Thermal and mass spectroscopic analysis of BF and BOF sludges:study of their behavior under air and inert atmosphere

Abstract Differential thermal analysis (DTA), thermogravimetry (TG), and mass spectrometry (MS) were used to study the thermal behavior of the blast furnace (BF) and basic oxygen furnace (BOF) sludges generated from the iron-making industry. The results indicated that under air atmosphere the two types of sludge are different in their thermal behavior. In BF sludge, the exothermic carbon gasification (CO/CO₂) reaction dominated the process, while in BOF sludge, the significant reaction occurred at 755 °C and was associated with a slight mass gain owing to the partial oxidation of Fe₃O₄ to Fe₂O₃. Under inert atmosphere, the thermal behavior of both BF and BOF sludges were dominated by a reduction reaction. In BF sludge, the endothermic reactions ranged from 785 to 1115 °C due to the reduction of iron oxides as follows: Fe₂O₃ → Fe₃O₄ → FeO → Fe. A total mass loss of about 27.78% was observed in the TG curve. While in BOF sludge, the endothermic peaks corresponded to magnetite reduction to iron (Fe). The overall mass loss of the BOF was approximately 16.92%. The mass spectrum of gases evolution for both BF and BOF sludges revealed that CO/CO₂ gases were released from the sludges

Improving zinc recovery from steelmaking dust by switching from conventional heating to microwave heating

Abstract Recently, microwave energy has attracted increasing interest for accelerating thermal reactions. This study investigated the impact of microwave heating on the zinc recovery rate from electric arc furnace (EAF) and chromium converter (CRC) dusts. The results indicated that microwave heating required a lower temperature to recover zinc from EAF and CRC dusts compared with that in conventional thermal heating. For CRC dust, zinc recovery rates of 37.84% and 97.43% were obtained with conventional and microwave heating, respectively, at 850 °C. For EAF dust, zinc recovery rates of 79.88% and 98.20% were obtained with conventional and microwave heating, respectively, at 850 °C. The improved zinc recovery in this study was concluded to results from the rapidity of microwave heating and the interactions between the electromagnetic microwave field and the molecules of heated materials

Microwave catalyzed carbothermic reduction of zinc oxide and zinc ferrite:effect of microwave energy on the reaction activation energy

Abstract Recently, more attention has been paid to the use of microwave (MW) energy in accelerating chemical reactions. The effect of microwave energy on the reduction of zinc oxide and zinc ferrite was investigated. The results indicated that the temperatures required to initiate zinc oxide and zinc ferrite reduction under MW heating were 550 and 450 °C, respectively, while under conventional thermal (CT) heating, were 950 and 850 °C, respectively. Apparently, the MW reaction had a negative standard Gibbs free energy (ΔG) at a lower temperature (∼400 °C) when compared to the CT reaction. Additionally, the activation energy (Ea) substantially decreased from 223.7 and 221.1 kJ mol−1 under CT heating to 64.8 and 32.9 kJ mol−1 under MW heating for Zn oxide and zinc ferrite, respectively. The enhancement in zinc reduction under MW energy was due to the rapid and bulk heating phenomena of MWs as well as the interactions occurring between the electromagnetic MW pattern and the molecules of heated materials

Isothermal and non-isothermal reduction behaviors of iron ore compacts in pure hydrogen atmosphere and kinetic analysis

Abstract This study examines the isothermal and non-isothermal reduction behaviors of iron ore compacts in a pure hydrogen atmosphere and compares the results obtained during the reduction process by CO. The different phases accompanying the reduction reactions were identified using X-ray diffraction (XRD) and its morphology was microscopically examined. In isothermal experiments, temperature plays a significant role in the reduction process. At any given temperature, the reduction rate during the initial stages is higher than that during the final stages. The reduction rate in H₂ atmosphere was faster than in CO gas. The comparison of activation energy values suggested that reduction with H₂ is more efficient than with CO. At the same temperature, the time required to achieve a certain degree of reduction was lower when using H₂ gas than CO atmosphere. In non-isothermal tests, the heating rate has a significant effect on the reduction rate and reduction extent. At the same heating rate, the degree of reduction was higher in H₂ atmosphere than in CO gas. Based on experimental data, the parameters of reaction kinetics were deduced by application of model-free and model-fitting methods. The reduction in H₂ atmosphere was controlled by nucleation model (Avrami-Erofeev model), while the CO reduction reaction was controlled by gas diffusion

Comparative study on the isothermal reduction kinetics of iron oxide pellet fines with carbon-bearing materials

Abstract The isothermal reduction of iron oxide pellet fines–carbon composites was investigated at temperatures of 900–1100 °C. The reduction reactions were monitored using the thermogravimetric (TG) technique. Alternatively, a Quadruple Mass Spectrometer (QMS) analyzed the CO and CO² gases evolved from the reduction reactions. The effect of temperature, carbon source, and reaction time on the rate of reduction was extensively studied. The phase composition and the morphological structure of the reduced composites were identified by X-ray diffraction (XRD) and a scanning electron microscope (SEM). The results showed that the reduction rate was affected by the temperature and source of carbon. For all composite compacts, the reduction rate, as well as the conversion degree (α) increased with increasing temperature. Under the same temperature, the conversion degree and the reduction rate of composites were greater according to using the following carbon sources order: Activated charcoal > charcoal > coal. The reduction of the different composites was shown to occur stepwise from hematite to metallic iron. The reduction, either by activated charcoal or charcoal, is characterized by two behaviors. During the initial stage, the chemical reaction model (1 − α)−2 controls the reduction process whereas the final stage is controlled by gas diffusion [1 − (1 − α)1/2]². In the case of reduction with coal, the reduction mechanism is regulated by the Avrami–Erofeev model [−ln (1−α)²] at the initial stage. The rate-controlling mechanism is the 3-D diffusion model (Z-L-T), namely [(1−α)−1/3−1]² at the latter stage. The results indicated that using biomass carbon sources is favorable to replace fossil-origin carbon-bearing materials for the reduction of iron oxide pellet fines

