Lithium Recovery from LFP Battery Black Powder via Chlorine Roasting
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Solution Overview
Problem
Current recycling methods for lithium in waste lithium iron phosphate batteries are inefficient, costly, and environmentally harmful due to complex processes and low lithium recovery rates.
Innovation Solution
A roasting method using controlled chlorine flow rates to manage temperature in a roasting processing furnace, converting lithium into water-soluble lithium chloride, followed by water immersion, suction filtration, and evaporation to produce lithium chloride crystals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet processes and pyrometallurgical processes are used for recycling lithium, then the batteries can be processed, but the process flow becomes long and complex with high cost
Solution Approach 1:
The patent segments the recycling process into distinct functional stages: roasting treatment to convert lithium compounds into water-soluble lithium chloride, filtration to separate lithium chloride from insoluble residues, and evaporation to crystallize pure lithium chloride. This segmentation transforms the complex wet/pyrometallurgical processes into a simplified three-step method, directly resolving the contradiction between process effectiveness and complexity
Solution Approach 2:
The patent extracts the lithium recovery function from the complex battery recycling system by focusing specifically on converting lithium compounds to water-soluble lithium chloride through controlled roasting, then separating and crystallizing it. This extraction approach isolates the essential lithium recovery mechanism from unnecessary process complexity, achieving high lithium recovery rates with a simplified process flow
2Productivity
If conventional recycling methods are used, then batteries can be processed, but the lithium element recycling rate is low resulting in poor economic benefits
Solution Approach 1:
The patent applies parameter changes by controlling the roasting temperature (400-600°C) and chlorine gas flow rate to optimize the conversion of lithium iron phosphate to water-soluble lithium chloride. By precisely adjusting these parameters, the process achieves over 95% lithium recovery rate, directly resolving the contradiction between recovery efficiency and economic benefit
Solution Approach 2:
The patent converts the harmful chlorine gas, which would normally be a waste product or pollutant, into a useful reagent that drives the selective conversion of lithium compounds. The chlorine gas reacts with lithium iron phosphate to produce water-soluble lithium chloride, transforming a potential environmental hazard into the key mechanism for high-efficiency lithium recovery, thereby improving both recovery rate and economic efficiency
3Productivity
If high temperature roasting is used to convert lithium, then reaction efficiency improves, but energy consumption increases
Solution Approach 1:
The patent utilizes phase transitions by controlling the roasting temperature to convert lithium iron phosphate into water-soluble lithium chloride through a controlled phase change reaction. The process operates at moderate temperatures (400-600°C) rather than extreme high temperatures, achieving effective conversion while minimizing energy consumption. The subsequent water dissolution step leverages the phase transition from solid to aqueous solution, further reducing the need for high energy input
Solution Approach 2:
The patent introduces water as an intermediary substance that facilitates lithium extraction without requiring high temperatures. After roasting converts lithium compounds to water-soluble lithium chloride, water acts as the medium to dissolve and separate the lithium from the roasted mixture. This intermediary approach enables efficient lithium recovery at lower temperatures, resolving the contradiction between reaction efficiency and 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
Achieves a lithium recovery rate of over 95% with reduced energy consumption and production costs, while minimizing environmental impact.
Implementation Method 1
placing black powder of a positive electrode of a waste lithium iron phosphate battery in a roasting processing furnace filled with protective gas for a roasting reaction... a chemical reaction of one mole of lithium iron phosphate per minute in the roasting reaction
Implementation Method 2
Qc represents a heat dissipation quantity of the roasting processing furnace per minute
Implementation Method 3
immersing a roasted product after the roasting reaction in water to obtain a roasted product solution
Implementation Method 4
conducting suction filtration for the roasted product solution to obtain a filtrate
Implementation Method 5
conducting evaporation concentration for the filtrate and then drying the filtrate to prepare lithium chloride crystals
Data Source
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AI summary
The present invention provides a lithium recycling method for waste lithium iron phosphate batteries, comprises: placing black powder of a positive electrode of a waste lithium iron phosphate battery in a roasting processing furnace filled with protective gas for a roasting reaction. During this, the input chlorine flow rate is adjusted based on the mixture in the roasting processing furnace to control the roasting reaction temperature at 50-300°C. The roasted product is then immersed in water to obtain a roasted product solution. Suction filtration of the roasted product solution yields a filtrate. Evaporation concentration followed by drying of the filtrate prepares lithium chloride crystals. This one-step low-temperature roasting, with temperature controlled by adjusting the input chlorine flow rate, converts the lithium element into water-soluble lithium chloride. The method is simple, efficient, low in energy consumption, achieves over 95% lithium element recycling rate, and has significant industrial application value.