Investigation on the effect of ultrasonic pretreatment on selective separation of iron values from iron ore tailings by flocculation

Selective flocculation studies were carried out on Barsuan iron ore tailings having 50.5% iron, 7.2% alumina, and 7.8% silica in the absence and presence of ultrasonication at different experimental conditions using sodium hexametaphosphate as a dispersant and starch as a flocculant. The imposition of ultrasonication resulted in a marked improvement in grade as well as recovery. The results indicate that ultrasonication is able to mitigate the adverse effects of gangue materials. A concentrate assaying 59% iron with 75% recovery could be obtained without ultrasonication, while the application of ultrasonication led to an improvement in concentrate grade to 65% with a corresponding increase in recovery to 91%. The improvement is attributed to the disruption caused at a solid/liquid interface which results in favorable modification of the mineral surface, facilitating selective adsorption of flocculant on the iron ore fines. This, in turn, leads to enhancement in selectivity and recovery. In addition, ultrasonication also leads to effective dispersion, causing enhanced activity.