Entity

Time filter

Source Type

Kitakyusyu, Japan

Oshitani J.,Okayama University | Ohnishi M.,Okayama University | Yoshida M.,Okayama University | Franks G.V.,University of Melbourne | And 2 more authors.
Advanced Powder Technology | Year: 2013

A gas-solid fluidized bed has been used to separate particulate iron ore (+250-500 μm in size) by segregating the particles by density. The ore particles were put into a cylindrical column of inner diameter of 100 mm and bed height of 50 mm, and were fluidized at a given air velocity u 0/umf = 1.2-3.2 for 10 min. u0 and u mf are the superficial air velocity and the minimum fluidization air velocity, respectively. The bulk density of the ore particles after fluidization was measured as a function of height through the bed in 5 mm increments (the 50 mm height was divided into 10 layers) to investigate the density-segregation. The size of the particles in each of the 10 layers was also measured to investigate size-segregation. It was found that both density-segregation and size-segregation occurred as a function of height through the bed after fluidization at u0/umf = 2.0. However, the segregation did not occur near the bottom of the bed for lower u0/umf and did not occur near the top of the bed for larger u0/umf. The origin of the segregation-dependence on the air velocity was discussed considering the air bubbles size and the fluidizing intensity at upper and lower sections of the bed. The Fe content of the 10 layers at u0/u mf = 2.0 was measured to calculate the Fe-grade and Fe-recovery. The ore-recovery was also calculated using the weight of ore particles as a function of height through the bed. The feed Fe-grade (before separation) was 52.1 wt%. If the ore particles in the bottom half of the bed were regarded as the product, the Fe-grade was 59.0 wt%, and the Fe-recovery and the ore-recovery were 68.5 wt% and 60.5 wt%, respectively. © 2013 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. Source


Oshitani J.,Okayama University | Kajimoto S.,Okayama University | Yoshida M.,Okayama University | Franks G.V.,University of Melbourne | And 2 more authors.
Advanced Powder Technology | Year: 2013

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 diameter = 30 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 density = 2850 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/m 3 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%. © 2013 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved. Source


Yoshida M.,Okayama University | Nakatsukasa S.,Okayama University | Nanba M.,Okayama University | Gotoh K.,Okayama University | And 3 more authors.
Advanced Powder Technology | Year: 2010

In order to decrease Cl content in waste plastics, dry density float-sink separation of Cl-contained and Cl-free plastics was explored using a semi-continuous rotating-type gas-solid fluidized bed separator with silica sand. The separator has two distinctive features: (1) the plastics can be fed at a middle height of the sand bed, and (2) when the plastics are recovered with the sand from a container after the float-sink, the recovery height of the sand bed can be changed to designate the plastics as floaters or sinkers. The waste plastics of Cl content = 5.4 wt% were used in this study. The separation was investigated by changing the experimental conditions. As a result, the float-sink of the plastics was affected by the air velocity for fluidization, the float-sink time and the feed amount of plastics. The possible causes of the effects were discussed by focusing on the apparent density of fluidized bed, the fluidization intensity, the size segregation of fluidized particle, the shape of the plastics, and the interactions between the plastics during the float-sink. When the recovery height was changed at the adjusted conditions, the Cl content in the floaters was successfully decreased to be 0.4-0.85 wt%, at which the recovery of the Cl-free plastics was 40-60%. © 2009 The Society of Powder Technology Japan. Source

Discover hidden collaborations