Purification of specularite by centrifugation instead of flotation to produce iron oxide red pigment

This study used specularite, a high-gradient magnetic separation concentrate, as a raw material in reverse flotation.An iron concentrate with a grade of 65.1 wt% and a recovery rate of 75.31% were obtained.A centrifugal concentrator served as the deep purification equipment for the preparation of iron oxide red pigments, and its optimal rotating drum speed, feed concentration, and other conditions were determined.Under optimal conditions, a high-purity iron oxide concentrate with a grade of 69.38 wt% and a recovery rate of 80.89% were obtained and used as a raw material for preparing iron oxide red pigment.Calcining with sulfuric acid produced iron red pigments with different hues.Simultaneously, middlings with a grade of 60.20 wt% and a recovery rate of 17.51% were obtained and could be used in blast furnace ironmaking.High-value utilization of specularite beneficiation products was thus achieved.

Investigation on steelmaking dust recycling and iron oxide red preparing

To investigate the physical and chemical properties of the steelmaking dust, wet sieve separation, XRD, SEM, EDS, and traditional chemical analysis were carded out to obtain the particle size distribution, mineralogy, morphology, and the chemical composition of the dust. The dust with a total Fe content of 64.08wt% has coarse metallic iron, magnetite and hematite grains, while free clay minerals with a size of 〈38 μm are mainly iosidefite, calcium silicate, and calcite, which are conglomerated to each other. By following the procedures of wet magnetic separation, acid leaching, and oxidization calcination, magnetic materials were recycled and further prepared as iron oxide red with a productivity of 0.54 ton per unit ton of the dust. Middle iron concentrate with an Fe content of 65.92wt% can be reused as feeding material in the ironmaking industry. Additionally, washed water from acid leaching with an Fe^3＋ ion content of less than 5 g·L^-1 was recovered as feeding water in the wet magnetic separation procedure. 2008 University of Science and Technology Beijing. All fights reserved.

SURFACE-MODIFICATION OF FINE RED IRON OXIDE PIGMENT

Surface-modification of fine red iron oxide pigment was carried out in an aqueous solution of sodium poly-acrylate. The sedimentation time of modified samples in water increased from 1.05 to 264.4 hours while the particle size (d50 ) decreased from 1.09 to 0.85 mm, and the tinting strength increased from 100 to 115. The surface-modification as well as the dispersing and stabilizing mechanisms in aqueous solution of the samples were studied by means of IR, Thermal analysis and Zeta potential. The results showed that the modifier molecules acted on the surface of the particles by chemical and physical adsorption, and after the particles were dispersed in aqueous solution, endowing the particle surface with a relatively high negative Zeta potential, thus enhancing electrostatic and steric repulsion between particles for their effective stabilization.