• Otoole, Michael D.
• Peyton, Antony J.

Abstract

—Magnetic induction spectroscopy is the measurement of how a conductive object reflects and scatters a magnetic<br/>field over different frequencies in response to some excitation<br/>magnetic field. In recent work, we proposed using this technique<br/>to classify different non-ferrous metals for the recycling and<br/>resource recovery sector - specifically, to identify fragments of<br/>scrap aluminium, copper and brass in shredded waste streams<br/>for separation and recovery. We proposed a simple algorithm<br/>that used only two components of the spectra that gave strong<br/>purity and recovery-rates when tested on a manufactured control<br/>set cut from stock metals.<br/>In this paper, we re-examined this method using real scrap<br/>metal samples drawn from a commercial sorting line. We found<br/>moderate purity and recovery-rates of brass and copper of<br/>between around 70% and 90%. However, the classification of<br/>aluminium was poor with ≈55% and ≈80% purity and recovery<br/>rates respectively. Magnetic induction sensors are a natural fit<br/>for the specifications of the industry. They are capable of highthroughputs, are unaffected by dirt or contaminants and are<br/>mechanically and physically robust. Although our results are<br/>modest, they are not insignificant given the simplicity of the<br/>algorithm and the relatively low-cost of instrumentation. Our<br/>work suggests the MIS as a technique may have a significant role<br/>to play in the extraction and recovery of non-ferrous resources

Topics

• impedance spectroscopy
• extraction
• aluminium
• copper
• brass