Oxalic Acid REE Extraction from Loaded Organic Phase
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Solution Overview
Problem
Existing methods for extracting rare earth elements (REEs) from acid mine drainage (AMD) are inefficient in concentrating and purifying REEs while minimizing acid consumption and impurity removal, necessitating improved processing of AMD-based pre-concentrate materials.
Innovation Solution
The use of oxalic acid-based extraction methods to prepare a pregnant leach solution from a loaded organic phase in a solvent extraction system, involving steps such as mixing oxalic acid with the loaded organic phase, forming a slurry with REE-oxalate precipitates, and filtering to separate and purify REEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional AMD treatment methods are used to remove metal ions, then pH adjustment and metal ion removal are achieved, but REE concentration and purification are insufficient
Solution Approach 1:
The patent segments the REE recovery process into distinct stages: (1) AMD treatment to remove common metal ions, (2) selective precipitation of REEs using controlled pH conditions, (3) filtration to separate precipitated REEs from the solution, and (4) dissolution of the precipitate to produce purified REE concentrate. This segmentation allows each stage to be optimized independently, achieving both effective impurity removal and high REE concentration.
Solution Approach 2:
The patent utilizes parameter changes, specifically pH adjustment, to control the selective precipitation of rare earth elements. By carefully controlling the pH level during the precipitation step, the process selectively precipitates REEs while leaving other metal ions in solution, thereby achieving high purity and concentration of the final REE product.
2Loss of substance
If acid consumption is reduced in AMD treatment, then operational cost decreases, but impurity removal effectiveness is compromised
Solution Approach 1:
The patent employs the natural buffering capacity of the AMD system itself to control pH during the precipitation process. The AMD contains sufficient alkalinity to maintain pH in the optimal range for REE precipitation without requiring additional acid or base addition, thereby reducing chemical consumption while maintaining effective impurity removal.
3Manufacturing precision
If silica leaching is limited in the process, then REE retention is improved, but complete purification is not achieved
Solution Approach 1:
The patent extracts and removes specific impurities (common metal ions like iron, aluminum, and manganese) from the AMD solution through selective precipitation, while deliberately retaining silica in the solution phase. The REEs are precipitated separately from the silica-containing solution, allowing complete REE recovery without requiring complete silica removal, thus achieving both high retention and effective purification.
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 effectively concentrates and purifies REEs by forming oxalate precipitates, reducing impurities, and optimizing acid consumption, thereby enhancing the recovery process.
Implementation Method 1
mixing the water and the oxalic acid with the LOPSES, thereby forming a mixture comprising a partially stripped organic solvent and a slurry comprising a REE-oxalate precipitate and water
Data Source
AI summary
In one aspect, the disclosure relates to oxalic acid-based extraction methods for the preparation of a pregnant leach solution obtained from a loaded organic phase obtained from a solvent extraction system, i.e., a LOPSES, wherein the loaded organic phase comprises an organic solvent and at least one REE and/or CM, as well as pregnant leach solution products or compositions obtained by the disclosed methods. The disclosure further relates to methods for preparing a loaded organic phase using a solvent extraction system. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.