Abstract The concomitant clay minerals in coal commonly have adverse effects on the coal flotation. In this work, the regulation of coal flotation by cations (Na+ and K+) in the presence of clay was investigated to abate this deterioration. It was observed by SEM-EDS that the clay particles coating on the coal surface in low pH condition, which significantly reduced the hydrophobicity of coal. However, after introducing the cations (Na+ and K+), the clay particles originally adhering to the coal surface fall off and form large aggregates. The addition of Na+ and K+ affected the DLVO interaction energy between coal and clay, making the attracting tendency between clays stronger than the attraction between clay and coal. Moreover, the cation species have different regulation behaviors. Na+ improves the combustible recovery by inhibiting clay coating. While, K+ mainly promotes the aggregation of clay and inhibits the recovery of clay. Thermodynamic simulating calculation shows that the combination of clay and coal in the presence of Na+ will release more heat than K+ which is also conducive to hinder clay coating. The obtained behavior rules and mechanisms using cations regulating the coal flotation in the presence of clay can help decouple the adverse effect of clay on clean production of coal, especially in water-deficient and coastal areas.

中文翻译：

---

粘土存在下阳离子对煤浮选的调控

摘要 煤中伴生的粘土矿物通常对煤的浮选产生不利影响。在这项工作中，研究了在粘土存在下阳离子（Na+ 和 K+）对煤浮选的调节，以减轻这种劣化。SEM-EDS观察发现，在低pH条件下，粘土颗粒包覆在煤表面，显着降低了煤的疏水性。然而，在引入阳离子（Na+和K+）后，原本粘附在煤表面的粘土颗粒脱落并形成大的聚集体。Na+和K+的加入影响了煤与黏土之间的DLVO相互作用能，使黏土之间的吸引力强于黏土与煤之间的吸引力。此外，阳离子种类具有不同的调节行为。Na+ 通过抑制粘土涂层来提高可燃物回收率。而K+主要促进粘土的聚集，抑制粘土的回收。热力学模拟计算表明，在Na+存在下粘土与煤的结合会比K+释放更多的热量，这也有利于阻碍粘土的包覆。获得的在粘土存在下使用阳离子调节煤浮选的行为规则和机制可以帮助解耦粘土对煤炭清洁生产的不利影响，特别是在缺水和沿海地区。