Application of an anoxic-limestone prototype for treating acid drains produced synthetically, varying the concentration of FeâºÂ²

Abstract

Mining operations associated with the extraction of coal and emeralds in the department of Boyacá, Colombia, contribute to the generation of acid mine drainage (AMD), which affects the ecosystems close to the mining activity. Applying basic systems such as limestone anoxic drains (DAC) make it possible to counteract the acidity present in the MAD by raising the pH. However, they cannot significantly remove sulfate and ferrous iron from the waste. Due to the above, this work studies the behavior of anoxic synthetic acid drainage (SAD), treated through a DAC system, using the area's limestone as a future possibility of application for the treatment of these wastes at an industrial level. Synthetic samples were analyzed with hydraulic retention times of 8, 16, and 24 hours under anoxic conditions. The results show pH regulation after 8 hours of treatment. The alkalinity of the prepared 10 and 100 mg·L^-1 Fe⁺² samples reach their maximum peak in this same period, reducing the Fe⁺² concentration present in the DAS samples by 88% with a retention time of 24h. This study shows that the application of DAC to treat this type of water significantly reduces the concentration of Fe⁺², which may be associated with the formation of carbonates.