The application of a superconducting magnet system to the cleaning and desulphurization of coal

The basic requirements for high gradient, high intensity magnetic separation are reviewed and process limitations are emphasized. The principle innovations of the superconducting magnet system design for this work include an annular quadrupole magnet and corresponding slurry channel operating in an open field without secondary poles. The transverse secondary circulation set up in the slurry through the primary orbital flow is used to transport all particles into the region of high field intensity. Two Pennsylvania coals with high pyrite contents were treated. Test conditions and results are described and discussed. One of the coals yielded 81% recovery of "clean" coal and over 85% rejection of pyrite. Possible further improvements are discussed.