Lithium Hydroxide Purification Using Lower Alcohol for Fluoride Removal
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Solution Overview
Problem
The recovery of high purity lithium hydroxide from lithium-containing resources, such as lithium mineral Lepidolite and waste lithium ion batteries, is hindered by the presence of impurities, particularly fluoride ions, which are difficult to separate effectively using existing methods.
Innovation Solution
A process involving the dissolution of crude lithium hydroxide in a lower alcohol, followed by solid-liquid separation and optional crystallization, to achieve high purity lithium hydroxide by minimizing the presence of fluoride and other impurities, with specific control over alcohol and water ratios to optimize purification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional aqueous methods are used to recover lithium hydroxide from lithium-containing resources, then the recovery process is simple and cost-effective, but fluoride ions and other impurities remain difficult to separate effectively
Solution Approach 1:
The patent changes the solvent parameter from water to lower alcohols (methanol, ethanol, propanol, or butanol), which fundamentally alters the solubility characteristics of lithium hydroxide and fluoride salts. This parameter change enables effective separation of lithium hydroxide from fluoride impurities that cannot be achieved with conventional aqueous methods, achieving high purity lithium hydroxide while maintaining process simplicity
Solution Approach 2:
The lower alcohol acts as an intermediary solvent that mediates between lithium hydroxide and fluoride salts. By using this intermediate substance, the patent creates a system where lithium hydroxide remains soluble while fluoride salts precipitate, enabling clean separation without requiring complex multi-step purification processes
2Manufacturing precision
If more purification steps are added to remove fluoride impurities, then the purity of lithium hydroxide increases, but the process complexity and cost increase
Solution Approach 1:
The patent extracts fluoride impurities from the lithium hydroxide solution by adding lower alcohol, which causes fluoride salts to precipitate while lithium hydroxide remains in solution. This single extraction step removes fluoride effectively without requiring multiple purification cycles, maintaining high productivity while achieving the desired purity level
Solution Approach 2:
The purification process is segmented into distinct stages: (1) dissolution of crude lithium hydroxide in lower alcohol, (2) filtration to remove precipitated fluoride salts, and (3) optional concentration. This segmentation allows each step to be optimized independently and enables the process to be scaled efficiently without increasing overall complexity
3Manufacturing precision
If lower alcohol is used as solvent for dissolving crude lithium hydroxide, then fluoride separation efficiency improves significantly, but the process requires new equipment and operational procedures
Solution Approach 1:
The patent uses inexpensive lower alcohols (methanol, ethanol, propanol, or butanol) as the purification solvent. These are commodity chemicals that are readily available and inexpensive, making the transition to the new process economically feasible despite requiring new equipment. The simplicity of the chemistry involved means standard laboratory and industrial equipment can be adapted with minimal modification
Solution Approach 2:
The lower alcohol solvent serves multiple functions: it dissolves lithium hydroxide, precipitates fluoride salts, and can be easily removed by evaporation or distillation. This multi-functionality simplifies the overall process design and reduces the need for specialized equipment, making implementation more straightforward despite the novel chemistry
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 process efficiently reduces fluoride content in lithium hydroxide to low levels, achieving high purity lithium hydroxide products with minimal residual impurities, suitable for reuse in lithium ion batteries or electrode materials.
Implementation Method 1
the purification of a raw lithium hydroxide containing LiF and/or salts of amphoteric elements may efficiently be accomplished by dissolving such material in a lower alcohol
Implementation Method 2
combining the crude lithium hydroxide provided in step (A) with a lower alcohol
Data Source
AI summary
A process for the recovery of lithium from waste lithium ion batteries or parts thereof is disclosed. The process comprising the steps of A) providing a crude lithium hydroxide as a solid, which contains fluoride; and (B) dissolving the crude lithium hydroxide solid with a lower alcohol such as methanol or ethanol provides good separation of lithium in high purity.