Nanoparticle depressants in fine particle seperation - The Efeect of Colloidal Silica in Calcium Mineral Flotation

The micro particle separation of calcium minerals by means of selective froth flotation is a challenging task. The difficulty arises because of the similar surface properties of the minerals, and thereby similar responses to various known families of flotation collectors (selectively adsorbing surfactants). Within the scope of this study colloidal silica is investigated as a potential selectively interacting nanoparticle depressant in the flotation process of calcium minerals. The effect of the colloidal silica and its interactions with the reagent system were investigated by varying its modification and specific surface area/particle size. Single-mineral microflotation of scheelite (calcium tungstate), fluorite (calcium fluoride), calcite (calcium carbonate) and apatite (calcium fluoro phosphate) were used to determine if colloidal silica would have any effect on the minerals. First results show that colloidal silica prevents calcite from floating while scheelite, fluorite and apatite are unaffected by the presence of the reagent, regardless of the dosage.
First batch flotation tests have shown significant differences between the three modifications in terms of the significant effect on the selectivity. The same finding was made when varying the specific surface area/particle size. Further surface chemistry studies will provide more insight on the depression mechanisms of colloidal silica in calcium mineral flotation.