Lithium Recovery via Solvent Extraction at Controlled pH
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Solution Overview
Problem
Current methods for recovering lithium from lithium ion batteries are inefficient due to the presence of impurities like phosphorus and fluorine, which are not effectively removed, leading to contaminated lithium that cannot be reused as a high-quality component.
Innovation Solution
A lithium recovery method involving solvent extraction using an acidic solvent extractant at a pH of 4 to 9 and a temperature of 0 to 25°C, followed by a stripping process with an acid solution of pH 3 or less, to extract lithium ions from discharge and cleaning liquids, thereby suppressing hydrolysis reactions and removing impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If wet treatment is used to recover valuable metals from lithium ion batteries, then lithium can be recovered, but impurities such as phosphorus and fluorine are mixed in, preventing efficient recovery of high-quality lithium
Solution Approach 1:
The patent applies solvent extraction to separate lithium from impurities. The organic solvent selectively extracts lithium ions from the aqueous solution containing hydrolysis products, leaving phosphorus and fluorine impurities in the aqueous phase. This extraction process effectively removes impurities while recovering lithium in high purity form.
Solution Approach 2:
The patent controls the pH parameter to suppress hydrolysis reactions. By maintaining the solution pH in a specific range (pH 4-9 during extraction, pH 3 or less during stripping), the hydrolysis of lithium salts is minimized, preventing the formation of phosphorus and fluorine containing precipitates, thus ensuring high lithium purity recovery.
2Quantity of substance
If LiPF6 undergoes hydrolysis reaction through wet treatment, then lithium phosphate and lithium fluoride precipitates are formed, but lithium cannot be efficiently recovered in the form of a simple substance
Solution Approach 1:
The patent applies preliminary anti-action by controlling the pH environment to prevent hydrolysis reactions before they can occur. By maintaining pH 4-9 during extraction and pH 3 or less during stripping, the conditions for hydrolysis of LiPF6 are suppressed, preventing the formation of lithium phosphate and lithium fluoride precipitates that would contaminate the recovered lithium.
Solution Approach 2:
The patent replaces conventional precipitation methods with solvent extraction. Instead of allowing hydrolysis and precipitation to occur naturally, the invention uses an organic solvent system that selectively extracts lithium ions through solvation, substituting the chemical precipitation mechanism with a selective solvation mechanism that yields high-purity lithium.
3Quantity of substance
If conventional wet treatment methods are used, then lithium recovery is achieved, but the process complexity increases and cost reduction becomes difficult
Solution Approach 1:
The patent combines multiple functions into a single solvent extraction process. The organic solvent simultaneously performs lithium extraction and impurity separation in one operation, eliminating the need for separate precipitation, filtration, and purification steps required in conventional wet treatment methods, thus simplifying the overall process.
Solution Approach 2:
The solvent extraction system serves multiple functions: it extracts lithium from the aqueous solution, separates lithium from phosphorus and fluorine impurities, and produces high-purity lithium concentrate. This multi-functional approach replaces multiple separate treatment operations, reducing process complexity while achieving both quantity and quality recovery goals.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for the efficient recovery of high-purity lithium without phosphorus and fluorine contamination, enabling the reuse of lithium as a component in lithium ion batteries.
Implementation Method 1
allowing an acidic solvent extractant to be in contact with the discharge liquid and/or the cleaning liquid under a low temperature condition to extract lithium ions
Implementation Method 2
allowing the acidic solvent extractant having extracted the lithium ions to be in contact with an acid solution to strip the lithium ions
Implementation Method 3
This LiPF6 has a hydrolysis reaction through wet treatment, and forms a precipitate in the forms of lithium phosphate and lithium fluoride... by performing solvent extraction treatment to allow an acidic solvent extractant to be in contact with and stirred with a discharged liquid... under a low temperature condition
Data Source
Figure 1
AI summary
To provide a lithium recovery method which is capable of efficiently recovering lithium without containing impurities, such as phosphorus and fluorine. In the present invention, an alkali is added to a discharge liquid and/or a cleaning liquid containing lithium discharged in a process of recovering valuable metals from a lithium ion battery, an acidic solvent extractant is caused to be in contact with the discharge liquid and/or the cleaning liquid under a condition of pH 9 or less and a temperature of 0 to 25°C and lithium ions are extracted, and the acidic solvent extractant having extracted the lithium ions is caused to be in contact with an acid solution of pH 3 or less and the lithium ions are stripped.