The development of a New Process for Phosphate Thickening

In phosphate beneficiation process, thickening is used to concentrate the slurry or sludge in order to increase its solid content and recover the maximum of water. The addition of flocculants helps to form larger particles that can thicken out quickly. However, the high consumption of flocculant in the thickeners increases the cost of the operation. The purpose of this research is to study the effect of flocculant on sedimentation velocities of different particles size in order to develop a new thickening process which ensure the maximum thickening rate and a minimum flocculant consumption.To achieve this goal, initially the impact of flocculant on different size fraction was studied. The objective of this step is to define the cut-size from which the flocculant has no considerable effect on thickening. This granulometric slice can decant by a simple free sedimentation without needing the flocculant. After that, a hydrocyclone was dimensioned and modeled in order to eliminate this granulometric slice which will undergo free sedimentation. This allowed to design a new thickening technology that targets only fine particles overflow of the hydro-cyclone and that require the addition of flocculant. This technology will significantly reduce the flocculant consumption and ensure a better water recovery in the thickening process