Direct Reduction of Iron from Crystal Lattice of a Complex Oxide

2019 ◽  
Vol 946 ◽  
pp. 506-511
Author(s):  
S.P. Salikhov ◽  
A.V. Roshchin
Keyword(s):  
Iron Reduction ◽  
Direct Reduction ◽  
Reduction Process ◽  
Complex Oxide ◽  
High Rate ◽  
Deep Penetration ◽  
Experimental Conditions ◽  
Direct Reduction Of Iron ◽  
Fe Reduction ◽  
Iron Manganese

This work studied a decomposition and reduction of complex carbonate (sideroplesite) siderite lump ore from the Bakal’s deposit. The decomposition caused formation of complex oxides (Fe,Mg,Mn)O and (Fe,Mg,Mn)O·Fe2O3, and it preceded the Fe reduction; the weight loss during the decomposition process reached about 32%, being followed by the formation of a large number of pores. As the pores and micro-pores provide deep penetration of the carbon monoxide in the bulk of the ore lumps, it seemed that the pores would allow reduction of this ore without difficulties. However, during reduction experiments it was discovered that the distribution of the reduction process and formation of the metal phase were not connected with the pores’ distribution. The reduction process developed via an electrochemical mechanism, and the channels of the distribution of the reduction process were oxides of metals which were difficult to reduce under the presented experimental conditions; these oxides were mostly represented by the magnesia and silica compounds. The high rate of the iron reduction from the complex iron-manganese-magnesium oxides was explained by the high rate of distribution of the negatively charged anion vacancies forming on the surface of the oxide, due to reaction with a reducing agent.

Metallographic Estimation of the Number of Forming Metallic Particles Obtained during Direct and Indirect Reduction of Metals from Complex Oxides

2019 ◽  
Vol 946 ◽  
pp. 523-527
Author(s):  
Arman S. Bilgenov ◽  
P.A. Gamov ◽  
V.E. Roshchin
Keyword(s):  
Metal Forming ◽  
Solid Phase ◽  
Quantitative Estimation ◽  
Direct Reduction ◽  
Reduction Process ◽  
Complex Oxide ◽  
Experimental Results ◽  
Solid Carbon ◽  
Indirect Reduction ◽  
Co Gas

The direct reduction of metals from a complex oxide with low iron content by solid carbon and indirect reduction by CO gas were studied in a vertical laboratory resistance furnace at 1300 °C for an hour reduction time. The experimental results were described from the point of view of the electrochemical nature of the metal reduction process, that involves the interaction of ions and electrons in the oxide lattice. The technique was developed by using the two different software programs for the quantitative estimation of the areas, average size and number of the metal forming in a complex oxide with extensive fields of vision. The obtained results of the quantitative characteristics of the metal forming during solid-phase carbo-thermal reduction were presented. The processes of reduction by solid carbon and CO gas based on the areas occupied by metal particles were quantitatively compared. The experimental results and the prospects for further experimental work were assessed and outlined.

scholarly journals Reduction Kinetics of Hematite Powder in Hydrogen Atmosphere at Moderate Temperatures

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 751 ◽  
Author(s):  
Zhiyuan Chen ◽  
Jie Dang ◽  
Xiaojun Hu ◽  
Hongyan Yan
Keyword(s):  
Activation Energy ◽  
Direct Reduction ◽  
Reduction Process ◽  
Kinetic Mechanism ◽  
Hydrogen Atmosphere ◽  
Morphological Transformation ◽  
Iron And Steel ◽  
Multi Stage ◽  
Reduction Of Iron ◽  
Direct Reduction Of Iron

Hydrogen has received much attention in the development of direct reduction of iron ores because hydrogen metallurgy is one of the effective methods to reduce CO2 emission in the iron and steel industry. In this study, the kinetic mechanism of reduction of hematite particles was studied in a hydrogen atmosphere. The phases and morphological transformation of hematite during the reduction were characterized using X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. It was found that porous magnetite was formed, and the particles were degraded during the reduction. Finally, sintering of the reduced iron and wüstite retarded the reductive progress. The average activation energy was extracted to be 86.1 kJ/mol and 79.1 kJ/mol according to Flynn-Wall-Ozawa (FWO) and Starink methods, respectively. The reaction fraction dependent values of activation energy were suggested to be the result of multi-stage reactions during the reduction process. Furthermore, the variation of activation energy value was smoothed after heat treatment of hematite particles.

