عنوان مقاله [English]
نویسنده [English]چکیده [English]
Addition of flocculants to a dilute stable suspension creates bridges between particles, which then results in formation of flocs. Estimation of flocs size is of prime importance in solid-liquid separation studies but this task is challenging because flocs have complex and irregular shapes. Feret's diameter, minimum Feret's diameter, mean Feret's diameter, equivalent area diameter, and equivalent perimeter diameter are commonly used to describe flocs sizes. The flocs sizes formed in the tailings of the Gol-E-Gohar magnetite processing plant were estimated. The accuracy of aforementioned parameters were evaluated by determining the calculated settling velocities and comparing with the settling velocities of particles obtained in the batch settling tests. Image processing methods were used to measure flocs sizes and densities which were needed to calculate the settling velocities. The mean Feret's diameter and equivalent area diameter were found to be the appropriate parameters with the relative errors of 16 and 17%, respectively. Mean Feret diameter and settling velocity of flocs formed in a pulp containg 5% solids with 10 g/t flocculant were estimated to be 338 µm and 67 cm/min, respectively. In this condition, the experimental settling velocity obtained was 57 cm/min. Whereas the floc size and settling velocity were estimated to be 304 µm and 54.5 cm/min when the average of mean Feret’s diameter and equivalent area used as the floc size. When the average of mean Feret’s diameter and equivalent area used as the size to calculate the settling velocities the relative error reduced to 4.3%.