Lithium Carbonate Purification via Segmented Impurity Removal
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Solution Overview
Problem
The existing methods for producing lithium carbonate from lithium ore, such as the sulfuric acid process, face challenges in achieving high product quality due to incomplete impurity removal, leading to unstable product quality and increased production costs, particularly when using large amounts of alkali or ion exchange methods.
Innovation Solution
A method involving the preparation of lithium sulfate leachate, followed by pH adjustment and precipitation of Fe2+ and Al3+, subsequent ion exchange for removing Ca2+ and Mg2+, and membrane concentration using ultrafiltration and reverse osmosis to achieve a concentrated solution with low impurity levels, ultimately precipitating lithium carbonate with improved purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large amount of alkali is added to remove impurities, then impurity removal capability is improved, but production cost increases and product purity deteriorates due to incomplete removal and quality instability
Solution Approach 1:
The patent segments the impurity removal process into two distinct stages: first removing Fe2+ and Al3+ through pH adjustment and precipitation, then removing Ca2+ and Mg2+ through ion exchange treatment. This segmentation allows each stage to target specific impurities with optimized methods, avoiding the quality deterioration that occurs when using a single method with excessive reagents.
Solution Approach 2:
The patent changes the operational parameters by controlling pH value to 9-10 for optimal precipitation of Fe2+ and Al3+, and by selecting appropriate ion exchange resins for Ca2+ and Mg2+ removal. These parameter optimizations enable effective impurity removal without requiring excessive alkali addition, thereby maintaining product purity.
2Manufacturing precision
If ion exchange method is used to remove impurities, then product purity is improved, but production cost increases due to shorter service life of ion exchange resin
Solution Approach 1:
The patent performs preliminary removal of Fe2+ and Al3+ through pH adjustment and precipitation before the ion exchange step. This preliminary action prevents these impurities from reaching the ion exchange resin, avoiding resin oxidation and structural changes that would shorten its service life. By preparing the feed solution in advance, the resin operates more efficiently and lasts longer, reducing production costs.
Solution Approach 2:
The patent introduces pH adjustment and precipitation as an intermediary step between the leachate and the ion exchange process. This intermediary treatment removes problematic impurities (Fe2+ and Al3+) that would otherwise damage the resin, allowing the ion exchange method to maintain high product purity while extending resin service life and reducing costs.
3Use of energy by moving object
If evaporation method is used for concentration, then energy consumption is high, but if membrane concentration is used, then energy efficiency improves
Solution Approach 1:
The patent replaces the thermal evaporation process with a membrane concentration process that uses pressure-driven filtration instead of heat. This substitution eliminates the high energy consumption associated with heating and evaporation, while maintaining effective concentration capability through ultrafiltration and reverse osmosis membranes that selectively retain lithium sulfate.
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 approach enhances the purity of lithium carbonate, extends the service life of ion exchange resin, reduces production costs, and improves energy efficiency by replacing evaporation with membrane concentration, resulting in a more stable and cost-effective lithium carbonate production process.
Implementation Method 1
treating the filtered lithium sulfate leachate by an ion exchange method and removing Ca2+ and Mg2+ therefrom
Implementation Method 2
performing membrane concentration on the lithium sulfate leachate obtained by the ion exchange treatment to produce a concentrated solution of lithium sulfate leachate
Implementation Method 3
membrane concentration using ultrafiltration and reverse osmosis
Implementation Method 4
adjusting the pH value of the lithium sulfate leachate to 9-10 by adding alkali, and precipitating Fe2+ and Al3+ in the lithium sulfate leachate
Data Source
AI summary
Disclosed by the invention is a method for preparing lithium carbonate from lithium ore, comprising the steps of: preparing lithium sulfate leachate from lithium ore concentrate, removing Fe2+ and Al3+ from the lithium sulfate leachate by adding alkali, removing Ca2+ and Mg2+ from the lithium sulfate leachate by an ion exchange method, adding a saturated solution of soda ash into the obtained concentrated solution of lithium sulfate leachate, precipitating lithium carbonate, filtering and separating the lithium carbonate precipitate, washing with hot water and drying to obtain a finished lithium carbonate product. The invention saves the production cost, and obviously improves the purity of lithium carbonate as a final product. In addition, disclosed by the invention is also a system for realizing the method for preparing lithium carbonate from lithium ore.