Evaluation of Reflux Classifier Operation in Size Classification in the Cut Size of 45 Microns

Document Type : Research Article


ACECR Branch of Tarbiat Modares University, Tehran, I.R. IRAN


In unit operation processes; the control of feed size entering to equipments is essential in the optimization of overall operation performance which is usually accomplished by classifiers. In commercial scale unites, a considerable amount of classifier feed bypasses to the underflow non-selectively; especially in the cut sizes less than 45microns. This leads to deteriorate the process performance of the unite operation plant. In the present research, operation of a reflux classifier in the cut size of about 45microns was evaluated. The imperfection coefficient of classification in the all experiments were about 0.3 or less and the bypass of particles finer than 25 microns to underflow was between 8 to 13% which indicates a high performance of the reflux classifier in the size separation having cut size of 45 microns. It was found that fluidization water flow rate has a significant effect to bypass of particles; but excess of fluidization water flow rate caused mixing and in the vertical section that deranges sedimentation procedure leading to non-selective transport of fine particles to underflow. In order to evaluate mixing phenomenon in the vicinity of underflow valve, a Mixing Index was defined. If the defined index equals to unit, indicates to a non-mixing in the region of underflow. The higher index value than unite, indicates to more intense mixing in the vicinity of underflow valve resulting in disordering sedimentation of particles.


Main Subjects

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