Understanding the Mechanisms and Implications of the First Flush in Mine Pools: Insights from Field Studies in Europe’s Deepest Metal Mine and Analogue Modelling

Abstract

The chemical composition of mine water discharged from flooded underground mines typically improves over time. This phenomenon is called first flush and can be described by a characteristic curve. Shortly after the mine water begins to discharge, water constituent concentrations rise and then fall in an almost exponential curve, improving water quality over time. In this study, the change in mine water quality was investigated throughout the mine water body. This mine water body commonly consists of different water bodies with individual densities, resulting in mine water stratification. Anthropogenic disturbance of the mine water body can disrupt this stratification and also the positive effect of the first flush. To better understand and predict the first flush, the first flush was simulated experimentally using an analogue model of a flooded underground mine, the Agricola Model Mine. The results were compared with field studies to help understanding and predicting the change in mine water quality. Overall, the results suggest that the first flush occurs throughout the mine water body, making it similar to a chemical reactor. This better understanding of the process can lead to more effective mine water management and design of mine water treatment facilities.Graphical