Solvent Extraction for High-Purity Cobalt Sulfate Production
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Solution Overview
Problem
Current methods for producing cobalt sulfate from chloride solutions struggle to effectively remove impurities like calcium, magnesium, and sodium, resulting in low purity cobalt sulfate, which is essential for battery materials but requires stringent chloride ion levels below 0.1%.
Innovation Solution
A solvent extraction process involving a three-step method: Step 1 extracts cobalt from a chloride solution using an extractant at 10-30% volume concentration at pH 4.0-5.0, Step 2 transfers impurities into a cleaning liquid, and Step 3 adjusts pH to 0.5-1.0 with dilute sulfuric acid to produce high-purity cobalt sulfate, utilizing an acidic phosphoric acid ester-based extractant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional purification methods are used to obtain high purity cobalt sulfate, then product purity is improved, but production time and cost increase significantly
Solution Approach 1:
The patent uses solvent extraction to selectively extract cobalt from the chloride solution using an organic extractant. This separates cobalt from impurities (calcium, magnesium, sodium) in a single efficient operation, achieving high purity without multiple sequential purification steps that would consume excessive time
Solution Approach 2:
The organic extractant serves as an intermediary substance that facilitates the separation of cobalt from the aqueous chloride solution. The extractant temporarily binds cobalt in the organic phase, allowing impurities to remain in the aqueous phase, then cobalt is recovered in high purity form through back-extraction
2Manufacturing precision
If conventional purification methods are used to obtain high purity cobalt sulfate, then product purity is improved, but production cost increases
Solution Approach 1:
The solvent extraction process removes impurities in one efficient step, eliminating the need for multiple conventional purification operations. This reduces operational complexity and cost while achieving the required purity level for battery materials
Solution Approach 2:
The patent optimizes extraction parameters including pH control (maintaining pH 2-4 during extraction), extractant concentration (10-30% by volume), and liquid phase ratios to maximize cobalt extraction efficiency while minimizing impurity co-extraction. These optimized parameters reduce the need for additional purification steps, lowering overall production cost
3Productivity
If standard solvent extraction is used, then cobalt extraction is achieved, but impurities like calcium, magnesium and sodium are not effectively removed
Solution Approach 1:
The patent applies different pH conditions at different stages: pH 2-4 during extraction to favor cobalt extraction, then pH adjustment to 0.5-1.0 during back-extraction. This localized pH control optimizes selectivity for cobalt while preventing impurity co-extraction, achieving both high productivity and high purity
Solution Approach 2:
The patent specifies precise parameter ranges: extractant concentration (10-30% by volume), pH (2-4 during extraction, 0.5-1.0 during back-extraction), and organic-to-aqueous phase ratio (5:1 to 10:1). These controlled parameters ensure selective cobalt extraction while leaving calcium, magnesium, and sodium impurities in the aqueous phase
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 achieves high-purity cobalt sulfate with reduced calcium, magnesium, and sodium concentrations, and low chloride levels, enhancing the efficiency and cost-effectiveness of cobalt sulfate production.
Implementation Method 1
subjecting a chloride solution containing cobalt to a solvent extraction process composed of the following Step 1 to Step 3, and thereby producing cobalt sulfate: (1) Step 1 of bringing an extracting solvent containing an extractant at a proportion of 10% to 30% by volume into contact with a chloride solution containing cobalt at a pH in the range of 4.0 to 5.0, thereby extracting cobalt from the chloride solution containing cobalt
Implementation Method 2
Step 3 of adding dilute sulfuric acid as a stripped starting liquid to the cobalt-retaining organic phase after cleaning in the Step 2 so as to obtain a pH in the range of 0.5 to 1.0, thereby bringing the cobalt-retaining organic phase after cleaning into contact with dilute sulfuric acid, and thus producing a cobalt sulfate solution
Data Source
Figure 1~2
AI summary
Provided is a method for producing cobalt sulfate, wherein high purity cobalt sulfate is obtained by effectively eliminating impurities in a process for obtaining a cobalt sulfate solution with a high cobalt concentration by solvent extraction using an acidic organic extractant. Disclosed is a method in which, on the occasion of separating an acidic solution containing calcium, magnesium and sodium as impurities from a cobalt chloride solution by solvent extraction, when a diluent is added to the extractant to be used to dilute the extractant to a concentration of 10% to 30% by volume, and preferably 15% to 25% by volume; in Step 1, the operational pH is maintained in the range of 4.0 to 5.0 and the liquid volume ratio of organic phase/liquid phase is maintained in the range of 5.0 to 7.0; in Step 2, the operational pH is maintained in the range of 4.0 to 4.5 and the liquid volume ratio of organic phase/liquid phase is maintained in the range of 5.0 to 10.0; and in Step 3, the pH is maintained in the range of 0.5 to 1.0, the concentration ratios of calcium, magnesium and sodium with respect to the cobalt concentration in the cobalt sulfate solution thus obtainable are reduced to 0.0001, 0.0001, and 0.00005 or less, respectively. (213 words)