Removal of entrained organic matter in the copper electrolyte by ozonation

Abstract Organic matter-in-aqueous entrainment is a serious problem in the hydrometallurgical extraction of copper from ore. Current inefficiencies, changes in the morphology and orientation of cathode deposit are some of the problems when organic matter is present in the advance electrolyte. In addition, negative effects upon metabolic activity of bioleaching microorganisms are reported due to entrained organic matter in the raffinate electrolyte. In view of these problems, the objective of this study was to evaluate ozonation as an alternative method for the removal of entrained organic matter present in an advanced electrolyte. For this purpose, ozonation during 30 min of synthetic solutions using a bubble glass column reactor at different ozone concentrations, flow rates and temperatures were studied. It was found that the increase in all of these operating parameters is not necessarily associated with an increase of the removal efficiency, and their effects on the mass transfer rate, chemical reaction rate, ozone solubility and contact time play a decisive role in the ozonation process. Thus, the best operating conditions were found at 6.7 wt.%, 1 L min-1 and 27 °C and reached a removal efficiency of 94.5%. This result demonstrated that removal of entrained organic matter in strongly acid solution by ozonation could be an alternative technology.

摘要 从矿石中湿法冶金（hydrometallurgical extraction）提取铜时，水相夹带有机物是一类严峻的工程问题。当富电解液（advanced electrolyte）中存在有机物时，会引发多项弊端：包括提取效率低下、阴极沉积物（cathode deposit）的形貌与取向发生改变。此外，有研究表明，萃余液电解液（raffinate electrolyte）中夹带的有机物会对生物浸出微生物（bioleaching microorganisms）的代谢活性产生负面影响。鉴于上述问题，本研究旨在评估臭氧氧化（ozonation）法作为去除富电解液中夹带有机物的可行替代方案。为此，本研究采用鼓泡玻璃柱反应器（bubble glass column reactor），针对不同臭氧浓度、气体流量及反应温度条件下的合成溶液（synthetic solutions）开展了30分钟的臭氧氧化实验。研究发现，提升上述所有操作参数并不必然能提高有机物去除率；各参数对传质速率（mass transfer rate）、化学反应速率（chemical reaction rate）、臭氧溶解度（ozone solubility）及接触时间（contact time）的影响，在臭氧氧化过程中起着决定性作用。最终确定的最优操作条件为：臭氧浓度6.7 wt.%、气体流量1 L·min⁻¹、反应温度27 ℃，此时有机物去除率可达94.5%。该结果证明，采用臭氧氧化法去除强酸性溶液中的夹带有机物，有望成为一项可行的替代技术。