DSX Extractant Degradation Inhibition via pH Control
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Solution Overview
Problem
The degradation of extractants in the Boleo cobalt/zinc solvent extraction (DSX) process is accelerated by high pH levels, leading to increased extraction of impurities and reduced recovery rates of cobalt and zinc, resulting in a vicious cycle that requires continuous replenishment of extractants and incurs economic losses.
Innovation Solution
A method is introduced to inhibit extractant degradation by adjusting the pH of the aqueous phase to a range of 3 to 7, using soda ash, and controlling the concentration of zinc sulfate in the scrubbing solution, along with the use of oxime-based and neodecanoic acid-based extractants in kerosene, and employing multiple stirrer reaction tanks for controlled extraction and scrubbing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pH is increased to improve extraction rate of cobalt and zinc, then extraction rate improves, but extractant degradation accelerates and impurity extraction increases
Solution Approach 1:
The patent optimizes the pH parameter to a specific range (3-7) to balance extraction rate and extractant stability. By controlling pH within this range, the system achieves effective cobalt and zinc extraction while preventing extractant degradation that occurs at higher pH levels. This parameter optimization directly addresses the contradiction between productivity and reliability.
2Productivity
If pH is increased to improve extraction rate, then cobalt and zinc extraction improves, but manganese and copper impurity extraction increases
Solution Approach 1:
The patent applies selective extraction by creating different chemical environments for different metals. Through controlled pH adjustment and use of specific extractants, the system achieves selective extraction of cobalt and zinc while leaving impurities like manganese and copper in the aqueous phase. This local quality differentiation allows simultaneous improvement of productivity and purification.
3Productivity
If extractant is continuously replenished to maintain extraction rate, then productivity is maintained, but operational costs increase and degradation cannot be reversed
Solution Approach 1:
The patent implements preliminary protective measures by controlling pH and using auxiliary chemicals before extractant degradation can occur. By preemptively creating optimal extraction conditions and preventing degradation through controlled chemistry, the system maintains extractant effectiveness throughout operation, eliminating the need for continuous replenishment and reducing extractant loss.
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 approach effectively inhibits the degradation of extractants, maintaining optimal extraction rates and reducing the need for excessive extractant replenishment, thereby preventing economic losses and extending the operational lifespan of the DSX process.
Implementation Method 1
The cobalt/zinc solvent extraction is a process of simultaneously extracting cobalt and zinc using two solvents
Implementation Method 2
soda ash (Na2CO3) is added to adjust the optimum pH
Implementation Method 3
it reacts with cobalt or manganese so that cobalt carbonate (CoCO3) or manganese carbonate (MnCO3) are precipitated
Implementation Method 4
In the scrubbing step, the scrubbing solution is supplied by adjusting concentration of zinc using the zinc sulfate self-produced in Boleo. The solution is reacted with the solvent containing manganese. Thus, the substitution reaction is induced so that zinc is extracted by a solvent, and manganese is stripped by the solution
Implementation Method 5
Each step consists of three stirrer reaction tanks and a settler
Implementation Method 6
measuring the pH of the aqueous phase solution by separating mixture into the aqueous phase solution and the organic phase solvent using a settler
Data Source
AI summary
A method of inhibiting degradation of an extractant by utilizing several auxiliary means in the DSX process: includes (a) preparing adjustment of the concentration of an extractant of a DSX solvent to a certain range; (b) extracting a metal contained in a pregnant leached solution by adjusting the ratio of the extractant and the diluent in the DSX solvent to a certain range; (c) measuring the pH of the aqueous phase solution by separating mixture into the aqueous phase solution and the organic phase solvent using a settler after step of extracting; (d) controlling the pH by adding soda ash (Na2CO3) so as to maintain the pH of the aqueous phase solution to be 3 to 7; and (e) scrubbing with scrubbing solution having a zinc concentration of 2 to 20 g/L by zinc sulfate (ZnSO4) to remove the manganese from the organic phase solvent containing the extracted metal.