Definition of a clean energy system for decontamination of acid mine waters and recovering their metal load

Abstract

Acid mine drainage (AMD) is one of the largest hydrochemical problem resulting from anthropic activity, with consequences worldwide. For this reason is understandable the importance of innovative measures for recovering rivers affected AMD. Taken in account the substantial changes in terms of European legislation on water quality, under the framework of Directive 2000/60/EC (Water Framework Directive, WFD), the proposal of remediation measures for streams affected by AMD in the period marked by the standard has become even more relevant. The most common techniques, applying corrective measures to mitigate the process, have high costs of installation and maintenance, or poor performance. On the other hand, the cheaper approaches often cause undesirable discharges of pollutants. The aim of the system presented in this study is to neutralise acid mine waters and recover their metal load, using energy obtained from renewable sources. With this approach, the treated water is produced without releasing emissions into the atmosphere, without using fossil fuels and at an acceptable cost. At the same time, it allows the Cu dissolved in the waters to be separated from the rest of the metal load and sulphates. Therefore, it makes possible the metal´s recovery, transforming an environmental passive into an industrial income, in an economic context in which the price of Cu reaches around 7300 US$/ton.