A hybrid method for combining High-Gradient Magnetic Separation and centrifugation for a continuous process

High-Gradient Magnetic Separation (HGMS) is a batch-wise method for the separation of magnetizable particles out of fluid to a wire filter. The magnetic field is usually removed for backflushing, as the flow limit of magnetic particles in a field is significant and complicates the transport. A new hybrid method allowing discharge while a magnetic field is applied consists in combining centrifugation and HGMS. In this case particles are collected on the wire filter and cleared simultaneously from the filter to the centrifuge wall by centrifugal forces. A hybrid decanter was set up to transport particles out of the magnetic field. It combines the advantage of magnetic separation, i.e. selectivity and high separation efficiency, with the continuous use of a decanter. The machine was tested pumping suspension in a cycle. Separation efficiency depends on the magnetic field strength and is at high field strengths uncoupled from centrifugal velocity. Particle transport needs a minimum screw conveyor velocity and centrifuge rotational speed but is possible despite high field strengths. A method for analytical prediction is suggested. Experimental particle separation is compared with the analytical prediction. (C) 2014 Elsevier B.V. All rights reserved.