Abstract: To increase flocculation efficiency of slime and improve supplied materials characteristics from pressured filter,based on the analysis of raw coal types and size composition,the influence of reagent,reagent concentration,dosing position,dosage on slime water setting efficiency was investigated. Adding 0. 8 m L reagent at twice had similar effect of adding 1. 0 m L reagent at a time. The second dosage made the slime floc aggregate again,the bigger floc sank quickly. Secondary dosage avoided the pollution of clear water and reduced total reagent consumption. The shorter the mixing time between slime and flocculant,the better the setting effect. Over- mixing would decrease the setting velocity. The setting effect was better when the reagent was added separately at protection box and bridge. Adding reagent in multiple locations improved setting efficiency and decreased circulating content of slime.