Effect of Cation Valence and Flocculation Method on the Coal Slurry Sedimentation Mechanism

[Objective]In order to clarify the characteristics of coal slime in Zhuneng Coal Preparation Plant from the perspectives of technology and environment, the coagulation/flocculation behavior characteristics of coal slime water in Zhuneng Coal Preparation Plant in the presence of monovalent (Na+, K+) and divalent (Mg2+, Ca2+) metal cations and anionic flocculants (SPP-600) were studied. [Method]According to the characteristics of coal slime in Zhunneng Coal Preparation Plant, the coagulation/flocculation behavior characteristics of coal slime water in Zhunneng Coal Preparation Plant in the presence of monovalent (Na+, K+), divalent (Mg2+, Ca2+) cations and anionic flocculant (SPP-600) were studied from the technical and environmental perspectives. [Result]The results of the coagulation tests showed that while divalentions were more effective at 0.1 mol/dm3, higher settling rate and lower turbidity values were obtained in the presence of monovalent ions at 1 mol/dm3 concentration. The optimum flocculant dosage was obtained as 150 g/mg from the flocculation experiments. The floc-size and strength measurements indicated that the larger flocs were obtained with Na+ than Ca2+ in the presence of the flocculant. The strongest flocs were obtained at 0.1 mol/dm3 Ca2+ + 150 g/mg flocculant. [Conclusion]It can be concluded from this study that the coagulation followed by the flocculation method can be employed to obtain fast flocculation behavior and low turbidity for the dewatering of coal tailings.