TESTING METHOD FOR DETERMINING THE MAGNETIC PROPERTIES OF FERROMAGNETIC POWDERS

摘要

TESTING METHOD FOR DETERMINING THE MAGNETIC PROPERTIES OF FERROMAGNETIC POWDWERS The invention relates to a method permitting ferromagnetic powders to be readily tested for their qualification for use in heavy medium suspensions for the float-sink dressing of minerals. To this end, the invention provides a) for ferromagnetic powder particles with a size within the range 63 to 100 /u to be admixed with a quantity of a glycerol/watermixture necessary to obtain a heavy medium suspension having a specific density within the range 1.45 to 1.55 g/cm3; b) for the heavy medium suspension to be demagnetized in a cyclicly decreasing alternating field at maximum field strengths within the range 1200 to 1600 amperes/cm and for its relative sedimentation velocity to be determined by means of a sedimentometer; c) for the demagnetized heavy medium suspension to be magnetized in a magnetic steady field at field strengths within the range 700 to 900 amperes/cm and for its relative sedimentation velocity to be determined by means of a sedimentometer; and for d) the magnetized heavy medium suspension to be demagnetized in a cyclicly decreasing alternating field at maximum field strengths within the range 1200 to 1600 amperes/cm and for its relative sedimentation velocity to be determined by means of a sedimentometer. Ferromagnetic powder is fully serviceable for use in heavy medium suspensions in the event of the relative sedimentation velocity determined in step b) being smaller than 0.25 cm/second, that determined in step c) being greater than 2.5 cm per second and that determined in step d) being smaller than 0.4 cm/second.