Abstract: Bauxite ore dressing slime has the characteristics of small particles,negatively charged,fluid state and pH of weakly alkaline,which is difficult to settle naturally.In order to improve the coagulation and settlement effect of the slime,take the slime produced in the third stage of Pingguo Aluminum as the research object,investigate the coagulation and settling performance of polyaluminum aluminum chloride (PAC),polyaluminum ferric chloride (PFC) and polyacrylamide (PAM) on the slime,and study their mechanism of action.The results showed that the addition of PAC or PFC makes the pH of the slime system decrease,the conductivity increases,the Zeta potential of the slime particles increases,the particle size becomes smaller,and the sedimentation effect is poor.PAC or PFC is not suitable as a coagulant for the slime.Anionic polyacrylamide (APAM) mainly uses the polar group —CONH₂ to hydrogen bond with the kaolinite and diaspore in the slime,the coagulation and sedimentation effect of the sludge is very obvious,the suitable dosage is 40～60 g/t,and the best dosage is 60 g/t.Non-ionic polyacrylamide (NPAM) mainly uses macromolecular chains to wrap around,and the coagulation and sedimentation effect of the sludge is obvious,the suitable dosage is 50~70 g/t,and the best dosage is 70 g/t.Cationic polyacrylamide (CPAM) mainly uses electrostatic adsorption to adsorb sludge particles,the coagulation and sedimentation effect of sludge is average,the suitable dosage is 60~80 g/t,and the best dosage is 80 g/t.

Key words: bauxite ore slime,settlement characteristic,pH value,Zeta potential analysis,conductivity analysis,particle size distribution,FTIR analysis