Battery Black Mass Leachate Purification via Selective Phosphate Precipitation
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Solution Overview
Problem
The recycling of lithium-ion batteries faces challenges due to the lack of a standardized process, high cost, and inefficiencies in recovering valuable cathode metals like lithium, nickel, manganese, and cobalt, exacerbated by varying chemical compositions across different manufacturers.
Innovation Solution
A process involving the use of phosphoric acid to form iron phosphate (FePO4) and aluminium phosphate (AlPO4) precipitates, followed by two-stage pH adjustments and crystallization seeds, to efficiently separate and recover cathode metals from black mass, minimizing co-precipitation of valuable metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional acid leaching is used to recover cathode metals, then metal recovery is achieved, but co-precipitation of valuable metals with impurities occurs reducing purity
Solution Approach 1:
The patent applies preliminary action by adjusting the pH of the leachate before the main precipitation process. By pre-adjusting pH to specific ranges (pH 2-4 for iron, pH 1-2 for aluminum), the process ensures selective precipitation conditions are established in advance, preventing co-precipitation of valuable cathode metals while removing impurities efficiently
Solution Approach 2:
The patent employs parameter changes by systematically varying pH levels at different stages of the precipitation process. Different pH ranges are used for different impurities (pH 2-4 for iron phosphate, pH 1-2 for aluminum phosphate), and temperature is also adjusted (50-90°C) to optimize precipitation selectivity and prevent valuable metal co-precipitation
2Manufacturing precision
If multiple precipitation steps are used to remove impurities, then metal purity increases, but process complexity and time increase
Solution Approach 1:
The patent applies segmentation by dividing the impurity removal process into distinct sequential steps: first removing iron phosphate at pH 2-4, then removing aluminum phosphate at pH 1-2. Each step targets specific impurities with optimized conditions, achieving high purity through modular, manageable stages rather than a single complex process
Solution Approach 2:
By pre-adjusting pH and adding specific reagents (such as sodium hydroxide or ammonium hydroxide) before each precipitation step, the process simplifies the overall complexity. The preliminary preparation ensures that each subsequent precipitation step proceeds efficiently with minimal additional complexity
3Manufacturing precision
If high pH adjustment is used to remove all impurities, then purity increases, but valuable cathode metals co-precipitate
Solution Approach 1:
The patent prevents valuable metal loss by carefully controlling and changing pH parameters within specific ranges. For iron removal, pH is maintained at 2-4; for aluminum removal, pH is maintained at 1-2. These controlled parameter changes ensure impurities precipitate while valuable cathode metals remain in solution and can be recovered
Solution Approach 2:
The patent applies local quality by creating different local chemical environments at different stages of the process. Each precipitation step has its own optimized pH and temperature conditions tailored to remove specific impurities without affecting valuable metals. This localized optimization ensures high purity recovery without loss of cathode materials
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 achieves high recovery rates of NMC metals and lithium while reducing impurities, making it suitable for large-scale recycling with varying input compositions, and minimizing water consumption.
Implementation Method 1
adding phosphoric acid (H3PO4) to the leachate from step a), c) adjusting the pH to form iron phosphate (FePO4) and aluminium phosphate (AlPO4), d) precipitating and removing the formed FePO4 and AlPO4
Implementation Method 2
crystallization seeds, to efficiently separate and recover cathode metals from black mass
Data Source
AI summary
A process for removal of aluminium and iron in the recycling of rechargeable batteries comprising providing a leachate from black mass, adding phosphoric acid (H3PO4) to said leachate and adjusting the pH to form iron phosphate (FePO4) and aluminium phosphate (AlPO4), precipitating and removing the formed FePO4 and AlPO4, and forming a filtrate for further recovery of cathode metals, mainly NMC-metals and lithium.