绿泥石与黄铁矿的异相凝聚机理

Mechanism of hetero-aggregation of chlorite and pyrite

通过沉降实验、Zeta电位测试、电子显微镜观测、溶解试验和溶液化学计算,研究绿泥石和黄铁矿的异相凝聚现象,并对其机理进行分析。研究结果表明:黄铁矿在实验所研究的p H范围内荷负电,未检测到等电点,绿泥石等电点p H约为4.5;当p H大于4.5时,绿泥石和黄铁矿表面均荷负电,颗粒间静电作用能为相互排斥,二者不会发生异相凝聚现象。由于矿浆中氧存在,调浆过程中黄铁矿表面的铁氧化溶出,溶出的铁离子在p H大于4.5时主要以羟基铁和氢氧化铁形式存在,羟基铁和氢氧化铁荷正电,吸附在绿泥石表面,使绿泥石的Zeta电位发生改变,氧化也使黄铁矿的Zeta电位发生变化,从而使绿泥石与黄铁矿表面电性相反,由于静电吸引作用而发生异相凝聚。

The mechanism of hetero-aggregation of chlorite and pyrite was investigated through sedimentation tests, Zeta potential measurements, dissolution experiments, optical microscope photos and calculations of solution chemistry. The results .show that the pyrite is negatively charged in the experimental pH range and thus its isoelectric point （IEP） is not determined. The IEP of chlorite is about pH 4.5. When pH is above 4.5, both chlorite and pyrite are negatively charged, and therefore the electrostatic energy among particles is mutually repulsive and the hetero-aggregation never occurs. With the existence of oxygen in solution, the iron ions on the surface of pyrite are oxidized and dissolved in the process of pulp conditioning. The dissolved iron ions exist mainly in the form of iron hydroxyl and iron hydroxide, both of which are positively charged, bringing about the adsorption on chlorite surface. Consequently, the Zeta potentials of both pyrite and chlorite are changed to a different extent, causing their opposite electrical behavior and inter-attraction between them due to electrostatic interaction. So the hetero-aggregation occurs.