Characterization and prediction of acid mine drainage potential and metal solubility: Critical data for tailings and waste rock management in high sulfidation gold deposits

Abstract

Abstract In the Purnama gold deposit at the Martabe mine of South Tapanuli District, North Sumatra Province, Indonesia, gold is extracted from the ore and the remaining fine-sized material is stored in the tailings storage facility (TSF) and waste rocks are placed as TSF embankments. Without proper management, tailings and waste rocks from mining can create acid mine drainage (AMD) and release toxic chemicals, posing significant risks to local ecosystems and residents in mining areas. To address this, a mineralogical and geochemical characterization study was investigated, as well as the leaching behavior of heavy metals in the tailings leach column tests (LCT) was conducted. Geochemical characterization showed quartz hornblende andesite and hornblende dacite as NAF materials; clay breccia, volcanic andesite, carbonaceous clay, volcanic breccia, and silica breccia as PAF materials. Further tests revealed that volcanic breccia, carbon clay, and volcanic andesite were classified as high-risk PAF materials, supported by XRD test results. Finally, the LCT results showed that volcanic breccia produced rapid acid drainage, with arsenic (45.9 mg L−1), copper (41.4 mg L−1), and manganese (14.1 mg L−1) being the main dissolved metals. It is important to manage PAF rocks and ensure the water leachate does not contain high concentrations of these metals.