Agus Mirwan
Department of Chemical Engineering, Lambung Mangkurat University, Banjarbaru 70714, Indonesia

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Integrated GEE–ERT–XRF framework for detecting in-situ rare oxide formation in tropical lowland clays Uyu Saismana; Agus Mirwan; Sunardi; Suryajaya; Doni Rahmat Wicakso
Communications in Science and Technology Vol 11 No 1 (2026)
Publisher : Komunitas Ilmuwan dan Profesional Muslim Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21924/cst.11.1.2026.1883

Abstract

Understanding in-situ rare oxide formation in tropical lowlands remains challenging due to the extensive peat–clay cover and the limited surface accessibility. This study presents a reproducible integrated workflow combining cloud-based hydrographic analysis in Google Earth Engine (GEE), two-dimensional electrical resistivity tomography (ERT), and X-ray fluorescence (XRF) geochemistry to investigate rare oxide occurrence in South Kalimantan, Indonesia. MERIT Hydro data that had been processed within the GEE framework were utilized for the delineation of buried palaeochannel traces. This was followed by ERT profiling and core drilling to characterize the subsurface lithology. XRF analyses indicate Yb2O3 concentrations of 0.01–0.04 wt% and Re2O7 of 0.00–0.08 wt% within clay layers at approximately 3–4 m depth. The results of spatial correlation analysis demonstrate weak relationships between oxide distribution and palaeochannel proximity (|r| < 0.3) but strong positive relationship between resistivity and oxide concentrations (r > 0.75). The results obtained lend significant support to an in-situ formation model, primarily controlled by lithological and geochemical processes as opposed to fluvial transport. The proposed GEE–ERT–XRF workflow offers a preliminary operational framework for detecting subtle, clay-hosted rare oxide signatures in data-limited tropical lowland environments. The findings demonstrate that efficacy of subsurface resistivity as a proxy for identifying geochemical trapping horizons associated with rare oxide enrichment beneath peat–clay cover. The proposed workflow further provides a cost-effective, scalable, and reproducible approach for early-stage mineral exploration and subsurface resource screening in tropical lowland regions where conventional geological mapping is limited by poor surface exposure.
Insight into Aluminum Leaching with Microwave from Peat Clay: A Comparative Kinetic Study of SC and BIC Models Agus Mirwan; Hairullah; Rinny Jelita; Jefriadi; Meilana Dharma Putra; Bintang Hambela Ilmanto; Hexas Sarastiwi Handayani Putri; Muhammad Bahrul Ulum; Muhammad Rofi Haka; Muhammad Arif Darmawan
Communications in Science and Technology Vol 10 No 2 (2025)
Publisher : Komunitas Ilmuwan dan Profesional Muslim Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21924/cst.10.2.2025.1850

Abstract

The depletion of bauxite reserves has prompted the research of various types of soil as alternative sources of aluminum, such as the peat clay used in this study. The complexity of the minerals requires a more efficient leaching methods, while microwave-based leaching offers a potential approach through rapid and uniform heating. This study examines the effect of microwave power, HCl concentration, operating temperature, and particle size on the leaching efficiency of aluminum from peat clay soil. The leaching process was modeled using two approaches, namely the shrinking core (SC) model and the broken-intact cell (BIC) model under pseudo-steady state conditions. The results showed that increasing HCl concentration, microwave power, and temperature accelerated leaching, while increasing particle size decreased leaching efficiency. Optimum conditions were achieved at 4 M HCl concentration, 100 W power, 40 °C temperature, and 0.0074 cm particle size. The shrinking core (SC) model showed better fit under most conditions, while the intact-broken cell (BIC) model was more accurate at lower temperatures and particle sizes. The simulation results showed that the most suitable parameter values in the SC model were De = 0.0049 cm2/s, k = 10.5 cm/s, and kc = 2.49 cm/s, while in the BIC model De = 0.04808 cm2/s and K = 0.02689 g/cm3 were obtained. These results confirm the superiority of the SC model in representing microwave-based leaching mechanisms in general, while the BIC model provides additional insights under diffusion-limited conditions. Process Performance Index (PPI) analysis showed that optimum conditions were achieved at 4 M HCl and 40 °C, but lower acid concentrations also yielded competitive PPI. This confirms that leaching effectiveness is determined by a combination of alumina recovery and reagent consumption efficiency. These findings contribute to the development of leaching kinetics models and the optimization of more efficient and energy-saving aluminum extraction processes.