ABSTRACT

This study focused on the mechanisms of NaCl and CaCl₂ enhancing the oily-bubble flotation of lignite. The degree of surface hydration of coal particles before and after conditioning with NaCl/CaCl₂ was evaluated with the Einstein theory of dispersion viscosity, while the effect of these two electrolytes on lignite floatability was evaluated via attachment time and flotation tests. The results indicated the adsorption amount of Ca²⁺ on the coal sample was more than that of Na⁺ in the same electrolyte concentration. Owing to the cationic adsorption, the zeta potential of lignite particles increased with increasing NaCl and CaCl₂ concentrations, which thus decreased the electrostatic repulsion between coal particles and oily bubbles. Moreover, the hydration of the coal surface decreased when NaCl/CaCl₂ was added to flotation pulp, meaning the surface hydrophilicity of the coal sample was reduced. As a result, the attachment time between coal particles and oily bubbles decreased significantly, and the combustible-matter recovery correspondingly increased up to a maximum of 50.97% and 90.06% with increasing NaCl and CaCl₂ solutions concentration, respectively. However, it is necessary to keep the electrolyte solution concentration within a reasonable range for a good selectivity during the oily-bubble flotation.

摘要

本研究重点研究了NaCl和CaCl ₂促进褐煤油泡浮选的机理。_{用爱因斯坦分散粘度理论评价了用NaCl/CaCl 2}调节前后煤颗粒的表面水化程度，而通过附着时间和浮选试验评价了这两种电解质对褐煤可浮性的影响。结果表明，在相同电解液浓度下，Ca ²⁺在煤样上的吸附量大于Na ^{+ 。}由于阳离子吸附，褐煤颗粒的 zeta 电位随着 NaCl 和 CaCl _{2的增加而增加}浓度，从而降低了煤颗粒和油性气泡之间的静电排斥力。此外，在浮选矿浆中加入NaCl/CaCl _{2后，煤表面的水化作用降低，煤样的表面亲水性降低。}结果，煤颗粒与油性气泡的附着时间显着减少，可燃物回收率随着NaCl和CaCl ₂溶液浓度的增加相应增加，最高分别为50.97%和90.06%。然而，在油泡浮选过程中，为了获得良好的选择性，必须将电解液浓度保持在合理的范围内。