Solvent Extraction Selective Magnesium Separation
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Solution Overview
Problem
Existing methods fail to selectively separate magnesium from acidic aqueous solutions of sulfuric acid containing nickel and cobalt, leading to impurities in lithium-ion battery materials that deteriorate battery performance.
Innovation Solution
A solvent extraction method involving contact between an acidic aqueous solution of sulfuric acid containing nickel, cobalt, and magnesium with an organic solvent, using a dilute solution of bis(2-ethylhexyl) hydrogen phosphate as the extractant, with a concentration of 40-60 volume% and a pH of 1.5-2.0, to selectively extract magnesium into the organic phase while keeping nickel and cobalt in the aqueous phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing solvent extraction methods are used to separate nickel and cobalt, then nickel sulfate and cobalt sulfate solutions are obtained, but magnesium remains as impurity in the nickel sulfate solution and cannot be selectively removed
Solution Approach 1:
The patent changes the extraction parameters by using a specific extractant concentration range (40-60 volume%) and pH range (1.5-2.0) to achieve selective magnesium extraction. This parameter optimization allows magnesium to be extracted into the organic phase while nickel and cobalt remain in the aqueous phase, resolving the contradiction between obtaining pure nickel sulfate solution and removing magnesium impurities
Solution Approach 2:
The patent applies extraction principle by selectively transferring magnesium from the aqueous phase to the organic phase using an organic solvent containing bis(2-ethylhexyl) hydrogen phosphate. This separation process removes magnesium impurities from the nickel sulfate solution, achieving the desired purity while preventing magnesium from contaminating the final product
2Ease of manufacture
If magnesium is not removed from the acidic aqueous solution, then the processing is simpler, but the positive electrode material contains magnesium impurities that deteriorate battery charge/discharge capacity
Solution Approach 1:
The patent applies preliminary action by removing magnesium impurities from the acidic aqueous solution before manufacturing the positive electrode material. This pre-treatment step ensures that magnesium does not contaminate the final product, thereby maintaining battery performance while adding only one extraction step to the overall process
3Productivity
If the extractant concentration is increased to improve magnesium extraction efficiency, then more magnesium is extracted, but nickel and cobalt may also be extracted into the organic phase
Solution Approach 1:
The patent optimizes the extractant concentration to a specific range (40-60 volume%) and maintains pH between 1.5-2.0. This parameter optimization ensures high magnesium extraction efficiency while maintaining selectivity, preventing nickel and cobalt from being co-extracted into the organic phase
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 efficient separation of magnesium from nickel and cobalt, enhancing the purity of materials for lithium-ion batteries and reducing the need for post-extraction agents, thereby improving battery performance.
Implementation Method 1
bringing an acidic aqueous solution of sulfuric acid containing nickel, cobalt, and magnesium in contact with an organic solvent to selectively extract the magnesium from the acidic solution into the organic solvent
Data Source
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AI summary
Provided is a solvent extraction method that allows selectively separating magnesium from an acidic aqueous solution of sulfuric acid. The solvent extraction method includes: bringing an acidic aqueous solution of sulfuric acid containing nickel, cobalt, and magnesium in contact with an organic solvent to extract the magnesium into the organic solvent; and using the organic solvent produced by diluting an extractant made of alkylphosphonic acid ester with a diluent. A concentration of the extractant is set to 40 volume% or more and 60 volume% or less and a pH of the acidic aqueous solution of sulfuric acid is set to 1.5 or more and 2.0 or less, or the concentration of the extractant is set to 20 volume% or more and 50 volume% or less and the pH of the acidic aqueous solution of sulfuric acid is set to 2.0 or more and 2.5 or less.