Aluminum Scrap Sorting via Electrical Conductivity

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Solution Overview

Problem

Current methods for sorting aluminum scrap alloys are imprecise, especially when distinguishing between alloys with similar metallic compositions and density differences, leading to difficulties in separating alloys like the 5000 and 6000 series on an industrial scale.

Innovation Solution

The method involves measuring the electrical conductivity of aluminum scrap using eddy current technology, with crushed scrap being passed over a sensor field and the measured conductivity used to differentiate alloys, combined with position detection and pneumatic sorting for precise separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If density-based sorting methods are used, then sorting of aluminum scrap is possible, but sorting precision deteriorates when density differences are small

Engineering Contradiction:
Improvesorting precisionVSAvoidsorting capability
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the sorting parameter from density to electrical conductivity. By measuring electrical conductivity values of aluminum scrap particles, the system can differentiate between alloy groups (5000, 6000, 7000 series) and individual alloys within groups, achieving precise sorting where density-based methods fail due to similar density values.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces mechanical density-based separation with an electrical measurement system. Conductivity sensors measure the electrical conductivity of particles, and pneumatic actuators selectively remove identified particles from the conveyor, substituting mechanical sorting with electrical measurement and controlled removal.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If conventional sorting methods are used, then large mass flows can be processed, but alloy differentiation capability deteriorates

Engineering Contradiction:
Improvemass flow processing capabilityVSAvoidalloy differentiation precision
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent maintains continuous processing of large mass flows through a conveyor system that continuously transports shredded aluminum scrap particles. Conductivity sensors continuously measure particles on the conveyor, and pneumatic actuators continuously remove identified particles, enabling both high productivity and precise alloy differentiation simultaneously.

Inventive Principle:
Principle #20Continuity of useful action

3Measurement precision

If electrical conductivity measurement is implemented, then alloy sorting precision is improved, but device complexity increases

Engineering Contradiction:
Improvealloy identification precisionVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces conductivity sensors as intermediary measurement devices between the aluminum scrap particles and the control system. These sensors non-contactlessly measure electrical conductivity values, which serve as intermediaries to identify alloy types, enabling precise sorting without complex direct analysis of the materials.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses pneumatic actuators to selectively remove identified alloy particles from the conveyor. This pneumatic mechanism provides a relatively simple and effective means of particle removal compared to alternative mechanical or manual sorting methods, balancing the complexity introduced by conductivity measurement.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 allows for reliable and efficient sorting of aluminum alloys, including differentiation between 5000 and 6000 series, achieving higher purity levels than previous methods by utilizing electrical conductivity as a sorting criterion.

Implementation Method 1

measuring the electrical conductivity of aluminum scrap using eddy current technology

Methodology Applied
Scientific EffectEddy current: Eddy Currents

Data Source

PatentEP3133176B1Sorting of aluminium alloys using electrical conductivity values
Publication Date: 2020.04.15 HYDRO ALUMINUM RECYCLING DEUT GMBH
  • EP3133176B1 patent drawingFigure 1

AI summary

In order to provide a method and a device with which a sorting of light alloyed aluminium scrap is made possible, the invention proposes a method for sorting aluminium scrap and its alloys, wherein the aluminium scrap is fed to a measuring station, where the electrical conductivity of each aluminium part is measured and, depending on the measurement result, is conveyed further on a path provided for this purpose.