Alex Saul Redrován

Ms. Alex Saul Redrován

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Research Focus & Metrics

Academic Career Length

2Years (2025-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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14 February 2025 in Metals
Verified
Journal Article
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ARAlex Saul Redrován
Alex Saul Redrován
ETErnesto De la Torre
Ernesto De la Torre
CACarlos Aragón-Tobar
Carlos Aragón-Tobar
The thiosulfate–glycine–copper system has emerged as a promising alternative for gold recovery, offering significant advantages over cyanidation and ammoniacal thiosulfate leaching. Recognizing the limitations of thiosulfate degradation in ammoniacal systems, this study focused on optimizing the thiosulfate–glycine–copper system for gold recovery using an auriferous ore with (10 g t−1) of Au. The ore was associated with aluminosilicates such as grossular (64%) and clinochlore (12%). Leaching conditions were systematically varied, including thiosulfate (0.5–1 M), glycine (0.3–1.75 M), copper sulfate (2–10 mM), pH (9.3–10.5), temperature (20–60 °C), 6 h, and potassium permanganate concentrations (0.004–0.04 M), and dosing intervals were also optimized. Thus, the best conditions were thiosulfate (0.7 M), glycine (1.75 M), copper sulfate (5 mM), pH 9.3, 60 °C, and permanganate addition every 2 h. This system achieved 89.3% gold recovery in just 6 h, comparable to cyanidation (89.8% in 24 h) and ammoniacal thiosulfate (58% in 6 h), but without generating toxic effluents, such as in the cyanidation process. Additionally, a gold dissolution mechanism was proposed, highlighting glycine’s role in stabilizing cupric ions and enhancing thiosulfate efficiency. This study underscores the thiosulfate–glycine–copper system as a sustainable and effective method for gold recovery.

31 March 2025 in Molecules
Verified
Journal Article
Open access
PDF file
ETErnesto De la Torre
Ernesto De la Torre
ARAlex Saul Redrován
Alex Saul Redrován
CACarlos Aragón-Tobar
Carlos Aragón-Tobar
Palm kernel shells, an abundant agro-industrial residue in countries like Ecuador, can be valorized through their conversion into activated carbon for industrial applications. This study investigates the physical activation of carbonized palm kernel shells using both a Nichols furnace at the pilot scale and a rotary kiln at the industrial scale. The progressive conversion model was used to explain how the activation process works and to calculate the reaction rate constants for CO2 (krCO2) and H2O (krH2O). The experimental results demonstrated that activation in an H2O-rich atmosphere significantly enhanced porosity development and iodine index compared to CO2 alone. Additionally, the study confirmed that activation kinetics are primarily controlled by the chemical reaction rather than mass transport limitations, as indicated by the negligible effect of particle size on gasification rates. At 850 °C, the reaction rate constants were calculated to be krCO2 = 0.75 (mol·cm⁻3·s)⁻1 and krH2O = 8.91 (mol·cm⁻3·s)⁻1. The model’s predictions closely matched the experimental data, validating its applicability for process optimization at both the pilot and industrial scales. These findings provide valuable insights for improving the efficiency of activated carbon production from palm kernel shells in large-scale operations.