Parallel Session 2A

Sri Lanka possesses approximately 2.2 million tonnes of iron ore deposits, predominantly as hydrated iron oxides in regions like Dela and Pelpitigoda. This study investigates value addition pathways for these low-grade ores through strategic beneficiation. Four iron ore samples were characterized using XRD and ICP-MS, revealing goethite as the dominant phase in hydrated deposits with iron contents of 58.52% (Dela) and 31.23% (Pelpitigoda). Roasting of goethite samples at 450°C for 4 hours successfully transformed them into magnetite with 85-90% and 70-75% phase conversion efficiency, respectively. The converted magnetite showed iron enrichment to 64.83% (Dela) and 31.76% (Pelpitigoda) through structural water removal and exhibited strong ferromagnetic properties essential for downstream processing. As iron ore deposits in the country aren’t utilized in the steel industry due to low grades or low resource content, the converted magnetite enables multiple value-added opportunities, including ferrosilicon production for import substitution, iron oxide pigment synthesis, cement manufacturing applications, ceramic tile production, and emerging nanotechnology applications. This pre-processing step transforms underutilized hydrated iron ores into versatile industrial feedstock. The study demonstrates that goethite-to-magnetite conversion is essential for unlocking the economic potential of Sri Lanka's low-grade iron ore resources, supporting sustainable industrial development.

Sri Lanka consists of high-grade quartz deposits with a purity level of 99.5%. However, a huge amount of low-grade quartz is abandoned in mine sites without any processing, causing resource underutilization and environmental damage. Froth flotation has proven its efficiency for processing low-grade quartz in previous studies. Conventional collectors with more than 90% of high recovery used in those studies show environmental hazards and low biodegradability. These collectors are usually fatty acids or fatty amines. In this study, the quartz flotation potential of Sodium Cocoate, (a naturally derived fatty acid salt), as a flotation collector was evaluated under controlled conditions: pH 11, temperature of 28-30 °C, particle size range of 90-150 microns, slurry density of 1007 kg/m³, impeller speed 280 rpm and bubble rate 0.004 m3/s. The highest average recovery obtained was 28.19±1.28% out of 100 g of the initial quartz sample, which was comparatively low, suggesting that NaCo is a weak collector.

The glass industry necessitates stringent particle size specifications for raw materials such as dolomite to ensure product integrity and process quality. In this paper, it is suggested that there is a systematic study to optimize the grinding efficiency of a dolomite processing plant to meet such stringent specifications. The research focused on the optimization of a pre-existing secondary ball milling circuit to produce a higher dolomite percentage of particles size lesser than 700 µm, while closely controlling the production of fines (<150 µm). The selection of dolomite with improved grinding characteristics was based on material pre-characterization through Aggregate Impact Value (AIV) and moisture content. Three systematic ball mill studies were conducted to examine various breaking mechanisms in different feed size ranges (5-1.7 mm, 3-1.7 mm, and 1.7 mm-700 µm). The experiments indicate a interdependence between feed size and media charge. The final optimized trial, with a fine feed (1.7 mm‑700 µm) and intermediate-weighted ball charge (30% 60 mm, 50% 40 mm, 20% 30 mm), could successfully produce a product that contained 90.2% passing 600 µm while 29.3% passing 150 µm. The outcome confirms the two-stage grinding strategy and offers a fact-based path to success in meeting the glass industry's specifications.

This study presents a comparative evaluation of graphite oxide (GO) and microwave-exfoliated graphite oxide (MEGO) as anode materials for sodium-ion batteries, with synthesized sodium manganese oxide (NaMnO₂) serving as the cathode. GO was prepared via a modified Hummers method, and MEGO was obtained by subjecting GO to microwave irradiation. Structural and morphological characterization was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and quantitative image analysis with ImageJ software. Morphological analysis revealed that GO exhibited enhanced surface area enhancement (88.8% increase) compared to raw graphite. Surface roughness analysis demonstrated progressive texture enhancement, with microwave treatment contributing 75% of total surface roughness improvement. Sodium manganese oxide (NaMnO₂) cathodes were synthesized using both analytical-grade and recovered MnO₂ from spent Zn-MnO₂ batteries. XRD analysis revealed that recovered MnO₂ unexpectedly demonstrated enhanced phase purity (83% identified phases) compared to analytical-grade material (43% identified phases). Electrochemical testing showed GO-based anodes delivered approximately twice the capacity (0.232 mAh) compared to MEGO anodes (0.107 mAh), with better voltage stability and discharge duration. The results demonstrate the feasibility of utilizing recycled battery materials for cathode synthesis while establishing GO as a more promising anode material than MEGO for sodium-ion battery applications.

