Por: Francisco J. Sotillo, PerUsa EnviroMet Inc.AbstractThe use of rheology in the Phosphate Industry is not as extensive as it is in many other industries, such as coal, gold, silver and copper sulfides, alumina, etc. Rheology influences all major unit operations by modifying the aggregative stability and the sedimentation stability of the system. These concepts are related to the balance of attractive and repulsive forces and their effects on coarse and fine particles. The evaluation of the aggregative stability and sedimentation stability is done using different surface chemistry studies, parameters, and techniques; mainly by indirect measurements. Thus, it requires an understanding of the concepts, particle-particle interactions, and surface chemistry of the systems.Comparison of rheology applications in other industries in grinding, classification, design of slurry handling systems, gravity separation, flotation, pumping and storage of slurries, settling of tailings, and clays handling in comparison with the Phosphate Industry were presented. Grinding improvement for precious metals and sulfide ores have reported 16.5% increase in grinding efficiency with an increase in throughput of 8% to 9%. The Phosphate Industry’s limited exploration of the use of rheology modifiers in grinding resulted in increased solids content in the grinding system and 20% increase in throughput, but no further studies were followed. Gold and silver bearing sulfide ores showed that improving classification and gravity separation, by reducing the viscosity of the slurries, increased the gold and silver recovery by about 30% and 44% on a relative basis, respectively. Efforts to reduce the phosphate losses during desliming in vaults, settling tanks, and cyclones at pilot plant scale showed reduction of up to 54% to 57% in BPL-Ton in the phosphate feed, and cyclone efficiency increases from 60% to 80%. Again, no follow-up studies were conducted.Whereas the Coal Industry used rheology to handle the coal-water slurries at 90% minus 200 mesh and 70% solids content with the viscosity of fuel oil and no sedimentation, the Phosphate Industry did not explore this technology for pumping phosphate concentrates to the process plants, even though laboratory tests reported encouraging results. The use of rheology modifiers to improve flotation of phosphate ore was explored at the industrial scale showing improvements of 6% to 9% in absolute recoveries under the adequate conditions (different than the standard conditions). However, little interest in pursuing these novel concepts was found.