Black Mass Processing With Closed-Loop Lithium Sulfate Recovery
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Solution Overview
Problem
Current lithium ion battery recycling methods, particularly hydrometallurgical routes, face challenges such as high carbon footprint, significant wastewater generation, and the need for caustic chemicals, which increase costs and environmental impact, due to the use of high-temperature processes and expensive reducing agents, and result in impurity buildup during recycling.
Innovation Solution
A method involving leaching black mass with sulfuric acid and a reducing agent, followed by filtration, impurity removal using lithium hydroxide, chromatographic lithium separation, and ion exchange to produce lithium sulfate, which is then converted to lithium hydroxide, allowing in-situ production of process chemicals and reducing sodium sulfate discharge, thereby minimizing wastewater and CO2 footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-temperature pyrometallurgical processes are used for metal recovery, then metal separation efficiency is improved, but CO2 emissions and energy consumption increase significantly
Solution Approach 1:
The patent changes the temperature parameter from high-temperature pyrometallurgical processing to low-temperature hydrometallurgical processing. The leaching process occurs at ambient or mildly elevated temperatures, fundamentally altering the thermal regime to eliminate the need for energy-intensive high-temperature operations while maintaining effective metal recovery through chemical dissolution and selective precipitation
Solution Approach 2:
The patent replaces the mechanical/thermal pyrometallurgical system with a chemical hydrometallurgical system. Instead of using heat and mechanical energy for metal separation, the invention employs chemical reactions including acid leaching, complexation, and selective precipitation to achieve metal recovery, substituting one energy-intensive system with a chemically-driven alternative
2Measurement precision
If conventional hydrometallurgical routes use sodium or ammonium hydroxide for pH control, then metal separation is achieved, but sodium sulfate or ammonium sulfate waste accumulates in the process liquor
Solution Approach 1:
The patent implements self-service by using lithium hydroxide for pH control instead of external sodium or ammonium hydroxide. The lithium hydroxide is generated in-situ from lithium sulfate produced during the leaching process, creating a self-sustaining system where the process generates its own reagents. This eliminates the accumulation of sodium sulfate or ammonium sulfate waste because lithium sulfate is already present in the system and lithium hydroxide can be converted back to lithium sulfate through electrodialysis
Solution Approach 2:
The patent recovers lithium sulfate that would otherwise be considered waste or intermediate byproduct and converts it to lithium hydroxide through electrodialysis. This recovered lithium hydroxide is then reused for pH control in subsequent processing steps, creating a closed-loop system that prevents waste accumulation and reduces the need for external chemical inputs
3Manufacturing precision
If liquid-liquid extraction is used for metal separation, then purification efficiency is improved, but kerosene must be replaced at regular intervals due to fouling, increasing CO2 output
Solution Approach 1:
The patent substitutes the liquid-liquid extraction system using organic solvents like kerosene with an alternative separation approach based on selective precipitation and filtration. This replacement eliminates the need for organic solvents that require periodic disposal and replacement, thereby removing the associated CO2 emissions from solvent manufacturing and waste处理 while maintaining effective metal purification through chemical selectivity
4Quantity of substance
If reductive roasting followed by leaching is used for lithium recovery, then lithium extraction is achieved, but high temperatures (>500°C) and expensive reducing agents significantly increase the carbon footprint
Solution Approach 1:
The patent replaces the thermal reductive roasting process with direct acid leaching. Instead of using high-temperature thermal treatment with reducing agents like hydrogen or coal, the invention employs aqueous acid solutions to dissolve lithium and other metals directly from the black mass. This substitution eliminates the need for high-temperature heating and expensive reducing agents, dramatically reducing the carbon footprint while achieving effective lithium extraction
Solution Approach 2:
The patent fundamentally changes the temperature parameter from >500°C in reductive roasting to ambient or mildly elevated temperatures in acid leaching. This parameter change transforms the process from energy-intensive thermal treatment to a chemically-driven low-temperature process, eliminating the carbon emissions associated with high-temperature operation and reducing energy consumption
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 effectively recycles nickel, cobalt, manganese, and lithium while reducing operational expenses, lowering the CO2 footprint, and avoiding the use of caustic chemicals, thereby enhancing the sustainability and environmental friendliness of the recycling process.
Implementation Method 1
leaching the black mass using sulfuric acid and a reducing agent to produce a first process solution comprising lithium sulfate and at least one of manganese sulfate, copper sulfate, nickel sulfate and cobalt sulfate
Implementation Method 2
leaching the black mass using sulfuric acid and a reducing agent to produce a first process solution
Implementation Method 3
removing impurities from the first process solution using lithium hydroxide, to produce a second process solution
Implementation Method 4
separating lithium from the second process solution using chromatographic lithium separation producing lithium sulfate and a third process solution
Implementation Method 5
separating at least one of copper, nickel and cobalt from the third process solution by ion exchange producing lithium sulfate
Implementation Method 6
converting the lithium sulfate produced in step 3) and/or 4) by electrodialysis to lithium hydroxide to be used in at least one of the steps 2), 3) and 4), and to sulfuric acid to be used in step 1)
Implementation Method 7
converting the lithium sulfate produced in step 3) and/or 4) by electrodialysis to lithium hydroxide
Data Source
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AI summary
According to an example aspect of the present invention, there is provided a method for processing a black mass to battery chemicals. The method comprises leaching the black mass using sulfuric acid and a reducing agent to produce a first process solution comprising lithium sulfate and at least one of manganese sulfate, copper sulfate, nickel sulfate and cobalt sulfate, and impurities, which first process solution is separated from graphite by filtration. Thereafter, the process comprises removing impurities from the first process solution using lithium hydroxide, to produce a second process solution, separating lithium from the second process solution using chromatographic lithium separation producing lithium sulfate and a third process solution and separating at least one of copper, nickel and cobalt from the third process solution by ion exchange producing lithium sulfate. Finally, the process comprises converting the lithium sulfate produced by electrodialysis to lithium and to sulfuric acid to be used in the method.