Abstract
The materials used to conduct kinetic study on the leaching of silver in the S2O32−-O2-Cu2+ system were mining residues (tailings) from the Dos Carlos site in the State of Hidalgo, Mexico, which have an estimated concentration of Ag = 71 g∙ton−1. The kinetic study presented in this paper assessed the effects of the following variables on Ag dissolution rate: particle diameter (d0), temperature (T), copper concentration [Cu2+], thiosulfate concentration [S2O32−], pH, [OH−], stirring rate (RPM), and partial pressure of oxygen (PO2). Temperature has a favorable effect on the leaching rate of Ag, obtaining an activation energy (Ea) = 43.5 kJ∙mol−1 in a range between 288 K (15 °C) and 328 K (55 °C), which indicates that the dissolution reaction is controlled by the chemical reaction. With a reaction order of n = 0.4, the addition of [Cu2+] had a catalytic effect on the leaching rate of silver, as opposed to not adding it. The dissolution rate is dependent on [S2O32−] in a range between 0.02 mol·L−1 and 0.06 mol·L−1. Under the studied conditions, variables d0, [OH−] and RPM did not have an effect on the overall rate of silver leaching.
Highlights
In Mexico, mining accounts for 4% of gross domestic product, which places this country among the top ten world producers of sixteen minerals, among which silver stands out
The mineralogical characterization was performed by the X-Ray Diffraction (XRD) technique using a powder diffractometer, Philips model X’Pert and the Scanning Electron Microscopy-Energy-Dispersive X-Ray
X-ray fluorescence (XRF) determined the elements present the residues as oxides, obtaining following
Summary
In Mexico, mining accounts for 4% of gross domestic product, which places this country among the top ten world producers of sixteen minerals, among which silver stands out. One way to increase the production of silver is by reprocessing scrap, slag and mining waste that contain economically reasonable amounts of this metal. Minerals 2018, 8, 309 mining waste have been accumulated, and are nowadays posing a serious environmental problem [2,3]. Reprocessing these residues presents a challenge for the metallurgical industry because of the presence of quartz and pyrite ores, where the metal values of interest are encapsulated [4] In the State of Hidalgo, Mexico, due to the extensive mining activity that has lasted approximately 480 years in the mining districts of Pachuca and Mineral del Monte, millions of tons of Minerals 2018, 8, 309; doi:10.3390/min8070309 www.mdpi.com/journal/minerals
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