Influence of Temperature and Holding Time on Number and Size of Metal Particles during Solid-Phase Reduction of Iron by Carbon

2021 ◽  
Vol 316 ◽  
pp. 496-501
Author(s):  
A. Bil'genov ◽  
A.R. Tabylbaeva ◽  
P.A. Gamov
Keyword(s):  
Crystal Lattice ◽  
Solid Phase ◽  
Direct Reduction ◽  
Complex Oxide ◽  
Holding Time ◽  
Iron Particles ◽  
Experimental Conditions ◽  
Influence Of Temperature ◽  
Reduction Of Iron ◽  
Average Size

There is a lack of complete understanding of the mechanism and kinetics of reduction of metals from oxides. This paper presents results and methods of a series of experiments on direct reduction of metals by solid carbon in the form of graphite from a complex oxide with a low iron content in a laboratory muffle furnace at temperatures of 1300, 1400, 1500, 1600 °C and holding time of 1, 3, 5, 7 hours. The statistical analysis of amount and average size of reduced iron particles inside the oxide was studied. Dependence of amount and average size of the reduced iron particles on temperature and time of reduction is presented. The phenomena of iron crystals’ growth, occurring as a result of changes in the crystal lattice of oxide, was studied under experimental conditions. The influence of temperature and holding time on iron particles’ nucleation and their growth in the crystal lattice of a complex oxide were compared. Investigation of mechanism of metals’ reduction from complex oxides and influence of experimental conditions on the nucleation and growth enables to identify new patterns in the process of reduction of metals from their oxides, in general.

Stable iron isotope signals as indicators for iron reduction pathways in deep methanic sediments

2020 ◽  
Author(s):  
Susann Henkel ◽  
Bo Liu ◽  
Michael Staubwasser ◽  
Simone Kasemann ◽  
Anette Meixner ◽  
...  
Keyword(s):  
Pore Water ◽  
Marine Sediments ◽  
Iron Reduction ◽  
Reduction Process ◽  
Geochemical Data ◽  
Anaerobic Oxidation Of Methane ◽  
Iron Release ◽  
Microbial Utilization ◽  
Fe Reduction ◽  
Mud Area

<p>A number of studies have shown that iron reduction in marine sediments is not confined to sulfate- or sulfide-containing depths but may also affect deep methanic intervals. In particular dynamic depositional settings often show the release of dissolved iron below the sulphate-methane transition (SMT). The specific process behind this deep iron release is not well understood. It has been suggested that anaerobic oxidation of methane (AOM) mediated by Fe oxide reduction plays an important role. So there might be a close, so far unaccounted link between the Fe and C cycles in deep marine sediments.</p><p>Here we present a compilation of inorganic geochemical data including δ<sup>56</sup>Fe values of pore water and reactive Fe fractions for sediments of the Helgoland mud area (North Sea) for which a coupling between deep iron reduction and AOM has been proposed [1]. The sediments show a shallow SMT and increasing dissolved Fe concentrations of up to 400 µM further below. High sedimentation rates led to a fast burial and preservation of reactive Fe (oxyhydr)oxides, enabling deep iron reduction as we observe it today.</p><p>Isotopic fractionation of Fe has been demonstrated for DIR in culture experiments and in shallow marine sediments. Such studies build upon the principle that microbes preferentially utilize light Fe isotopes (<sup>54</sup>Fe) causing a fractionation between solid ferric and dissolved ferrous iron. For alternative biotic Fe reduction pathways in methanic environments, there are practically no data. We hypothesized that any microbially mediated iron reduction process would result in a similar preferential release of <sup>54</sup>Fe and, thus, shift pore water δ<sup>56</sup>Fe towards negative values. Furthermore we hypothesized that the microbial utilization of a specific Fe (oxyhydr)oxide pool would result in a relative enrichment of <sup>56</sup>Fe in the residual ferric substrate.</p><p>Close to the sediment-water interface pore water δ<sup>56</sup>Fe in the mud area is generally negative and shows a downward trend towards positive values as it can be expected for in-situ dissimilatory iron reduction (DIR) [2]. The Fe isotope signal close to the sulfidic interval is ~1‰ heavier than above and below as Fe sulfide precipitation preferentially removes <sup>54</sup>Fe from pore water. A pronounced downward shift of pore-water δ<sup>56</sup>Fe to more negative values within the methanic zone is a clear indication for microbial Fe reduction coupled to organic matter degradation. However, this shift does not coincide with the main interval of Fe release for which potential for Fe-AOM had been demonstrated [1]. In this deeper interval, the released Fe has an isotopic composition that matches that of the ferric substrates. We conclude that either 1) Fe-AOM plays a subordinate role for Fe release at depth or 2) does not go along with significant Fe isotope fractionation, which might be explained by different ways of electron transfer between microbe and the iron oxide compared to DIR.</p><p>[1] Aromokeye, D. et al., 2019. Frontiers in Microbiology, doi: 10.3389/fmicb.2019.03041.</p><p>[2] Henkel, S. et al., 2016. Chemical Geology 421: 93-102.</p>

