Kinetic of Self-Reducing Mixtures of Iron Ore and Biomass of Elephant Grass

Abstract

In this work, kinetic runs of self-reducing mixtures composed by pellet feed, BOF dust and biomass of elephant grass were performed using TGA-DSC method, for the temperatures, 900, 950, 1000, 1050 and 1100°C, and carbon percentages (15, 20 and 30% of carbon). The converted fraction versus time was calculated, and the different regions of the reactions progress were selected to analyze the reactions kinetics that occur in the mixture (devolatilization of biomass, Boudouard and sequence of reduction reactions). The kinetic behavior for the different steps showed good agreement with the first-order kinetic law. Using Arrhenius plot, was possible to estimate the apparent activation energy values obtained for the reaction mechanisms corresponding to Fe3O4→FeO and FeO→Fe. The kinetic constants for the 1100°C temperature and mixture containing 30% of carbon were the higher values: 0.0037 s-1 for the reaction Fe3O4 → FeO and 0.0258 s-1 for the mechanism FeO →Fe.

Computational Analysis of The Performance of Shaft Furnaces with Partial Replacement of The Burden with Self-Reducing Pellets Containing Biomass

“…The model developed was implemented to simulate the energy behavior of the shaft furnace according to the scheme presented in Table 4, therefore, the productivity and efficiency of the shaft furnace fed with synthetic gas were provided. The kinetic parameters obtained experimentally, such as the kinetic rate constants, were used in the model 18 .…”

“…The experiments were performed in a TGA/DSC Q600 furnace using inert atmosphere. The kinetic parameters used in this study were previously published by the authors 18 .…”

“…An example of the reaction rates measured in this study is shown in Figure 1. The time evolution of the mass conversion fraction exhibited the typical behavior for isothermal conditions, which were used to determine the kinetic rate constant based on Arrhenius plot 18 . A low heating rate was used until the temperatures 900 °C, 1000 °C, and 1100 °C were reached, therefore, the samples were kept in a constant temperature range for one hour.…”

“…A low heating rate was used until the temperatures 900 °C, 1000 °C, and 1100 °C were reached, therefore, the samples were kept in a constant temperature range for one hour. Details of the experimental runs and rate formulations can be found elsewhere 18 .…”

“…Therefore, to investigate the feasibility of these concepts, it was developed a multiphase and multicomponent mathematical model based on mass, momentum, and energy conservation equations for predicting the inner temperature distribution of a shaft furnace on an industrial scale. It was proposed rate equations that represent the new raw material used in the model, based on previous experimental studies 18 and for DRI pellets with composition considered in previous works 10,11,19 . It was developed simulation scenarios based on a reference case involving actual operation and those based on partial substitution of the charge with SRP (self reduced pellet).…”