蒙脱石与煤的异相凝聚机理

通过沉降试验、Zeta电位测试、光学显微镜观察和DLVO理论计算,研究了蒙脱石和煤颗粒间异相凝聚现象,并对其机理进行分析。试验结果表明:在试验p H值范围内蒙脱石与煤均会发生异相凝聚,但p H3时,蒙脱石和煤表面均荷负电,颗粒间静电作用为相互排斥,不利于两者凝聚。钙、镁离子对蒙脱石与煤的凝聚有促进作用,其中,游离态离子会压缩矿物双电层结构,减弱其表面负电性,并且部分离子可吸附在矿物的Stern层内,破坏双电层结构;水解形成羟基化合物和氢氧化物会吸附在矿物表面,促使蒙脱石和煤形成"静电桥"。DLVO理论证实钙、镁离子具有消除或减弱"位垒"的作用。添加抑制剂或消除矿浆中钙、镁离子,可有效减弱蒙脱石对煤泥浮选的不利影响。

Mechanism of hetero-aggregation of montmorillonite and coal

The mechanism of hetero-aggregation of montmorillonite and coal was investigated through sedimentation tests,Zeta potential measurements,optical microscope photos and some theoretical calculations of DLVO.The results showed that montmorillonite aggregated with coal in the experimental pH range.When pH was above 3,both montmorillonite and coal were negative charged,and the electrostatic interaction among particles was repulsive force,which was detrimental to the hetero-aggregation of montmorillonite and coal.Ca2+ and Mg2+ could promote the hetero-aggregation.Dissociative irons could compress the electric double layer weakening the negative charge of minerals.Some dissociative irons could broke the electric double layer by adsorbing in the Stern layer.Hydroxyl (MOH+) and hydroxide (M(OH)2) formed by ion hydrolysis could adsorb on minerals surface and form “ion electrostatic bridge”.DLVO theory proved that Ca2+ and Mg2+ could weaken or eliminate the energy barrier between montmorillonite and coal.Adding inhibitors or eliminating Ca2+ and Mg2+ in pulp could weaken the bad effects of montmorillonite on coal slime flotation.