Metal Recovery from Waste Incineration Slag
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Solution Overview
Problem
Existing methods for processing slag from waste incineration plants are inefficient in extracting metal parts, as they often fail to separate metals enclosed in slag or covered with slag, leading to significant metal loss and contamination, which hinders recycling and reuse of slag in civil engineering.
Innovation Solution
A method combining magnetic and eddy current separation with an induction measuring method to identify metal-containing slag, followed by a comminution process using rotor elements with opposing rotation directions to crush slag while preserving metals, and subsequent separation using sieves or air classifiers to extract metals without crushing them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional magnetic and eddy current separation is used to extract metals from slag, then free metals can be separated, but metals enclosed in or covered with slag are not effectively recovered, leading to significant metal loss
Solution Approach 1:
The patent applies preliminary action by using an induction measuring device to detect metals within slag before the separation process. This allows identification of metal-containing slag portions prior to mechanical treatment, enabling targeted processing that recovers enclosed metals that would otherwise be lost in conventional separation methods.
Solution Approach 2:
The patent introduces an intermediary mechanical treatment step (impact crushing or grinding) between detection and separation. This intermediary action breaks open slag enclosures to free trapped metals, allowing subsequent separation devices to recover metals that were previously inaccessible due to being enclosed or covered by slag.
2Loss of substance
If mechanical crushing is applied to slag to free enclosed metals, then metal recovery improves, but the metals themselves may be crushed or damaged
Solution Approach 1:
The patent performs preliminary detection of metal locations within slag using induction measurement before applying mechanical treatment. This allows the crushing or grinding intensity to be optimized and directed, freeing enclosed metals while avoiding excessive force that would damage the metals themselves.
Solution Approach 2:
The patent replaces intensive mechanical crushing with a more selective approach combining induction detection with gentle mechanical treatment. The mechanical action is applied selectively based on detection signals, and the process is controlled to free metals without subjecting them to forces that would cause damage, unlike conventional intensive crushing methods.
3Productivity
If intensive mechanical treatment is used to process slag, then metal extraction efficiency improves, but energy consumption and operational complexity increase
Solution Approach 1:
The patent uses preliminary induction measurement to identify and locate metals within slag before mechanical treatment. This preliminary action enables targeted processing of only those slag portions containing metals, avoiding intensive mechanical treatment of the entire slag volume and thereby reducing energy consumption while maintaining high extraction efficiency.
Solution Approach 2:
The patent applies partial action by treating only the portions of slag that are detected to contain metals, rather than processing the entire slag mass. This selective approach uses induction detection to identify target areas, applying mechanical treatment only where needed to free enclosed metals, thus optimizing energy use and operational efficiency.
4Reliability
If conventional separation methods are used, then processing speed is maintained, but the quality and purity of recovered metals deteriorate due to slag contamination
Solution Approach 1:
The patent applies preliminary induction measurement to detect and locate metals within slag before separation. This preliminary detection enables more precise separation operations, recovering metals with higher purity by identifying and isolating metal-containing portions from slag-free portions, thereby improving metal quality without significantly reducing processing speed.
Solution Approach 2:
The patent introduces an intermediary detection and classification step between the raw slag input and the final separation. The induction measuring device acts as an intermediary that identifies metal locations, enabling subsequent separation processes to operate more selectively and efficiently, producing higher purity metal outputs while maintaining productive processing rates.
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 effectively recovers metals from slag, reducing harmful metal content and enabling their recycling, while preparing slag for further use by converting it into a more processed and safer form for civil engineering applications.
Implementation Method 1
separated by a magnetic and eddy current separation process
Implementation Method 2
separated by a magnetic and eddy current separation process
Implementation Method 3
The slag is then separated into metal-free slag and metal-containing slag as well as free metals with the aid of a further method, in particular an induction measuring method
Data Source
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Figure 2
AI summary
A process for obtaining metal parts from residues of waste incineration processes, comprising the following steps: a metal-detecting method, in particular an inductive measuring method, is used to separate the residues into metal-free and metal-containing slag and also pure metals, the metal-containing slag and free metals are introduced into the upper inlet of a shaft of a comminution apparatus, in which process rotor elements which are axially spaced apart and preferably consist of chains are driven in rotation about a vertical axis, wherein the material falls through the shaft from top to bottom, wherein mineral constituents of the slag are comminuted to form fine, granular material, free metals are freed from adhering slag, the metal parts remain substantially uncomminuted and the material which falls freely out of the shaft and emerges from a lower outlet of the comminution apparatus is subsequently sorted into metal parts and the remaining material.