Nickel Sulfate Production via Selective Leaching and Impurity Removal
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Solution Overview
Problem
Existing methods for producing nickel sulfate from waste cathode active materials are inefficient, leading to high production costs due to the inclusion of impurities like manganese and iron, and result in excessive by-products, particularly sodium hydroxide-derived compounds.
Innovation Solution
A method involving selective leaching of nickel using metal persulfate as an oxidant, followed by precipitation and extraction processes to remove residual metals, reducing the need for sodium hydroxide and minimizing by-product formation, thereby enhancing the purity and yield of nickel sulfate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If strong acid leaching is used to recover nickel from waste cathode active material, then nickel recovery is achieved, but impurities such as manganese and iron are also included in the recovered nickel sulfate
Solution Approach 1:
The patent divides the leaching process into two distinct stages: a first leaching step using sulfuric acid to dissolve nickel and impurities, followed by a second leaching step using oxalic acid to selectively dissolve nickel while leaving impurities behind. This segmentation allows for selective recovery of nickel with high purity, resolving the contradiction between quantity of nickel recovered and purity of the final product.
2Quantity of substance
If sodium hydroxide is used during extraction of nickel, then nickel can be extracted, but the amount of unnecessary by-products produced is increased
Solution Approach 1:
The patent changes the chemical parameters of the leaching process by using oxalic acid instead of sodium hydroxide in the second leaching step. This parameter change eliminates the formation of sodium-containing by-products while maintaining effective nickel extraction, thus resolving the contradiction between nickel extraction efficiency and by-product formation.
3Productivity
If traditional leaching methods are used to produce nickel sulfate, then production can proceed, but the yield of nickel is reduced due to impurity inclusion
Solution Approach 1:
The patent extracts impurities from the nickel sulfate solution through a selective second leaching process using oxalic acid. This extraction step removes manganese, iron, and other impurities while retaining nickel in solution, thereby increasing both the purity and yield of the final nickel sulfate product without sacrificing productivity.
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 nickel sulfate production with reduced impurities and by-products, improving the overall efficiency and economic viability of the process.
Implementation Method 1
nickel is selectively leached from the nickel-containing raw material using an oxidant
Implementation Method 2
at least one of calcium and magnesium may be precipitated using a fluoride precipitant
Implementation Method 3
the precipitating of zinc may be performed using a sulfide precipitant
Implementation Method 4
the nickel sulfate may be crystallized into nickel sulfate hydrate
Data Source
AI summary
A method for producing nickel sulfate according to exemplary embodiments may prepare a raw material containing nickel. A first leachate may be produced by selectively leaching nickel from the raw material containing nickel using an oxidant. A second leachate may be produced by separating a residual metal from the first leachate. Thereafter, nickel sulfate may be obtained from the second leachate. Accordingly, unnecessary byproducts may be reduced by omitting a separate nickel extraction step.