In this work a heterocoagulation in fluorite ore slurry from a Mexican mine has been experimentally studied through measurements of granulometric analysis and scanning electronic microscope (SEM). The experimental results have shown that there was a strong heterocoagulation in the form of slime coating in the fluorite ore slurry at pH 9, which might be attributed to the electrical double layer attraction between particles of fluorite/quartz and calcite/quartz in aqueous solutions, and very weak electrical double layer repulsion between fluorite/calcite particles in aqueous solutions. Also, the elimination of the heterocoagulation has been investigated through using chemical dispersants, CMC (carboxymethyl cellulose) or water glass, in order to improve the beneficiation of the fluorite ore by froth flotation. It has been found that the dispersion processing with CMC as dispersant could effectively improve the fluorite flotation, increased the fluorite recovery from 72% to 78.5% at the same concentrate grade of 98% CaF2. (C) 2005 Elsevier Ltd. All rights reserved.