Kinetics of Direct Reduction Titanomagnetite Briquette Produced from Rossetta-Ilmenite via Hydrogen

El-Hussiny, N.A.; El-Amir, Atef; Abdel-Rahim, Saied Thabet; Hossiny, Khaled El; Shalabí, M. E. H.

doi:10.4236/oalib.1100662

Cited by 4 publications

(2 citation statements)

References 18 publications

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“…This may be due to the fact that as the reduction percentage increases with increase in temperature as the number of reacting moles having excess of energy increased. Moreover, the raise of temperature may lead to an increase of the rate of mass transfer through diffusion as well as the rate of desorption [26][27][28][29].…”

Section: The Changing Of the E/o Ratio Upon The Reduction Process At ...mentioning

confidence: 99%

The Effect of Adding El-Dekhilla Waste Pellets Upon The Quality and Reduction Kinetics of El-Baharia Iron Ore Briquettes Using Hydrogen Gas

El-Dars,

Salah,

Elsaby

et al. 2017

The Bulletin Tabbin Institute for Metallurgical Studies (TIMS)

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The effect of the addition of El-Dekhilla waste pellets fines (E) upon the quality of El-El-Baharia iron ore (O) briquettes was investigated in this study. The kinetics of the reduction of the briquettes formed having different composition using hydrogen gas was studied at different temperatures (700°C-950°C). The results indicated that best ore reduction was achieved at 950°C. The kinetic of the reduction process was studied using different models and the best-fit models determined was (Kt = 1-(1-R) 1/2 and kt = R+ (1-R) ln (1-R)). XRD analysis was used to identify the main crystalline phases present within the reduced briquettes at the optimal temperature and it was found that the metallic iron (syn. Fe) was predominantly formed.

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Section: The Changing Of the E/o Ratio Upon The Reduction Process At ...mentioning

confidence: 99%

The Effect of Adding El-Dekhilla Waste Pellets Upon The Quality and Reduction Kinetics of El-Baharia Iron Ore Briquettes Using Hydrogen Gas

El-Dars,

Salah,

Elsaby

et al. 2017

The Bulletin Tabbin Institute for Metallurgical Studies (TIMS)

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“…In recent years, gas-based DR has become increasingly recognised as a promising alternative process for titanomagnetite ore reduction [18]- [20]. Gas-based DR processes do not require the coking process required for conventional BF ironmaking.…”

Section: Background Of the Studymentioning

confidence: 99%

Reduction of New Zealand Titanomagnetite Ironsand pellets in H2 Gas at High Temperatures

