Features of the Iron Ore Pellets Structure Depending on the Concentrate Enrichment Degree

• Published in: Steel in translation Vol. 53; no. 4; pp. 328 - 335
• Main Authors: Bersenev, I. S., Bragin, V. V., Gruzdev, A. I., Bardavelidze, G. G., Pokolenko, A. Yu, Spirin, N. A.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.04.2023; Springer Nature B.V
• Subjects: Additives; Chemistry and Materials Science; Crystal defects; Crystal lattices; Diffusion rate; Fluxing; Hematite; Iron; Iron ores; Iron oxides; Materials Science; Metallurgy; Pellets; Phase composition; Phase transitions; Porosity; Sintering (powder metallurgy); magnetite; microstructure; strength; mineral phases; reducibility; pellets; metallurgical properties; hematite
• ISSN: 0967-0912; 1935-0988
• DOI: 10.3103/S0967091223040034

Aspects of the pellets structure are analyzed: the phase composition; features of interphase element migration; size of crystals of individual phases and their mutual arrangement; porosity; zoning; metallurgical properties. The structural features of pellets that determine their metallurgical properties include the nature of porosity and the structure (defects) of raw pellets, which are largely inherited by calcined pellets. The influence of the mineral composition of the silicate bond decreases as the concentrate enrichment degree increases. Accordingly, as the iron content in the concentrate increases, the effect of pellet fluxing on their properties decreases. Iron-rich pellets are more prone to destruction in the conditions of a blast furnace or shaft reduction unit. In general, the trend towards an increase in the iron content in concentrates entering the pellet production creates a new request for research into the pellets structure and their properties the study and modification of 95% iron oxide pellets or more. This requires the development of solutions that minimize the effect of stresses in the sintered mass during the “magnetite-hematite” phase transition; the formation of an open pores system (subject to pellets fluxing), which ensures high pellets reducibility; the search for optimal binders compositions that form the raw pellets structure with a minimum number of defects; the use of additives and technical solutions that increase the rate of oxygen diffusion through the crystal lattice of pellet minerals to increase the rate of its reduction, and a number of other tasks. Emphasis on these tasks will effectively implement the trend towards an increase in the iron content in concentrates.