Optimizing the Tailings Dewatering Circuit in a Coal Preparation Plant Through Industrial Trials

Abstract

Coal preparation plants produce large volumes of fine tailings, posing persistent challenges in water recovery, handling, and environmentally responsible disposal. Unlike previous studies, which were limited to laboratory-scale or isolated unit operations, this research presents a comprehensive, plant-scale optimization of the tailings dewatering circuit at the Parvadeh coal preparation plant in Iran. The existing system, comprising a high-capacity thickener followed by pressure filter presses, was underperforming, prompting a series of industrial-scale trials targeting key operational parameters. Optimization of flocculant dosage (70 g/t), solution concentration (0.60 g/L), and feed dilution significantly improved thickener performance, increasing underflow solids concentration from 45.0 % to 47.50 % and reducing overflow turbidity from 151.1 to 87.9 NTU. In the filtration stage, adjustments to flocculant addition (20 g/t), filtration cycle time (25 min), and aeration duration (45 s) reduced filter cake moisture from 25.30 % to 20.10 % and filtrate turbidity from 139.8 to 73.5 NTU. All improvements were statistically significant (p<0.0001). These results demonstrate the value of integrated, data-driven process optimization under real industrial conditions, offering a scalable pathway to enhanced water recovery, drier tailings, and reduced environmental impact in coal processing operations.