High gradient magnetic separation is a new solids removal technique in which paramagnetic solids can be trapped in a separator by magnetic forces and then flushed out when the field is switched off Theoretical formulas exist that enable equipment to be specified at least approximately. The method has important potential advantages for nuclear fuel reprocessing. It has been laboratory and pilot-scale tested for removal of (simulated) insoluble fission products from dissolver liquor and on a laboratory scale for removing ferric hydroxide floc from aqueous streams.