Because of the common presence of different silicate minerals, like kaolinite, montmorillonite and muscovite as gangue minerals in the beneficiation of copper oxide ores, the interaction between copper(II) ions in solution and each of these minerals is a field of strong interest, considering their implications on the aggregation of these minerals in the extreme pH conditions typical of hydrometallurgical unit operations for copper production. After copper adsorption isotherms determination at pH 2 and 4, specific adsorption data were fitted to both Langmuir and Freundlich models. It was found that adsorption is systematically larger at pH 4, and that montmorillonite is the mineral that displays a larger adsorption capacity, as in principle expected by its larger cation exchange capacity, CEC. A good fitting to the Langmuir model was obtained for the three samples, and montmorillonite also appears to conform to Freundlich isotherm predictions, as the tested concentrations of copper(II) do not allow to reach saturation. Furthermore, some desorption is measured for kaolinite and muscovite at the highest copper concentrations, probably because of significant interactions between the adsorbed ions. No such desorption was detected in montmorillonite samples. An XPS analysis of the surfaces of the three minerals suggests that copper adsorption in kaolinite is not associated to a cation exchange process but rather to electrostatic interactions between silica-like faces of the clay. In contrast, ionic exchange of structural calcium (for montmorillonite) or potassium (in the case of muscovite) seems to be the predominant mechanism of Cu(II) adsorption in the other two samples. Electrophoretic mobility determinations agree with this hypothesis: the mobility (always negative, with no traces of charge inversion) decreases in absolute value when kaolinite particles are in contact with solutions of increasing copper concentration at pH 2 or pH 4. On the other hand, the electrophoretic mobility values of muscovite and montmorillonite showed a weak pH and copper concentration dependence, a result that matches well with the ion exchange processes detected in the XPS measurements.

中文翻译：

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层状硅酸盐矿物上铜 （II） 吸附的基本原理与堆浸液溶剂萃取中溶剂萃取中污垢的形成有关


由于在氧化铜矿石选矿中普遍存在不同的硅酸盐矿物，如高岭石、蒙脱石和白云母作为脉石矿物，考虑到它们在铜生产湿法冶金装置操作的典型极端 pH 条件下对这些矿物聚集的影响，溶液中的铜 （II） 离子与这些矿物中的每一种矿物之间的相互作用都是一个备受关注的领域。在 pH 2 和 4 下测定铜吸附等温线后，将特异性吸附数据拟合到 Langmuir 和 Freundlich 模型。研究发现，在 pH 值为 4 时，系统吸附力更大，而蒙脱石是表现出更大吸附能力的矿物，正如其较大的阳离子交换能力 CEC 原则上所预期的那样。这三个样品与 Langmuir 模型拟合良好，蒙脱石似乎也符合 Freundlich 等温线预测，因为测试的铜 （II） 浓度不允许达到饱和。此外，在最高铜浓度下测量到高岭石和白云石的一些解吸，这可能是因为吸附离子之间存在显着的相互作用。在蒙脱石样品中没有检测到这种解吸。对三种矿物表面的 XPS 分析表明，高岭石中的铜吸附与阳离子交换过程无关，而是与粘土的二氧化硅状表面之间的静电相互作用有关。相比之下，结构钙（用于蒙脱石）或钾（在白云母的情况下）的离子交换似乎是其他两个样品中 Cu（II） 吸附的主要机制。 电泳迁移率测定与这一假设一致：当高岭石颗粒在 pH 2 或 pH 4 下与铜浓度增加的溶液接触时，迁移率（始终为负，没有电荷反转的痕迹）绝对值降低。另一方面，白云母和蒙脱石的电泳迁移率值显示出较弱的 pH 值和铜浓度依赖性，这一结果与 XPS 测量中检测到的离子交换过程非常吻合。