Recovering Platinum Group Metals from Spent Catalyst Leachate
Solution Overview
Problem
Current methods for recovering platinum group metals from spent catalysts, such as those used in automobile exhaust gas purification and petrochemical processes, are inefficient, particularly in recovering rhodium and result in high processing costs due to the inability to effectively leach rhodium and the need for costly waste disposal.
Innovation Solution
A method involving filtering and heating a leaching solution to recover acid, followed by a substitution reaction with metals having a higher ionization tendency than platinum group metals, and using the recovered acid for cleaning solids to achieve high recovery rates of platinum, palladium, and rhodium, with the acid being reused in subsequent processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If aqua regia is used to leach platinum group metals from spent catalysts, then platinum and palladium can be leached, but rhodium is not leached at all and processing costs are high
Solution Approach 1:
The patent changes the chemical parameters of the leaching solution by using hydrochloric acid with specific concentration ranges (3-12 M) instead of aqua regia, and controls leaching temperature (20-80°C) and time (1-24 hours) to achieve effective leaching of all platinum group metals including rhodium, while reducing processing costs
Solution Approach 2:
The patent employs inexpensive hydrochloric acid as the leaching agent instead of expensive aqua regia, and uses readily available metals (iron, aluminum, zinc) for the substitution reaction, thereby significantly reducing the overall processing cost while achieving high recovery rates
2Quantity of substance
If conventional leaching methods are used, then some platinum group metals can be recovered, but rhodium recovery is ineffective and waste disposal costs are high
Solution Approach 1:
The patent uses a substitution reaction where inexpensive metals (iron, aluminum, zinc) replace the expensive platinum group metals in the leaching solution, effectively recovering rhodium and other PGMs that would otherwise be lost, thereby eliminating waste disposal costs and achieving high recovery rates
Solution Approach 2:
The patent transforms the waste leaching solution into a valuable resource by performing substitution reactions to recover platinum group metals from what would have been discarded waste, converting a loss into a recovery opportunity and eliminating disposal costs
3Loss of substance
If acid is not recovered from the leaching solution, then the process is simple, but acid consumption is high and environmental impact is negative
Solution Approach 1:
The patent recovers and reuses hydrochloric acid from the leaching solution through evaporation and condensation processes, transforming what would be waste acid into a reusable resource, thereby reducing acid consumption and environmental impact while maintaining process efficiency
Solution Approach 2:
The patent implements a self-sustaining system where the acid used in leaching is recovered and reused in subsequent leaching operations, reducing the need for continuous acid input and minimizing waste discharge, thereby creating a more sustainable and environmentally friendly process
4Productivity
If high temperatures are used for leaching, then leaching efficiency may improve, but energy consumption increases and acid loss increases
Solution Approach 1:
The patent optimizes the leaching temperature to a moderate range (20-80°C) that achieves high leaching efficiency without excessive energy consumption or acid loss, finding the optimal balance between productivity and resource conservation
Solution Approach 2:
The patent maintains continuous leaching action at optimized moderate temperatures, ensuring efficient metal extraction while avoiding the energy spikes and acid losses associated with high-temperature intermittent processing, thereby sustaining productivity with lower energy input
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 the high recovery of platinum, palladium, and rhodium from spent catalysts, reduces processing costs, conserves energy, and provides an environmentally friendly approach by reusing recovered acid in leaching, filtering, and cleaning processes.
Implementation Method 1
a spent catalyst is leached
Implementation Method 2
heating the filtered leaching solution to recover acid included in the leaching solution
Implementation Method 3
adding a metal having a higher ionization tendency than the platinum group metal for a substitution reaction
Implementation Method 4
a solid, which is separated by solid-liquid separation after recovering the acid
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to a method of recovering acid and a platinum group metal from a leaching solution of a spent catalyst, more particularly, to a method of recovering acid and a platinum group metal from a leaching solution of a spent catalyst, the method including: filtering a leaching solution of a spent catalyst, providing the filtered leaching solution into a concentration chamber, and heating the filtered leaching solution to recover acid included in the leaching solution; providing a concentrated solution of the leaching solution into a substitution chamber after recovering the acid, and adding a metal for a substitution reaction; and cleaning a solid, which is separated by solid-liquid separation after the substitution reaction, with acid and recovering the platinum group metal.