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For controlling fugitive dust emitted from stone quarrying plant, the dust collection efficiency of a simple wetted screen with mesh size of 250 μm under various conditions of air velocity and inlet dust concentration was experimentally examined. It has been found that without the water supply the collection efficiency of dried screen ranged only from 4% to 12%. However, the wetted screen with a water flow rate of 810 (cm 3 /sec)/m 2 could provide the collection efficiency which was increased up to 82% depending on the inlet dust concentration. With the shuttering action of water film on the wetted screen, a maximum collection efficiency of 95% could be achieved as long as the water film could be maintained.

A 20 mm-diameter electrical hydrocyclone was developed and tested. The presence of the underflow results in a smaller d50 than the absence of the underflow. Additionally, the higher the feed flow rate, the smaller d50. Effect of central rod diameter and initial pH of suspension on the separation cut size was examined with and without underflows. The d50 decreases with the increase of central rod diameter and initial pH values in both with and without the underflow. The zeta potential of particles increases proportionally with the initial pH of suspension. The electrical potential exhibits a stronger effect when the suspension has a higher pH. The d50 becomes smallest under largest central rod diameter, highest pH and longest slurry collecting box condition operates with the positive electrical potential at side wall in the presence of the underflow. Based on the experimental data, general semi-empirical correlations were proposed and the effect of each parameter on d50 was examined.