Study On Reverse Flotation Inhibitors Of Iron Concentrate From Magnetizing Roasting-Magnetic Separation Of Xuanlong Oolitic Hematite Ore

Xuanlong type iron ore belongs to oolitic structure ore. It has the characteristic of very fine dissemination of iron minerals, which cement with gangue minerals in the form of mosaic to form the oolite. So it is hard for traditional grinding technologies to completely separate iron minerals from gangue minerals, as a result, the processing cost is high, and the economic benefit is very poor as well. Therefore, appling a magnetizating roasting-magnetic separation process to obtain a magnetic concentrate, and finding reasonable reagent system for the reverse flotation of the magnetic concentrate to obtain iron concentrate with high grade have been investigated in this thesis.With the condition of grinding fineness of-0.074mm accounting for58.32%, roasting temperature of800℃, ratio of coal to ore accounting for12%, roasting time of45min, the grinding fineness of-0.074mm accounting for91.02%in magnetic separation and magnetic field strength of105.6kA/m, the iron concentrate with iron grade of61.98and iron recovery of89.13%could be obtained.It is an important issue for the reverse flotation of iron concentrate to find an effective iron mineral inhibitor. The effects of corn starch, dextrin, sodium humate,(NaPO3)6, Na2SiO3and Ca2+on single minerals including roasted magnetite, natural magnetite and quartz in sodium oleate flotation system have been studied. The results show that these inhibitors have strong depressing effect on the two magnetite minerals when the pH value is over11, the flotability of quartz would be poor if CaCl2is used with sodium humate,(NaPO3)6or Na2SiO3, the flotability of roasted magnetite is worse than that of natural magnetite, and the influence degree of inhibitors on roasted magnetite was lower than that on natural magnetite.The characterizing methods of infrared spectroscopy (IR) and zeta potential were used to understand the mechanism of interactions between inhibitors and minerals.With the condition of iron grade of iron concentrate from magnetic separation61.42%, the grinding fineness of-0.074mm accounting for82.64%, the dosage of sodium oleate500g/t, the study result of inhibitors show that iron grade and operational recovery would reach63.99%and84.75%, respectively when the dosage of starch is1000g/t, the dosage of CaO is3000g/t, and the pH value is12. Iron grade and operational recovery would reach64.12%and89.15%, respectively when the dosage of dextrin is1000g/t, the dosage of CaO is750g/t, and the pH value is11.5. And iron grade and operational recovery would reach63.87%and86.21%, respectively when the dosage of sodium humate is1500g/t, the dosage of CaO is1000g/t, and the pH value is11.5. The result can not be improved effectively if sodium humate is added in grinding. Iron grade and operational recovery would reach63.57%and87.92%, respectively when the dosage of lignin sulfonate is1500g/t, the dosage of CaO is4000g/t, the pH value is11.5, and the result can not be improved effectively if (NaPO3)6or Na2SiO3is added.The analyses of flotation products by SEM-EDS show that fine iron mineral particles and gangue mineral are wrapped up by each other seriously for the reason of magnetic coagulation and bridging-association, as a result, a part of iron minerals enter tailings following gangue minerals, so the iron grade of tailing is relatively high and recovery is on the low side; the iron grade of concentrate is relatively low due to the existence of iron mineral-gangue mineral intergrowth.