Lithium Extraction Purification via Staged pH Adjustment
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Solution Overview
Problem
Existing technologies for extracting lithium from aluminum electrolysis waste and preparing lithium carbonate products face challenges in comprehensively removing impurities from the lithium-extraction dissolving-solution, resulting in a high lithium loss rate and low recovery rate of lithium carbonate.
Innovation Solution
A purification method and system that involves adding an alkaline mixture to the lithium-extraction dissolving-solution to adjust the pH, followed by filtration and the addition of a decalcification agent and catalyst to further purify the solution, effectively removing impurities while minimizing lithium loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing purification methods are used, then the process is simple, but impurities are not completely removed and lithium loss rate is high
Solution Approach 1:
The purification process is divided into multiple sequential stages: first adding stabilizer (calcium sulfate) to precipitate calcium fluoride and remove fluoride ions, then adding regulator (calcium oxide/calcium hydroxide) to adjust pH and remove aluminum ions, and finally adding decalcification agent and catalyst for further purification. Each stage targets specific impurities, achieving comprehensive removal while minimizing lithium loss through controlled precipitation and pH adjustment.
Solution Approach 2:
The method systematically changes pH parameters through controlled addition of alkaline substances. The pH is first adjusted to remove fluoride ions, then further adjusted to remove aluminum ions, and finally optimized for lithium carbonate precipitation. This staged parameter adjustment ensures complete impurity removal while maintaining high lithium recovery rate by preventing premature lithium precipitation.
2Manufacturing precision
If existing purification methods are used, then the process is simple, but impurity removal is insufficient
Solution Approach 1:
The purification method uses a multi-functional reagent addition sequence where each added substance serves multiple purposes: calcium sulfate acts as both stabilizer and fluoride removal agent, calcium oxide/calcium hydroxide serves as both pH regulator and aluminum removal agent, and the final decalcification agent and catalyst work together for comprehensive purification. This multi-functionality approach achieves complete impurity removal without requiring separate complex treatment systems for each impurity type.
3Loss of substance
If existing purification methods are used, then lithium loss is high, but recovery rate of lithium carbonate is low
Solution Approach 1:
The method performs preliminary removal of fluoride ions and aluminum ions before lithium carbonate precipitation. By first adding stabilizer to remove fluoride, then regulator to remove aluminum, the solution is prepared in advance for optimal lithium carbonate formation. This preliminary action prevents impurity interference during lithium precipitation, ensuring high recovery rate while minimizing lithium loss through controlled selective precipitation.
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 comprehensive removal of impurities, with fluoride ion concentrations below 10 mg/L and other impurity ions close to zero, while ensuring minimal lithium loss, thereby improving the recovery rate of lithium carbonate products.
Implementation Method 1
adding an alkaline mixture to the lithium-extraction dissolving-solution until a pH of the lithium-extraction dissolving-solution reaches a first target pH and performing a first reaction in the lithium-extraction
Implementation Method 2
adding a decalcification agent and a catalyst to the first filtrate until a pH of the first filtrate reaches a second target pH and performing a second reaction in the first filtrate
Implementation Method 3
filtering the first filtrate to obtain a purified dissolving-solution
Data Source
AI summary
A purification method and system for a lithium-extraction dissolving-solution of an aluminum electrolysis waste, the method includes: adding an alkaline mixture to the lithium-extraction dissolving-solution until a pH of the lithium-extraction dissolving-solution reaches a first target pH, and filtering the lithium-extraction dissolving-solution to obtain a first filtrate after performing a first reaction in the lithium-extraction dissolving-solution; the first target pH is 11.5˜12; and adding a decalcification agent and a catalyst to the first filtrate until a pH of the first filtrate reaches a second target pH, and filtering the first filtrate to obtain a purified dissolving-solution after performing a second reaction in the first filtrate, the second target pH being 11.5˜12.