Two-Stage Solvent Extraction for High-Purity Ni-Co-Mn Separation
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Solution Overview
Problem
Existing hydrometallurgical processes for recovering nickel, cobalt, and manganese from lithium secondary batteries are limited in their ability to individually separate and recover these valuable metals, often resulting in alloys or mixed metal products, and the use of sodium-based neutralizing agents leads to decreased process efficiency due to metal salt formation.
Innovation Solution
A two-stage solvent extraction method involving a first step to recover manganese sulfate and a second step to separately recover nickel and cobalt sulfate, utilizing phosphoric and phosphinic extractants to manage pH levels and minimize the use of sodium-based neutralizing agents, enhancing recovery rates and process efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage extraction process is used, then the process complexity is reduced, but the ability to individually separate and recover Ni, Co, and Mn is lost
Solution Approach 1:
The extraction process is divided into two distinct stages: first extraction for Mn separation and second extraction for Ni-Co separation. This segmentation allows each stage to target specific metals with optimized conditions, achieving individual metal recovery while maintaining manageable process complexity through systematic division of tasks.
Solution Approach 2:
The patent employs dynamic adjustment of pH conditions and extractant types across different extraction stages. The first extraction uses pH 3-4 with specific extractants for Mn, while the second extraction adjusts to pH 1-2 for Ni-Co separation. This dynamic parameter adjustment enables precise control over metal separation selectivity.
2Temperature
If sodium-based reagents (NaOH, Na2CO3, Na2SO4) are used to increase pH, then the pH control is achieved, but process efficiency decreases due to metal salt formation
Solution Approach 1:
The patent changes the chemical parameter approach by using potassium hydroxide (KOH) instead of sodium-based reagents for pH adjustment. This parameter substitution prevents the formation of insoluble metal salts that would reduce process efficiency, while still achieving the required pH levels for effective extraction.
3Ease of operation
If conventional extraction methods are used, then the process is simple to operate, but the recovery rate of valuable metals is limited
Solution Approach 1:
The patent implements continuous counter-current extraction where the leachate flows through multiple extraction stages with fresh and regenerated extractants. This continuous process maximizes metal recovery by repeatedly contacting the solution with extractants, ensuring thorough separation while maintaining operational simplicity through a standardized flow pattern.
Solution Approach 2:
The patent introduces specific organic extractants as intermediary substances that facilitate selective metal transfer between aqueous and organic phases. These intermediaries (such as phosphoric acid esters and carboxylic acid derivatives) enable high-selectivity extraction of different metals, dramatically improving recovery rates while keeping the overall process operationally simple.
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 allows for the individual separation and recovery of nickel, cobalt, and manganese with high purity, increasing recovery rates and minimizing process inefficiencies caused by metal salt formation, while reusing by-products to prepare nickel hydroxide, thus optimizing the extraction process.
Implementation Method 1
a first solvent extraction step of separating Mn contained in the raw material leachate as a manganese sulfate aqueous solution (MnSO4)
Implementation Method 2
a second solvent extraction step of separating Ni and Co contained in the raw material leachate from which Mn is separated as a nickel sulfate aqueous solution (NiSO4) and a cobalt sulfate aqueous solution (CoSO4)
Implementation Method 3
a leaching step of adding sulfuric acid to the starting material cake for reaction
Implementation Method 4
an iron precipitation step of adding hydrogen peroxide and nickel hydroxide (Ni(OH)2) to a reaction product formed through the leaching step to precipitate an iron component
Data Source
AI summary
Proposed is a solvent extraction method using two-stage extraction for separation and recovery of nickel, cobalt, and manganese. More specifically, the method relates to a two-stage extraction-based solvent extraction method for separately recovering nickel, cobalt, and manganese from a starting material containing nickel, cobalt, and manganese. The method includes a first solvent extraction step in which manganese is recovered from the starting material and a second solvent extraction step in which nickel and cobalt are extracted from the starting material so that three kinds of valuable metals can be separately recovered.