Magnetite recovery in coal washing by high gradient magnetic separation. Final report

Abstract

The report describes a demonstration of the successful recovery of magnetite from mixtures of magnetite and coal, like those found in a coal-washing circuit, by High Gradient Magnetic Separation. The demonstration was part of a research program at Francis Bitter National Magnet Laboratory. High values of magnetite recovery were achieved at reasonably high material throughput rates with little coal found reporting to the magnetics. A single-stage separator incorporating a new matrix design was used at rates up to 4.4 tons of solids per hour per square foot of matrix cross section (300 gpm/sq ft). At this troughput rate, more than 99% of the magnetite was trapped along with less than 5% of the coal. Magnetic field values no higher than 6 kilogauss were used to achieve these results, a value well within the range of present commerical magnet designs.