Abstract

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.