Lithium Hydroxide Production via Barium Sulfate Precipitation

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Solution Overview

Problem

Traditional methods for preparing lithium hydroxide, such as converting lithium carbonate to lithium hydroxide, face challenges due to low aqueous solubility of reactants, leading to high energy consumption and impurities like calcium carbonate, which reduce battery performance and require multiple recrystallization steps.

Innovation Solution

A method involving the mixing of lithium sulfate and barium hydroxide, followed by roasting to form insoluble barium sulfate and water-soluble lithium hydroxide, allowing for solid-liquid separation and evaporation to obtain high-purity lithium hydroxide with low lithium loss and no waste generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If lithium carbonate is converted to lithium hydroxide using calcium hydroxide in water-based reaction, then lithium hydroxide is produced, but the low aqueous solubility of reactants limits the amount of reactants that can be reacted at a time and requires large amounts of water to be evaporated, resulting in high energy consumption

Engineering Contradiction:

Improveamount of reactants that can be reacted at a timeVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent changes the reaction parameters by using a non-aqueous solvent system (such as dimethyl carbonate or ethyl methyl carbonate) instead of water-based reaction. This parameter change allows for higher reactant concentrations and eliminates the need for large-scale water evaporation, thereby increasing productivity while reducing energy consumption.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes phase transition properties by selecting solvents with appropriate boiling points and solubility characteristics. The reaction is conducted in a liquid phase solvent that allows high reactant solubility, and the product is obtained through controlled phase separation or crystallization, avoiding the energy-intensive water evaporation process.

Inventive Principle:

Principle #36Phase transitions

2Manufacturing precision

If lithium carbonate is converted to lithium hydroxide using calcium hydroxide, then lithium hydroxide solution is obtained, but calcium carbonate remains as an impurity that reduces battery performance and requires multiple recrystallization steps

Engineering Contradiction:

Improvepurity of lithium hydroxideVSAvoidnumber of recrystallization steps

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts and removes calcium carbonate impurities through filtration or decantation steps after the reaction, separating them from the lithium hydroxide solution. This extraction approach achieves high purity lithium hydroxide in a single step without requiring multiple recrystallization cycles, thereby improving manufacturing precision while reducing process complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses an intermediary solvent system that facilitates selective solubility differences between lithium hydroxide and calcium carbonate. The chosen solvent allows lithium hydroxide to remain in solution while calcium carbonate precipitates or can be easily separated, acting as a mediator that enables single-step purification to high purity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enables direct, high-purity lithium hydroxide production with low energy consumption and no waste, improving the efficiency and environmental sustainability of lithium hydroxide preparation.

Implementation Method 1

preparing a second mixture that is converted into insoluble barium sulfate (BaSO4) and water-soluble lithium hydroxide (LiOH) by roasting the first mixture

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

dissolving the second mixture to precipitate the insoluble barium sulfate (BaSO4)

Methodology Applied

Scientific EffectPrecipitation: Precipitation

Implementation Method 3

evaporating the solution from which the barium sulfate (BaSO4) is separated to obtain lithium hydroxide (LiOH)

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS20230373802A1Method for preparing lithium hydroxide using lithium sulfate and barium hydroxide

Publication Date: 2023.11.23 IND FOUND OF CHONNAM NAT UNIV

AI summary

In a method for preparing lithium hydroxide, a first mixture of lithium sulfate (Li2SO4) and barium hydroxide (Ba(OH)2) is prepared, a second mixture that is converted into insoluble lithium sulfate (BaSO4) and soluble lithium hydroxide (LiOH) is prepared by roasting the first mixture, the second mixture is dissolved to precipitate the insoluble barium sulfate (BaSO4), the precipitated barium sulfate (BaSO4) is separated by solid-liquid separation, and the solution from which the barium sulfate (BaSO4) is separated is evaporated to obtain lithium hydroxide (LiOH).