Pure Iron Precursor Purification by Selective Acid Dissolution
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Solution Overview
Problem
Current methods for producing high-purity iron for lithium-ion batteries are costly and complex, requiring multiple steps to remove impurities from relatively inexpensive iron materials.
Innovation Solution
A method involving the dissolution of direct reduced iron in organic and/or inorganic acids, followed by separation of insoluble impurities, results in a high-purity iron containing compound or aqueous solution. This process maintains insoluble impurities in solid form during dissolution, allowing for their effective separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional purification methods (electrolytic precipitation, gas phase purification) are used to produce high purity iron, then the purity of iron is improved, but the production cost increases significantly
Solution Approach 1:
The invention changes the chemical parameters of the dissolution process by using specific organic acids (oxalic acid, citric acid, acetic acid) instead of conventional strong inorganic acids, and controls the pH and temperature parameters to achieve selective dissolution of iron while leaving impurities undissolved, thereby obtaining high purity iron at lower cost
Solution Approach 2:
The invention extracts the iron from the impure iron material by selective dissolution in organic acid, separating it from the insoluble impurities. The iron is taken out in soluble form while impurities remain in the solid phase, allowing for simple filtration and obtaining high purity iron without complex purification steps
2Manufacturing precision
If multiple washing steps are used to remove impurities from iron precursors, then the purity of the material is improved, but the production time and complexity increase
Solution Approach 1:
The invention extracts iron into solution while leaving impurities behind in the solid phase during dissolution. A single filtration step removes all impurities, eliminating the need for multiple washing steps that would be required in conventional methods, thus significantly reducing production time
Solution Approach 2:
The organic acid acts as an intermediary that selectively dissolves iron while leaving impurities undissolved. This intermediary enables a single-step separation through filtration, replacing multiple washing operations and reducing overall process time
3Ease of manufacture
If conventional iron materials are used as starting material, then the raw material cost is reduced, but the complexity and cost of impurity removal increases
Solution Approach 1:
The invention changes the chemical environment by using organic acids instead of conventional inorganic acids, creating conditions where iron dissolves selectively while impurities remain undissolved. This parameter change simplifies the purification process despite using low-cost impure starting materials
Solution Approach 2:
The invention applies local quality by creating a selective dissolution environment where only iron reacts with the organic acid while impurities remain unaffected. This selective interaction simplifies the overall process complexity by naturally separating iron from impurities without requiring complex purification equipment
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 method achieves high-purity iron containing compounds and solutions at a lower cost compared to existing technologies, with the resulting materials suitable for use in lithium iron phosphate cathodes.
Implementation Method 1
dissolving the direct reduced iron in organic and/or inorganic acids to provide an iron containing aqueous solution
Data Source
AI summary
The present invention relates to a method of producing an iron containing compound, iron containing precursor, or iron containing aqueous solution comprising the steps of:providing direct reduced iron;dissolving the direct reduced iron in organic and/or inorganic acids to provide an iron containing aqueous solution, wherein insoluble impurities of the direct reduced iron are maintained in solid form throughout the dissolution process, to obtain an iron containing aqueous solution with suspended insoluble impurities;separating the said insoluble impurities from the iron containing aqueous solution obtaining a purified iron containing aqueous solution; andoptionally solidifying said purified iron containing aqueous solution to provide the iron containing compound or iron containing precursor, by drying.The present invention further relates to iron containing compounds, iron containing precursors, and iron containing aqueous solutions, and their use in battery components.