Work

Coating development on mine waste rocks as a protective sink to attenuate the off-site migration of antimony in the environment

Year: 2024

Type: article

Abstract: This study explored the feasibility of depositing protective coatings with an Sb scavenger function on mine waste rocks derived from the exploitation of stibnite deposits. Encapsulation treatments were performed using ferrous sulfate as the coating precursor. Different Fe/Sb leachable molar ratios (0.1, 1, and 10) were evaluated using hydrothermal and thermal processes at various temperatures (30, 50, 100, and 150 °C). The environmental characterization of the coated mine waste was established using standard leaching tests. The most effective coatings were analyzed for their mineralogy, chemical composition, and Sb attenuation using X-ray powder diffraction, scanning electron microscopy, and digestion/extraction processes. Additionally, stability tests were conducted to assess the effectiveness of encapsulation under changing environmental conditions. The Fe/Sb leachable molar ratio was found to be a critical factor in reverting the toxic and hazardous characteristics of mine wastes, with an optimal value of 10. The coatings were primarily composed of Fe oxyhydroxy sulfates/Fe oxyhydroxides and calcium sulfate minerals with a bulk Sb content of approximately 1 %. The adsorbed Sb content in the coatings was a small fraction of the total Sb content (< 0.5 %), indicating a strong retention. Moreover, such coatings were stable under different pH (3−8) and redox (100 to −100 mV) conditions. • Protective coating development on Sb mine wastes is a useful tool to their management. • Ferrous sulfate at an Fe/Sb leachable molar ratio of 10 is an effective coating precursor. • Coatings act as Sb sinks [bulk Sb content: 1 %, mostly in non-desorbable form (> 95 %)]. • Coatings make wastes to satisfy the non-hazardous waste landfill Sb leaching limit. • Coatings are stable under diverse pH/redox values, highly abating Sb release (81-96 %).

Source: Journal of Hazardous Materials

DOI: 10.1016/j.jhazmat.2024.136503

Authors: M. Campos-Ballesteros, E. Álvarez-Ayuso

Institutions: Instituto de Recursos Naturales y Agrobiología de Salamanca, Consejo Superior de Investigaciones Científicas

Language: English

Topic: Mine drainage and remediation techniques

Subfield: Environmental Chemistry

Field: Environmental Science

Domain: Physical Sciences

SDGs: Responsible consumption and production, Clean water and sanitation

Open Access status: hybrid

Estimated APC paid: $4,340