Synergistic Effect of Polar Group Containing Collectors and Synthesized Frother on Flotation Performance of Oxidized Coal

• Published in: International journal of coal preparation and utilization 2021-05, Vol.41 (5), p.307-320
• Main Authors: Patra, Abhay Shankar, Basu, Abhirup, Biswas, Amrita, Das, Arijit, Anjoom, Sayed Janishar, Mukherjee, A. K.
• Format: Article
• Language: English
• Subjects: Accumulators; Air bubbles; clean coal yield; Coal; Collectors; Contact angle; Diesel; Flotation; Hydrophilicity; hydrophobic-hydrophilic balance; Hydrophobicity; Methyl isobutyl carbinol; Oxidation; Oxidized coal; Polyethylene glycol; Pretreatment; Reagents; Synergistic effect; Synthesis; Yield
• ISSN: 1939-2699; 1939-2702
• DOI: 10.1080/19392699.2021.1883595

High-rank coals are generally more floatable than low rank or oxidized coals due to their higher hydrophobicity. Surface oxidation of coals due to the exposure to atmospheric oxygen renders the surface some hydrophilic character. As a result, the low rank or oxidized coals do not effectively attach to air bubbles and result in lower flotation yields. Nonpolar collectors like diesel and other commercial collectors when used in a flotation process do not effectively attach to the hydrophilic sites of the oxidized coal surface leading to lower yields. Researchers have generally tried pre-treatment with reagents to improve the floatability of these types of coals. In the present work, we have synthesized two collectors, tetrahydrofurfuryl oleate based (C1) and tetrahydrofurfuryl ether based (C2), which contain both hydrophilic and hydrophobic components in some rationale so that they can attach to hydrophobic as well as hydrophilic sites of the oxidized coal. The attachment of synthesized collectors to the oxidized coal can provide better particle-bubble attachment which was evident from the improvement in contact angle from 73.4° to a maximum of 88.54°. Flotation results showed that the yield increased from 8% in absence of any collectors to 40% in presence of collector 1. The flotation performance was further enhanced by the synthesis of a novel frother and the synergistic effect of developed collectors and frothers produced higher yield (53%) and lower ash (10%) clean coal fines compared to some of the well-known collectors like diesel, polyethylene glycol and frothers like Methyl Isobutyl Carbinol (MIBC) used in the study.