摘要
In Morocco, the phosphate industry generates by washing during the ore beneficiation in humid way, big quantities of sludge loaded in fine mineral particles （or slimes） with contents of water in the order of 90-95%. The specific consumption in water for the beneficiation of one tone of dry ore is approximately 0.6 m3. The management of this sludge and the recycling of process water are played to a schema of solid-liquid separation by flocculation, settling then stocking in basins of several dozens hectares. Recovered clear waters are recycled into the circuit of washing. The principal motivation of this work which is a part of EL MAA project is dedicated to the study of the impact of the speed of agitation on the flocculation behavior in terms of dewatering of the phosphate slimes and recycling of the process water. Study was driven on sample of slimes taken in entrance of the thickeners of a Moroccan washing plants, before flocculation. The raw slimes have a concentration in solid of 75.5 g·L^-1, a P205 grade of 17.3% and a free settling velocity 9 cm·h^-1. Fine fraction -2 μm, responsible for the poor settling of slimes is composed in practice of nearly 96% of smectite. It represents 9% of the dry solid content in the slimes. Measurements reveal important variations of the granulometric and textural properties of large floes in response to flocculation, opening ways of optimization for the velocity gradient.
