Amide-Containing Tertiary Amine for Rhodium Extraction
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Solution Overview
Problem
Current methods for recycling platinum group metals, particularly rhodium, are inefficient due to the lack of effective separation reagents in solvent extraction processes, leading to economic losses and incomplete recovery of rhodium, the most expensive metal in this group.
Innovation Solution
An amide-containing tertiary amine compound is used as a separation reagent to selectively extract and recover rhodium, platinum, and palladium from acidic solutions, with high extraction efficiencies achieved through contact with hydrochloric and nitric acid solutions, allowing for the selective recovery of rhodium and subsequent separation of palladium and platinum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solvent extraction methods are used for platinum group metal recovery, then palladium and platinum can be separated, but rhodium cannot be effectively extracted and must be recovered from separation residue
Solution Approach 1:
The invention changes the chemical parameters of the extraction system by introducing amide-containing tertiary amine compounds with specific molecular structures (formula 1) that have different coordination properties compared to conventional extractants. This parameter change enables selective extraction of rhodium along with palladium and platinum, resolving the inability to effectively extract rhodium with conventional methods
Solution Approach 2:
The invention uses composite extractant systems combining amide-containing tertiary amine compounds with specific hydrocarbon solvents (aliphatic, alicyclic, or aromatic). This composite approach creates a synergistic extraction system that achieves high extraction percentages for all three platinum group metals while enabling subsequent selective separation, particularly of rhodium
2Loss of substance
If rhodium is recovered from separation residue after other metals are separated, then complete recovery is achieved, but it is economically inefficient as the most expensive metal is left until the end
Solution Approach 1:
The invention performs preliminary extraction of rhodium along with palladium and platinum in the first extraction step using amide-containing tertiary amine compounds. This preliminary action allows rhodium to be recovered early in the process rather than left until the end, improving both process efficiency and economic viability while maintaining complete recovery
3Ease of operation
If dihexyl sulfide is used as extractant for palladium, then mutual separation of palladium and platinum is achieved, but extraction percentage is insufficient and sulfide groups are likely to be oxidized
Solution Approach 1:
The invention replaces the expensive and unstable dihexyl sulfide with amide-containing tertiary amine compounds that are more stable and provide higher extraction percentages. The new extractants maintain the separation capability between palladium and platinum while improving extraction efficiency and resistance to oxidation, making them more reliable for industrial application
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
The amide-containing tertiary amine compound enables high extraction and selective recovery of rhodium, platinum, and palladium, improving the efficiency of platinum group metal recycling by allowing for earlier recovery of rhodium, which was previously left until the end of the process, thereby enhancing economic viability.
Implementation Method 1
a solvent extraction method has been widely employed because of its economical efficiency and operability
Implementation Method 2
Selective extraction of palladium with a sulfur-containing organic compound, dialkyl sulfide (DAS), has widely been used
Data Source
AI summary
The present invention provides a novel separation reagent capable of obtaining a high extraction % of rhodium in a chlorine-based acid solution, which has never existed heretofore, and a method for separating and recovering a platinum group metal using the same. An organic phase composed of an amide-containing tertiary amine separation reagent represented by the structural formula shown below is brought into contact with an acid solution containing a platinum group metal, thereby extracting rhodium, platinum and palladium with the organic phase. Among the metals extracted with the organic phase, rhodium is selectively back-extracted with a highly-concentrated hydrochloric acid solution, while palladium and platinum are back-extracted with a highly-concentrated nitric acid solution:wherein at least one of R1, R2 and R3 represents an amide group represented by:R1 to R3 other than the amide group and R4 to R6 represent a group selected from an optionally branched chain hydrocarbon group of 1 to 18 carbon atoms, an alicyclic hydrocarbon group of 1 to 10 carbon atoms, and an aromatic hydrocarbon group of 1 to 14 carbon atoms.