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Induration of ilmenite pellets by oxidation is an essential step in the pelletization process since it decides the physical and metallurgical properties of the pellets. In this regard, the induration parameters such as temperature and roasting time have been optimized to obtain good quality ilmenite pellets made of concentrates obtained from low-grade ilmenite ores of Odisha, India. The oxidation temperature of 900 °C at a short roasting time of 15 min has been found suitable to achieve recommended requirements of various pellet properties such as cold compressive strength, porosity, metallization, tumble, and abrasion indices. X-ray diffraction and microstructural analysis indicate that the recrystallization of hematite in the oxidation process improves the mechanical strength of the pellets. In contrast, the formation of ferric pseudobrookite phase at 1000 °C and 1100 °C oxidation temperatures impairs the pellet strength. Unlabelled Image • The readiness of the ilmenite pellets for the reduction process was assessed through induration studies. • Different metallurgical properties were analyzed as a function of temperature and time. • Desirable pellet properties were attained at a temperature of 900 °C and a period of 15 min. • The phases changes occurred during induration were clarified using in-depth XRD, SEM, and EPMA analyses. • The oxidation mechanism of ilmenite pellets was correlated to the pellet consolidation. [ABSTRACT FROM AUTHOR]

Portland pozzolana cement (PPC) and ordinary Portland cement (OPC) OPC-53 grades of cement are commonly used in India. The thermal responses of these types of Portland cement (PC) differed upon analysing the compressive strengths of their hydrated cement block specimens at elevated temperatures. At 800°C, PPC was able to maintain the integrity of the cube, while OPC-53 failed to do so at 500°C. Thermal analyses were performed to interpret the performance of these two types of PC, and four critical regions of interest, – namely, 100°C, 400°C, 500°C and 800°C – were selected. X-ray diffraction and carbon hydrogen nitrogen sulfur-oxygen elemental analysis were conducted on both cements, and variations in the elemental and phase percentages were observed. The number of pores in OPC-53 was 4·51 times greater than that in PPC at 800°C. Additionally, relatively small pore radii ranging from 2·54 μm to 34·80 μm were observed for OPC-53 at 400°C; however, PPC contained pores with radii ranging from 2·54 μm to 67·23 μm. Ultimately, the development of micropores constitutes one of the primary reasons for structural collapse. [ABSTRACT FROM AUTHOR]

Mine overburden removed during surface mining is considered as “waste” or “spoil” that is consuming a vast tract of land for storage. Due to high ash content (30–50%) of Indian coals, 130 million tons of fly ash per year is generated with less than 50% of it is being used. Many a time thermal power plants are close to coal mines. Hence, in the present study it is proposed that a mixture can be prepared using fly ash and coal mine overburden with or without cement, which can be used as a stabilized pavement material. The present study deals with characterization of cement stabilized mine overburden fly ash mixture as a pavement material. Mixtures with varying cement percentage of 4–7% were prepared. Based on the unconfined compressive strength and California Bearing ratio values of the stabilized mixture, it was observed that it can be used as a stabilized pavement material. [ABSTRACT FROM AUTHOR]