دانلود مقاله : Continuous float–sink density separation of lump iron ore using a dry sand fluidize

چکیده : 

A continuous separator based on float–sink density separation using a gas–solid fluidized bed dense medium

was used to upgrade iron ore. The separator has three devices for (A) conveying floaters, (B) recovering

floaters, and (C) conveying and recovering sinkers. The optimum speeds of these devices were

investigated using density adjusted spheres of the mm in the range of 2400–3300 kg/m3

in density increments of 100 kg/m3. A mixture of zircon sand and iron powder was used as the fluidized

medium to adjust the fluidized bed density to produce a separation kg/m3, a typical separation

density for lump iron ore wet separation. The recovery of the spheres as floaters or sinkers

depended on the speed of the devices, because the recovery was affected by the number density of

spheres directly under the feeder, the local fluidized bed density, and flow currents in the medium

derived from the movement of the devices. The optimum speeds were determined to be 3.5 cm/s for

(A), 2.0 rpm for (B) and 1.0 cm/s for (C), respectively. Continuous separation experiments were conducted

on lump iron ore particles in the size range of +11.1–31.5 mm in the fluidized bed with medium density

of 2850 kg/m3 and feed rate of 200 kg/h. Comparison of the feed rate and the recovery rate indicated that

the feed and the recovery were in equilibrium after 10 min of operation. The experiments resulted in

nearly perfect separation; 98.4% of the ore with density greater than 2850 kg/m3 was recovered. The

Fe, Al and Si content of the feed ore particles (before the separation) and the floaters and sinkers (after

the separation) was measured using inductively coupled plasma spectrometry. The separator produced

an upgrade in iron content of 3.3 wt% and reduced the Al and Si content by 44%.