Particle size dependence in high gradient magnetic separation

The performance has been studied of a high gradient magnetic separator with well defined physical and geometrical properties on a slurry of particles which could also be well defined in terms of size distribution, susceptibility, and density. A special high gradient magnetic separator was constructed whose matrix was a three-dimensional array of parallel stainless steel wires. A slurry of particles of known susceptibility and density was used. The particle size distributions for both the feed slurry and the captured and noncaptured products were determined. By means of an analysis using dimensionless groups, it was found that the particle recovery plotted against the appropriate dimensionless ratio defined a universal curve such that, at a fixed flow velocity, experimental data points corresponding to a wide range of particle sizes and magnetic fields all fell close to this curve. Data points for two different flow velocities defined separate curves. The probable reason for this is that the particle shapes are irregular, and consquently, the fluid drag coefficients which enter into the dimensionless ratio are unknown and were approximated by the coefficients for spheres of equivalent size.