Studies On Effect Of Anionic Starch On The Floatability Of Aluminum-silicon Minerals And Its Mechanism

Pure specimens of diaspore,kaolinite,illite and pyrophyllite were studied as the subjects in this paper to investigate the effect of pulp pH, type and dosage of anionic starch on flotation behavior of the four minerals on a size-by-size basis(-0.074mm+0.038mm,-0.038mm).Zeta potential,adsorption capacity,infrared spectrum,SEM and EDS were used examining the mechanism of the agents on aluminum-silicon mineralsand the results were applied to the flotation of mineral.Pure specimens flotation results show flotation behavior of aluminum-silicon minerals differ greatly with different particle sizes and that the dosage of anionic starch is a key factor affecting the separation of diaspore from silicate minerals.When the pH was at 6 and the concentration of DTAC at 3×10^-4mol·L^-1,with the increase of anionic starch usage,the recovery of disapore decreases for the (-0.074+0.038)mm fraction whereas the kaolinite and illite were activated at low anionic starch dosage and inhibited with increasing anionic dosage. With the -0.038mm fraction of aluminum-silicon minerals,however, illinite was inhibited with increasing dosage of anionic starch while diaspore and kaolinite was activated at low starch dosage,but was inhibited at high starch dosage.The flotation results also show that the effect of anionic starch on pyrophyllite was collector-dependent.With the collector concentration at 3×10^-4mol·L^-1,anionic starch inhibits the flotation of both particle sizes while pyrophyllite of both particle sizes were activated at low anionic dosage and were inhibited at a certain starch dosage when the collector concentration was increased to 7×10^-4 mol·L^-1.The effect of anionic starch on flotation of(-0.074+0.038)mm pyrophyllite was much greater than -0.038mm fraction.The analyses of zeta potential,Infrared spectrum and adsorption capacity show that anionic starch was adsorbed to aluminum-silicon minerals through hydrogen-bonding and electrostatic force what lowers the zeta potential of the four minerals while the zeta potential was increased when cationic collector was adsorbed to the surface.The adsorptive capacity sequence of aluminum-silicon minerals to DTAC was: pyrophyllite＞kaolinite＞illinite＞diaspore.The adsorption of DTAC on four minerals was enhanced at low anionic starch dosage and high starch dosage doesn't affect DTAC isothermal adsorption capacity.The flotation experiments on mineral show that anionic starch is an effective depressant in the reverse flotation of aluminum-silicon minerals. A concentrate aluminum-silicon ratio of 8.12 and recovery of alumina being 81.07%could be reached with the mineral aluminum-silicon ratio of 4.71.The dissertation was supported by "National Key Basic Research Program(973)"(2005CB623701).