ABSTRACT

In situ recovery (ISR) has the potential to recover metals at a lower cost, create less waste and significantly reduce energy usage and the environmental footprint of a mining operation compared with conventional mining. Only preliminary research has been conducted on ISR-related mass transfer enhancement methods. Improved mass transfer may allow for greater contact of lixiviant with ore surfaces in an ISR operation, improved leaching kinetics and an increased overall metal recovery from the in-situ environment. One approach to improve mass transfer in ISR is to use an electrokinetic method. The electrokinetic method induces ion migration using an electric potential difference across a medium immersed in liquid. The focus of this study was twofold: to evaluate the effect of different parameters on the migration of ions in an electrokinetic setup and to propose a standard laboratory-scale setup to perform mass transfer measurements for ISR. A series of experiments were conducted in which the propagation of lixiviant solution in an electrokinetic setup was monitored and the experimental results were analyzed by different methods. Experiments were performed using different voltages (but in a constant voltage setup) using two experimental setup configurations (with and without hydraulic pressure), synthetic core samples of different permeabilities and different membrane types at the ends of the experimental setup middle section. It was found that an increase in applied voltage across a non-reactive silica sample increased ion migration. At 20 V and above, more ions moved to the target reservoir over 4 days compared with 15 V, and at 15 V, more time was needed to reach maximum ion migration. The use of different membrane types did not affect lixiviant ion migration significantly. Lower-permeability synthetic core samples hindered lixiviant ion migration.

摘要

与传统采矿相比，原位回收 (ISR) 有可能以更低的成本回收金属，产生更少的废物，并显着减少能源使用和采矿作业的环境足迹。仅对与 ISR 相关的传质增强方法进行了初步研究。改进的传质可以允许浸出剂在 ISR 操作中与矿石表面有更多的接触，改进的浸出动力学和增加从原位环境中的整体金属回收率。在 ISR 中改进传质的一种方法是使用电动方法。电动方法使用浸没在液体中的介质之间的电势差来诱导离子迁移。这项研究的重点是双重的：评估不同参数对电动装置中离子迁移的影响，并提出标准实验室规模的装置来执行 ISR 的传质测量。进行了一系列实验，其中监测了电动装置中浸出溶液的传播，并通过不同方法分析了实验结果。使用不同的电压（但在恒定电压设置中）进行实验，使用两种实验设置配置（有和没有液压），在实验设置中间部分的末端具有不同渗透率和不同膜类型的合成岩心样品。发现增加非反应性二氧化硅样品上施加的电压会增加离子迁移。在 20 V 及以上时，与 15 V 相比​​，更多离子在 4 天内移动到目标储层，而在 15 V 时，需要更多时间才能达到最大离子迁移。使用不同的膜类型不会显着影响浸出离子迁移。低渗透性合成岩心样品阻碍了浸出离子迁移。