六偏磷酸钠对浮选中煤泥与黏土颗粒间相互作用的影响

Influences of sodium hexametaphosphate on interactions of coal and clay particles in flotation

通过浮选试验、Zeta电位测试、吸附量试验和扩展的DLVO理论计算,考察六偏磷酸钠对浮选中煤泥与黏土颗粒间相互作用的影响,研究六偏磷酸钠的作用机理。结果表明:高岭石含量较多时会对煤泥浮选产生不利影响,高岭石含量达到20%,精煤回收率降低18.70%;低用量的六偏磷酸钠会抑制高岭石上浮而对煤影响较小,高用量的六偏磷酸钠会失去选择抑制性;六偏磷酸钠用量为1 000 g/t时,能使煤和高岭石的Zeta电位分别从-25 m V、-39 m V移至-32 m V、-57 m V,增强了颗粒间静电排斥作用;同时,六偏磷酸钠水解形成的大分子吸附于高岭石表面,当颗粒相互靠近时产生较强的排斥力,增强了颗粒之间的空间稳定化作用能。

The influences of sodium hexametaphosphate on interfacial properties of fine minerals in coal flotation were investigated by many tests,including flotation,Zeta potential measurement,adsorptive capacity and theoretical calculations of extended DLVO. The flotation results showed that high content of kaolinite is unfavorable for coal flotation. An addition of 20% kaolinite decreased the coal recovery by 18. 70%. At low concentration,sodium hexametaphosphate depressed the flotation of kaolinite,whereas it had little effect on coal flotation. At high concentration,sodium hexametaphosphate lost the selective inhibition ability. With 1 000 g/t sodium hexametaphosphate,the Zeta potentials of coal and kaolinite particles were shifted from-25 m V,-39 m V to-32 m V and-57 m V,respectively. As a result,the electrostatic repulsion between coal particles and kaolinite particle were enhanced. In addition,by adsorbing on the surface of kaolinite,sodium hexametaphosphate increased the steric hindrance repulsion and strengthened the dimensional stabilization effect when particles approached to each other.