Low-rank coals are generally processed with wet methods including washing, flotation, etc.
Fine-sized tailings of these processes are discharged to tailing ponds with a significant amount of
associated water which contains a high amount of dissolved ions. These tailings should be dewatered
employing coagulation/flocculation in terms of technological and environmental aspects. In this study,
the coagulation/flocculation behavior of coal processing plant tailings obtained from Manisa, Turkey
was investigated in the presence of monovalent (Na+, K+) and divalent (Mg2+, Ca2+) ions and an anionic
flocculant (SPP-600). First, the coagulation properties of coal tailings were determined. Then, the
flocculation experiments were carried out, and the turbidity values of the suspensions were measured.
Moreover, the sizes of the flocs were determined using a laser diffraction particle size analyzer to
analyze the strength of the flocs. The results of the coagulation experiments showed that while divalent
ions were more effective at 10-1 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 flocculation experiments. The floc size and strength measurements
indicated that larger flocs were obtained with Na+ than Ca2+ in the presence of the flocculant. The
strongest flocs were obtained at 10-1 mol/dm3 Ca2+ + 150 g/Mg flocculant. 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.