Rare Earth Extraction from Coal Feedstocks via Mild Pyrolysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for extracting rare earth elements (REEs) from coal-based feedstocks face environmental and health hazards due to the use of high-temperature combustion and strong acids, which convert REEs into glassy phases, making them difficult to recover and requiring aggressive chemicals.
Innovation Solution
A method involving pyrolysis of coal-based intermediates at lower temperatures, followed by solvent extraction and contact with weak acids, to extract REEs without combustion, using mild thermal treatment and environmentally friendly solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-temperature combustion is used to process coal feedstock, then REEs are converted into glassy phases, but this makes REE recovery difficult and requires aggressive strong acids
Solution Approach 1:
The patent applies preliminary action by conducting mild pyrolysis treatment on coal feedstock before REE extraction to prevent the formation of glassy phases. This preparatory step modifies the coal structure at lower temperatures (below combustion levels) to make REEs more accessible for subsequent extraction with weak acids, thereby avoiding the need for aggressive chemical processing while maintaining effective REE recovery
2Productivity
If strong acids are used for REE extraction, then REE recovery is achieved, but environmental and health hazards increase
Solution Approach 1:
The patent applies parameter changes by substituting strong acids with weak acids for REE extraction. This chemical parameter change maintains effective REE recovery while significantly reducing environmental and health hazards. The mild pyrolysis预处理 of coal feedstock enables this parameter change by making REEs accessible without requiring aggressive chemical conditions
Solution Approach 2:
The patent employs weak acids as disposable, environmentally friendly extraction agents that can be used without the severe environmental consequences associated with strong acids. These weaker chemicals can be handled more safely and disposed of more easily, reducing the overall environmental burden of the REE extraction process
3Quantity of substance
If fly ash is used as feedstock, then REE concentration is higher than raw coal, but high temperature processing vitrifies REEs making recovery impractical
Solution Approach 1:
The patent applies preliminary action by performing mild pyrolysis on coal feedstock before extraction to prevent vitrification. This preparatory treatment at controlled lower temperatures preserves REE accessibility while still allowing concentration benefits, avoiding the high-temperature combustion that creates unrecoverable glassy phases in fly ash
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 allows for efficient extraction of REEs from coal-based intermediates, reducing environmental impact and health risks while achieving higher recovery rates using less harmful chemicals.
Implementation Method 1
The pyrolysis of the present disclosure occurs at substantially lower temperatures than experienced in industrial coal combustion processes
Implementation Method 2
contacting the coal-based intermediate product with a weak acid; and extracting at least some REEs from the coal-based intermediate product via the weak acid
Data Source
AI summary
In one embodiment, a method for extracting rare earth elements from coal includes preparing a coal-based intermediate product from a coal feedstock sourced from available natural occurring material associated with coal mining, wherein the a coal-based intermediate product has not been generated through the process of combustion: contacting the coal-based intermediate product with a weak acid; and extracting at least some rare earth elements from the coal-based intermediate product via the weak acid to produce a rare earth extract. The coal-based intermediate may be produced via a combination of pyrolysis and solvent extraction.