High Purity Lithium Fluoride Production via Gaseous HF Reaction
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Solution Overview
Problem
Current processes for producing high-purity lithium fluoride are complex and often fail to meet purity requirements, requiring separate purification steps and involving conversion to more water-soluble lithium hydrogen carbonate.
Innovation Solution
A process involving the reaction of an aqueous medium containing dissolved lithium carbonate with gaseous hydrogen fluoride to form an aqueous suspension of solid lithium fluoride, followed by separation and drying, which simplifies the production and achieves high purity without complex purification operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional processes are used to produce lithium fluoride from technical lithium carbonate, then purity requirements can be met through multiple purification steps, but the process complexity increases significantly
Solution Approach 1:
The invention extracts and removes the complex purification steps (ion exchange, multiple conversions) from the conventional process, replacing them with a single direct reaction step that inherently produces high-purity lithium fluoride without requiring separate purification operations
Solution Approach 2:
The invention changes the reaction parameters by using gaseous hydrogen fluoride instead of aqueous hydrofluoric acid, and by maintaining specific temperature ranges (0-60°C) and pH conditions (3-8) during the reaction, which enables direct formation of pure lithium fluoride precipitate without requiring subsequent purification steps
2Manufacturing precision
If complete conversion to lithium hydrogen carbonate is performed before converting to lithium fluoride, then purity can be improved, but the process time and steps increase
Solution Approach 1:
The invention performs preliminary purification by dissolving technical lithium carbonate in water to remove insoluble impurities before the main reaction, which allows the subsequent direct conversion to lithium fluoride without requiring complete conversion to lithium hydrogen carbonate as an intermediate step
Solution Approach 2:
The invention skips the intermediate conversion to lithium hydrogen carbonate and the associated ion exchange purification step, rushing directly from dissolved lithium carbonate to lithium fluoride formation through reaction with gaseous hydrogen fluoride, thereby significantly reducing process time
3Ease of manufacture
If technical lithium carbonate with 98.0-99.8 wt.% purity is used as starting material, then the process can be simplified, but achieving high-purity lithium fluoride becomes more challenging
Solution Approach 1:
The invention uses water as an intermediary medium to dissolve technical lithium carbonate and perform preliminary purification, removing insoluble impurities before the main reaction with gaseous hydrogen fluoride, which enables the use of lower-purity starting material while still achieving high-purity product
Solution Approach 2:
The invention maintains an inert aqueous environment during the reaction with gaseous hydrogen fluoride, controlling pH and temperature to prevent contamination and ensure high-purity lithium fluoride formation even when starting with technical-grade lithium carbonate containing foreign metal ions
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 method consistently produces high-purity lithium fluoride with improved morphology, suitable for use in subsequent reactions, particularly in the production of fluorine-containing conductive salts for lithium-ion batteries, with high yields and reduced foreign ion content.
Implementation Method 1
Reaction of the aqueous medium provided according to a) with gaseous hydrogen fluoride to form an aqueous suspension of solid lithium fluoride
Implementation Method 2
Separation of the solid lithium fluoride from the aqueous suspension
Implementation Method 3
Drying of the separated lithium fluoride
Data Source
Figure 1
AI summary
The invention relates to a method for producing high-purity lithium fluoride from lithium carbonate, and to lithium fluoride with a preferred morphology.