Study of an organic binder of cold-bonded briquettes with two different iron bearing materials

Abstract The aim of this study was to investigate the properties of an organic binder used in cold-bonded briquettes (CBBs) prepared from two different iron bearing materials. The applied binder is a type of starch as indicated by chemical analysis, iodine-starch staining and Fourier transform infrared analyses. Thermogravimetric differential scanning calorimetry showed that the binder pyrolysis undergoes four stages: moisture desorption, ash volatilization, pyrolysis of organic matter and decomposition of materials with high activation energy. The difference between the dry and heat-treated samples during the macroscopic failure process is the instability propagation of the crack. The CBB shows a low decrepitation index at 700 °C. The returned fines of CBBs used with the organic binder were applied in two blast furnaces. The industrial trials showed that the CBBs do not influence the performance of the blast furnace and can reduce the fuel consumption rate. The curing rate of the binder decreases, and the growth rate of compressive strength decreases during the curing process. Iron ore particles are bonded together and exist in the form of aggregation after mixing with water and binder. The edges and corners of the particles become blurred, and the original surfaces of the particles are covered with binder film, the surface of which is covered with fine particles. The multi-branched structure of amylopectin provides omnibearing adhesion sites, thus forming binder agglomeration and film leading to a strong adhesion between binder and iron ore particles. Binder film and binder agglomeration work together to make the CBB perform well

Non-isothermal reduction kinetics of iron ore fines with carbon-bearing materials

Abstract This study investigates the non-isothermal reduction of iron ore fines with two different carbon-bearing materials using the thermogravimetric technique. The iron ore fines/carbon composites were heated from room temperature up to 1100 °C with different heating rates (5, 10, 15, and 20 °C/min) under an argon atmosphere. The effect of heating rates and carbon sources on the reduction rate was intensively investigated. Reflected light and scanning electron microscopes were used to examine the morphological structure of the reduced composite. The results showed that the heating rates affected the reduction extent and the reduction rate. Under the same heating rate, the rates of reduction were relatively higher by using charcoal than coal. The reduction behavior of iron ore-coal was proceeded step wisely as follows: Fe₂O₃ → Fe₃O₄ → FeO → Fe. The reduction of iron ore/charcoal was proceeded from Fe₂O₃ to FeO and finally from FeO to metallic iron. The reduction kinetics was deduced by applying two different methods (model-free and model-fitting). The calculated activation energies of Fe₂O₃/charcoal and of Fe₂O₃/coal are 40.50–190.12 kJ/mol and 55.02–220.12 kJ/mol, respectively. These indicated that the reduction is controlled by gas diffusion at the initial stages and by nucleation reaction at the final stages

Additional file 1 of FFAR4 activation inhibits lung adenocarcinoma via blocking respiratory chain complex assembly associated mitochondrial metabolism

Additional file 1: Figure S1. Aberrant expression of FFAR4 is correlated with clinicopathologic findings in LUAD patients. Figures (A-G) illustrate the relationship between the expression of FFAR4 and Pathologic stage, T Stage, Primary therapy outcome, number_pack_years_smoked and Smoker, DSS event, PFI event among LUAD patients in TCGA database. Data are expressed as the mean ± standard error of the mean. P < 0.05 was considered statistically significant using two-way ANOVA; NS, not significant

Studies on the reduction behavior of Iion oxide pellet fines with hydrogen gas:mechanism and kinetic analysis

Abstract The present study contributes to the current worldwide activities aiming to replace fossil carbon in steel making processes with hydrogen causing considerable reduction of greenhouse gas emissions. Compacts prepared from iron oxide pellets fines were isothermally reduced in pure hydrogen gas and a mixture of hydrogen and argon in the temperatures range from 700 to 1100 °C. The total weight loss produced during the reduction process was continuously recorded using thermogravimetric analysis (TG) technique. The findings demonstrated that the temperature has a considerable impact on the conversion and reduction rates. At a given temperature, the reduction rate was accelerated as the amount of H₂ increased in the reducing gas. The results indicated that H₂ content does not have an effect on reduction behavior, when it is higher than 80%. The reduction reaction of samples was shown to takes place in a step wise manner from hematite to metallic iron. The reduction kinetic and mechanism were deduced from the application of mathematical models and the morphological structure of the reduced samples and correlated with the apparent activation energy (Ea) values. The Ea values at the early, intermediate and final stages were 16.36, 29.24 and 49.35 kJ/mole, respectively. The early stage of the reduction process was controlled by chemical reaction, whereas the gaseous diffusion was controlled the latter stage. At the intermediate stage, the reduction process was controlled by mixed mechanism of gaseous diffusion and chemical reaction