Cobalt Solution Purification by Magnesium-Selective Solvent Extraction

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Solution Overview

Problem

The recovery of cobalt and nickel from lithium ion battery waste is hindered by the presence of magnesium ions, which reduce the purity of the cobalt and nickel solutions, making them unsuitable for effective reuse in lithium ion batteries.

Innovation Solution

A method involving solvent extraction using carboxylic acid-based extracting agents to separate cobalt ions from magnesium ions, followed by stripping to obtain a high-purity cobalt solution, and using phosphonate ester-based extracting agents to separate nickel ions from magnesium ions at specific pH levels, followed by stripping to obtain a high-purity nickel solution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional solvent extraction methods are used to recover cobalt and nickel from lithium ion battery waste, then metal recovery is achieved, but magnesium ions remain in the solution reducing purity

Engineering Contradiction:
Improvepurity of cobalt and nickel solutionsVSAvoidconcentration of magnesium ions
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The patent extracts magnesium ions from the metal mixed solution using a specialized extracting agent system. The first extracting agent selectively removes magnesium ions in an initial extraction step, separating them from cobalt and nickel ions before subsequent recovery processes, thereby achieving high purity metal solutions.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent controls pH parameters throughout the extraction process to optimize magnesium ion removal. By adjusting pH to specific ranges during different extraction stages, the extracting agents achieve selective binding with magnesium ions while leaving cobalt and nickel ions in solution, resolving the purity issue.

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If multiple extraction steps are added to remove magnesium ions, then purity of cobalt and nickel solutions is improved, but process complexity increases

Engineering Contradiction:
Improvepurity of cobalt and nickel solutionsVSAvoidnumber of extraction steps
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent divides the extraction process into distinct sequential steps: first extraction for magnesium removal, followed by second extraction for cobalt recovery, and third extraction for nickel recovery. Each step uses optimized extracting agents and pH conditions to achieve selective separation, improving purity without requiring excessive process complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent employs a multi-functional extracting agent system where the first extracting agent is designed to handle magnesium removal while being compatible with subsequent cobalt and nickel recovery steps. This universal approach allows one extraction system to serve multiple separation functions, reducing overall process complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

The method effectively removes magnesium ions, resulting in cobalt and nickel solutions with minimal impurities, suitable for the production of lithium ion batteries.

Implementation Method 1

a method involving solvent extraction using carboxylic acid-based extracting agents to separate cobalt ions from magnesium ions

Methodology Applied
Scientific EffectSolvent extraction: Liquid-Liquid Extraction

Implementation Method 2

using phosphonate ester-based extracting agents to separate nickel ions from magnesium ions at specific pH levels

Methodology Applied
Scientific EffectSolvent extraction: Liquid-Liquid Extraction

Data Source

PatentEP4417721B1Method for producing cobalt solution
Publication Date: 2026.04.01 JX METALS CIRCULAR SOLUTIONS CO LTD
  • EP4417721B1 patent drawingFigure 1~2
  • EP4417721B1 patent drawingFigure 3~4
  • EP4417721B1 patent drawingFigure 5~6

AI summary

A method for producing a cobalt solution by removing magnesium ions from a cobalt-containing solution obtained by subjecting battery powder resulting from lithium ion battery waste to at least a leaching process, the cobalt-containing solution containing magnesium ions, wherein the method includes: a magnesium separation step of extracting cobalt ions from the cobalt-containing solution using a solvent containing a carboxylic acid-based extracting agent to separate the magnesium ions, and then stripping the cobalt ions from the solvent to obtain the cobalt solution as a stripped solution.