Upgrading a Brahmaputra River sand from northern Bangladesh by flotation to produce a high-grade silica glass sand concentrate

ABSTRACT A study into the possible separation of feldspar from quartz in a Bangladesh river sand sample was undertaken with the aim of producing a high-grade quartz product for potential use in glassmaking. Flotation was used to upgrade two river sand concentrates, with sizings of +250 µm and −250 µm, from the Brahmaputra River. Feldspar was floated from quartz using dodecylamine as collector in an acidic circuit at pH 2–2.5 after a mica prefloat. For the −250 µm fraction, the best quality quartz product assayed 96.8 wt% SiO2 and 1.95 wt% Al2O3 with 46.7 wt% of the feed quartz recovered at a quartz content of 89.1 wt% quartz. A test on the +250 µm fraction, which was firstly ground then deslimed at 50 µm before mica and feldspar flotation stages, produced a quartz product assaying 99.5 wt% SiO2 and only 0.3 wt% Al2O3 with a quartz content of 98 wt%.