Experiments and Kinetic Modeling for Reduction of Ferric Oxide-biochar Composite Pellets

Abstract

The reduction behavior, phase transformation and microstructure evolution of four ferric oxide-biochar composite pellets (RLC-pellet, PHC-pellet, MCC-pellet and PSC-pellet) were investigated by use of nonisothermal thermogravimetric, X-Ray diffraction (XRD) and Scanning electron microscopy (SEM) analysis. The apparent kinetic parameters of reduction process were estimated by fitting the experimental data to the three parallel nth order rate models. The results showed that ferric oxide-biochar composite pellet reduction process was divided into three stages of Fe 2 O 3 →Fe 3 O 4 , Fe 3 O 4 →FeO and FeO→Fe, where the first stage was independent to the next two stages. The sequence of reduction reactivity as to all samples was MCC-pellet > PHC-pellet > PSC-pellet > RLC-pellet. Meanwhile, increasing heating rate could efficiently improve the reduction reactivity. Through kinetic analysis, it was found that three parallel nth order rate models could well represent reduction process, and activation energies of three stages calculated by the model were 204.9-405.5 kJ/mol, 259.6-643.8 kJ/mol and 291.5-685.8 kJ/mol, respectively. The marked compensation effect was also presented between the activation energy and pre-exponential factor.

Reduction Reactivity of Low Grade Iron Ore-Biomass Pellets for a Sustainable Ironmaking Process

“…Consequently, processes at higher temperatures nearby overlap each other. On the other side, there is a temperature differential through the sample's cross-section at a high heating rate which prevents heat Some of the qualitative characterization parameters used include [21]: Ti and Tf, which are the initial temperature and the final temperature for weight loss from the reduction process, respectively; Tmax-1, Tmax-2, Tmax-3, and Tmax-4, which are the peak temperatures of the reaction rate for the four stages, respectively; dm/dtmax-1, dm/dtmax-2, dm/dtmax-3, and dm/dtmax-4, which are the peak values of the reaction rate for the four stages, respectively; tr is the reaction time from Ti to Tf; and S is the comprehensive reactivity index of the iron ore-biomass pellets, where the values are according to the following Equation ( 1):…”

“…Consequently, processes at higher temperatures nearby overlap each other. On the other side, there is a temperature differential through the sample's cross-section at a high heating rate which prevents heat transfer [21]. However, the pattern of the thermal decomposition does not alter.…”

“…Several studies have analyzed the effect of heating rate changes on reduction reactivity through thermogravimetric analysis (TGA). The study utilized carbonized goethite ore samples [12] and iron ore-biochar pellets [21]. These studies show that increasing the heating rate on the same reducing agent will shift the initial temperature of the weight loss.…”

Effect of SiO2 on the Mechanical Property and Reduction of Calcium Ferrite

“…Two-dimensional diffusion cylindrical symmetry D2 The relationship between reduction degree and temperature of powdered samples with different SiO2 content is shown in Figure 3. The maximum reduction degree and its corresponding time for samples are shown in Table 4, where xm, Ti and Tf [27] are the maximum reduction degree, initial mass loss temperature and maximum mass loss temperature of reduction reaction, respectively. With the increase of SiO2 content, the initial reduction temperature decreases gradually, and when w(SiO2) content exceeds 3%, the initial reduction temperature is stable (508.6-510.6 °C).…”

Utilização de carvões provenientes de biomassas como fonte de energia renovável na autorredução de briquetes confeccionados com poeira de aciaria LD, elétrica e ferrita de zinco.

“…El-Hussiny e Shalabi(2011)mencionam em seu trabalho a redução de hematita com carbono em pó. Os autores determinaram a energia de ativação de 300kJ/mol para a faixa de temperatura entre 957°C e 1087°C Wang et al (2017). realizaram a redução de pelotas de óxidos de ferro com biocarvão.…”