Density-based separation in a vibrated reflux classifier with an air-sand dense-medium: tracer studies with simultaneous underflow and overflow removal
Density-based separation in a vibrated reflux classifier with an air-sand dense-medium: tracer studies with simultaneous underflow and overflow removal
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DOI：
10.1016/j.mineng.2011.05.002
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发表时间：
2011-08
影响因子：
4.8
通讯作者：
S. Macpherson;S. Iveson;K. Galvin
中科院分区：
文献类型：
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作者：
S. Macpherson;S. Iveson;K. Galvin
研究了示踪粒子在气-砂重介质回流分级机中的连续分离。回流分级器由1 m长的垂直流化床段和2 m长的通道组成，通道与安装在上方的水平方向成70°，两者的横截面均为20 × 100 mm。使用平均直径为220 μm（−355 + 125 μm）的硅砂作为致密介质。回流分级器对尺寸从6.35 mm到1.0 mm的示踪剂颗粒进行了良好的密度分离。通过改变底流率，密度切割点可在1418 ~ 2130 kg/m3之间变化，根据颗粒大小和气速的不同，密度切割点在0.06-0.46 × 103 kg/m3之间变化。在一定的气体流量和底流条件下，六种粒径的密度切割点在1534和1619 kg/m3之间，抑制了粒径对密度切割点的影响。随着空气流量从4.03 × 10− 4 m3/s增加到5.64 × 10− 4 m3/s，密度分界点增加，Ep也增加。在与倾斜床相同的实验条件下，垂直流化床的Ep值在0.07 ~ 1.49 × 103 kg/m3之间，密度截点随实验条件的变化较大。在流化床上方增加斜面提供了一个更稳定的系统，允许更大的分离效率和最小化改变条件的影响。增加砂介质向底流的流量，降低了密度切割点，而增加气体流量，提高了密度切割点。提高气体速率也增加了系统的可变性，这导致较低的分离效率。
The continuous separation of tracer particles in the air-sand dense-medium Reflux Classifier was investigated. The Reflux Classifier consisted of a 1 m long vertical fluidized bed section with a 2 m long channel inclined at 70° to the horizontal mounted above, both with a 20 × 100 mm cross section. Silica sand of 220 μm average diameter (−355 + 125 μm) was used as the dense medium. The Reflux Classifier produced good density separations for tracer particles ranging in size from 6.35 down to 1.0 mm. The density cut-point could be varied from 1418 to 2130 kg/m3by varying the underflow rate and theEpwas within the range of 0.06–0.46 × 103kg/m3depending on particle size and gas rate. At certain gas flowrate and underflow conditions the density cut point ranged between 1534 and 1619 kg/m3across six particle sizes, suppressing the effects of particle size on the density cut point. As air rates increased from 4.03 to 5.64 × 10−4m3/s the density cut-point increased, as did theEp. The results were compared with separations in a vertical fluidized bed of the same total length.Epvalues in the vertical fluidized bed ranged between 0.07 and 1.49 × 103kg/m3over the same experimental conditions as the inclined bed and the density cut point showed more variability with the conditions. The addition of an incline above the fluidized bed provides a more stable system allowing for greater separation efficiency and minimizing the effect of changing conditions. Increasing the flow of sand medium to the underflow decreased the density cut point while raising the gas rate increased the density cut point. Raising the gas rate also increased the variability of the system which resulted in a lower separation efficiency.