Phase and Microstructural Characterization of Iron Ore Pellet and their Relation with Cold Crushing Strength Test

Abstract

The use of microstructural characteristics as a quality control tool has been increasingly employed in iron ore agglomeration processes. In the production of the pellets, phase identification for specific sintering condition is of prime importance in understanding the basis for the production and the required properties. The application of a methodology involving optical and electron microscopy applying the electron backscatter diffraction (EBSD) technique opened a broad possibility to combine the routinely use of the optical microscope with the powerful EBSD tool in order to establish a base for the relationship between heat-treated pellet microstructural features and cold crushing strength. The optical images is the starting point and reveal the general aspects of the aggregate such as porosity, the iron oxide phases and the sintering stage of the ferritic matrix. The use of the scanning electron microscope equipped with the EBSD has a twofold purpose. First for the usual magnification which has a deep observation of the pore space and the microstructure at a submicron scale. Second, the crystallographic Downloaded by [University of California Santa Barbara] at 09:27 27 June 2016A c c e p t e d M a n u s c r i p t 2 information obtained from the EBSD plus the chemical information acquired from the combined use of energy dispersive X-Ray analyzer allow the determination of the any crystalline phase present in the pellet, in addition to the quantification of the phases. The first results from the conjoined application of these techniques show that the cold crushing strength of the pellet increase with the decrease of porosity, the appearance of the fayalite, as well as the presence of magnetite-unoxidized.

Experimental Investigation of Different Fineness and Firing Temperatures on Pellets Properties of Different Iron Ore fines from Indian Mines

“…CaO additive usage at a different temperature to form calcium ferrite and other ingredients of solid solution and space vacant behind makes pores. When CaO is exhausted, small and uniform grains are closely arranged with fine boundaries, and few porous examples have appeared [9]. The Iron Ore No.1 pellet shave good enough porosity, as compared to Iron Ore No.2 pellets.…”

“…EDS was done with X Flash 6130 (Bruker Company). The image analysis tool (ImageJ) was used to measure the area fraction and phase density of different phases in the microstructure [9].…”

“…For the finest ore, the Blaine (3218 cm 2 /g for Iron Ore No.1 pellet sand 3461 cm 2 /g for Iron Ore No.2 pellets) corresponds to 400 mesh, assimilation of grains in melt occurs vigorously, phase discrimination becomes difficult even after crystallization, smaller pores become irregular, and bigger pores decrease P.P.G.D. for both Iron Ore No.1 and No.2 pellets [9]. Magnetite Phase Grain Density (M.P.G.D.)…”

“…A comparative study has been done on fineness, as well as the drying and heating processes. As per the chemistry of an ore pellet's microstructure, the formation and impact on physical and physicochemical properties were investigated [9,10].…”

Effect of Finely Ground Limestone and Dolomite on Compression Strength and Reduction Swelling of Vanadium-Titanium Pellets

“…Pellets, as one of the iron-bearing burdens of blast furnaces, present many advantages, including excellent metallurgical performance, low energy consumption in the production process, and fewer pollution emissions compared with using sintering ore. According to China’s pig iron production in 2016 (700 Mt), which was used to calculate the pollutant emissions, it can be estimated that the emissions of dust, CO 2 , SO 2 , and NOx could be reduced by 0.04, 500, 0.2, and 0.35 Mt, respectively, if the 75% sinter was replaced by 60% pellets, including flux pellets [ 11 , 12 , 13 , 14 ]. To further improve the metallurgical properties of pellets, and to satisfy the requirements of blast furnace slag basicity, some fluxing materials have been added to the pellet.…”