Magnetizing Roast for Chalcopyrite: Effect of Particle Size and Dilution

In excess oxvgen, 0-37 μm CuFeS2 became magnetic at a temperature of 280ºc. The magnetic product is copper ferrite, CuO.Fe203. The ‘magnetizing’ temperature increased with particle size apparently following the trend reported for the ignition temperature. Dilution increased the magnetizing temperature; 80% dilution by PbS, MoS2 or SiO2 increases the temperature from 280ºC to over 420ºC. Sinterina was a concurrent reaction. Nevertheless, a chalcopyrite/ galena mixture after roasting and gentle grinding was readily separated on a Davis tube.