Magnetic separation of kaolin clay using an advanced 9 T separator

A comprehensive series of magnetic separation tests for the removal of mineral contaminants from kaolin clay was performed on five different types of kaolin clays representing major kaolin deposits worldwide. Tests were made on a superconducting magnetic separator operating at fields of 2.0 T to 9.0 T. Results show that there was a progressive improvement in extraction as the field was increased to 9 T. This is the highest field separator known to be in use. These results are consistent with the fact that the extracted impurities are paramagnetic and do not saturate at the field strengths tested. A practical conclusion is that higher fields can either produce better quality, increased throughput, or a lengthened duty cycle with each stepwise increase in the magnetic field. Magnetic fractionation of extracted contaminants at high fields was demonstrated using a new elutriation technique.