Abstract: Static flocculation and sedimentation experiments with polyacrylamide and unclassified tailings from a mine were completed to study the effects of feeding concentration and flocculants’ unit consumption on the maximum sedimentation velocity and limit concentration of tailings under static sedimentation.A simple model of sedimentation velocity was established through regression analysis on experimental data.The model was divided into six phases including turbulent flow affected segment,accelerating sedimentation segment,terminal velocity segment,interference sedimentation segment,dewatering sedimentation segment,and limit sedimentation segment.The rationality of the model was explained by the two-phase flow theory and the flocculation theory.The results show that at a certain unit consumption of flocculants (20g·t^-1),the sedimentation velocity is negatively correlated and the limit concentration is positively correlated to the feeding concentration.At the feeding concentration of 20%,the critical value of unit consumption is 30g·t^-1,and the limit concentration is negatively correlated to the unit consumption.A project was proposed that the feeding concentration is 20% and the unit consumption of flocculants is 20g·t^-1.