Abstract
Results of a study of kinetics of siderite ore roasting process in flows of air, helium and hydrogen presented. The study was carried out at mass measuring device with continuous registration of mass changing. An expression received for determining of apparent decarburization degree and its dependence determined on a piece dimension, thermal treatment duration and gas phase content. Using a generalized chemical kinetics equation, a formula received for determining of decomposition time of siderite ore specimens. Increase of decarburization pace at temperature rise determined for specimens of all dimensions independent on the atmosphere content and mechanism of decarburization process at low temperatures considered. A possibility shown to describe the process of thermal dissociation of siderite ore by a kinetic equation of first order and an expression obtained for determining of this process duration depending on different parameters. By application of generalized chemical kinetics equation a formula obtained, which was used to check the expression, describing the test data. Kinetic of roasted ore specimens reduction studied at different temperatures and specimens dimensions.The results obtained in this work were used for optimization of structural and mode parameters of siderite ore roasting process in shaft furnaces. They will be applicable at designing of a shaft furnace, comprising decarburization zone, reduction zone (metallization zone) and cooling zone of the metalized product, that will enable to increase the iron content in the final product till 65–70%.
Highlights
An expression received for determining of apparent decarburization degree and its dependence determined on a piece dimension, thermal treatment duration and gas phase content
Using a generalized chemical kinetics equation, a formula received for determining of decomposition time of siderite ore specimens
A possibility shown to describe the process of thermal dissociation of siderite ore by a kinetic equation of first order and an expression obtained for determining of this process duration depending on different parameters
Summary
С использованием обобщенного уравнения химической кинетики получена формула для определения времени разложения образцов сидеритовой руды. Показана возможность описания процесса термической диссоциации сидеритовой руды с помощью кинетического уравнения первого порядка и получено выражение для определения продолжительности этого процесса в зависимости от различных параметров. Целью данной работы являлось изучение кинетики процесса обжига сидеритовой руды в различных газовых средах и определение зависимости степени декарбонизации от размера куска и продолжительности термообработки. Зависимость кажущейся степени декарбонизации от температуры и продолжительности нагрева образцов размером 20 мм в потоках воздуха и гелия приведена на рис. Полученных для случая нагрева образцов в потоке гелия, показала, что для описания процесса термической диссоциации сидеритовой руды применимо кинетическое уравнение первого порядка dγ. 2. Кинетика разложения образцов сидеритовой руды размером 40 мм в атмосфере гелия с последующим окислением на воздухе при температуре обжига: 1 ― 900 °С; 2 ― 800 °С; 3 ― 700 °С. Ниже представлены опытные (τоп) и расчетные (τр) значения времени диссоциации кусков руды в потоке воздуха (числитель) и потоке гелия (знаменатель) (табл. 2)
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