Rare Earth Recovery via Solvothermal Crystallization
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Solution Overview
Problem
Current methods for recovering rare earth elements from spent catalysts and waste sources often rely on strong acids, leading to environmental issues and inefficiencies, as they require high temperatures and pressures, and do not effectively recover rare earth metals from materials like spent catalysts and fluorescent lights.
Innovation Solution
A solvothermal process using a rare earth element crystallization medium comprising 80-100% amides and 0-10% organic acids, under controlled temperature and pressure conditions, to selectively crystallize rare earth elements, allowing for gravity or magnetic separation and subsequent purification into rare earth oxides without the need for strong acids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If strong acid digestion is used to recover rare earth elements, then rare earth elements can be dissolved and extracted, but environmental harm and waste disposal issues increase
Solution Approach 1:
The patent changes the chemical parameters of the digestion process by replacing strong mineral acids with organic acids (acetic acid, formic acid, or their mixtures), thereby maintaining effective rare earth element dissolution while eliminating the environmental harm associated with strong acid waste disposal
Solution Approach 2:
The patent uses inexpensive organic acids that can be easily disposed of or neutralized compared to persistent strong mineral acids, reducing the long-term environmental impact and waste management burden
2Productivity
If high temperature and pressure conditions are used for rare earth element recovery, then dissolution and extraction efficiency improve, but energy consumption increases
Solution Approach 1:
The patent optimizes the temperature and pressure parameters of the solvothermal process to achieve effective rare earth element extraction at lower energy inputs compared to conventional high-temperature acid digestion methods, by utilizing the unique solvolytic properties of organic acid-amide systems
3Productivity
If conventional acid digestion methods are used, then rare earth elements can be recovered, but the process complexity and equipment requirements increase
Solution Approach 1:
The patent employs simple, inexpensive organic acids and amides that can be handled with basic equipment, eliminating the need for complex specialized apparatus required for handling hazardous strong acids and high-temperature processes
Solution Approach 2:
The organic acid-amide system provides self-regulating solvolytic properties that facilitate rare earth element dissolution and crystal formation without requiring complex process control or specialized equipment
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 enables efficient and environmentally friendly recovery of rare earth elements from complex mixtures, reducing waste and resource depletion, with the ability to recycle amides and minimize environmental impact, achieving high yields and purity of rare earth metal crystals and oxides.
Implementation Method 1
adding the material and a rare earth element crystallization medium into a temperature and pressure controlled vessel under solvothermal conditions sufficient to selectively crystallize the rare earth elements
Implementation Method 2
selectively crystallize the rare earth elements to form a rare earth metal crystals
Implementation Method 3
a separator for separating the rare earth metal crystals from the material to form a purified rare earth metal crystalline composition
Implementation Method 4
the separator is a gravity separator, while in other embodiments, the separator is a magnetic separator
Data Source
AI summary
Methods and systems for recovering or extracting rare earth elements under mild conditions include subjecting a material including rare earth element to a rare earth element crystallization medium under solvothermal conditions sufficient to form rare earth element crystals capable of gravity separation and purification.