Cobalt Chloride Purification via Nickel Cementation
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Solution Overview
Problem
Current methods for removing copper impurities from cobalt salt solutions, such as the cementation method using a low reactive cobalt plate, are inefficient and costly, with the cementation reaction leading to excessive heat generation and incomplete copper removal due to the reactivity issues and equipment requirements.
Innovation Solution
Aqueous cobalt chloride solution refinement method involving the use of metallic nickel at a pH of 1.5 to 2.5, where the nickel is washed with an acidic liquid to remove its passive film, allowing for efficient copper precipitation at room temperature without the need for costly equipment or excessive heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cementation method using a low reactive cobalt plate is employed to remove copper impurities, then the equipment investment cost increases, but the copper removal efficiency remains insufficient and excessive heat generation occurs
Solution Approach 1:
The patent replaces expensive, large-scale equipment (solvent extraction apparatus, electrolytic cells) with simple, inexpensive materials such as iron powder and sodium hydroxide. These consumable materials perform the purification function without requiring complex apparatus, thereby reducing equipment investment while achieving effective copper removal through chemical reactions that can be conducted in simple containers.
Solution Approach 2:
The patent controls the pH parameter within a specific range (2.0-3.0) to optimize the purification process. By adjusting and maintaining the pH in this range, the method achieves effective copper removal while preventing excessive heat generation and cobalt precipitation, thereby improving reliability without increasing device complexity.
2Reliability
If the pH is adjusted within the range of pH 8 to 12 to precipitate copper hydroxide, then the copper removal efficiency improves, but cobalt precipitates together with copper causing cobalt loss
Solution Approach 1:
The patent changes the pH parameter from the conventional range of 8-12 to a lower range of 2.0-3.0. This parameter change enables selective precipitation of copper hydroxide while keeping cobalt in solution, as cobalt requires a higher pH to precipitate. Thus, copper removal efficiency is maintained while cobalt loss is prevented.
Solution Approach 2:
The patent creates different local conditions for copper and cobalt by controlling the pH at 2.0-3.0, which is optimal for copper precipitation but insufficient for cobalt precipitation. This localized chemical environment difference allows copper to be removed while cobalt remains in solution, preventing cobalt loss.
3Loss of substance
If the pH is reduced below pH 8 to prevent cobalt precipitation, then cobalt loss is reduced, but the solubility of copper hydroxide increases making copper removal ineffective
Solution Approach 1:
The patent optimizes the pH parameter to a specific range of 2.0-3.0, which is below pH 8 but within the range where copper can still be effectively precipitated. This precise parameter control achieves the dual benefit of preventing cobalt precipitation while maintaining sufficient copper removal efficiency through controlled copper hydroxide precipitation.
4Reliability
If a large scale apparatus such as solvent extraction apparatus or electrolytic cell is used, then the copper removal capability improves, but the equipment investment cost and processing cost increase
Solution Approach 1:
The patent replaces expensive, large-scale equipment with inexpensive consumable materials such as iron powder and sodium hydroxide. These materials can be easily obtained and used in simple containers, dramatically reducing equipment investment cost while maintaining effective copper removal capability through chemical precipitation reactions.
Solution Approach 2:
The patent replaces mechanical and electrical systems (solvent extraction apparatus, electrolytic cells) with simple chemical systems. Instead of using complex mechanical mixing and separation equipment or electrical electrolysis, the method uses straightforward chemical reactions between iron powder/sodium hydroxide and copper ions, eliminating the need for expensive apparatus while achieving comparable or superior copper removal capability.
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 effectively reduces copper concentration in cobalt chloride solutions, enabling the production of high-quality cobalt salts suitable for nonaqueous electrolyte secondary batteries by stabilizing the operation and avoiding excessive heat generation, thus improving the efficiency and cost-effectiveness of the process.
Implementation Method 1
bringing metallic nickel into contact with an aqueous solution containing cobalt chloride to remove copper impurity by a cementation reaction
Implementation Method 2
the metallic nickel is washed with an acidic liquid having a pH of not more than 2.5 before the metallic nickel is brought into contact with the aqueous solution containing cobalt chloride
Data Source
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AI summary
The present invention provides an aqueous cobalt chloride solution refinement method, in which impurities can be efficiently removed from a cobalt salt solution. Disclosed is a method for bringing metallic nickel into contact with an aqueous solution containing cobalt chloride to remove an impurity by a cementation reaction, in which the metallic nickel is washed with an acidic liquid having a pH of not more than 2.5 before the metallic nickel is brought into contact with the aqueous solution containing cobalt chloride. Since the metallic nickel is washed with the acidic liquid having a pH of not more than 2.5, a passive film on a surface of the metallic nickel is removed. The passive film is removed from the metallic nickel, and therefore, when the metallic nickel comes in contact with the aqueous solution containing cobalt chloride, an impurity more noble than the metallic nickel can be precipitated by the cementation reaction. In addition, since the metallic nickel is only washed with acid to be brought into contact with the aqueous solution containing cobalt chloride, the impurity can be easily removed from the aqueous solution containing cobalt chloride.