Nickel Sulphide Precipitation at Ambient Conditions
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Solution Overview
Problem
Current processes for removing nickel from aqueous solutions require low pH and elevated temperatures and pressures, which are inefficient and costly, especially for solutions with low nickel concentrations.
Innovation Solution
A process that precipitates nickel ions from aqueous solutions at relatively high pH and ambient temperatures and pressures, using a contactor with stoichiometric excess sulphide to form solid nickel sulphide, allowing for efficient separation and recycling of nickel sulphide sludge, and optionally using coagulants to enhance separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If low pH and elevated temperatures and pressures are used to precipitate nickel sulphides, then nickel removal efficiency is improved, but energy consumption and operational cost increase
Solution Approach 1:
The patent fundamentally changes the pH parameter from acidic (low pH) to alkaline (high pH) conditions, enabling nickel sulphide precipitation to proceed efficiently at ambient temperatures and pressures. This parameter inversion resolves the contradiction by achieving high removal efficiency without the energy-intensive conditions previously required.
Solution Approach 2:
The process uses readily available, inexpensive reagents such as sodium hydroxide for pH adjustment and sodium sulphide or ammonium sulphide for sulphide addition. These simple, low-cost chemicals enable efficient nickel precipitation without requiring expensive equipment or energy-intensive operations.
2Manufacturing precision
If low pH and elevated temperatures and pressures are used to precipitate nickel sulphides, then nickel removal efficiency is improved, but operational complexity and cost increase
Solution Approach 1:
By changing to high pH conditions, the process eliminates the need for high-pressure vessels, heating systems, and complex temperature control mechanisms. The precipitation occurs readily at ambient conditions, dramatically simplifying the operational complexity while maintaining high nickel removal efficiency.
Solution Approach 2:
The alkaline environment promotes spontaneous precipitation of nickel sulphide without requiring external energy input or complex control systems. The process essentially self-regulates at ambient conditions, reducing operational complexity.
3Manufacturing precision
If stoichiometric excess sulphide is used to precipitate nickel, then nickel removal efficiency is improved, but sulphide consumption increases
Solution Approach 1:
The process employs pH control as a feedback mechanism to optimize sulphide consumption. By maintaining pH between 9-11, the process ensures complete nickel precipitation while minimizing excess sulphide usage. The alkaline environment promotes complete reaction efficiency, reducing waste.
Solution Approach 2:
The high pH condition enhances the reactivity and efficiency of sulphide-nickel interaction, allowing for more complete precipitation with less excess sulphide required compared to acidic conditions. This parameter change optimizes the stoichiometric ratio and reduces substance loss.
4Ease of operation
If nickel sulphide particles are formed at high pH, then particle size and separability are improved, but pH control requirements increase
Solution Approach 1:
By establishing high pH as the operating condition, the process achieves spontaneous formation of larger, more separable nickel sulphide particles. The alkaline environment promotes particle growth and aggregation, improving settling and filtration characteristics without requiring additional separation equipment.
Solution Approach 2:
The high pH condition self-promotes particle aggregation and growth, reducing the need for complex separation systems. The particles naturally form larger sizes that are easier to separate, with the pH environment itself facilitating the separation process.
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 process efficiently removes nickel from solutions with low concentrations, achieving high removal efficiency and producing barren water that meets environmental discharge standards, with the ability to recycle and reuse process water, and operates effectively at low temperatures and pressures.
Implementation Method 1
Pregnant solutions may be contacted with a dissolved sulphide in a contactor, to form solid nickel sulphide
Implementation Method 2
In some embodiments, a coagulant may be dissolved in the pregnant aqueous solution, so that a dissolved coagulant is present when contacting the pregnant solution with the dissolved sulphide
Implementation Method 3
In some embodiments, at least a portion of the nickel sulphide sludge may be recycled to the contactor to seed nickel sulphide particle growth
Data Source
AI summary
The invention provides hydrometallurgical processes by which dissolved nickel may be removed from water at ambient temperature and low system pressure.