pH-Controlled Leaching of Rare Earth Elements
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Solution Overview
Problem
The extraction of rare earth elements and critical minerals from organically associated materials is costly and environmentally impactful due to high reagent and acid usage, as well as solubility-based hindrances in existing methods.
Innovation Solution
A pH-driven leaching method involving the addition of acid to maintain a pH of 0.25 to 4 in a mixture of organically bound rare earth elements, followed by dewatering and recycling of washing liquids to reduce acid and water consumption, and enhance recovery rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional leaching methods are used to extract rare earth elements from organically associated materials, then extraction is achieved, but acid and water usage is high and recovery rates are limited due to solubility-based hindrances
Solution Approach 1:
The patent applies parameter changes by controlling pH within a specific range (0.25 to 4) to optimize the leaching process. This pH control enables efficient rare earth element extraction while reducing acid consumption by 40% and water consumption by 50% compared to conventional methods, simultaneously improving recovery rates and reducing radioactive element co-extraction
Solution Approach 2:
The patent implements feedback through recycling the washing liquid back to the leaching process. This closed-loop system allows the washing liquid, which still contains dissolved rare earth elements, to be reused as leaching agent, thereby reducing fresh water and acid requirements while maintaining high recovery rates through cumulative concentration effects
2Productivity
If high reagent and acid usage is employed to increase rare earth element recovery, then extraction efficiency improves, but costs and environmental impact increase
Solution Approach 1:
By optimizing pH control within the range of 0.25 to 4, the patent achieves high extraction efficiency while minimizing reagent consumption. This parameter optimization reduces acid usage by 40% and eliminates the need for extensive water washing, thereby lowering both operational costs and environmental impact associated with hazardous waste disposal
Solution Approach 2:
The patent converts the potentially harmful washing liquid, which would normally be treated as waste requiring disposal, into a valuable resource by recycling it back to the leaching process. This transforms an environmental liability into a process asset, reducing both waste generation and fresh reagent requirements
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 decreases acid and water usage by up to 40% and 50% respectively, while increasing rare earth element recovery and reducing radioactive element recovery, thereby lowering costs and environmental impact.
Implementation Method 1
maintaining the slurry at a pH of 0.25 to 4 for a period of time, resulting in a liquor and a leached slurry
Implementation Method 2
adding an acid to a slurry comprising organically bound rare earth elements
Data Source
AI summary
A method for extracting rare earth elements and critical minerals including adding an acid to a mixture comprising organically bound rare earth elements. The mixture is maintained at a pH of 0.25 to 4 for a period of time, resulting in a liquor and a leached mixture. The liquor is removed from the leached mixture to form a dewatered cake. The dewatered cake is washed to form a washing liquid. The washing liquid is recycled to create a second slurry comprising organically bound rare earth elements.