Iridium Oxide Recovery via Reduction-Assisted Mild Acid Dissolution
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Solution Overview
Problem
Current methods for recovering iridium from spent catalysts are time and energy consuming, environmentally harsh, and inefficient due to the high corrosion resistance of iridium oxides, necessitating extreme conditions like pyrometallurgy and acidic baths.
Innovation Solution
A method involving a reduction step with a reducing agent, followed by mild acidic conditions to dissolve iridium oxides into an acidic solution, forming a suspension of lower oxidation state particles, which are then processed to produce iridium ions or compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If harsh acidic baths like Aqua regia are used to dissolve iridium oxides, then dissolution is achieved, but the process becomes time and energy consuming and environmentally harmful
Solution Approach 1:
The patent applies preliminary action by performing a reduction step before dissolution. The spent catalyst is first treated with a reducing agent (such as formic acid, hydrazine, or sodium borohydride) to reduce Ir(IV) oxide to Ir(0) or lower oxidation states, which are much more soluble. This preliminary reduction enables subsequent dissolution in mild acidic conditions rather than requiring harsh acids like Aqua regia, thereby reducing environmental harm while maintaining productivity
Solution Approach 2:
The patent changes the chemical state parameter of iridium from high oxidation state (Ir(IV)) to low oxidation state (Ir(0) or Ir(II)) through reduction. This parameter change fundamentally alters the solubility characteristics of iridium compounds, enabling dissolution in environmentally friendly mild acids at ambient or near-ambient conditions instead of requiring harsh acidic environments
2Reliability
If pyrometallurgy or harsh acidic conditions are used to recover iridium, then recovery is achieved, but the process requires extreme conditions and high energy input
Solution Approach 1:
The patent changes the chemical parameter of iridium from oxidized state to reduced state, which fundamentally alters its dissolution behavior. This enables the process to proceed at ambient or near-ambient temperatures using mild acids, eliminating the need for pyrometallurgy or high-temperature harsh acid treatments, thereby dramatically reducing energy consumption while maintaining reliable recovery efficiency
Solution Approach 2:
The patent replaces mechanical/thermal systems (pyrometallurgy, high-temperature processing) with a chemical system based on reduction chemistry. By using reducing agents to convert Ir(IV) to soluble lower oxidation states, the process substitutes energy-intensive thermal treatment with chemically-driven dissolution at much lower energy input
3Productivity
If strong acids are used to dissolve iridium oxides directly, then dissolution occurs, but the process is very slow due to high corrosion resistance
Solution Approach 1:
The patent applies preliminary action by performing reduction before dissolution. The reducing agent treatment converts resistant Ir(IV) oxide into much more reactive and soluble Ir(0) or lower oxidation state species. This preliminary chemical modification dramatically accelerates the subsequent dissolution step, reducing processing time from hours or days to minutes or seconds while using mild acids instead of strong acids
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 significantly enhances the dissolution rate of iridium oxides, allowing for efficient recovery with reduced time, energy, and environmental impact, enabling the production of iridium compounds suitable for industrial applications.
Implementation Method 1
treating the body with a reducing agent or with means providing a reducing agent, thereby forming a suspension
Implementation Method 2
dissolving the suspension by exposing the suspension to an acidic solution, thereby forming a solution comprising iridium ions
Data Source
AI summary
The present invention relates to a method of recovering iridium in the form of iridium solutions, metal, oxides or salts from a body, such as a spent catalyst, comprising iridium oxides.