Abstract
To study the process of magnetite oxidation the experiments had been conducted on large single crystals of magnetite having octahedral form and retrieved from chlorite schist in Shabrovski talc mine (the Middle Urals). Using the method of diff erential thermal curves obtained by diff erential heating of samples the good reproducibility of the processes that occur during oxidative roasting magnetite was shown. The mechanism of the magnetite oxidation and temperature ranges of exothermic and endothermic reactions in various stages of magnetite oxidation was considered. Using the method of separated standard the unknown thermal eff ect of magnetite oxidation was determined in accordance with the standard thermal effect (CaCO3 ) and the values obtained in the areas of the fi gures in thermograms concluded between the diff erential heating curve and the axis of time proportional to the thermal eff ects of the standard and the test substances (Fe3O4 ). The obtained results are of some interest. Knowing the temperature intervals of magnetite oxidation, it can be taken into account in establishing the mode of burning heat source for technological zones in conveyor type roasting machines. This achieves optimization of the fi ring thermal regime and reduction in specifi c fuel consumption
Highlights
To study the process of magnetite oxidation the experiments had been conducted on large single crystals of magnetite having octahedral form and retrieved from chlorite schist in Shabrovski talc mine
Using the method of differential thermal curves obtained by differential heating of samples the good reproducibility of the processes that occur during oxidative roasting magnetite was shown
Using the method of separated standard the unknown thermal effect of magnetite oxidation was determined in accordance with the standard thermal effect (CaCO3) and the values obtained in the areas of the figures in thermograms concluded between the differential heating curve and the axis of time proportional to the thermal effects of the standard and the test substances (Fe3O4 )
Summary
Уральский федеральный университет им. первого Президента России Б.Н. Ельцина Методом раздельного эталона тепловой эффект окисления магнетита определен по тепловому эффекту эталона (CaCO3) и величинам площадей фигур на термограммах (между дифференциальными кривыми нагрева и осью времени). Для применения полученных дифференциальных кривых для количественных расчетов тепловых эффектов при окислении магнетита были сняты дифференциальные кривые нагрева образцов карбоната кальция марки ЧДА с содержанием основного компонента около 98 %, максимум отклонений которых от оси времени находился при температуре 1173 К. В соответствии с методом раздельного эталона неизвестный тепловой эффект можно определить по тепловому эффекту эталона (CaCO3) и величинам площадей (S) фигур на термограммах между дифференциальными кривыми нагрева и осью времени, которые пропорциональны тепловым эффектам эталона и исследуемого вещества (Fe3O4): откуда (2) (2, а). – тепловой эффект реакции окисления оставшегося в объеме зерен оксида Fe3O4 при температуре. – тепловой эффект реакции поверхностного окисления зерен магнетита при температуре 613 К, кДж/моль.
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