Wet-drum magnetic separation of dense-medium slurries containing fine coal refuse

Laboratory testing was carried out to evaluate the performance of a wet-drum magnetic separator (WDMS) when treating magnetite dense-medium slurries containing fine bituminous coal refuse material. Test variables included slurry feed rate, magnetite-to-coal ratio, and size distribution of the coal refuse. The separations were carried out with and without the application of ultrasonic energy. The performance of the WDMS was evaluated based on the purity of the magnetic concentrate and recovery of magnetic material. As expected, the purity of the products depended on the operating conditions, whereas magnetic recovery was essentially independent of operating conditions. Moreover, under many conditions, the purity of the magnetic material increased slightly after ultrasonic treatment. For selected tests, the size distributions of the magnetic material were determined for both the magnetic concentrate and nonmagnetic streams. This analysis indicated that after demagnetization, the size distributions of the magnetic material in both the concentrate and nonmagnetic streams were similar.