Research On Reverse Flotation Performance Of Magnetic Roasting-magnetic Separation Iron Concentrate

Since2007, degree of dependence on imported iron ore which was more than50%was a major source of hidden danger in economic security of China iron and steelindustry.Using great refractory iron ores was a security strategy choice for economic andsocial sustainable development in China.Magnetic roasting-magnetic separation processwas one of the effective ways to treat weakly magnetic iron ore, grade of magneticconcentrate from55%to58%.Experts put forward as early as2000, to improve utilizationcoefficient of blast furnace, ironmaking must base on the concentrate, grade of blastfurnace should be more than60%.In order to meet needs of market, reverse flotation couldfurther improve magnetic separation concentrate grade.This article carried on research to improve quality and reduce impurity of ironconcentrate with two kinds of magnetic roasting-magnetic separation concentrate andnatural magnetite as the research object. The optimum reverse flotation process conditionsof three kinds of mineral were worked out based on single factor condition experiments.Concentrate grade of two kinds of magnetic roasting-magnetic separation concentrateimproved from60.56%to62.51%、55.51%to59.87%respectively by anionic reverseflotation, just2-4%increased,concentrate of natural magnetite grade can be increased from51.76%to above62%with whether anionic reverse flotation technology or cationicreverse flotation technology, reverse flotation concentrate grade10%increased thanmagnetic concentrate grade with about80%recovery rate.Spectrophotography was adopted to study selectivity of collector adsorption onmagnetic roasting-magnetic separation concentrate, results showed that within a certaindosage of reagents, there was a great difference in adsorption of collector between quartzand magnetite, collector can selective adsorption on the surface of natural magnetite,average sodium oleate adsorption rate of valuable mineral and gangue mineral differ by38.25%, and fatty acid type of collector adsorption selectivity of magnetic roasting-magnetic separation concentrate was small, the average adsorption rate differ by onlyabout1%. Surface hydrophobic character of magnetic roasting-magnetic separation concentratewas measured by relative contact angle and wetting heat. Concentrate and tailing fromreverse flotation, for same wetting liquid, the contact angle of magnetic roasting-magneticseparation concentrate were only separated by10°,while the contact angle of naturalmagnetite were separated by above20°. When wetting liquid was water, wetting heat ofmagnetic roasting-magnetic separation concentrate along with reverse flotation concentrateand tailing were greater than natural magnetite along with reverse flotation concentrate andtailing. At the same time, wetting heat of concentrate and tailing from magneticroasting-magnetic separation concentrate reverse flotation differ only0.012J/g, wettingheat ratio was106.21%; while wetting heat of concentrate and tailing from naturalmagnetite reverse flotation differ0.072J/g, wetting heat ratio was176.59%，almost by onetime.Mineral composition of gangue of raw ore and roasting ore was observed withpolarization microscope, silicon of raw ore existed in the form of detrital quartz andsiliceous mudstone, while silicon of roasting ore existed in the form of silica quartz, andpart of the quartz was coated with iron ore, more widely spread than raw ore. X-raydiffraction (XRD) analysis showed that the mineral ore mineral mainly existed in the formof Fe2O3and the gangue minerals were mainly silicon, after roasting, mineral phasecomposition changed, iron ore occurrence of the converted to Fe3O4Fe2O3was givenpriority to, also with Fe2O3FeO, Fe, useful mineral composition changed, enhancedmineral inhomogeneity. Iron mainly existed in magnetite and maghemite, peak of laihuniteand iron silicate appeared in roasting ore; there were laihunite,quartz in magneticseparation concentrate of roasting ore, and in natural magnetite silicon existed in the formof quartz; part of quartz still existed in reverse flotation concentrate,part of laihunite andiron silicate entered the reverse flotation concentrate, laihunite into tailings part alsocaused iron loss, Fe3O4peak appeared in the reverse flotation tailings.