Nickel Sulphate Purification by Two-Step Solvent Extraction
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Solution Overview
Problem
Existing methods for producing high-purity nickel sulphate solutions are cumbersome, dangerous, and inefficient in removing impurities such as cobalt, calcium, magnesium, and other metals, making them unsuitable for high-purity applications like electroless deposition of nickel metal layers or battery materials.
Innovation Solution
A two-step solvent-extraction process using different alkylphosphorus-based extractants and diluents to completely separate cobalt, calcium, and other impurities from nickel, followed by a second step to remove residual magnesium, resulting in a high-purity nickel sulphate solution with minimal nickel loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a selective nickel sulphide precipitation step is introduced to remove impurities, then nickel sulphate purity is improved, but the process complexity increases and hydrogen sulphide generation risk arises
Solution Approach 1:
The patent applies solvent extraction to separate impurities (cobalt, magnesium, calcium) from nickel sulphate solution using organic extractants. This extraction process removes harmful impurities without requiring precipitation and redissolution steps, thereby improving purity while avoiding the complexity and safety hazards of sulphide precipitation methods.
2Manufacturing precision
If solvent extraction is used to remove cobalt and magnesium impurities, then nickel sulphate purity is improved, but the process time and number of steps increase
Solution Approach 1:
The patent combines multiple impurity removal functions into a single solvent extraction step that simultaneously removes cobalt, magnesium, and calcium impurities using an appropriate extractant system. This merged approach achieves high purity nickel sulphate without requiring separate precipitation, filtration, and redissolution steps, thereby reducing overall process time.
3Manufacturing precision
If nickel sulphide precipitation is performed to remove impurities, then nickel sulphate purity is improved, but hydrogen sulphide generation risk increases
Solution Approach 1:
The patent replaces the harmful sulphide precipitation method with a beneficial solvent extraction process that uses safe organic extractants to remove impurities. This substitution eliminates hydrogen sulphide generation risk while maintaining effective impurity removal capability, converting a harmful process into a safe one.
4Manufacturing precision
If multiple solvent extraction units are used to remove copper, manganese and cobalt in separate steps, then nickel sulphate purity is improved, but investment costs and process complexity increase
Solution Approach 1:
The patent employs a universal solvent extraction system using alkylphosphorus-based extractants that can simultaneously remove multiple impurity types (copper, manganese, cobalt, magnesium, calcium) in a single or few extraction steps. This multi-functional extractant system eliminates the need for multiple specialized extraction units, reducing both investment costs and process complexity while maintaining high purity.
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 process achieves a nickel sulphate solution with at least 99.8% purity, avoiding complex mixtures and environmental hazards, and allows for the production of cobalt-rich eluates suitable for further processing.
Implementation Method 1
a two-step solvent-extraction process using different alkylphosphorus-based extractants and diluents to completely separate cobalt, calcium, and other impurities from nickel
Implementation Method 2
using a first organic phase comprising a first alkylphosphorus-based extractant (I) and a first diluent, thereby obtaining an aqueous raffinate solution (A1) comprising nickel and a residual magnesium content
Data Source
AI summary
The present invention provides a process for preparing a high-purity nickel sulphate solution, comprising the steps of: i. providing an aqueous feed solution comprising nickel, cobalt, calcium and magnesium: ii. extracting cobalt, calcium, and partly magnesium from said aqueous feed solution using a first solvent comprising a first alkylphosphorus-based acidic extractant, thereby obtaining an aqueous raffinate comprising nickel and magnesium: iii. extracting magnesium from said aqueous raffinate solution comprising nickel and magnesium using a second solvent comprising a second alkylphosphorus-based acidic extractant, thereby obtaining a high-purity aqueous nickel sulphate solution comprising nickel and magnesium: iv. stripping the first loaded solvent comprising cobalt, calcium and magnesium with an aqueous solution comprising a mineral acid.