scholarly journals Detailed Modeling of the Direct Reduction of Iron Ore in a Shaft Furnace

2018 ◽  
Author(s):  
Hamzeh Hamadeh ◽  
Olivier Mirgaux ◽  
Fabrice Patisson
Keyword(s):  
Iron Ore ◽  
Shaft Furnace ◽  
Direct Reduction ◽  
Central Zone ◽  
Reduction Process ◽  
Furnace Operation ◽  
Direct Reduction Of Iron ◽  
Energy And Momentum ◽  
Thermal Phenomena ◽  
Volume Method

This paper addresses the modeling of the iron ore direct reduction process in the context of the reduction in CO2 emissions from the steel industry. The shaft furnace is divided into three sections (reduction, transition, and cooling), and the model is two-dimensional (cylindrical geometry for the upper sections and conical geometry for the lower one) to correctly describe the lateral gas feed and the cooling gas outlet. This model relies on a detailed description of the main physical-chemical and thermal phenomena using a multi-scale approach. The moving bed is assumed to be comprised of pellets of grains and crystallites. Eight heterogeneous and two homogeneous chemical reactions are taken into account. The local mass, energy and momentum balances are numerically solved using the finite volume method. This model was successfully validated by simulating the shaft furnaces of two direct reduction plants of different capacities. The calculated results reveal the detailed interior behavior of the shaft furnace operation. Eight different zones can be distinguished according to their predominant thermal and reaction characteristics. An important finding is the presence of a central zone of lesser temperature and conversion.

scholarly journals Experimental Study on the Preparation of Cementing Materials by Direct Reduction Coupling of a Hematite-Carbon Base

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1086 ◽  
Author(s):  
Ruimeng Shi ◽  
Junxue Zhao ◽  
Xiaoming Li ◽  
Chong Zou ◽  
Yaru Cui ◽  
...  
Keyword(s):  
Experimental Study ◽  
Iron Ore ◽  
Raw Materials ◽  
Direct Reduction ◽  
Tricalcium Silicate ◽  
Dicalcium Silicate ◽  
Raw Material ◽  
Experimental Conditions ◽  
Reduction Of Iron ◽  
Direct Reduction Of Iron

