Magnetic separation of kaolin clay using a high temperature superconducting magnet system

A team consisting of Aquafine, Sumitomo Electric and DuPont has performed a successful magnetic separation for removal of mineral contaminants from kaolin, a white clay used extensively in paper processing, using an HTS magnet. The magnetic separation tests consisted of removal of ferromagnetic and paramagnetic mineral contaminants from five different types of kaolin clays representing major kaolin deposits worldwide. Tests were performed using both conventional and HTS magnets operating at 2.0 T. In addition, magnetic separation tests were performed at 2.5 T using the HTS magnet. All post processed clays were analyzed using the brightness tests in accordance with the TAPPI standard. Results showed that at 2.0 T, conventional and HTS magnets produce consistent brightness results while operating under similar test conditions. Most important was the determination that the higher magnetic field of 2.5 T, generated by the HTS magnet, enabled higher clay slury throughput without loss of quality. The details of the HTS magnet design and operation and the results of the kaolin tests are briefly discussed.