ABSTRACT

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.

摘要

高等级煤由于其较高的疏水性，通常比低等级或氧化型煤更易于漂浮。由于暴露于大气中的氧气，煤的表面氧化使表面具有一定的亲水性。结果，低等级或氧化的煤不能有效地附着在气泡上，并导致浮选产量降低。当在浮选过程中使用时，非极性捕收剂（例如柴油）和其他商用捕收剂不能有效地附着在氧化煤表面的亲水部位上，从而导致收率降低。研究人员通常尝试使用试剂进行预处理，以改善这些类型的煤的漂浮性。在目前的工作中，我们合成了两种捕收剂，基于四氢糠基油酸酯（C1）和基于四氢糠基醚（C2），它们在某些原理上既包含亲水成分又包含疏水成分，因此它们可以连接到氧化煤的疏水位点和亲水位点。合成捕收剂在氧化煤上的附着可以提供更好的颗粒气泡附着，这从接触角从73.4°改善到最大88.54°可以明显看出。浮选结果表明，在没有任何捕收剂的情况下，收率从8％提高到在有捕收剂1的情况下达到40％。通过合成新型起泡剂，进一步提高了浮选性能，发达的捕收剂与起泡剂的协同作用产生了更高的收率（与研究中使用的一些著名收集器（例如柴油，聚乙二醇和起泡剂，例如甲基异丁基甲醇（MIBC））相比，清洁煤粉的含量降低了53％，灰分含量降低了（10％）。