Noble Metal Recovery from Catalyst Bodies via Batch Leaching
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Solution Overview
Problem
Current methods for removing noble metals like silver from catalyst support materials are inefficient, requiring energy-intensive comminution and mechanical effort, and existing centrifuges are unsuitable due to imbalance, continuous operation, and abrasive material handling issues.
Innovation Solution
A process involving initial leaching with nitric acid, followed by conveying whole catalyst bodies to a pull filter or inverting filter centrifuge for further leaching and liquid separation, eliminating the need for comminution and using a discontinuous batch mode to ensure effective precious metal extraction without material reshaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If comminution is used to increase leaching effectiveness, then precious metal extraction efficiency is improved, but energy consumption and mechanical effort increase
Solution Approach 1:
The invention applies preliminary action by conducting the leaching process before comminution. The shaped catalyst bodies are leached with nitric acid while maintaining their original form, and only after leaching are they comminuted. This reverses the conventional sequence (comminution then leaching) to eliminate the need for energy-intensive size reduction to enhance leaching effectiveness
Solution Approach 2:
The invention replaces the mechanical comminution system with a chemical leaching system. Instead of using mechanical energy to grind the catalyst bodies to increase surface area for leaching, the process uses chemical dissolution in nitric acid to extract precious metals directly from the intact shaped bodies, substituting mechanical action with chemical action
2Ease of operation
If conventional centrifuges are used for liquid separation, then operation is simplified, but they cause imbalance, require continuous operation, and cannot handle abrasive materials
Solution Approach 1:
The invention segments the centrifuge operation into distinct batch cycles: filling phase, washing/leaching phase, and discharge phase. This discontinuous batch operation allows the centrifuge to be filled with shaped catalyst bodies, undergo a controlled washing cycle with nitric acid, and then discharge the washed material. The segmentation enables proper drainage and washing without requiring continuous operation, addressing the reliability issues of conventional centrifuges
Solution Approach 2:
The invention implements periodic action through cyclic batch operation of the centrifuge. The centrifuge operates in repeating cycles of filling, washing with nitric acid, and discharge, rather than continuous operation. This periodic action allows sufficient residence time for the diffusion-controlled washing process while maintaining operational flexibility and avoiding the problems of continuous centrifuges
3Productivity
If scraper tubes or knives are used for centrifuge emptying, then discharge is achieved, but they are unsuitable for hard and abrasive carrier materials
Solution Approach 1:
The invention replaces the mechanical scraper system with a pneumatic or gravitational discharge system. The centrifuge is designed to discharge washed catalyst bodies through air flow or gravity without requiring physical contact from scrapers. This substitution avoids the mechanical stress and abrasion that scraper tubes or knives would inflict on hard carrier materials like aluminum oxide or aluminum oxide/zirconium oxide
Solution Approach 2:
The invention introduces an intermediary mechanism (air flow or gravity) to facilitate material discharge without direct mechanical contact. Instead of using scrapers that physically push or scrape the abrasive carrier materials, the system uses air streams or gravitational forces to move the washed catalyst bodies out of the centrifuge, protecting the material from mechanical damage
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 significantly increases silver extraction efficiency while minimizing energy consumption and mechanical effort, achieving a largely silver-free carrier material with automatic, quasi-continuous emptying of the centrifuge.
Implementation Method 1
Leaching of the precious metal from a bed of shaped catalyst bodies
Implementation Method 2
The leaching in step A and D takes place in the case of silver with nitric acid
Implementation Method 3
Separation of the remaining mother liquor by centrifugation
Implementation Method 4
Automatic conveying of the shaped bodies into a centrifuge
Implementation Method 5
conveyed to the centrifuge by means of screw conveyors or vibrating chutes
Implementation Method 6
conveyed to the centrifuge by means of screw conveyors or vibrating chutes
Data Source
Figure 1
AI summary
Procedure for removing a noble metal from noble metal containing catalyst-molded body, comprises: (a) leaching the noble metals from a bulk good of the catalyst molded body; (b) removing the mother liquor; (c) automatically feeding the molded body in to a centrifuge; (d) once again leaching the noble metals; and (e) separating the remaining mother liquor by centrifugation.