Nickel Hydrometallurgy Neutralization pH Control via Titration Ratio
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Solution Overview
Problem
The pH meter in the neutralization step of hydrometallurgical nickel oxide ore processing is affected by temperature changes and precipitate adhesion, leading to inaccurate pH measurements, resulting in inefficient zinc removal and clogged filters due to insufficient or excessive neutralizing agent addition.
Innovation Solution
Adjusting the neutralizing agent addition based on a neutralizing agent addition ratio (R = Qc / Qs × C), which relates the neutralizing agent flow rate to the free sulfuric acid coefficient, allowing for precise pH control without relying on pH meters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pH meter is used to measure pH in the neutralization step, then pH control is possible, but measurement accuracy deteriorates due to temperature changes and precipitate adhesion
Solution Approach 1:
The invention extracts the pH meter from the neutralization control system and replaces it with a titration-based measurement method. By removing the pH meter, the problems of temperature sensitivity and precipitate adhesion are eliminated, while pH control is maintained through alternative chemical titration methods that are not susceptible to these interference factors.
Solution Approach 2:
The invention replaces the electronic measurement system (pH meter) with a chemical measurement system (titration). This substitution eliminates the electronic sensor's vulnerability to temperature and contamination, using instead a chemical reaction-based method that is more robust in the harsh neutralization environment.
2Reliability
If insufficient neutralizing agent is added, then pH control is conservative, but zinc removal efficiency deteriorates
Solution Approach 1:
The invention implements a feedback control system where the actual pH value (measured by titration) is continuously monitored and compared against the target pH range. Based on this feedback, the neutralizing agent addition rate is dynamically adjusted to maintain optimal pH for zinc removal, ensuring both stable control and high removal efficiency.
Solution Approach 2:
The invention transitions from static pH control to dynamic pH control. The neutralizing agent addition rate is continuously adjusted based on real-time pH measurements and process conditions, allowing the system to adapt to changing conditions and maintain optimal performance throughout the neutralization process.
3Productivity
If excessive neutralizing agent is added, then pH control is aggressive, but filter clogging increases
Solution Approach 1:
The feedback control system monitors pH in real-time and adjusts neutralizing agent addition to maintain pH within the optimal range. This prevents excessive addition that would cause rapid pH increase and subsequent filter clogging, while still achieving efficient neutralization through controlled, continuous adjustment.
Solution Approach 2:
The invention optimizes the pH parameter to a specific target range that balances neutralization efficiency with prevention of harmful effects. By controlling pH within this optimized range, the system achieves fast neutralization without generating excessive precipitates that would clog filters.
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 stabilizes the pH of the neutralized solution, maintaining zinc removal efficiency and preventing filter clogging, thereby enhancing the overall solid-liquid separation process.
Implementation Method 1
a crude nickel sulfate aqueous solution obtained in a sulfuric acid leaching step is neutralized
Implementation Method 2
zinc is precipitated and removed as zinc sulfide
Data Source
Figure 1
AI summary
Provided is a method for neutralizing a sulfuric acid acidic solution, whereby the pH of a neutralized solution can be stabilized, and also provided is a hydrometallurgical method for nickel oxide ores. The hydrometallurgical method comprises a sulfuric acid leaching step of leaching an ore slurry of a nickel oxide ore with sulfuric acid, a neutralization step of neutralizing a crude nickel sulfate aqueous solution by adding a neutralizing agent thereto, and a dezincification step of removing zinc as zinc sulfide by adding a sulfurizing agent to a neutralized solution; wherein in the neutralization step, the amount of the neutralizing agent added is adjusted using, as an index, a neutralizing agent addition ratio that indicates the amount of the neutralizing agent added relative to the amount of free sulfuric acid in the crude nickel sulfate aqueous solution. This method is not affected by changes in the liquid temperature or by neutralized precipitates adhering to a pH meter, can prevent insufficient addition and excessive addition of the neutralizing agent, and can stabilize the pH of the neutralized solution. The removal efficiency of zinc can be maintained in the dezincification step, and the efficiency of solid-liquid separation can be maintained.