Abstract: To solve the problem of worse settlement effect of coal slime water in Sanhejian coal separating plant,the coal slime with high concentrating feeding was studied.Based on the analysis of properties of coal slime,a series of slime water settlement experiments with different kinds of coagulants and flocculants were carried out.The effect of concentration of slime water,coagulant and flocculant dosage on the settlement effect of slime water was systematically investigated.Results show that the low metamorphic grade of raw coal,the finer particle size of coal slime and the existence of clay minerals increase the difficulty of slime water treatment.PAC and PAM with 10 million molecular weights are the best combination of drugs,which optimal dosage are 780 g/t and 15 g/t respectively,when the slime water concentration is 70 g/L.The settlement effect of slime water is the best in this condition with supernatant turbidity 18 NTU and settlement speed 11.16 cm/min.The dosage of flocculant and coagulant have a significant influence on the settlement effect of slime water,and the change of slime water concentration in small range has no obvious effect on that.