Demonstration of dry magnetic separation to upgrade the Mn:Fe ratio of a ferromanganese ore sample

Sighter Induced Roll Magnetic Separation tests were conducted on a ferromanganese ore sample to determine the potential to significantly upgrade the Mn content and Mn:Fe ratio. The sample had a Mn:Fe ratio of 1.3 and was comprised of hematite, cryptomelane, pyrolusite, quartz, goethite and braunite. Tests at 4.7, 2.3 and 1 mm top sizes revealed better separation of Fe from Mn at the 2.3 and 1 mm top sizes. This reflected the better liberation and separation characteristics of Fe oxides at 2.3 mm and both Fe and Mn oxides at 1 mm. A test on the -2.3 + 0.6 mm size fraction improved the Mn:Fe ratio to 4.6, the Mn content to 41.5 wt% with 69.4% mass recovery and 84.2% Mn recovery. Particle magnetic susceptibility was influenced by particle microporosity, and its effect on apparent density, resulting in some Mn oxides reporting to the magnetic concentrate and Fe oxides to the tails.