【作者】 孙伟；

【导师】 胡岳华； 邱冠周；

【作者基本信息】 中南大学 ， 矿物加工工程， 2001， 博士

【摘要】 铅锌硫硫化矿的分离一直是选矿界研究的热点，其难点在于这些矿物性质相似，可浮性相近，矿物彼此间相互活化和相互影响的现象比较严重，高碱电位调控技术的出现成功地解决了这个难题。本研究利用腐蚀电化学研究方法、旋转圆盘电极、机械电化学研究方法以及表面检测技术对高碱环境中矿物与矿物、矿物与药剂、矿物与磨矿介质之间的各种作用以及机械力对这些作用的影响进行了研究，并利用分子力场理论、量子化学理论和半导体能带理论对这些作用和影响进行了计算与分析，以揭示高碱电位调控浮选的微观机理，为寻找更加高效的电化学浮选方法提供依据。研究的主要内容如下： 利用单矿物电位调控浮选和循环伏安扫描方法研究了浮选与电位的关系，考察了每种矿物的浮选电位范围(电极电位)，并绘出了方铅矿、黄铁矿和闪锌矿在不同环境中的Eh-pH-C图，研究了影响电极电位的各种因素，并对这些因素进行了分类，发现影响矿物电极电位的因素可以分为两类，一类因素既影响矿物表面电极电位，又影响矿物的可浮电位区间，这类因素主要包括：浓度、pH值等。另一类因素，只影响矿物的表面电极电位，而不影响矿物的可浮电位区间，这类因素主要有：pH介质、磨矿介质、加药方式、搅拌等。高钙高碱电位调控技术正是根据以上原理而开发的硫化矿分离技术，单矿物试验、混合矿试验证明高钙高碱电位调控技术是可行的。 针对常规体系，采用旋转圆盘电极技术研究了硫化矿表面氧化还原反应的反应电子数和反应机制，并研究了影响表面反应机制的各类因素，指出表面活性对反应类型和反应机制的影响至关重要。 利用腐蚀电化学技术研究了高碱环境中矿物、介质、药剂间的各种作用，通过不同电极电位下电化学阻抗谱的变化研究了硫化矿表面反应的变化，通过腐蚀电位腐蚀电流的对比，并运用缓蚀效率表征了矿物与各类药剂之间的作用力，研究指出高碱体系对于三种硫化矿的腐蚀行为的影响是不同的，三种硫化矿受影响的顺序为黄铁矿)闪锌矿)方铅矿，关于捕收剂的研究表明，对于黄药和乙硫氮两种捕收剂来说，黄药对三种硫化矿都表现出了相当的作用能力，表现为极化电阻增大，显著的缓蚀效率，而乙硫氮只对方铅矿表现出较强的作用能力。 为了考察石灰对硫化矿浮选行为的影响，运用分子力场方法对钙系化合物在铅锌硫化矿表面选择性吸附进行了动力学，结果表明：OH~-和CaOH~+两种离子在黄铁矿表面的吸附能力最强，因此无论是NaOH体系，还是石灰体系，黄铁矿都会受到抑制。在闪锌矿表面，CaOH~+的吸附要强于OH~-，方铅矿对于两种离子最不敏感，吸附量最小，吸附能最正。 运用机械电化学技术，研究了磨矿介质类型、机械力的大小对矿物电极电位和表面反应电流的影响，并考察了矿物与矿物之间、矿物与介质之间存在的腐蚀电偶作用，发现这些作用会对硫化矿表面的氧化还原反应机制产生影响，进而影响到矿物表面的疏水和亲水性。硫化矿在不同机械力下的表面形貌的研究进一步证明了上述结论。 依据半导体能带理论和密度函数理论以及分子轨道理论，探讨了不同类型硫化矿表面与捕收剂作用的微观机理，结果表明不同的硫化矿具有不同的表面结构，即使是同一种硫化矿，在不同环境下，表面电子结构也会发生变化，这种变化是导致不同表面反应的根本原因。 在理论研究的基础上，进行了硫化矿电位调控浮选的应用研究，电位调控浮选在广东凡口铅锌矿的成功应用表明高碱电位调控浮选具有较大的优越性，指标好，药耗低，该工艺2000年获得国家科技进步一等奖，并在全国逐渐推广。更多还原

【Abstract】 Froth flotation is a commonly used separation technique for sulfide minerals. It is proved that several electrochemical processes occur in flotation which involve the valuable minerals, flotation reagents, and the species dissolved in aqueous phase and grinding media. All these kinds of actions including mineral oxidation, dissolution, adsorption, surface reaction, mechanical reaction and precipitation will lead to undesired flotation and difficulties in separation. This thesis is focused on these behaviors in order to find a better way to enhance the efficiency of flotation.To better understand the relation between mineral electrode potential and flotation behaviors, the Cyclic Voltammeter of freshly fractured sulfides electrodes and single mineral potential-controlled flotation tests were used. The results showed that the recovery of sulfide minerals depended on its surface potential. Different minerals have different potential region for flotation. It predicted that to control the potential of sulfide minerals could modify the results of flotation. The factors, which can affect the variation of mineral surface potential, were also studied. These factors can be divided into two classes, one of them can affect not only potential of sulfides but also range of flotation potential, including concentration of reagents, pH value, the other can only affect sulfides potential, such as grinding media, pH modifiers, agitation etc. From these conclusions, a new technique of sulfides flotation, Original Potential Flotation (OPF), which controlled potential of minerals by grinding environment in alkali pulp, was invented for Lead-Zinc complex sulfides. The flotation results implied that it is doable.In order to investigate the mechanism of oxidation and reduction occurring on mineral surface, the Rotating Disc Electrode technique was undertaken. The results illustrated that the activity of surface have an important effect on reaction mechanism.The Electrochemical Impedance Spectroscopy (EIS) was used to probe the interaction among minerals, reagents, grinding medias. The inhibition efficiency ( η) was used to weigh the action between reagents and minerals. The results suggest that alkali pulp have different effect on different sulfide minerals, the ranking of anti-alkali ability of sulfides is >ZnS>FeS2.To make out the function of lime in OPF, the Force Field Method was employed to simulating the adsorption of calcium species on sulfides minerals.The result indicated that both OH" and CaOH can adsorbed on pyrite surface, but only CaOT have adsorptive action on saphalerite surface. As far as PbS is concerned, neither of above ions can adsorb on it.A special cell was designed to study mechanical electrochemistry phenomena in grinding environment. The effect of grinding media type and mechanical pressure on potential and current of mineral surface was researched; the galvanic couple between mineral and medias were also researched. The results showed that these effects can change activity of surface, which have an important effect on reaction mechanism.The quantum methods were employed to investigate the micro mechanism of reaction between mineral surfaces and collectors. The conclusion expressed that every minerals has it own surface electro-structure, different structure has different properties, which determine what kind of reaction would be occur.At last, the OPF was applied in Fankou Lead-Zinc Mine, the index of industrial experiment showed that the new technique has glorious foreground.更多还原