Trials were carried out to improve the slow settling velocity of phosphate slimes, produced during the beneficiation of an Egyptian phosphate ore, by their flocculation using corn starches as local flocculants. The different types of corn starch such as food starch, acidic, oxidised and its unmodified form were tested in this study. The influences of the main parameters affecting the process, such as starch concentration, pH, pulp density, temperature, water hardness and ionic strength were investigated. The unmodified form of corn starch gave the best flocculation power. Its efficiency was greatly improved at pHs 4–6 and at the temperature range 60–75°C where its gelatinization temperature range existed. The adsorption of starch, and in turn, the settling rate were further improved by the presence of soluble ions, such as Ca 2+, Mg 2+ and Na +, in the suspending medium due to their reduction of the repulsive forces. The mechanism of hydrogen bonding was shown to play an important role in the adsorption of such non-ionic starch molecules on the surface of phosphate slimes.