Zhang¹

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To reduce the emission of carbon dioxide (CO2) from industrial ironmaking in New Zealand (NZ), it is proposed to perform direct reduction (DR) of NZ titanomagnetite ironsand pellets using H2 gas. In this thesis, the H2 reduction behaviour of pellets made from the NZ ironsand are examined. The aim of the thesis is to understand the reduction mechanism, and develop an analytical kinetic model to describe the reduction progress with time. This has been addressed through a series of reduction experiments in H2 gas. The overall reduction kinetics are examined in a Thermogravimetric analysis system (TGA); the phase evolution during reduction is measured by an in-situ neutron diffraction (ND) method; and the evolution of pellet- and particle-scale morphologies are analysed by scanning electron microscopy (SEM) of quenched samples. Based on the analysis of results from these experiments, the mechanism of the reduction is found to be adequately described by a single interface shrinking core model (SCM). Two different types of pellet are considered in this work: Ar-sintered pellets were sintered in an inert atmosphere to produce pellets containing mainly titanomagnetite (TTM). Pre-oxidised pellets were sintered in air to produce pellets containing mainly titanohematite (TTH). The reduction rate of both types of pellets is found to increase with reduction temperature, H2 gas flow rate, and H2 gas concentration. Above 1143 K, it is found that both types of pellets present a similar reduction rate, while below 1143 K, the reduction of pre-oxidised pellets is much faster than that of Ar-sintered pellets. For both pellets, the maximum reduction degree can reach ~97%. After complete reduction, metallic Fe coexists with other unreduced Fe-Ti-O phases (FeTiO3, TiO2 or pseudobrookite (PSB)/ferro-PSB), which is consistent with the observed reduction degree of < 100%. During reduction of both types of pellets, any TTH present is rapidly reduced first. After this step, TTM is then reduced to FeO, with Ti becoming enriched in the remaining unreduced TTM. FeO is further reduced to metallic Fe, which makes up to ~90% reduction degree. Eventually Ti-enrichment of the TTM leads to a change in the reduction pathway and it instead directly converts to metallic Fe and FeTiO3. Above ~90% reduction degree, reduction of the remaining Fe-Ti-O phases occurs (leading to the formation of TiO2 or PSB/ferro-PSB). The enrichment of Ti in TTM which accompanies the generation of FeO is substantially different from conventional non-titaniferous ores. This enrichment is confirmed by EDS-maps of the particles and stoichiometric calculations of the molar fraction Ti within the TTM phase. This enrichment effect changes the morphology of FeO in the particles, leading to the formation of FeO channels surrounded by Ti-enriched TTM. At the pellet-scale, both types of pellets present a single interface shrinking core phenomenon at higher temperatures. Metallic Fe is generated from pellet surface with a reaction interface moving inwards. However, at lower temperatures this pellet-scale interface becomes less defined in the pellets. Instead, particle-scale reaction fronts are observed. A single interface shrinking core model (SCM) is shown to successfully describe the reduction of pellets for reduction degrees < ~90% at all temperatures studied. However, at reduction degrees > ~90% this model fails. This is attributed to the change in reaction mechanism required to reduce the residual Fe-Ti-O phases that remain dispersed throughout the whole pellet at this stage of the reaction. The single interface SCM indicates that the reduction rate of the Ar-sintered pellets is controlled by the interfacial chemical reaction rate. However, two different temperature regimes are identified. Above 1193 K, the activation energy is calculated to be 41 ± 1 kJ/mol, but below 1193 K the calculated activation energy increases to 89 ± 5 kJ/mol. This change in activation energy appears to be associated with the change of the rate-limiting reaction from FeO → metallic Fe to TTM → FeO. By contrast, the pre-oxidised pellets exhibit mixed control at 1043 K, where a role is played by both the interfacial chemical reaction rate and the diffusion rate through the outer product layer. However, at temperatures of 1143 K and above, the pre-oxidised pellets also exhibit interfacial chemical reaction control, with a single activation energy of 31 ± 1 kJ/mol, which again seems to be consistent the rate-limiting reaction being FeO → metallic Fe. In summary, the findings in this thesis contribute to understanding of the reduction of NZ ironsand pellets in H2 gas, and establish a kinetic model to describe this process. In the future, this information will be applied to develop a prototype H2-DRI shaft reactor for NZ ironsand pellets.

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Solid State Reduction of Iron, Manganese and Chromium Oxide Ores with Methane

Eric

Bhalla

Halli

et al. 2017

The Minerals, Metals &Amp; Materials Series

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Kinetics of Direct Reduction Titanomagnetite Briquette Produced from Rossetta-Ilmenite via Hydrogen

Cited by 4 publications

References 18 publications

The Effect of Adding El-Dekhilla Waste Pellets Upon The Quality and Reduction Kinetics of El-Baharia Iron Ore Briquettes Using Hydrogen Gas

The Effect of Adding El-Dekhilla Waste Pellets Upon The Quality and Reduction Kinetics of El-Baharia Iron Ore Briquettes Using Hydrogen Gas

Reduction of New Zealand Titanomagnetite Ironsand pellets in H2 Gas at High Temperatures

Solid State Reduction of Iron, Manganese and Chromium Oxide Ores with Methane

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