Magnetization Control of Magnetic Liquids for Sink-Float Separations

The cut-density of sink-float separations with water-based magnetic liquids linearly depends on the magnetization of the process liquid. The control of the magnetization of the liquid, by means of measurement followed by extraction of water from the process liquid by membranes or mixing with water or concentrated magnetic liquid, is therefore a critical part of the technology. A potential problem with mixing-in concentrated magnetic liquid is that the process liquid may become inhomogeneous and will segregate in the magnetic field region. Mixing experiments for various scenarios were carried out on a simplified experimental process line and magnetization levels were compared with theoretical models. The results show as process liquid segregation, due to incomplete mixing, can be avoided for all conceivable control strategies by using static mixers. A measurement tool based on a magneto-gravimetric principle was shown to have sufficient sensitivity to detect and control fluctuations of the magnetization of such a fluid in an industrial