A laser particle size analyzer was used to study kinetics of the flocculation of fine phosphate ore residues in the presence of polyacrylamide(PAM) in a stirred tank. The investigation included the adding method of polyacrylamide and the relationship between flocs particle size distributions and time. A rapid initial flocculation was found. The initial flocculation rate was enhanced by increasing temperature

agitation speed and PAM dosage separately

but decreased with increasing viscosity of fluid and average primary residue sizes. There was an optimal PAM dosage associating with solids concentration. The kind of electricity on residue surface was detected by electrophoresis. From flocculation of residues with different types and different amounts of flocculent

it is shown that the flocculation of residues with cationic APAM in a neutral aqueous solution is carried out mainly by charge neutralization

and the flocculation follows the bridging mechanism in the leaching solution of phosphoric acid.