Reduction Behaviour of Self-reducing Blends of In-plant Fines in Inert Atmosphere

Ahmed, Hesham M.; Persson, Amanda; Ökvist, Lena Sundqvist; Björkman, Bo

doi:10.2355/isijinternational.isijint-2015-182

Cited by 17 publications

(17 citation statements)

References 15 publications

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“…[8,14] First step corresponds to the conversion of magnetite to wu¨stite which was observed to occur between 1173 K and 1413 K (900°C and 1140°C) during continuous heating at a rate of 7 K/min. The second step corresponds to the reduction of wu¨stite to metallic iron and is fast [15] unlike the relatively slow first stage. This is attributed to the autocatalytic effect of iron on Boudouard reaction (gasification of graphite) [16] (Eq.…”

Section: Discussionmentioning

confidence: 99%

Changes in Effective Thermal Conductivity During the Carbothermic Reduction of Magnetite Using Graphite

Kiamehr

Ahmed

Nurni

et al. 2017

Metall Mater Trans B

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Knowledge of the effective thermal diffusivity changes of systems undergoing reactions where heat transfer plays an important role in the reaction kinetics is essential for process understanding and control. Carbothermic reduction process of magnetite containing composites is a typical example of such systems. The reduction process in this case is highly endothermic and hence, the overall rate of the reaction is greatly influenced by the heat transfer through composite compact. Using Laser-Flash method, the change of effective thermal diffusivity of magnetite-graphite composite pellet was monitored in the dynamic mode over a pre-defined thermal cycle (heating at the rate of 7 K/min to 1423 K (1150°C), holding the sample for 270 minutes at this temperature and then cooling it down to the room temperature at the same rate as heating). These measurements were supplemented by Thermogravimetric Analysis under comparable experimental conditions as well as quenching tests of the samples in order to combine the impact of various factors such as sample dilatations and changes in apparent density on the progress of the reaction. The present results show that monitoring thermal diffusivity changes during the course of reduction would be a very useful tool in a total understanding of the underlying physicochemical phenomena. At the end, effort is made to estimate the apparent thermal conductivity values based on the measured thermal diffusivity and dilatations.

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Section: Discussionmentioning

confidence: 99%

Changes in Effective Thermal Conductivity During the Carbothermic Reduction of Magnetite Using Graphite

Kiamehr

Ahmed

Nurni

et al. 2017

Metall Mater Trans B

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“…The experiments were performed using a TGA, Netzsch STA 409 instrument (sensitivity ±1 µg) (Netzsch, Selb, Germany) attached to a Quadrupole Mass Spectroscopy (QMS, Netzsch, Selb, Germany) to monitor the mass loss and off-gases, respectively. The TGA used in this study is described in detail in reference [34]. In the mass spectrometer, compounds are ionized and separated on the basis of the mass/charge (m/z) ratio number.…”

Section: Experimental Methodsmentioning

confidence: 99%

Devolatilization Kinetics of Different Types of Bio-Coals Using Thermogravimetric Analysis

El-Tawil

Ahmed

Ökvist

et al. 2019

Metals

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The interest of the steel industry in utilizing bio-coal (pre-treated biomass) as CO2-neutral carbon in iron-making is increasing due to the need to reduce fossil CO2 emission. In order to select a suitable bio-coal to be contained in agglomerates with iron oxide, the current study aims at investigating the thermal devolatilization of different bio-coals. A thermogravimetric analyzer (TGA) equipped with a quadrupole mass spectrometer (QMS) was used to monitor the weight loss and off-gases during non-isothermal tests with bio-coals having different contents of volatile matter. The samples were heated in an inert atmosphere to 1200 °C at three different heating rates: 5, 10, and 15 °C/min. H2, CO, and hydrocarbons that may contribute to the reduction of iron oxide if contained in the self-reducing composite were detected by QMS. To explore the devolatilization behavior for different materials, the thermogravimetric data were evaluated by using the Kissinger– Akahira–Sonuse (KAS) iso-conversional model. The activation energy was determined as a function of the conversion degree. Bio-coals with both low and high volatile content could produce reducing gases that can contribute to the reduction of iron oxide in bio-agglomerates and hot metal quality in the sustained blast furnace process. However, bio-coals containing significant amounts of CaO and K2O enhanced the devolatilization and released the volatiles at lower temperature.

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“…Detailed description of the used instrument is given an earlier publication. 20) Gently ground pellets were agglomerated into small briquettes (3 mm height and 2 mm diameter) using a specially designed mold. The briquette was then centered on a flat alumina pan and then introduced to the hot zone of a horizontal tube furnace.…”

Section: Methodsmentioning

confidence: 99%

“…A Netzsch STA 409 thermo-gravimetric analyzer 20) with sensitivity ± 1 μg (TGA) was used to evaluate and analyze the effect of olivine particle size on the process kinetics. Two different sets of experiments were conducted.…”

Section: Methodsmentioning

confidence: 99%

Effect of Added Olivine on Iron Ore Agglomerate During Induration

et al. 2018

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Reduction Behaviour of Self-reducing Blends of In-plant Fines in Inert Atmosphere

Cited by 17 publications

References 15 publications

Changes in Effective Thermal Conductivity During the Carbothermic Reduction of Magnetite Using Graphite

Changes in Effective Thermal Conductivity During the Carbothermic Reduction of Magnetite Using Graphite

Devolatilization Kinetics of Different Types of Bio-Coals Using Thermogravimetric Analysis

Effect of Added Olivine on Iron Ore Agglomerate During Induration

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