Ontlametse Molatlhegi, Lana Alagha^*

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Department of Mining and Nuclear Engineering, Missouri University of Science and Technology, Rolla, USA.
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Abstract: The current study investigated the effects of novel hybrid polyacrylamide polymers as ash (slime) depressants in fine coal flotation to enhance combustible recovery and ash rejection. Coal samples at P₈₀ of approximately 45 um with ~25% ash content were floated in the presence of in-house synthesized hybrid aluminum hydroxide polyacrylamide polymers (Al(OH)₃-PAM, or Al-PAM). All flotation experiments were carried out in a 5-L Denver flotation cell. Various influencing factors were examined to optimize the flotation process in the presence of the Al-PAM polymers, including the Al-PAM dosage, Al-PAM conditioning time, impeller rotation speed and pulp pH. Comparative and synergistic studies were also performed using organic polyacrylamide polymers (PAMs), commercial dispersants and Al-PAM/dispersant system. Results showed a significant improvement in both combustible recovery and ash rejection at an Al-PAM dosage of 0.25 mg/L. The maximum combustible recovery obtained, at natural pH, with Al-PAM and Al-PAM/dispersant system was determined to be 70% and 66% at ash content of 7.74% and 7.4%, respectively. Zeta potential values of both the raw coal and concentrate products showed a large shift toward more positive values (from ˉ50 mV to ˉ13 mV), indicating a significant decrease in ash-forming minerals (slimes) when Al-PAM polymers were applied.

Keywords: Fine Coal Flotation, Novel Organic/Inorganic (Hybrid) Polyacrylamide, Zeta Potential, Slime Coating

Cite this paper: Molatlhegi, O. and Alagha, L. (2016) Ash Depression in Fine Coal Flotation Using a Novel Polymer Aid. International Journal of Clean Coal and Energy, 5, 65-85. doi: 10.4236/ijcce.2016.54006.

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