http://ore.immt.res.in/handle/2018/4 Wed, 07 Oct 2026 09:19:55 GMT 2026-10-07T09:19:55Z http://ore.immt.res.in/handle/2018/4042 Mineralogical Characterization and Leaching Kinetic Investigation of Nigerian Bismutite-Rich Zinnwaldite Ore by Methanesulfonic Acid Balogun, A. F.; Baba, A. A.; Tripathy, B. C. The global demand for bismuth has increased significantly, a trend heightened by stricter environmental regulations. As a critical metal, bismuth is essential for advancements in the pharmaceutical industry. This study investigates the leaching kinetics of bismuth from bismutite-rich zinnwaldite ore using methanesulfonic acid (MSA, CH3SO3H) as a biodegradable leaching agent. Experiments were designed to assess the effect of MSA concentration, iron powder concentration, reaction temperature, and particle size on leaching efficiency. The optimal leaching conditions were determined to be a MSA concentration of 3.0 mol/L, iron powder at 0.5 mol/L, leaching time of 120 min, temperature of 80 degrees C, and particle size of 45 & micro;m. Under these conditions, the bismuth leaching efficiency reached 92.30%. Kinetic modelling demonstrated that the leaching process is governed by diffusion through a product layer, with a reaction order of 0.908 and an apparent activation energy of 17.35 kJ/mol. X-ray diffraction analysis of the leach residue identified quartz (Si6.00O6.00: 91-900-5019), and minor residual polylithionite K(Al0.90Li0.90Fe0.80Mn0.20 (Si3.10Al0.90)(OH0.40)F1.60: 00-042-1399) as the main undissolved phases. Thu, 01 Jan 2026 00:00:00 GMT http://ore.immt.res.in/handle/2018/4042 2026-01-01T00:00:00Z http://ore.immt.res.in/handle/2018/4041 Mechanistic insights into corrosion processes of RF-sputtered TiMoN coatings through distribution of relaxation time analysis Priyadarshini, B.; Anwar, M. S.; Sagdeo, A.; Anwar, S. Reactive RF sputtering was used to deposit TiMoN coatings on 304 stainless steel by varying the N2flow while keeping the Ar flow constant. The Nitrogen (N2) flow strongly affected phase evolution, crystallite size, microstructure and electrochemical response, with the coating deposited at Ar:N2= 20:03 showing the optimum combination of mechanical and electrochemical properties. XRD revealed a transition from crystalline to nanocrystalline/amorphous-like structural character at higher N2flow, while plan-view and cross-sectional FESEM showed corresponding changes in surface and cross-sectional morphology. While nanoindentation confirmed the highest hardness and elastic modulus for the 20:03 coating. In 3.5 wt% NaCl, this coating also exhibited the lowest corrosion current density, the highest polarization and charge-transfer resistance and the lowest porosity, indicating superior barrier behavior. Importantly, Distribution of Relaxation Time analysis resolved two dominant relaxation processes and confirmed that the optimized coating suppresses both coating/ electrolyte and defect-controlled interfacial corrosion pathways. The combined electrochemical and microstructural evidence identifies 20:03 as the optimum gas ratio for producing TiMoN coatings with enhanced mechanical integrity and robust corrosion resistance in chloride media. Thu, 01 Jan 2026 00:00:00 GMT http://ore.immt.res.in/handle/2018/4041 2026-01-01T00:00:00Z http://ore.immt.res.in/handle/2018/4040 Investigation on Bauxite Slurry Transportation: Rheological and Pilot Plant Characteristics Reddy, N. V. K.; Dubey, A.; Pothal, J. K. The current work investigates the transportation of bauxite slurry through rheology as well as experimental pilot plant studies in horizontal pipelines. The work utilizes the sample prepared at a median particle size (d50) of 23.3 mu m, followed by its characterization including temperature-dependent rheology to understand the flow behavior. The tests performed through 50 mm and 100 mm NPS (nominal pipe size) loops on three solids concentrations, 35.2%, 40%, and 45.3% by weight, showed non-Newtonian pseudoplastic behavior with yield stress. The slurry showed a good fit to the Herschel-Bulkley (H-B) model in the tested concentrations. The effect of solids concentration and nominal pipe size on the pressure drop were studied at an operating velocity range of 0.57-1.86 m/s. The semiempirical H-B models developed by Torrance, Wilson and Thomas (W&T), Slatter, Chilton and Stainsby (C&S), along with extended modifications to Tomita and Dodge and Metzner (D&M) models were used to estimate the pressure drop and transition from laminar to turbulent flow regime. The W&T model showed minimum NRMSE (normalized root mean squared error) for all the concentrations in both pipe sizes. The work also estimates the optimum solids concentration for a given throughput of 1,500 tons per hour (TPH) based on the W&T model. Finally, the challenges faced in determining the critical settling velocity and transition point of flow regime were addressed with possible adaptive methods for further investigation. Thu, 01 Jan 2026 00:00:00 GMT http://ore.immt.res.in/handle/2018/4040 2026-01-01T00:00:00Z http://ore.immt.res.in/handle/2018/4039 Electroactive coupling of formate dehydrogenase with Ni-modified triazine frameworks for efficient and selective CO2 photoreduction Kumar, N.; Mrinalini, M.; Chaudhary, Y. S. Developing an efficient and selective catalyst for solar-driven CO2 conversion remains a critical challenge owing to the high thermodynamic stability and sluggish reduction kinetics of CO2. Herein we report a robust bio-inspired enzyme-semiconductor hybrid photocatalyst fabricated via electroactive immobilization of formate dehydrogenase (Fatedh) onto Ni-decorated-nitrogen-deficient mesoporous triazine frameworks (Ni-mpg-C3Nx) for selective CO2 reduction. The integrated Ni atomic sites act as redox intermediaries to accelerate the interfacial electron transfer while nitrogen vacancies assist with the reactant adsorption and chemical activation process. Isothermal titration calorimetry (ITC) reveals exceptionally strong enzyme-support affinity, yielding low dissociation constant (Kd) ranging from 9.33 & times; 10-7 to 8.15 & times; 10-7. The electroactive coupling promotes efficient NAD+/NADH regeneration, facilitating the enzymatic CO2 conversion at the active Mo/W catalytic center of Fatedh. Consequently, the optimized photocatalyst Ni-mpg-C3Nx_Fatedh achieves a remarkable formic acid yield of 6.8 mmol, which is 4.5-fold improvement over mpg-C3Nx_Fatedh (1.5 mmol) and a 7-fold enhancement compared to that of bare mpg-C3N4 with a TOF of 9.36 & times; 105 s-1. Kelvin probe force microscopy (KPFM) demonstrates an elevated surface potential (similar to 4000 & micro;V) that plays a vital role in suppression of charge recombination and improves the charge carrier mobility across the bio-inorganic heterointerface. Notably, the hybrid photocatalyst is stable and highly selective for CO2 reduction under ambient conditions, without requiring an inert atmosphere, offering pathways towards sustainable solar fuel production. Thu, 01 Jan 2026 00:00:00 GMT http://ore.immt.res.in/handle/2018/4039 2026-01-01T00:00:00Z