Facultad de Ingeniería

URI permanente para esta comunidad

http://repositorioabierto.uantof.cl/handle/uantof/7

Examinar

Examinando Facultad de Ingeniería por Materia "mine tailings"

Mostrando 1 - 2 de 2
  • Miniatura
    Ítem
    Alkali-Activated Mine Tailings and Solid Wastes as Precursors for Geopolymers
    (Avestia, 2024) Samarina, Tatiana; Reyes, Arturo; Letelier, María Victoria; Castillo Godoy, Daniza; Silva Urrego, Yimmy; Cuevas, Jacqueline; Takaluoma, Esther
    Former mining activities may pose a threat to the environment if not being handled correctly due to neglecting proper conservation methods at the time of mine closure. While dumping is the most common way of disposing of solid industrial waste such as tailings, fly and bottom ashes, slags etc., those materials are in fact a valuable source of secondary raw minerals. Thus, they could be recycled in a variety of products to turn the waste streams into value via the promising geopolymerisation technology. This article presents a study on the conversion of mine tailings and industrial by-products into geopolymers. Geopolymers based on alumino-silicate fines (steel-making slags and mine tailings) were synthesized using alkaline activation comprising sodium silicate. While the hardening of compositions occurs slowly at ambient temperature, elevated temperatures could change the leaching behaviour and decrease copper release from geopolymer matrix. Compressive strength of the proposed composition was 49±2 MPa after 90 days of curing. The results provide insights of possible reduction of the environmental footprints and potential economic benefits of mine tailings-based geopolymer composites for building applications utilizing mine tailings as suitable concrete material.
  • Miniatura
    Ítem
    MICP mediated by indigenous bacteria isolated from tailings for biocementation for reduction of wind erosion
    (Frontiers Media SA, 2024) Maureira, Alejandro; Zapata, Manuel; Olave, Jorge; Jeison, David; Wong, Liey-Si; Panico, Antonio; Hernández, Pía
    In this study, native ureolytic bacteria were isolated from copper tailings soils to perform microbial-induced carbonate precipitation (MICP) tests and evaluate their potential for biocement formation and their contribution to reduce th dispersion of particulate matter into the environment from tailings containing potentially toxic elements. It was possible to isolate a total of 46 bacteria; among them only three showed ureolytic activity: Priestia megaterium T130-1, Paenibacillus sp. T130-13 and Staphylococcus sp. T130-14. Biocement cores were made by mixing tailings with the isolated bacteria in presence of urea, resulting similar to those obtained with Sporosarcina pasteurii and Bacillus subtilis used as positive control. Indeed, XRD analysis conducted on biocement showed the presence of microcline (B. subtilis 17%; P. megaterium 11. 9%), clinochlore (S.pasteurii, 6.9%) and magnesiumhornblende (Paenibacillus sp. 17.8%; P. megaterium 14.6%); all these compounds were not initially present in the tailings soils. Moreover the presence of calcite (control 0.828%; Paenibacillus sp. 5.4%) and hematite (control 0.989%; B. subtilis 6.4%) was also significant unlike the untreated control. The development of biofilms containing abundant amount of Ca, C, andOon microscopic soil particles was evidenced by means of FE-SEMEDX and XRD. Wind tunnel tests were carried out to investigate the resistance of biocement samples, accounted for a mass loss five holds lower than the control, i.e., the rate of wind erosion in the control corresponded to 82 g/m2h while for the biocement treated with Paenibacillus sp. it corresponded to only 16.371 g/m2h. Finally, in compression tests, the biocement samples prepared with P. megaterium (28.578 psi) and Paenibacillus sp. (28.404 psi) showed values similar to those obtained with S. pasteurii (27.102 psi), but significantly higher if compared to the control (15.427 psi), thus improving the compression resistance capacity of the samples by 85.2% and 84.1% with respect to the control. According to the results obtained, the biocement samples generated with the native strains showed improvements in the mechanical properties of the soil supporting them as potential candidates in applications for the stabilization of mining liabilities in open environments using bioaugmentation strategies with native strains isolated from the same mine tailing.