Application of Silicate-Based Coating on Pyrite and Arsenopyrite to Inhibit Acid Mine Drainage

• Published in: Bulletin of environmental contamination and toxicology 2022-03, Vol.108 (3), p.532-540
• Main Authors: Kollias, Konstantinos, Mylona, Evangelia, Papassiopi, Nymphodora, Thymi, Sofia
• Format: Article
• Language: English
• Subjects: Acid mine drainage; Aquatic Pollution; Arsenicals; Arsenopyrite; Calibration; Coal mining; Coating; Coatings; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Hydrogen Peroxide; Iron; Iron Compounds; Mine drainage; Mine tailings; Mine wastes; Minerals; Mines; Oxidants; Oxidation; Oxidation-Reduction; Oxidizing agents; Pollution; Polyamines; Pyrite; Quality control; Silicates; Silicon; Soil Science & Conservation; Sulfides; Sulfur; Tailings; Toxicology; Waste Water Technology; Water Management; Water Pollution Control
• ISSN: 0007-4861; 1432-0800
• DOI: 10.1007/s00128-021-03310-8

The prevention of acid generation from sulfidic mine wastes is a problem that challenges the global scientific community for decades. A promising strategy is related to the formation of coating layer around sulfides for inhibiting surface oxidation. In the current research, the conditions favoring the formation of an efficient silicate-based coating around pyrite and arsenopyrite were studied, using batch tests. The coating solutions contained silicate-oxyanions, an oxidant (H 2 O 2 ) and buffered at pH 6. The effect of Si concentration (0.1–50 mM), liquid/solid ratio (5–100 mL/g) and contact time (up to 24 h) was investigated. Pyrite tailings treated with a solution of 1 mM Si/0.1 M H 2 O 2 at L/S:100 mL/g for 24 h resulted in the optimum formation of a coating, which reduced the amount of SO 4 −2 -released by 72%, compared to the sample treated in the absence of Si. However, silicate treatment had a negative effect on arsenopyrite tailings inducing As mobilization.