Molecular Physics seminar

Chemical Reactivity of the Sulfide Minerals – Connection to Acid Rock Drainage

by Hélio Anderson Duarte (Universidade Federal de Minas Gerais / Brazil)

FB54 ()


Sulfide minerals comprise an important group of minerals in the earth´s crust and they are the main natural source of metals such as copper, zinc, nickel, lead, gold and silver. Sulfide mineral oxidation in the presence of water and air forming sulfuric acid, called acid rock drainage (ARD), is a critical environmental problem near mining regions. ARD is responsible for acidifying aquifers and mobilizing heavy metals in the environment. The chalcopyrite leaching for copper extraction from low grade ores is another technological challenge due to its low kinetics but it is of great relevance since 80% of the copper in earth is available as chalcopyrite. The surface reconstruction and the water and ions adsorption on sulfide minerals are the primary steps for understanding their chemical stability and the oxidation mechanism in the presence of water and air. Plane wave/density functional calculations have been performed for different sulfide minerals such as covellite (CuS),[1] chalcopyrite (CuFeS2),[2-5] pyrite (FeS2) and arsenopyrite (FeAsS2) to better understand the interaction of such chemical species with these minerals and provide a detailed description of the oxidation mechanism at a molecular level. References: 1. A. L. Soares Jr., E. C. Dos Santos, A. Morales-Garcia, T. Heine, H. A. De Abreu, H. A. Duarte; "Two-dimensional crystal CuS - Electronic and structural properties", 2D Materials, 41(1), 0150041 (2017). 2. A. L. Soares Jr., E. C. Dos Santos, A. Morales-Garcia, H. A. Duarte, H. A. De Abreu; "The Stability and Structural, Electronic and Topological Properties of Covellite (001) Surfaces", Chemistry Select, 1,2730 (2016). 3. E. C. dos Santos, J. C. M. Silva, H. A. Duarte; "Pyrite Oxidation Mechanism by Oxygen in Aqueous Medium", J. Phys. Chem. C , 120, 2760-2768, (2016). 4. J. C. M. Silva, H. A. De Abreu, H. A. Duarte; "Electronic and structural properties of arsenopyrite bulk and its cleavage surfaces - A DFT study", RSC Advances, 5, 2013-2023 (2015). 5. A. Morales Garcia, A. L. Soares, E. C. Dos Santos, H. A. De Abreu, H. A. Duarte; "First-principles calculations and electron density topological analysis of covellite (CuS)", J. Phys. Chem. A, 18(31), 5823-5831 (2014). 6. C. de Oliveira, G. F. De Lima, H. A. De Abreu, H. A. Duarte; "Reconstruction of the Chalcopyrite Surfaces - A DFT Study", J. Phys. Chem. C, 116, 6357-6366 (2012).