Efficient dewatering of unclassified tailings with flocculant: role of ultrasound.

Abstract

Flocculants play an important role in the solid-liquid separation of tailings slurry, and its dosage directly impacts on the dewatering efficiency of tailings. Herein, the influence of ultrasonication on flocculant dosage in dehydration process of unclassified tailings was studied. The effects of flocculant dosage on initial settling rate (ISR), underflow concentration, and effective settling time in the process were investigated in detail. The directivity characteristics of ultrasound transducers with different frequencies in unclassified tailings slurry was simulated by MATLAB. The morphologies of underflow tailings at different flocculant dosages were detected by environmental scanning electron microscope (E-SEM). The relationship between flocculant dosage and fractal dimension (DF) was quantitatively analyzed based on fractal theory. The influence mechanism of flocculant on the settling and thickening of unclassified tailings was revealed. The results show that the optimum flocculant dosage for the ultrasonically treated tailings slurry is 40g/t, at which the ISR reach a maximum value of 0.262cm/min and the final underflow concentration (FUC) reach a maximum value in 60min. Compared with settling without ultrasonication, the optimum flocculant dosage is reduced by 10g/t, the ISR increases by 10.45%, the effective settling time is reduced by 50min, and the FUC increases by 1.65%. The fractal dimension of underflow tailings first increases and then decreases with the increase in flocculant dosage, the relationship of which is in accordance with Lorentz model.