Dry Magnetic Separation of Rod-Mill Feed at Minntac: Progress Report No. 1

Abstract

Pilot-plant testing at the Coleraine Research Laboratory has indicated the potential benefits of dry magnetic separation (cobbing) of Minntac rod-mill feed. Therefore, a prototype commercial unit was installed on line 18 to establish the benefits of dry cobbing. Line 18 was operated with and without dry cobbing on alternate days. The initial test period indicated, that for a short period and one splitter position, dry cobbing produced about a 5 percent increase in the magnetic iron tons in the wet cobber concentrate with a concurrent 2 percent loss in magnetic iron recovery. About 25 percent of that iron loss was associated with fine material being carried along with the dry cobber tailings. In the second test period, a flow meter and density guage were installed in the final concentrate line so that the actual long tons per hour of concentrate produced could be measured. The second test period ran for.about 2 weeks and showed a production increase of about 3 percent with essentially no loss in magnetic iron recovery. While the tests are not totally conclusive they do indicate potential benefits with dry cobbing. It is anticipated that with the recommended optimization of the splitter position and with the potential for increased iron recovery by screening the dry cobbing tailings that production increases of greater than the observed 3 percent will be realized.