Lithium Carbonate Recovery via Sodium Sulfate Crystallization
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Solution Overview
Problem
Current methods for recycling lithium from lithium-ion battery waste streams face challenges in effectively separating and recovering lithium from sodium due to their similar solubility and solubility products, leading to inefficient lithium recovery and environmental concerns.
Innovation Solution
A system comprising an evaporator and crystallizer unit that evaporates water from a lithium sulfate and sodium sulfate solution, followed by cooling to solidify sodium sulfate, and then reacts the remaining solution with sodium carbonate to produce lithium carbonate, utilizing a lithium recovery unit with a reactor and solid-liquid separator to achieve high purity lithium carbonate recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional hydrometallurgical methods are used to recover lithium from battery waste streams, then lithium can be obtained in the form of lithium carbonate, but the separation efficiency from sodium is low due to their similar solubility properties
Solution Approach 1:
The patent applies parameter changes by controlling temperature and evaporation conditions to exploit the differential solubility behavior of lithium sulfate and sodium sulfate. Through controlled evaporation and cooling cycles, the system changes the physical parameters (temperature, concentration) to achieve selective crystallization of sodium sulfate while maintaining lithium in solution, thereby improving separation efficiency despite similar solubility properties
Solution Approach 2:
The patent utilizes phase transitions by evaporating water to concentrate the solution, then cooling it to induce selective crystallization of sodium sulfate. The phase change from liquid to solid for sodium sulfate allows separation from lithium remaining in the liquid phase, addressing the separation efficiency problem through controlled phase transitions
2Productivity
If water is evaporated from the lithium sulfate and sodium sulfate solution to concentrate it, then lithium recovery efficiency improves, but energy consumption increases
Solution Approach 1:
The patent applies self-service by using the evaporated water vapor to provide cooling to subsequent batches of hot solution. The system recycles the thermal energy internally, where the vapor condensing on cooler surfaces provides the cooling effect needed for crystallization, reducing external energy input while maintaining high lithium recovery efficiency through the evaporation-concentration process
3Manufacturing precision
If the crystallizer unit cools the effluent stream to solidify sodium sulfate, then sodium separation improves, but the process time increases
Solution Approach 1:
The patent applies preliminary action by first evaporating and concentrating the solution to high solids content before cooling. This pre-concentration step reduces the amount of water that needs to be removed during cooling, allowing sodium sulfate to crystallize more quickly and efficiently. The preliminary evaporation creates a supersaturated solution that requires less cooling time to achieve selective sodium crystallization, thereby reducing overall process time while maintaining high separation purity
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
The system achieves a lithium recovery efficiency of greater than 75% and produces lithium carbonate with a purity level of at least 80% by weight, effectively addressing the challenges of lithium and sodium separation and reducing environmental impact.
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
reacts the remaining solution with sodium carbonate to produce lithium carbonate
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.