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Mechanical, chemical, and Thermal processing of acid-grade fluorspar concentrates:
(GMIT, Nalaikh, 2026-06-20) Dulguun S.; Supervisor 1nd, Purev-Ochir T., Prof. Dr.; Supervisor 2st, Narangarav T., Dr.
This study investigates the chemical purification of fluorite (CaF₂) concentrate toward acid-grade quality (≥97% CaF₂) using sequential hydrochloric acid (HCl) and sodium hydroxide (NaOH) leaching. The feed material, obtained as a flotation concentrate from a Mongolian deposit, contained approximately 93.02% CaF₂, with silica (2–4%), iron (0.11–0.13%), and carbonate minerals as the primary impurities. The purification process was evaluated through a series of controlled experiments, varying NaOH concentration (1–4 M) and temperature (70–90°C) while maintaining consistent HCl leaching conditions (1 M, 50°C). Chemical and mineralogical characterization was conducted using X-ray fluorescence (XRF), supported by titration and gravimetric analysis for accurate determination of CaF₂, CaCO₃, and SiO₂ contents. HCl leaching was found to be highly effective in removing carbonate and iron impurities, resulting in a consistent decrease in iron content and an apparent increase in calcium concentration due to gangue dissolution. However, silica remained largely unaffected during acid treatment, confirming the chemical stability of quartz. In contrast, NaOH leaching demonstrated that temperature is the dominant factor controlling silica removal. At 70°C, silica reduction was negligible, whereas at 90°C, a maximum reduction of approximately 16.5% was achieved, indicating enhanced dissolution of silica under elevated temperature conditions. The combined treatment resulted in an increase in CaF₂ grade to a maximum of 95.18%, representing a significant improvement over the feed material. However, the acid-grade
specification was not achieved, primarily due to incomplete silica removal, with residual silica remaining in the range of 3–4%. The results confirm that sequential HCl and NaOH leaching is an effective approach for fluorite purification, particularly for the removal of iron and carbonate impurities. Nevertheless, further optimization of alkaline treatment conditions, including increased temperature, extended reaction time, or improved mineral liberation, is required to achieve complete silica removal and meet industrial acid-grade specifications.
Assessment and Modernization of Relay Protection Systems for Auxiliary Transformers at Thermal Power Plant No. 4: Bachelor Thesis
(GMIT, Nalaikh, 2026-06-20) Namuun Ts.; Ankhbayar V. Thesis Supervisor 1st; Ariunbolor P. Ph.D, Thesis Supervisor 2nd
This thesis presents an engineering assessment and modernization proposal for the relay protection system of auxiliary transformer 2BT at Thermal Power Plant No. 4 in Mongolia. The reliable operation of the auxiliary power supply system is essential for maintaining the continuous and safe operation of major plant auxiliaries, including boiler feed pumps, draft fans, circulating pumps, and other motor-driven equipment required for unit operation. The study evaluates the technical condition of the existing 25 MVA, 10.5/6.3/6.3 kV auxiliary transformer 2BT and its associated relay protection system. The assessment includes connected load analysis, transformer loading verification, short-circuit current
calculation, review of the existing protection functions, selection of a suitable replacement transformer, and calculation of relay protection settings for the proposed modernization scheme. The load calculation was performed using the demand-factor method, while the short-circuit current calculation was carried out using the per-unit method. The calculated apparent load of transformer 2BT is 26.25 MVA, which exceeds the rated capacity of the existing 25 MVA transformer. This indicates insufficient loading reserve under the considered operating condition and justifies the replacement of the existing unit with a higher-rated transformer. Based on technical compatibility and capacity requirements, the ТРДНС-32000/10 У1 transformer with a rated power of 32 MVA is selected as the preferred replacement option. The calculated three-phase short-circuit currents are 26.07 kA at the 10.5 kV side and 15.08 kA at the 6.3 kV auxiliary bus section. The existing electromechanical relay protection devices are technologically outdated because they offer limited setting flexibility, lack self-diagnostics, lack disturbance recording, and have restricted communication capability. Therefore, the SEL-387A microprocessor-based transformer protection relay is proposed for modernization. This relay provides three-winding differential protection, backup overcurrent protection, harmonic restraint, thermal overload protection, breaker failure protection, event recording, and communication functions. The economic evaluation shows an estimated annual saving of 33,000,000 MNT and a payback period of approximately 9.4 years. The results demonstrate that the proposed transformer replacement and relay protection modernization will improve the reliability, selectivity, sensitivity, and maintainability of the auxiliary power supply system at TPP-4. Assessment and Modernization of Relay Protection Systems for Auxiliary Transformers at TPP-4
DESIGN AND IMPLEMENTATION OF A SENSOR-BASED WATER QUALITY MONITORING DEVICE: Bachelor's Thesis
(GMIT, 2026-06-20) Batnyam B.; Odbileg Norovrinchen Ph.D,; Young Suk Kim Ph.D,
This thesis presents the design, integration, and development of a sensor-based water quality monitoring device utilizing an ESP32 microcontroller, aimed at enabling real-time, accessible, and cost-effective water quality assessment. The system integrates four key sensors such as pH, turbidity, oxidation-reduction potential (ORP), and total dissolved solids (TDS), all managed through the ESP32 microcontroller. These sensors continuously measure fundamental water quality parameters, which are displayed on an LCD screen and transmitted via a Wi-Fi module for remote monitoring through computers or other smart devices. The system’s primary objective is to provide an efficient, portable, and affordable tool that allows users to easily evaluate water quality without the need for laboratory equipment. In the future, the system can be extended with additional sensors such as temperature, dissolved oxygen, or conductivity sensors to further enhance measurement precision and environmental adaptability. Overall, this research successfully demonstrates a compact, modular, and practical prototype that contributes to improving water quality monitoring practices and supports
sustainable water management solutions.
