MEASUREMENT OF AXIAL PRESSURE PROFILES IN LARGE-SIZE INDUSTRIAL FLOTATION COLUMNS

A portable and submergible pressure sensor was developed in order to m easure the axial pressure profiles in large-size industrial flotation columns. The system was used to evaluate the effects that operating va riables, such as pulp density (1.1.-1.3 g/cm(3)), gas flowrate (1-2 cm /s) and interface level (0.2-2.5 m), have upon the pressure profile. I t was found that local pressure varies with changes in pulp level, in the same order of magnitude that varies with common changes in gas flo wrate and pulp density. These measurements show the large uncertainty in pulp level estimation using a single pressure sensor. Axial pressur e profiles were estimated from different baffled section in large-size flotation columns. Typically, the data observed from different column sections showed an homogeneous gas distribution over the cross-sectio n of the column. Local pressure measurement was used to estimate the a xial gas hold up profile along the collection zone of large-size colum ns. A typical increase in gas hold up of 50-60(%), from the bubble gen erator up to the interface level was determined in industrial columns of 14-15(m) height and 1-16(m(2)) in cross-section. These data allowed the validation of models to estimate local mean bubble size. Average bubble sizes in the order of 0.9-1.3(mm), were estimated at superficia l gas rates of 1.1-2.1(cm/s).