Effects Of Grinding Factors On The Flotation Behaviors Of Typical Silicates

This paper is mainly focused on the grinding-flotation system of typical silicates, such as zircon, aquamarine, spondumene, feldspar and quartz. Through XPS, XRD, ? potential measurement, scanning electron and energy spectrum analysis, the potential influence of zirconium ball dry grinding, zirconium ball wet grinding, iron ball dry grinding, and iron ball wet grinding on the silicate mineral surface morphology and properties as well as pulp properties and flotation behaviors was studied. Moreover, based on the theory of mineral crystal chemistry, flotation solution chemistry, molecular modeling, and flotation kinetics, the mechanism of the inner relationship between grinding condition and behavior of silicate minerals under flotation environment was studied and discussed.The results under four different grinding conditions were compared. For dry grinding by zircon balls, minor change of morphology and elements abundance on the surface is detected, while the percentage of wastage of grinding medium is relatively high, resulting a higher concentration of metal ions in the slurry after grinding. Since Zr ion has lower activity, minimum influence of the flotation behavior is expected. For wet grinding by zircon balls, change of appearance and content of minerals on the surface is observed. Under such condition, highest concentration of metal ions was detected, and has influence on flotation behaviors, especially for those collectors by electrostatic adsorption, such as amine. For dry grinding by iron balls, the surface morphology and elements abundance on the mineral surface were changed, the concentration of the metal ions in the slurry is the lowest among all the test series, while the content of Fe increased, which will had influences on the mineral flotation. The reason lies on the presence of Fe-hydroxyl complex will interact with both cationic and anionic collectors.For wet grinding by iron balls, substantial surface morphology change and surface elements change was observed, the concentration of metal ions in the slurry is between that in zirconium ball dry-grinding and iron ball dry-grinding, while the content of Fe increases dramatically, and had a largest impact on the PZC of the minerals. PZC after wet grinding by iron balls is the highest among all the test conditions, and had relatively huge impacts on both cationic and anionic collectors.When laurylamine was selected as the collector under wet-grinding condition, and below the optimal flotation PH, the flotation recoveries of zircon, aquamarine, lithium, pyroxene and quartz from zirconium grinding are higher than those by iron balls. When the flotation PH is higher than optimal flotation PH, the recoveries by zircon balls grinding of zircon, beryl, spodumene and quartz are lower or barely the same as iron ball grinding. The recovery difference of feldspar is small for both grinding conditions. When sodium oleate is appllied as the collector, the flotation recoveries of zircon, beryl, spodumene, feldspar and quartz are overall lower than those ground by iron balls.When laurylamine is chosen as collector under dry-grinding condition, and below the optimal flotation pH, the flotation recovery of zircon, aquamarine, lithium pyroxene and quartz by zircon grinding is higher than those by iron grinding. When the flotation pH is higher than optimal flotation pH, the recoveries after zircon grinding of zircon, beryl, spodumene and quartz is slightly lower or the same as those by iron grinding. When sodium oleate is applied as collector, the flotation recoveries of zircon, beryl, spodumene, feldspar and quartz is overall lower than those by iron ball grinding.Grinding method, grinding medium and the collector type have profound effects on the mineral floatability and floating velocity constant. For nesosilicate of the zircon with laurylamine as collector, grinding factors has relatively huge influence on the mineral floatability and floating velocity content. For tectosilicate of the feldspar, most significant effect was observed from grinding method to the its floatability and floating velocity content. When sodium oleate is selected as the collector, iron ball medium has significant positive effect on aquamarine, which will influence the minerals floatability and floating velocity.Based on the interaction energy calculations of silicates and the reagents, with iron ball grinding, adsorption of all kinds of iron hydroxyl complex was observed on the silicates surface, which makes the interaction energy between cationic collector of the laurylamine and minerals increase, and interaction energy between anionic collector of the sodium oleate and minerals decrease. This will have impacts on the interaction between collectors and minerals. By calculating the change of ion concentration of laurylamine in the interface layer, also proved that the iron ball grinding weakened silicates flotation by laurylamine. Overall, after iron ball grinding, silicates will prevent laurylamine adsorbing on the surface of the minerals, and in turn active the anionic collector of the sodium oleate, and help the oleate ions adsorbing on the mineral surface.