The increasing global demand for copper has driven the search for more efficient and sustainable extraction methods, particularly due to the environmental concerns associated with conventional processes. This study investigated the leaching of copper minerals MC (Cu₂O) and malachite (Cu₂CO₃(OH)₂) using glycine as an organic ligand in an alkaline medium, and evaluated the efficiency of hydrogen peroxide (H₂O₂) and ozone (O₃) as oxidizing agents. Chemical and mineralogical characterization using XRD, XRF, ICP, and SEM confirmed the predominance of MC and malachite, along with secondary phases such as hematite and calcite. Leaching experiments were carried out by varying glycine and oxidant concentrations at pH 10, with a reaction time of 240 min, agitation at 800 min⁻¹, a solution volume of 300 mL, and a mineral sample concentration of 0.33 g·L⁻¹. The results showed that O₃ exhibited low efficiency due to its limited solubility, whereas H₂O₂ achieved dissolution rates of 69.7% for MC in 150 min and 96.3% for MMin just 60 min. The glycine-H₂O₂ system optimized reaction time by 84% compared to conventional methods, emerging as a sustainable alternative due to the low toxicity and biodegradability of glycine.

Mine tailings are a byproduct of mineral extraction and often pose an environmental challenge due to the contamination of soil and water bodies with dissolved metals. However, this type of waste offers the opportunity for the recovery of valuable metals such as silver (Ag). In the present investigation, an integral analysis of a sample of tailings was carried out, addressing granulometry, elemental composition, neutralization potential (NP), and acid potential (AP), as well as mineralogy, for the dissolution of silver from this type of waste. For this purpose, thiourea (CH₄N₂S) was used as a leaching agent due to its low toxicity, and potassium oxalate (K₂C₂O₄) was used as an organic additive to improve the leaching of the silver phases (argentite and polybasite) present in the tailings. The effects of CH₄N₂S and K₂C₂O₄ concentrations, temperature, and pH on the leaching efficiency of silver (Ag), copper (Cu), iron (Fe), and arsenic (As) were systematically studied. The results revealed that the maximum silver dissolution rate reached 90.75% under optimal conditions: 0.2 M L⁻¹ of thiourea and 0.2 M L⁻¹ of potassium oxalate, at 35 °C and a pH of 2.

Selective alkaline leaching was evaluated to remove arsenic (As) and antimony (Sb) from a polymetallic copper concentrate from Zimapán, Mexico, where these metalloids cause environmental risk and smelter penalties. Batch tests used sodium sulfide (Na₂S) in alkaline media, varying reagent concentrations and temperature; kinetic modeling identified the rate-controlling step, and X-ray diffraction (XRD) plus scanning electron microscopy/energy-dispersive spectroscopy (SEM–EDS) assessed phase changes. The kinetic analysis indicated chemical control with a higher reaction order for Na₂S than for NaOH. A quadratic regression described the process and identified Na₂S concentration and temperature as the dominant factors. Maximum extractions reached 91.9% for As and 72.1% for Sb while limiting dissolution of value-bearing sulfides, as supported by XRD and SEM–EDS. Environmental indices (I_geo, EF) classified As and Sb as highly contaminating and geochemically enriched in the feed, underscoring the need for selective removal. Overall, alkaline leaching with Na₂S provides a technically feasible and environmentally favorable route to remediate metalloids and upgrade polymetallic concentrates.

Mine tailings are a byproduct of mineral extraction and often pose an environmental challenge due to the contamination of soil and water bodies with dissolved metals. However, this type of waste offers the opportunity for the recovery of valuable metals such as silver (Ag). In the present investigation, an integral analysis of a sample of tailings was carried out, addressing its granulometry, elemental composition, neutralization potential (NP) and acid potential (AP), as well as its mineralogy; for the dissolution of silver from this type of waste. For this purpose, thiourea (CH₄N₂S) was used as a leaching agent due to its low toxicity and potassium oxalate (K₂C₂O₄) as an organic additive to improve the leaching of the silver phases (argentite and polybasite) present in the tailings. The effects of CH₄N₂S and K₂C₂O₄ concentrations, temperature, and pH on the leaching efficiency of silver (Ag), copper (Cu), iron (Fe), and arsenic (As) were systematically studied. The results revealed that the maximum silver dissolution rate reached 90.75% under optimal conditions: 0.2 M L⁻¹ of thiourea, 0.2 M L⁻¹ of potassium oxalate, at 35°C and a pH of 2.

Silver leaching from metallic sulfide concentrates represents a significant challenge in extractive metallurgy, particularly for mineralogically complex matrices where phase heterogeneity and the coexistence of base metals limit the performance of conventional reagents. In this work, the kinetics of silver leaching from a complex concentrate in an alkaline thiosulfate–potassium hydroxide system is investigated, with emphasis on the in-situ generation of a favorable redox environment induced by the interaction between the mineral matrix and the leaching solution. Leaching experiments were conducted by varying thiosulfate concentration, potassium hydroxide concentration, temperature, particle size, and agitation speed. Kinetic parameters were obtained from conversion–time data using the shrinking-core model for spherical particles. The results demonstrate that silver dissolution can be sustained under self-generated redox conditions without the addition of external oxidants, due to redox mediation by metallic species released from the mineral matrix that contribute to stabilizing the oxidation–reduction potential of the system. Kinetic analysis indicates that the process is dominated by diffusion through the liquid film, with a fractional dependence on thiosulfate concentration, an inhibitory effect associated with potassium hydroxide, and moderate thermal sensitivity, consistent with a mass-transfer-controlled regime at the solid–liquid interface. From an operational perspective, the leaching kinetics indicate marginal gains in Ag extraction upon increasing operating variables, suggesting that moderate changes in reaction conditions are sufficient to achieve efficient silver extraction. Overall, this study provides a fundamental description of silver leaching in the thiosulfate–potassium hydroxide system, highlighting the potential of simplified and self-regulated reactive systems for treating mineralogically complex sulfide concentrates.