Assessing Geomaterials and Waste Products for Potentially Toxic Elements Retention in Acid Mine Drainage from the Iberian Pyrite Belt, Southwest Portugal.

Abstract

The Iberian Pyrite Belt (IPB), dating back to the Devonian Period, is a volcanic-sedimentary complex extending across the Iberian Peninsula. It encompasses several major volcanogenic massive sulfide ore deposits. Located in southern IPB, Portugal's Grândola region, the Caveira Mine is an abandoned ore deposit rich in Cu, Pb, Zn, Ag, and Au. Historically exploited from Roman times until the 1960s, the mine was abandoned with approximately 2 Mt of oxidizing sulfide-bearing waste, leading to important environmental degradation through erosion, leaching, and diffusion. These processes contaminate downstream sediments with high concentrations of Potentially Toxic Elements (PTE), while low pH values in these sediments and watercourses indicate ongoing acid mine drainage (AMD) generation. Thus, the primary objective of the present study is to develop an effective, low-cost remediation strategy using geomaterials and waste products to mitigate AMD impacts on sediments