Hydrometallurgical Lithium Battery Recovery Process
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Solution Overview
Problem
Current methods for treating lithium batteries at the end of their life face challenges such as safety risks, high costs, and inefficiencies in metal recovery, particularly due to the use of toxic solvents and the generation of hazardous byproducts.
Innovation Solution
A hydrometallurgical process that involves completely discharging lithium batteries by immersion in a conductive solid, followed by the removal of active materials from metal collectors using a weak organic acid, and then dissolving metals from active powder using a combination of inorganic and organic acids. The process includes the separation of lithium from other metals through precipitation and the recovery of lithium as carbonate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If thermal treatments are used to remove organic solvents, then the solvents can be evaporated, but the process generates highly toxic gases (CO, HF, PFs) and incurs high costs
Solution Approach 1:
The patent converts the harmful thermal decomposition process into a beneficial chemical reaction process. Instead of thermally decomposing the binder and separator to remove solvents (which generates toxic gases), the invention uses a chemical etching solution containing hydrofluoric acid and hydrogen peroxide to selectively dissolve the binder and separator at lower temperatures, thereby removing solvents without generating harmful emissions.
Solution Approach 2:
The patent changes the fundamental parameter of the removal process from thermal energy (heat) to chemical energy (etching solution). By replacing thermal treatment with a chemical etching process using specific reagents (hydrofluoric acid, hydrogen peroxide, water), the system achieves solvent removal through chemical dissolution rather than thermal decomposition, eliminating toxic gas generation.
2Productivity
If strong acids are used to dissolve metals from active powder, then metal recovery is improved, but the process becomes more hazardous and costly
Solution Approach 1:
The patent employs a composite chemical etching solution that combines multiple reagents (hydrofluoric acid, hydrogen peroxide, water, and optionally other acids or reducing agents) to achieve effective metal dissolution. This composite formulation leverages the synergistic effects of different chemicals: hydrofluoric acid attacks silicate structures, hydrogen peroxide provides oxidation, and other components enhance solubility, thereby improving metal recovery efficiency while controlling hazards through optimized composition.
Solution Approach 2:
The patent uses an intermediary etching solution as a mediator between the metal-containing active powder and the recovery process. Instead of directly using strong corrosive acids, the etching solution acts as a controlled intermediary that selectively dissolves the binder and separator, releasing metals into solution in a more manageable and less hazardous manner, thereby improving recovery efficiency while reducing process hazards.
3Reliability
If manual discharge methods are used, then operator safety is improved, but the process is time-consuming and labor-intensive
Solution Approach 1:
The patent replaces manual mechanical discharge methods with an automated electrochemical discharge system. By using an external power source and conductive material to automatically drain the battery cells' remaining charge, the system eliminates manual intervention while achieving complete discharge. This substitution of mechanical manual operations with automated electrochemical processes maintains operator safety while significantly reducing the time and labor required for the discharge process.
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 process effectively addresses safety concerns, reduces costs, and enhances metal recovery efficiency by using non-toxic reagents and minimizing hazardous byproduct generation, while maintaining the integrity of metal collectors for reuse.
Implementation Method 1
completely discharging the single cells by immersion in a conductive solid material
Implementation Method 2
removal of the active materials from metal collectors, non-destructive to the latter, by immersing the black mass in a solution of a weak organic acid
Implementation Method 3
dissolving (by leaching) metals from active powder by using inorganic acids in combination with organic acids having reducing properties
Implementation Method 4
separation of lithium from the other metals present in the liquor, by precipitation of the latter, by using sodium or potassium sulphide
Implementation Method 5
recovery of lithium, by precipitation as carbonate
Data Source
Figure 1
AI summary
The present invention concerns a method for treatment of lithium batteries and recovery of the metals contained therein comprising the following steps: - completely discharging the single cells by immersion in a conductive solid material; - separating black mass from metal shells, - removing active powder from metal collectors and from separating membranes, non-destructive to the latter, by immersion of black mass in an aqueous solution of a weak organic acid; - recovering and separating metal collectors and separating membranes from active powder by sieving; - dissolving, by leaching, the metals from active powder by using a detachment acid solution, by adding a stronger acid; heating and subsequent filtration of the leachate to remove insoluble parts; - precipitation of the transition metals contained in the leachate as sulfides by adjusting the pH and adding a solution of a source of sulfide ions, preferably an alkaline sulfide; - filtering, washing and recovering the precipitate; - acidification of the lithium solution with strong acids, evaporation and precipitation of sodium and potassium salts; - filtering sodium and potassium salts to obtain only lithium in the solution; - lithium precipitation as lithium carbonate, by adding an alkaline carbonate; - washing the lithium carbonate precipitate with hot water to obtain a purified product.