High-Frequency Eddy-Current Separator for Foundry Sands
EMPS with the assistance of the I&I program has developed a new approach that uses magnetic-field frequencies of 50 to 100 kHz to recover metal fragments of 0.2 mm and greater at an efficiency rate of 95% to 98%. The high-frequency eddy-current separator (HFECS) is easily adaptable to existing foundry sites and replaces other environmentally hazardous recovery methods that use toxic solvents to separate the metal granules from foundry sand. The new HFECS uses a radio-frequency electrical supply that generates an alternating magnetic field when passing through a wire coil. When an electrically conducting particle of metal passes through this magnetic field, an electro-motive force (EMF) is generated to the particle itself. Due to this EMF, an eddy current flows to the particle and creates a magnetic field around it, causing the metal particle to experience a repelling force. When dry foundry sands used in the casting process pass through the high-frequency alternating field magnet, the metallic granules are repelled from the falling stream and sand. Grains of sand fall into one bin while metal pieces fall into another. This project was awarded in March of 2001. So far EMPS has acquired the necessary test equipment, assembled the power supply rack and controls, acquired the necessary power amplifier equipment, and has begun testing on schedule. While prototype testing, EMPS discovered a new phenomena where testing caused particle attraction into the magnetic field. The prototype testing has been slightly interrupted due to this new finding. The exact completion date for this project is still unknown.