Managing automotive end-of-life NiMH and Li-ion batteries in Mongolia: a Material Flow Analysis to assess challenges and opportunities for circular batteries in the Global South
(Frontiers Media S.A., 2026-02-12) Gantuya Ganbat; Daniel Karthe
Introduction: Mongolia’s transition to electric mobility presents environmental opportunities to mitigate air pollution and potentially reduce greenhouse gas emissions but also generates complex waste streams such as end-of-life (EoL) Nickel Metal Hydride (NiMH) and Lithium-Ion Batteries (LIB). This study investigates the status of Mongolia’s waste management system and how it can be optimized to enhance the circularity of such waste streams.
Methods: Original data was collected through field research at collection, repair, storage, and disposal sites, and complemented by stakeholder interviews and an analysis of the country’s waste management legislation. Official vehicle fleet statistics (2010–2023) were used to forecast the quantity of EoL NiMH and LIB until 2050 and conduct a Material Flow Analysis for 10 different scenarios. The dataset comprises both qualitative data, describing the current waste management scenario, and quantitative data on vehicle imports, fleet composition, and battery specifications, with assumptions for missing values based on market trends.
Results: Results reveal that Mongolia lacks infrastructure and policy for safe and sustainable EoL battery management. EoL battery outflows were estimated using a two-parameter Weibull distribution model; forecast reliability was assessed via out-of-sample backcasting of the vehicle-fleet projection against historical fleet statistics (2019–2023 hold-out: MAPE = 4.71%). The results of the EoL battery quantities are scenario- and parameter-dependent projections for the lifetime and battery-specification assumptions. The results show that cumulatively (from 2023 to 2050), in the Current Scenario, 10,302 tons of EoL NiMH and 38,650 tons of EoL LIB are expected to be generated. In contrast, for the Climate Focus Scenario, 10,455 tons of EoL NiMH and 102,586 tons of EoL LIB are expected.
Discussion: The lower values of NiMH in 2050 are due to the expected transition from NiMH to LIB in HEV. Recommendations to enhance EoL battery management’s circularity include focusing on improving EoL battery collection, implementing Extended Producer Responsibility, integrating the existing informal sector, enhancing regional and international cooperation, and improving data acquisition and management. In summary, a combined approach involving local and international cooperation and socio- and technological development is essential for improving the circularity of EoL battery management in Mongolia.
1 Introduction
Spatiotemporal Variability of Near-Surface Temperature Inversion over Ulaanbaatar City, Mongolia
(MDPI, 2026-08-14) Gantuya Ganbat
Near-surface temperature inversions are prevalent during the cold months in Ulaanbaatar city, Mongolia, and significantly degrade urban air quality by trapping hazardous pollutants within a shallow atmospheric boundary layer. This study investigates spatiotemporal variability, physical mechanisms, and long-term evolution of near-surface temperature inversions over Ulaanbaatar by integrating 25 years (2000–2024) of ground-based meteorological and radiosonde observations, with high-resolution Weather Research and Forecasting (WRF) model simulations for 2012–2023. Our results demonstrate the fourdimensional data assimilation (FDDA) grid nudging effectively captures localized topographic influences in the WRF simulations, showing a strong agreement with radiosonde observations (R2 = 0.783, p < 0.000). Near-surface temperature inversions are strongly controlled by the Siberian High, with the highest frequency occurring from December to February, when up to 67% of morning observations exhibit inversion conditions. A pronounced diurnal cycle was identified, with inversion intensity peaking at 5.6–6.8 ◦C during the early morning hours (02:00–08:00 LST) before reaching a minimum around 14:00 LST. Spatially, the strongest inversions occur along the low-lying Tuul River valley, where the planetary boundary layer is compressed to below 350 m and wind speeds decrease to less than 2.4 m·s−1, creating persistent atmospheric stagnation. Despite these favorable conditions for inversion formation, long-term observations indicate that regional warming (+2.0 ◦C) and the urban heat island effects have reduced inversion frequency by 31%, inversion thickness by 170 m, and inversion intensity by 0.9 ◦C over the past 25 years. These findings demonstrate the strong coupling between regional complex terrain, and boundary layer thermodynamics, highlighting the need to incorporate urban ventilation corridors and topography-informed planning into climate adaptation and winter air-quality management strategies.