In situ removal of arsenic from the mine drainage of the la Calzada mine environmental liability by neutralization with limestone

In Peru, mining environmental liabilities (MEL) are a health hazard for the surrounding population. We located and performed a test of the acidic waters of the La Calzada MEL. The results showed metal contents such as: arsenic 0.353 mg/L, and pH level 3.46 (acid), we determined that the acidic waters were above the maximum permitted limit of the annual average; for arsenic removal and pH neutralization we used crushed limestone rock with a purity of 87% calcium carbonate (CaCO3). We applied CaCO3 to the acidic water and obtained a reduction of arsenic from 0.353 mg/L to 0.023 mg/L and an increment of pH from 3.46 to 7.31. In conclusion, calcium carbonate was able to remove 93.48% of the arsenic.