Design and implementation of a Hall Effect sensor array applied to recycling hard drive magnets

Rare earths are an important resource for many electronic components and technologies. Examples abound including Neodymium magnets used in mobile devices and computer hard disk drives (HDDs) and in a variety of renewable energy technologies (e.g, wind turbines). More than 23,000 metric tons of Neodymium are processed annually; less than 1% is recycled. An economic system to assist in recycling magnet material from post-consumer goods, such as neodymium iron boron magnets commonly found in HDDs, is presented. A central component of this recycling measurement system uses an array of 128 Hall Effect sensors arranged in two columns to detect the magnetic flux lines orthogonal to the HDD. Results found using the system to scan planar shaped objects (e.g, HDDs) to identify and spatially locate rare earth magnets for removal and recycling from HDDs are presented. Other applications of the sensor array for identification and localization of magnetic components and assemblies are presented.