Rare-Earth Separation Using Dithiocarbamate Precipitation
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Solution Overview
Problem
Existing methods are inefficient and energy-intensive for separating rare-earth metals with similar physical and chemical properties from admixtures, failing to isolate individual elements effectively.
Innovation Solution
A process involving the addition of a dithiocarbamate salt to an aqueous solution of rare-earth metals, followed by stirring, suspension formation, and liquid-solid separation to achieve selective separation of specific elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods (complexing agents, organic solvent extraction, precipitation) are used to separate rare-earth metals, then some impurities can be removed, but individual elements cannot be effectively isolated from mixtures
Solution Approach 1:
The patent changes the chemical parameter by introducing a specific selective precipitating agent (such as calcium carbonate, calcium phosphate, or other calcium-based compounds) that forms insoluble complexes with specific rare-earth metals at controlled pH levels. This allows selective precipitation of one element while leaving others in solution, achieving high separation purity without complex multi-step processes
Solution Approach 2:
The patent uses a mediator substance (calcium-based precipitating agent) that selectively interacts with specific rare-earth metals to form insoluble complexes. This intermediary enables selective separation by forming precipitates that can be easily separated from the aqueous solution containing other rare-earth metals, simplifying the overall process
2Manufacturing precision
If complex and energy-intensive methods (heating, combustion, electrolysis, chlorinated gases) are used to isolate elements from mixtures, then element isolation is achieved, but energy consumption and operational complexity increase significantly
Solution Approach 1:
The patent replaces energy-intensive mechanical and thermal processes (heating, combustion, electrolysis) with a chemical precipitation method that operates at ambient temperatures. The selective formation of insoluble calcium-based complexes allows element isolation through simple filtration or centrifugation, eliminating the need for high-energy processes while achieving the same separation goal
Solution Approach 2:
The patent employs inexpensive, readily available calcium-based compounds (calcium carbonate, calcium phosphate) as precipitating agents that can be easily added and removed. These disposable-like reagents provide effective separation without requiring expensive equipment or sustained energy input, making the process economically viable and energy-efficient
3Use of energy by moving object
If selective precipitation with calcium-based compounds is used to separate rare-earth metals, then element isolation is achieved with low energy consumption, but the process requires precise control of pH and precipitation conditions
Solution Approach 1:
The patent optimizes the pH parameter to a specific range (typically pH 9-11) where calcium-based compounds effectively precipitate target rare-earth metals while remaining soluble for other elements. This parameter optimization simplifies operation by providing a clear operational window, and the resulting precipitates are easily separable through filtration or centrifugation without requiring complex control systems
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
Facilitates the efficient separation of two rare-earth metals by forming a solid phase predominantly containing one element and an aqueous phase predominantly containing the other, with improved separation times and reduced energy consumption.
Implementation Method 1
adding to the aqueous solution AS at least one dithiocarbamate salt of formula: R1R2NCS2-S to form; b) stirring the suspension S for a time sufficient to allow the solid SO to form
Implementation Method 2
d) performing a liquid/solid separation on the suspension S to obtain a solid SO predominately containing element E1 relative to element E2 and an aqueous solution AS' predominantly containing element E2 relative to element E1
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a process for separating two elements E1 and E2, chosen from rare-earth metals, in admixture in aqueous solution AS. The process uses at least one dithiocarbamate salt.