Mathematical model for a straight grate iron ore pellet induration process of industrial scale

A mathematical model is developed for induration of the iron-ore pellets in an industrial-scale plant based on the laws of mass, heat and momentum transfer. Physicochemical processes occurring during the induration of pellets such as drying of moisture, calcination of limestone and coke-magnetite reaction are considered to evaluate the gradient of temperature within the pellets. Differential equations describing transport phenomena in a grate bed are simultaneously solved by dividing the space in both x- and z- directions and numerically solving the phenomenological equations. A kinetic model is used for estimation of the change of the strength of the pellets due to firing. The model involves gas-flow through different zones of a typical industrial plant. Different conditions are used for determination of the effect of addition of carbon to the green pellets on performance of the induration process. The optimum carbon content is determined to be 0.75% for green pellets. This results in a productivity enhancement of 20%, an N.G. fuel consumption decrease of 17% and an electrical power saving of 17%. Based on the model calculations, the volumes of the wasted greenhouse gases diminish with addition of the carbon content of the pellets.

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