Lithium Carbonate Production via pH-Controlled Electrolysis
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Solution Overview
Problem
The growing demand for lithium carbonate exceeds current production capacity, and existing methods for preparing lithium carbonate are limited and require multiple purification steps, necessitating an alternative and efficient process.
Innovation Solution
A process involving the electrolysis or electrodialysis of an aqueous lithium sulphate composition at a pH of 1 to 4 to convert lithium sulphate into lithium hydroxide, followed by conversion to lithium carbonate, which includes leaching acid-roasted lithium-containing materials, reacting with bases to precipitate metal ions, and using ion exchange resins to remove impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional precipitation methods with sodium carbonate are used to prepare lithium carbonate, then lithium carbonate can be produced, but multiple purification steps are required and the process is complex
Solution Approach 1:
The invention changes the pH parameter during electrolysis to maintain it between 1-4, which prevents precipitation of lithium carbonate during the electrolysis step itself. This parameter control allows the process to skip multiple purification steps that would otherwise be required, directly resolving the contradiction between ease of manufacture and purification time
Solution Approach 2:
The invention performs preliminary purification by removing calcium and magnesium ions through precipitation with bases at controlled pH levels before the electrolysis step. This preliminary action prevents these ions from interfering with subsequent electrolysis, eliminating the need for multiple purification steps later in the process
2Productivity
If electrolysis is performed without pH control, then lithium carbonate may precipitate during the process, but this requires additional purification steps and reduces manufacturing efficiency
Solution Approach 1:
The invention maintains pH between 1-4 during electrolysis to prevent lithium carbonate precipitation, and then adjusts pH to 9.5-11.5 after electrolysis to enable controlled precipitation. This sequential parameter change optimizes both productivity during electrolysis and purity during the final precipitation step, resolving the contradiction between production efficiency and purity control
3Productivity
If existing lithium carbonate production methods are used, then current production capacity is maintained, but the growing demand cannot be met
Solution Approach 1:
The invention merges multiple operations into fewer steps: electrolysis simultaneously converts lithium sulphate to lithium hydroxide while generating sulfuric acid, and the sulfuric acid is then used in the leaching step. This merging of operations increases production capacity while reducing the total number of process steps required
Solution Approach 2:
The invention makes the electrolysis step multi-functional by simultaneously achieving: (1) conversion of lithium sulphate to lithium hydroxide, (2) generation of sulfuric acid for leaching, and (3) concentration of lithium hydroxide solution. This multi-functionality increases productivity without adding process complexity
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 process provides a reliable and efficient method for producing high-purity lithium carbonate, addressing the demand shortfall and simplifying the purification process by directly converting lithium sulphate to lithium carbonate with reduced impurity content.
Implementation Method 1
submitting an aqueous composition comprising lithium sulphate to an electrolysis or an electrodialysis under conditions suitable for converting at least a portion of the lithium sulphate into lithium hydroxide
Implementation Method 2
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
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
Data Source
AI summary
There are provided processes comprising submitting an aqueous composition comprising lithium sulphate and/or bisulfate to an electrolysis or an electrodialysis for converting at least a portion of said sulphate into lithium hydroxide. During electrolysis or electrodialysis, the aqueous composition is at least substantially maintained at a pH having a value of about 1 to about 4; and converting said lithium hydroxide into lithium carbonate. Alternatively, lithium sulfate and/or lithium bisulfate can be submitted to a first electromembrane process that comprises a two-compartment membrane process for conversion of lithium sulfate and/or lithium bisulfate to lithium hydroxide, and obtaining a first lithium-reduced aqueous stream and a first lithium hydroxide-enriched aqueous stream; and submitting said first lithium-reduced aqueous stream to a second electromembrane process comprising a three-compartment membrane process to prepare at least a further portion of lithium hydroxide and obtaining a second lithium-reduced aqueous stream and a second lithium-hydroxide enriched aqueous stream.