Lithium Recovery Process Using Evaporation and Sulfate Crystallization
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Solution Overview
Problem
Existing methods are inefficient in recovering lithium from lithium-ion battery waste streams, leading to valuable metals like lithium being discarded, which exacerbates environmental issues and depletes precious metal ores.
Innovation Solution
A system comprising an evaporator and crystallizer unit with a lithium recovery unit, utilizing heat exchangers and pumps to separate and concentrate lithium sulfate, followed by crystallization to produce lithium carbonate (Li2CO3) and sodium sulfate (Na2SO4) as byproducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional hydrometallurgical methods are used to recover lithium, then lithium can be obtained in the form of lithium carbonate, but the recovery process is inefficient and lithium is still discarded
Solution Approach 1:
The patent segments the lithium recovery process into distinct functional units: evaporation system for water removal, crystallization system for lithium carbonate formation, and filtration system for product separation. This segmentation allows each unit to be optimized independently, improving overall recovery efficiency and minimizing lithium loss at each stage.
Solution Approach 2:
The patent applies preliminary action by first evaporating water from the lithium-containing solution before crystallization. This pre-concentration step ensures that lithium is in the optimal concentration range for efficient crystallization, preventing lithium loss that would occur if crystallization were attempted on diluted solutions.
2Manufacturing precision
If lithium is recovered through evaporation and crystallization, then high purity lithium carbonate exceeding 80% by weight is achieved, but the process requires complex equipment including evaporators, crystallizers, and heat exchangers
Solution Approach 1:
The patent merges multiple functions into integrated system components. The evaporation system and crystallization system are connected through shared heat exchange networks, allowing thermal energy to be reused across process stages. This merging reduces the number of independent equipment pieces while maintaining high lithium carbonate purity through coordinated operation.
Solution Approach 2:
The patent implements multi-functionality through heat exchangers that serve dual purposes: cooling the evaporator output to initiate crystallization and pre-heating incoming feed solutions. This universal heat recovery approach simplifies the thermal management system while ensuring precise temperature control for high-purity lithium carbonate production.
3Quantity of substance
If the crystallizer unit cools the effluent stream to form solid sodium sulfate, then sodium sulfate byproduct is recovered, but energy is consumed for cooling and heating operations
Solution Approach 1:
The patent maintains continuous useful action through a closed-loop heat exchange system where cooling water from the crystallizer is continuously heated by the evaporator. This continuous thermal energy transfer converts what would be wasted cooling energy into useful heating energy, enabling sustained sodium sulfate crystallization while minimizing net energy consumption.
Solution Approach 2:
The patent converts the harmful waste heat from the cooling process into a beneficial resource. The cooling water, which would normally be discarded after removing heat from the crystallizer, is instead routed through heat exchangers to pre-heat feed solutions and sustain evaporation. This transforms energy loss into energy recovery, reducing overall energy consumption while maintaining high sodium sulfate recovery rates.
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 high purity lithium carbonate recovery exceeding 80% by weight, enabling effective recycling and reducing environmental impact by conserving metal ores.
Implementation Method 1
at least a portion of the water from the liquid stream is evaporated in the evaporator to generate water vapor
Implementation Method 2
The crystallizer unit is downstream of the evaporator that receives and cools the effluent stream to form solid sodium sulfate (Na2SO4)
Implementation Method 3
a heat exchanger that receives water vapor from the evaporator and the liquid stream in a heat exchange relationship to increase a temperature of the liquid stream
Data Source
AI summary
Systems and methods for recovering lithium (Li) from a lithium-ion battery waste stream including lithium sulfate (Li2SO4), sodium sulfate (Na2SO4), and water (H2O) are provided. The systems may include an evaporator unit with an optional heating system and a crystallizer unit downstream or upstream of the evaporator unit for cooling and solidifying sodium sulfate (Na2SO4). A lithium recovery unit is disposed downstream of the crystallizer unit or the evaporator unit that generates lithium carbonate (Li2CO3) product. Methods include evaporating a portion of water from the waste stream to generate water vapor and an effluent stream, which is then cooled to solidify sodium sulfate (Na2SO4) in a crystallizer vessel. The solid sodium sulfate (Na2SO4) is removed and the effluent stream is heated, followed by introducing sodium carbonate (Na2CO3) to produce lithium carbonate (Li2CO3) product, which is then recovered.