mix the modified carboxylic acid extractant, co-solvent and diluent to form an aluminum solvent extraction system; (2) Contact the solvent extraction system configured in step (1) with a certain amount of alkali to saponify the modified carboxylic acid extractant therein to obtain a saponified solvent extraction system; (3) Pass the saponified solvent extraction system obtained in step (2) and the solution to be extracted into the extraction equipment to mix, and perform a single-stage extraction or multi-stage countercurrent extraction reaction to obtain an aluminum-loaded organic phase. The pH at which the extraction reaction is balanced The value range is 2.5-4.5; (4) The aluminum-loaded organic phase obtained in step (3) is subjected to single-stage washing or multi-stage countercurrent washing with washing liquid to remove co-extracted impurity ions, and obtain the washed aluminum-loading organic phase; (5) Perform single-stage back-extraction or multi-stage counter-current back-extraction on the washed organic phase obtained in step (4) with stripping liquid to obtain the stripped organic phase and high-purity aluminum salt solution; (6) Return the stripped organic phase obtained in step (5) to the organic phase storage tank, saponify it again, and recycle it for aluminum extraction. 5. The method according to claim 4, characterized in that: in step (2), based on the molar concentration of aluminum in the solution to be extracted, the concentration of the carboxylic acid extractant in the solvent extraction system is determined, and the amount of alkali added is determined, The saponification rate of the extraction agent ranges from 5% to 100%, and the alkali is sodium hydroxide, potassium hydroxide, ammonia or any mixture thereof. 6. The method according to claim 4, characterized in that in step (3), the volume ratio of the saponified solvent extraction system and the liquid to be extracted is 1:50-50:1. 7. The method according to claim 4, characterized in that: in step (4), the washing liquid is water, dilute hydrochloric acid or dilute sulfuric acid, and the concentration of the hydrochloric acid or sulfuric acid solution is 0.01-3.0mol/L; organic The volume ratio of phase to washing liquid is 1:50-50:1. 8. The method according to claim 4, characterized in that: in step (5), the stripping liquid is hydrochloric acid or sulfuric acid solution, with a concentration of 0.1-12.0 mol/L; the volume of the organic phase and stripping liquid The ratio is 1:50-50:1. 9. Use of the aluminum solvent extraction system according to any one of claims 1 to 3 for extracting aluminum ions from a mixed metal ion solution. 10. The use according to claim 9, wherein the extraction of aluminum ions from mixed metal ion solutions includes aluminum removal from rare earth separation raw material liquids, aluminum recovery from decommissioned battery leaching liquids, aluminum magnesium lithium separation from coal slag leaching liquids, and aluminum separation from laterite nickel ores. .