Acid mine drainage: Why don't we look at it as energy?

Abstract

Acid mine drainage (AMD) or acid metalliferous drainage has become the main subject of the impact of mining activities, whether coal mining or gold mineral ore mining. Currently, AMD is considered as a "disgrace"for mining companies that cannot manage their AMD to fulfill environmental quality standards. Environmentalists often use AMD as the main theme to criticize the mining activities in Indonesia. Various environmental issues in mining business activities often raise AMD hazards for public health, aquatic biota and ecosystems around the mining activities. One of the characteristics of acid mine water is having a pH of 2-5. The AMD contains hydrogen ion (H+) and sulfuric ion (SO42-) which have similar characteristics as the electrolyte used for Voltaic and Galvanic battery cells. The battery uses a sulfuric acid (H2SO4) solution which has elements of H+ and SO42-. The research aims to determine AMD as energy, which uses the parameter of energy like an electrolyte. This research began by taking AMD samples from mineral mines and coal mines then were analyzed its initials electrolyte parameters (pH, EC, SG, TDS), running tests using lead-acid cells with 7.5 Watt incandescent lamp loads. The lead-acid cell was dipped into AMD sample from coal mining and mineral mining, then measured its voltage and electric current until the lamp is off and no current. The sediment that occurred from the process was analyzed their sediments using XRF analysis. Data were analyzed descriptive and variations. The lead-acid cell which was dipped into AMD sample have contents pH 3-4 shows that there is a potential difference of 2.52-7.86 V and electric current starting at 0.35-0.46A, decreasing to 0.15-0.2A for 373 seconds. The acidity of AMD after process indicates that pH becomes 5.8-6.5 and metal content on AMD was settled. AMD characteristic as energy can be identified by Voltage, SG, pH, for initial identify and EC, and TDS for the transformation process to energy. This research shows that the energy potential of AMD lake is very large, even though the energy content is very low. Nevertheless, this result has an impact on a new paradigm about how to handle AMD to become a potential energy source from a post-mining operation. It can reduce the treatment cost significantly compared to the existing AMD treatment method.