Kaolinite clay has emerged as a valuable material in environmental remediation, particularly for treating contaminated water. This study examines the potential of kaolin clay, in both its raw and modified forms, for the efficient removal of heavy metals, particularly lead (Pb), from wastewater. The unique physical and chemical properties of kaolin, such as its high surface area, adsorption capacity, and structural stability, make it an effective adsorbent for a wide range of contaminants. This research evaluates various modification methods, including acid activation, intercalation, and calcination. Treatment with coal fly ash, aimed at enhancing its adsorption properties through intercalation, is also investigated. Characterization techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) were employed to assess the structural and chemical changes induced by these modifications. Adsorption kinetics were evaluated to measure effectiveness during the study. The study showed higher lead adsorption in coal fly ash-treated kaolin compared to its raw form. Kaolin clay, being a naturally abundant and cost-effective mineral, presents a sustainable solution for water treatment, demonstrating significant potential for future applications in heavy metal removal.

This study investigates the long-term durability and mechanical performance of cement plaster incorporating 100% quarry dust as a sustainable replacement for river sand, with a focus on behavior under accelerated climatic ageing. Two mix ratios commonly used in external (1:4) and internal (1:6) wall plastering were prepared using both river sand and quarry dust as fine aggregates. Workability was evaluated using flow table tests, while compressive strength and water absorption were measured over a six-week period involving repeated thermal shock cycles to simulate severe environmental conditions. Results showed that quarry dust mixtures required significantly more water to achieve standard workability due to their angular and poorly graded particle structure. Despite this, all quarry dust-based mixes consistently exceeded the 3 MPa compressive strength threshold after ageing, comparable to river sand controls. Initial strength reductions from thermal shocks were mitigated by ongoing hydration, particularly in quarry dust specimens, while water absorption stabilized as calcium silicate hydrate developed. The findings demonstrate that quarry dust is a viable and durable alternative to river sand in cement plaster, supporting sustainable construction practices and resource conservation in regions facing sand scarcity.

Effective coal quality estimation, particularly ash content prediction, plays a vital role in mine planning, resource evaluation, and environmental management. However, conventional geostatistical methods, such as kriging, often face limitations in sparsely drilled areas due to their linear assumptions and inability to capture complex geological variability. This study implements a residual-based integration of geostatistics and machine learning for ash estimation. Ordinary kriging was first applied using a spherical variogram with strong geometric anisotropy (ranges: 2500 m horizontal, 20 m vertical) and a negligible (≈0) nugget indicated by the experimental variogram. The kriging baseline achieved RMSE = 1.485 (leave-one-out), and kriging variance was retained as an uncertainty indicator. Machine learning algorithms, including support vector machine, XGBoost, random forest, and LightGBM were then trained on the kriging residuals, incorporating the kriging variance as an additional input feature to capture complex non-linear patterns. The models were optimized using advanced hyperparameter tuning methods such as GridSearchCV and genetic algorithm. The hybrid framework substantially improved predictive accuracy, with the optimized random forest model achieving a reduced RMSE of 1.26 on the test set. These results demonstrate that integrating geostatistics with AI-based residual modeling enhances estimation robustness in sparse-data mining environments. The improvement, reflected in a 15% reduction in RMSE compared to kriging alone, provides a statistically significant basis for coal quality prediction, particularly in data-scarce environments.

Sustainable water treatment solutions are critical to managing natural resources and minimizing environmental pollution, especially in regions facing industrial wastewater challenges and freshwater scarcity. This study presents a bio-based adsorbent developed from cellulose functionalized with two natural polyphenols, tannic acid (TA) and lignin (LN), for the simultaneous removal of heavy metals and phenol. To enhance water stability and reduce leaching, TA and LN were polymerized via laccase-mediated oxidation and further stabilized through epichlorohydrin crosslinking, forming a robust polyphenol network on the cellulose surface. The resulting composite showed high adsorption capacities: 2.52 mmol/g for Cu²⁺, 0.74 mmol/g for Pb²⁺, and 0.44 mmol/g for phenol at pH 4.0, with equilibrium behavior well-described by the Langmuir isotherm model. FTIR, SEM, and UV-vis spectroscopy confirmed successful polymerization and surface functionalization. The proposed adsorption mechanisms include chelation, ion exchange, electrostatic attraction, and π–π interactions. Reusability tests showed that over 90% of Cu²⁺ and Pb²⁺ could still be adsorbed after three cycles, demonstrating excellent material durability and regeneration potential. These results highlight the potential of cellulose-polyphenol composites as green, low-cost, and reusable materials for sustainable water purification, promoting the circular use of lignocellulosic biomass and natural polyphenols in environmental remediation and industrial wastewater treatment.

This final segment invites reflections from presenters and attendees, synthesizing key insights from the session. The session chair will formally conclude the discussion by summarizing thematic threads, highlighting interdisciplinary contributions, and outlining potential collaborative directions.