Sedimentation of colloids in high magnetic fields

Magnetic flocculation experiments are described for a number of mineral suspensions in high fields. Their sedimentation behaviour has been observed in situ by a novel optical monitoring technique. Anomalous negative enhancement of sedimentation rates in these suspensions has been observed at low fields, and this phenomenon is explained in terms of particle anisotropy. Results are shown of field-induced selective sedimentation in heterogeneous suspensions of fly ash. Finally, for the first time, binary magnetic flocculation is reported for a diamagnetic colloid.