International Symposium on Earth Resources Management and Environment

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Browsing International Symposium on Earth Resources Management and Environment by Subject "Acid mine drainage"

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    Recovery of valuable metals from acid mine drainage using aluminum-iron (AL-FE) bimetallic particles
    (Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Dano, DTR; Park, I; Ito, M; Resabal, VJT; Tabelin, CB; Iresha, H; Elakneswaran, Y; Dassanayake, A; Jayawardena, C
    Acid mine drainage (AMD) is a mining industry waste that has been identified as a global critical pollutant. Due to its high acidity and high metal content, it poses detrimental effects to the environment and ecosystems. Current approaches to the study of AMD control perceive it as an environmental concern due to its nature; with current mitigation and remediation methods focusing on either controlling its acidity or sequestering the metals present in the waste effluent. The high metallic nature of AMD, however, may be viewed not only as an environmental concern but also as a potential secondary source for valuable metals. This study investigated the viability of utilizing locally sourced recycled Al-scrap to synthesize magnetic Al-Fe bimetallic materials to recover copper (Cu) and zinc (Zn) from synthetic AMD. The effects of varying bimetal dosages (5, 10, and 20 g/L) and contact times (5–120 mins.) were investigated (see Figure 1). The results revealed that Al/Fe bimetallic materials can positively recover Cu and Zn and that both bimetal dosage and contact time were significant factors in metal recovery. For Cu, a maximum recovery of 100% is observed after 10 min using 10 g/L bimetal dosage. A maximum recovery of 98% for Zn was obtained after 120 mins at 20 g/L bimetal dosage. XPS and SEM-EDX results revealed the presence of zero-valent Cu and Zn on the bimetal surface after the recovery process. This suggests that the main mechanism for the metal recovery is electrochemical reduction from three occurrences: (1) direct reduction by Al, (2) direct reduction by Fe, and (3) reduction from the galvanic interaction in the Al/Fe bimetal system. Furthermore, a significant increase in pH from 2.12 to 5.72 was recorded after the process. This suggests that the application of Al-Fe bimetallic materials does not only have potential in metal recovery but also in simultaneously neutralizing the AMD. Hence, the recovery of valuable metals from AMD using scrap-based Al-Fe bimetallic materials shows promise as a metallurgical extraction method which additionally offers a practical approach for possible remediation and sustainable management of waste streams, specifically mining effluents such as AMD.
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    Seasonal dynamics of nickel attenuation in acid mine seepage: implications for remediation strategies at BCL copper-nickel mine tailings, Botswana
    (Division of Sustainable Resources Engineering, Hokkaido University, Japan, 2024) Godirilwe, J; Otake, T; Kikuchi, R; Iresha, H; Elakneswaran, Y; Dassanayake, A; Jayawardena, C
    Mining activities in Botswana have posed significant environmental challenges, notably acid mine drainage (AMD) resulting from sulfide ore processing at the BCL copper-nickel mine tailings. This generates AMD seepage characterized by low pH and high concentrations of dissolved toxic metals such as Fe, Ni, Cu, Pb, Zn, and Mn. The elevated concentration of heavy metals, particularly nickel, in the surrounding environment, groundwater, and nearby river underscores the challenge of remediating nickel contamination from tailings seepage. Thus, understanding nickel's behavior from acidic mine seepage is crucial for developing sustainable recovery and remediation strategies. The study aims to investigate the mechanisms controlling the natural attenuation processes of nickel from tailings seepage during rainy and dry seasons, informing geochemical passive treatment strategies. Objectives include determining the chemistry and behavior of toxic elements (Ni) from tailings seepage to the nearby river system in different seasons, understanding the release and mobility of toxic metals from the tailings, and elucidating the seasonal dynamics of nickel's natural attenuation from the tailings. Field surveys were conducted during both rainy and dry seasons, collecting tailings sediment, precipitate samples around the tailings, and sediment samples. Water samples were collected from the underground mine, tailings, and nearby river system. Heavy metal concentrations (Fe > Ni > Cu > Mn > Co > Pb > Ag > Cr) in the tailings seepage were notably high in both seasons, with higher values during the dry season. However, heavy metal concentrations exceeded the World Health Organization (WHO) and Botswana (BOBS) effluent standards in both seasons. In the dry season, heavy metal concentrations decreased post-treatment, except for nickel concentrations from the holding dam to the river, surpassing BOBS standards. Conversely, in the wet season, toxic metal concentrations, including nickel, fell below BOBS standards. Detailed analyses of tailing seepage, wastewater, river water, tailings sediments, precipitates, and river sediment furthered understanding of nickel's natural attenuation mechanism.
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    Water hyacinth (eichornia crassipes) as a phytoremediation agent for heavy metal removal in acid mine drainages generated from the urban mining of e-wastes: a bibliometric review
    (Department of Earth Resources Engineering, University of Moratuwa, 2021-12) Perera, JADS; Sonnadara, SP; Lakmal, DA; Dassanayaka, DMSM; Jayawardena, CL; Dissanayake, DMDOK; Jayawardena, CL
    Generation of Acid Mine Drainage (AMD) is a problem that is associated with the urban mining of e-waste. Raised acidic conditions resulting from AMD discharge into the surrounding environments and cause toxic heavy metals (HMs) to dissolve, transport, and accumulate in the aquatic environments. Since the elevating concentrations of heavy metals due to AMD discharge exceed the threshold limits, beyond which the health of the living organisms is compromised, remediation of AMD has proven to be taken into consideration. Out of many strategies, passive treatment techniques can be mentioned as the newest approach to remediation AMD. Remediation methods for AMD can be divided into two categories, and they are active systems and passive systems. When comparing these two methods, active systems accrue more financial costs than passive treatments. More than 50 studies have focused on constructed wetland systems under passive technologies since it is self-sustaining once established, and they are cheaper than active treatment systems. The use of several aquatic plants such as water hyacinth, water lettuce, and water cabbage for the remediation process is of significance in constructed wetland systems. This study reviews the experimental findings on HM removal under several conditions using water hyacinth plants in different studies that have been done previously.