The magnetization intensity of some artificial suspensions while flocculating in a magnetic field

Abstract

SUMMARY The magnetization intensity of suspensions containing kaolinite or quartz as a non-magnetic fraction and maghemite or magnetite as a magnetic fraction, while flocculating in the geomagnetic field, was measured as a function of time. The measurements were repeated for a range of different salinities. For all compositions studied, it is found that the initial intensity of suspension magnetization rises with rising low salinity and then at some higher salinity falls to a very low value. For all compositions the intensity of suspension magnetization decays in time at a salinity-dependent rate. The magnetization (DRM) of the completely settled sediment is always much weaker than the magnetization of the initial suspension, to an extent which again depends on salinity. The results indicate that the characteristics of the ultimate DRM originate from (flocculation) processes which occurred already at an early instance in the suspensions, and consequently do not have much relationship with the sedimentation process itself. Different from our experiments, floc-formation in nature usually involves organic compounds which act as a glue. It is suggested that this natural flocculation is a major cause for the undersaturation of the intensity of natural DRM.