Platinum Recovery from Filter Cake via Cyanide Leaching
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Solution Overview
Problem
Current processes for recovering platinum group metals from filter cakes are inefficient, requiring improved techniques to effectively extract and recover these metals with minimal halide anion content and high recovery rates.
Innovation Solution
A metallurgical extraction technique involving re-pulping, grinding, leaching with a hot alkaline cyanide solution, liquid-solid separation, and cementing with aluminum or zinc to recover platinum group metals from filter cakes, with pre-leaching steps to remove base metals and enhance metal concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional processes are used for recovering platinum group metals from filter cakes, then the recovery process is simpler, but the recovery rate is low and efficiency is poor
Solution Approach 1:
The recovery process is divided into multiple sequential stages: grinding the filter cake to reduce particle size, leaching with hot alkaline cyanide solution to dissolve platinum group metals, liquid-solid separation to isolate the leachate, and cementing with aluminum or zinc to precipitate the metals. Each stage targets a specific function to maximize overall recovery efficiency
Solution Approach 2:
The filter cake undergoes preliminary grinding before leaching to reduce particle size and increase surface area, enhancing the subsequent leaching efficiency. This preliminary size reduction ensures that the platinum group metals are more accessible to the cyanide solution, improving recovery rates
2Productivity
If conventional leaching methods are used, then the process is faster, but the extraction efficiency of platinum and palladium is insufficient
Solution Approach 1:
The leaching process uses hot alkaline cyanide solution with specific pH and temperature parameters optimized for maximum platinum and palladium dissolution. The alkaline condition and elevated temperature enhance the leaching kinetics and selectivity, achieving high extraction efficiency within a reasonable time frame
Solution Approach 2:
The cementing step uses aluminum or zinc metal to precipitate the dissolved platinum group metals from the leachate, creating a cemented filter cake that concentrates the recovered metals. This secondary reaction ensures complete metal recovery while allowing time for thorough precipitation
3Productivity
If the filter cake contains high halide anion content, then the feed material is more abundant, but the recovery process becomes less effective
Solution Approach 1:
The hot alkaline cyanide solution provides a specific chemical environment (high pH, elevated temperature) that enhances the selectivity of platinum group metal leaching while minimizing the dissolution of halide-containing compounds. This localized optimization of leaching conditions maintains effectiveness even with variable halide content in the feed
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 achieves high platinum and palladium recovery rates, with over 80% of platinum and palladium extracted in a metal form, resulting in a concentrated precious metals powder suitable for refining, while minimizing halide anion content and ensuring economic viability.
Implementation Method 1
leaching the ground filter cake slurry in a hot alkaline cyanide solution to provide dissolved platinum group metals
Implementation Method 2
recovering the dissolved platinum group metals by cementing the dissolved platinum group metals with a precipitating metal comprising an aluminum or a zinc to make a cemented filter cake
Data Source
AI summary
This application provides a metallurgical extraction technique, comprising:a) re-pulping a feed filter cake to make a filter cake slurry;b) grinding the filter cake slurry;c) leaching the ground filter cake slurry in a hot alkaline cyanide solution to provide dissolved platinum group metals;d) liquid-solid separating of the dissolved platinum group metals; ande) recovering the dissolved platinum group metals by cementing the dissolved platinum group metals with a precipitating metal comprising an aluminum or a zinc; wherein the feed filter cake has the platinum group metals at a total amount from 0.1 to 1.5 wt % and a halide anion content from zero to less than 4 wt %. This application provides a process for platinum group metal recovery, comprising: converting a catalyst which was in contact with a water reactive ionic liquid catalyst into a non-water reactive filter cake and extracting the platinum group metals.