新型硫脲类捕收剂CPTU对黄铜矿及黄铁矿浮选的电化学机理研究

采用循环伏安、Tafel法及红外光谱分析研究了新型硫脲类捕收剂CPTU在黄铜矿及黄铁矿表面吸附的电化学行为及机理。试验结果表明, 当pH值低于9.18时, 黄铜矿电极从0 V左右开始氧化, 出现了一个新的氧化峰, CPTU在黄铜矿表面电化学吸附形成疏水性产物Cu(CPTU)和单质S; 随着pH值增大, 氧化峰电流减小, 疏水性增强并产生钝化; 当pH值高于11.0时, 黄铜矿自身的氧化占据了主导地位。对于黄铁矿而言, 在整个pH范围内, 捕收剂CPTU的加入并未改变循环伏安曲线的形状。并且, 碱性条件下黄铁矿腐蚀反应产物更容易在矿物表面形成氢氧化物沉淀, 阻碍了CPTU在其表面电化学反应的进行, 证明CPTU对黄铜矿和黄铁矿的捕收有选择性。红外光谱分析表明, CPTU在黄铜矿表面的吸附属于化学吸附, 而在黄铁矿表面的吸附属于物理吸附。

Electrochemistry Mechanism of New-type Thiourea Collector CPTU in Collecting Chalcopyrite and Pyrite

The electrochemical behavior and mechanism of a new type thiourea collector, CPTU, being adsorbed on the surface of chalcopyrite and pyrite were studied by Tafel, CA voltammetry and infrared spectroscopy. For chalcopyrite, an oxidation peak appeared from about 0 V with pH<9.18, which meant that the hydrophobic entity Cu(CPTU) and elemental S were formed thereon, and the oxidation peak currents decreased with the increasing of pH value, resulting in a strengthened hydrophobicity and surface passivation, while, its self-oxidation predominated at a pH value over 11.0. With regard to pyrite, the curve shape of CA voltammetry remained unchanged throughout the entire pH range in the presence of CPTU. Furthermore, as the hydroxide product of corrosion reaction was easier to deposit onto pyrite surface and therewith prevented its electrochemistry reaction with CPTU, the selectivity of CPTU in collecting chalcopyrite and pyrite could be explained. Infrared spectroscopy analysis indicated that CPTU is chemisorbed onto chalcopyrite and physisorbed onto pyrite.