Abstract
The burned pellets must retain the strength from the time they come off the roasting machine until they are loaded into the blast furnace. One indicator of the strength of burned pellets is the compressive strength, i.e., the maximum applied load at which the iron-ore pellet completely collapses. The paper studies the character of destruction of burned iron-ore titanomagnetite pellets of fraction 10 - 16 mm in the static compression test according to the Russian State Standard 24765-81. It is shown that the main type of destruction during the test is the emergence and development of plane cracks passing through the center of the magnetite core, where the maximum radial tensile stresses act or in the immediate vicinity. In some cases, the trajectory of one of the destructive cracks deviates from the above plane and envelopes the magnetite core. Obviously, this is due to the presence of a second area of tensile stress concentration at the boundary of the magnetite core and the hematite shell, formed during cooling of the pellets, due to differences in their mechanical and thermophysical properties. As a result, the final structure of pellets is characterized by the presence of two zones -peripheral hematite and central magnetite. The role of the relative size of the magnetite core on the compressive strength of burned pellets has been determined. It was established that the strength characteristics of the pellet increase with a decrease in relative size of the magnetite core. During the process of magnetite complete oxidation (when the whole volume of the pellet consists of hematite), the maximum level of the pellets compressive strength can be: the maximum destructive force - 3300 N, destructive energy - 0.55 J, mass destructive energy - 0.18 J/g.
Highlights
It was established that the strength characteristics of the pellet increase with a decrease in relative size of the magnetite core
During the process of magnetite complete oxidation, the maximum level of the pellets compressive strength can be: the maximum destructive force – 3300 N, destructive energy – 0.55 J, mass destructive energy – 0.18 J/g
‒ написание текста рукописи, получение и анализ данных, обзор публикаций по теме статьи, получение данных для анализа
Summary
Одним из показателей прочности обожженных окатышей является прочность на сжатие, т. В работе изучен характер разрушения обожженных неофлюсованных железорудных титаномагнетитовых окатышей фракции 10 ‒ 16 мм при испытании на статическое сжатие согласно ISO 4700. Что при испытании основным видом разрушения является возникновение и развитие трещин плоскости, проходящих через центр магнетитового ядра, где действуют максимальные радиальные растягивающие напряжения, или в непосредственной близости от него. Определена роль влияния относительного размера магнетитового ядра на прочность при сжатии обожженных окатышей. При протекании процесса полного окисления магнетита (когда весь объем окатыша состоит из гематита) максимальный уровень предельных характеристик прочности на сжатие окатышей может быть следующим: максимальное разрушающее усилие 3300 Н, энергия разрушения 0,55 Дж, массовая энергия разрушения 0,18 Дж/г. Влияние структуры обожженных окатышей на прочность и разрушение при испытании на статическое сжатие // Известия вузов.
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