Patent ID: 7658291

Claim:
A sorting apparatus for sorting metal pieces from mixed materials comprising: a surface for transporting the metals and the mixed materials; a first array of inductive proximity sensors and a second array of inductive proximity sensors that produce electrical signals when the metals are detected within a detection range of the inductive proximity sensors; a separation unit for separating the metals from the mixed materials; and a computer coupled to the plurality of inductive proximity sensors and the separation unit; wherein a first array of inductive proximity sensors are mounted a first distance under the surface and a second array of inductive proximity sensors are mounted a second distance under the surface and the computer instructs the separation unit to separate the materials that have been detected by the first array of proximity sensors or the second array of proximity sensors from the mixed materials and wherein if a first metal piece is detected by the first array of inductive proximity sensors but not detected by the second group of inductive proximity sensors, the computer identifies the one piece as being a first type of metal and if a second metal piece is detected by the first array of inductive proximity sensors and also detected by the second array of inductive proximity sensors, the computer identifies the second piece as being a second type of metal.