Lithium Hydroxide Preparation Using pH-Controlled Electrolysis
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Solution Overview
Problem
The existing methods for producing lithium hydroxide face challenges in achieving high purity with low impurity levels, particularly sodium, calcium, and chlorides, leading to increased time and cost due to the need for additional purification steps, and the use of natural brines results in high magnesium concentrations making lithium recovery uneconomical.
Innovation Solution
A process involving electrolysis or electrodialysis of an aqueous lithium compound composition at controlled pH conditions, combined with leaching, precipitation, and ion exchange to convert lithium compounds into lithium hydroxide, effectively reducing impurity levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If natural brines are used as starting material, then production cost is reduced, but impurity content (sodium, calcium, chlorides, magnesium) increases
Solution Approach 1:
The purification process is divided into multiple sequential stages: primary purification to remove magnesium and calcium, followed by secondary purification to remove sodium and chlorides. Each stage targets specific impurities, progressively improving purity without requiring excessive chemical reagents at any single stage.
Solution Approach 2:
Chemical reagents are introduced as intermediaries to facilitate selective precipitation of impurities. For example, reagents are added to precipitate magnesium and calcium as insoluble compounds, which are then filtered off, leaving purified lithium solution.
2Manufacturing precision
If additional purification steps are performed to achieve low impurity levels, then product purity is improved, but production time and cost increase
Solution Approach 1:
The process performs preliminary removal of major impurities (magnesium and calcium) before the main electrolysis step. This preliminary purification prevents these impurities from interfering with the electrolysis process and reduces the burden on subsequent purification steps, thereby reducing total production time.
Solution Approach 2:
The process optimizes pH conditions during electrolysis to maintain pH between 1-4, which maximizes the efficiency of lithium hydroxide production while minimizing co-precipitation of impurities. This parameter control allows for effective purification in a single electrolysis pass rather than requiring multiple sequential purification steps.
3Quantity of substance
If natural brines with high magnesium concentration are used, then raw material availability is improved, but lithium recovery becomes uneconomical
Solution Approach 1:
The process selectively extracts and removes magnesium from the brine solution through controlled precipitation. By adjusting pH and adding appropriate reagents, magnesium is precipitated as insoluble compounds that can be easily separated, leaving lithium in solution for subsequent recovery.
Solution Approach 2:
The process controls pH parameters during electrolysis to optimize lithium hydroxide production while preventing magnesium interference. By maintaining pH between 1-4 during electrolysis, the process ensures high current efficiency for lithium recovery while magnesium remains in a form that does not compete for electrolysis current.
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 achieves high-purity lithium hydroxide production by significantly reducing impurities such as sodium, calcium, and chlorides, optimizing yield and reducing production time and costs.
Implementation Method 1
submitting an aqueous composition comprising a lithium compound to an electrolysis or an electrodialysis under conditions suitable for converting at least a portion of the lithium compound into lithium hydroxide
Implementation Method 2
submitting an aqueous composition comprising a lithium compound to an electrolysis or an electrodialysis under conditions suitable for converting at least a portion of the lithium compound into lithium hydroxide
Implementation Method 3
reacting the aqueous composition comprising Li+ and the at least one metal ion with a base so as to obtain a pH of about 4.5 to about 6.5 and thereby at least partially precipitating the at least one metal ion under the form of at least one hydroxide
Implementation Method 4
contacting the aqueous composition comprising Li+ and having a reduced content of the at least one metal ion with an ion exchange resin so as to at least partially remove at least one metal ion from the composition
Data Source
AI summary
There are provided system for preparing lithium hydroxide from an aqueous composition comprising a lithium compound and use of the system thereof to prepare lithium hydroxide, the system comprising an electrochemical cell, a pH probe and at least one inlet for receiving acid or base for maintaining pH. For example, the lithium compound can be lithium sulphate and the aqueous composition can be at least substantially maintained at a pH having a value of about 2 to about 4.