Characterization and flocculation studies of fine coal tailings
S Kumar, S Bhattacharya, NR Mandre
The re-use of waste water from coal preparation plant tailings is always
desirable, but is generally problematic in terms of solid-liquid separation.
Dewatering and disposal of coal slurry at a high percentage of moisture
poses a major technological and environmental challenge to mining and
mineral processing industries world-wide. Characterization and flocculation
of these coal tailings reveals that the separation of fine coal tailings
depends on factors such as size distribution, slurry viscosity, zeta
potential, pulp density, circuit design, plant operating parameters, and the
behaviour of solid particles in an aqueous medium. The present study was
carried out on -600 mm coal tailings collected from a coking coal
preparation plant of Jharia Coalfield, India, using anionic flocculent.
Characterization studies revealed that the zeta potential was highest
(-44 mV) at a pH of 9.0, the size range of the particles was 1.1–700 µm,
and the average ash content was 62.57%. Flocculation studies were
performed at different solid concentrations, pH values, and polymer
dosages. The results indicated an efficient settling rate of 178.15 mm/min
at 8% solid (w/w) at a flocculent dosage of 32.50 g/t solid. The turbidity of
the clear liquid obtained was 7.42 NTU.
Keywords: flocculation, coal fines, settling, dewatering.