The reduction of iron in hematite and process coupling of cementing material generated from gangue components are explored in this paper, and a technical proposal for preparing directly reduced iron and cementing materials considering the processes of energy and material flows is proposed. An experimental study preparing cementing materials, such as tricalcium silicate and dicalcium silicate, by roasting the components, was performed. In this study, hematite was used as the raw material and powdered carbon was added, as the reducing agent, with CaO; at the same time, the gangue components of iron ore were used as the principal raw materials for the process of directly reduced iron preparation by direct reduction of iron ore. The FactSage software package was used to perform thermodynamic calculations of the reduction of iron and its influence on the formation of tricalcium silicate and dicalcium silicate. The feasibility of the direct reduction of iron to elemental iron and preparation of cementing materials by roasting of gangue components under the studied thermodynamic conditions was discussed. Different temperature control strategies were used to verify the reaction coupling test. The results showed that zero-valent iron could be produced by roasting and reducing hematite under certain experimental conditions, and cementing materials, such as tricalcium silicate and dicalcium silicate, could be produced simultaneously by reacting the gangue components with CaO. Fe2O3 exerted an adverse effect on the formation of tricalcium silicate, and sufficient reduction of the iron was a precondition for the formation and stability of tricalcium silicate.

The sticking problem during direct reduction of fine iron ore in the fluidized bed

10.30544/378 ◽  
2004 ◽  
Vol 10 (4) ◽  
pp. 309-328 ◽  
Author(s):  
Mirko Komatina ◽  
HEINRICH W. GUDENAU
Keyword(s):  
Fluidized Bed ◽  
Iron Ore ◽  
Review Paper ◽  
Direct Reduction ◽  
Reduction Process ◽  
Experimental Investigations ◽  
Inert Material ◽  
Reduction Of Iron ◽  
Fine Iron ◽  
Direct Reduction Of Iron

In this review paper described are possible chemical reactions and their thermodynamic analysis during direct reduction. The sticking mechanism during direct reduction in the fluidized bed was analysed, and the reasons for the sticking appearance explained. The most important parameters on the sticking were analysed. The ways for prevention and observation were considered. The plan for experimental investigations was proposed. The investigations could be performed in fluidized bed reactor. Coal will be used as inert material. Separately, the influence volatile content in the coal on the reduction process and sticking appearance, will be analysed. As results of these investigations would be some improvements of the method direct reduction of iron ore in the fluidized bed.

scholarly journals Detailed Modeling of the Direct Reduction of Iron Ore in a Shaft Furnace

2018 ◽  
Author(s):  
Hamzeh Hamadeh ◽  
Olivier Mirgaux ◽  
Fabrice Patisson
Keyword(s):  
Iron Ore ◽  
Shaft Furnace ◽  
Direct Reduction ◽  
Central Zone ◽  
Reduction Process ◽  
Furnace Operation ◽  
Direct Reduction Of Iron ◽  
Energy And Momentum ◽  
Thermal Phenomena ◽  
Volume Method

This paper addresses the modeling of the iron ore direct reduction process, a process likely to reduce CO2 emissions from the steel industry. The shaft furnace is divided into three sections (reduction, transition, and cooling), and the model is two-dimensional (cylindrical geometry for the upper sections and conical geometry for the lower one), to correctly describe the lateral gas feed and cooling gas outlet. This model relies on a detailed description of the main physical–chemical and thermal phenomena, using a multi-scale approach. The moving bed is assumed to be comprised of pellets of grains and crystallites. We also take into account eight heterogeneous and two homogeneous chemical reactions. The local mass, energy, and momentum balances are numerically solved, using the finite volume method. This model was successfully validated by simulating the shaft furnaces of two direct reduction plants of different capacities. The calculated results reveal the detailed interior behavior of the shaft furnace operation. Eight different zones can be distinguished, according to their predominant thermal and reaction characteristics. An important finding is the presence of a central zone of lesser temperature and conversion.

scholarly journals Detailed Modeling of the Direct Reduction of Iron Ore in a Shaft Furnace

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1865 ◽  
Author(s):  
Hamzeh Hamadeh ◽  
Olivier Mirgaux ◽  
Fabrice Patisson
Keyword(s):  
Iron Ore ◽  
Shaft Furnace ◽  
Direct Reduction ◽  
Central Zone ◽  
Reduction Process ◽  
Furnace Operation ◽  
Direct Reduction Of Iron ◽  
Energy And Momentum ◽  
Thermal Phenomena ◽  
Volume Method

This paper addresses the modeling of the iron ore direct reduction process, a process likely to reduce CO2 emissions from the steel industry. The shaft furnace is divided into three sections (reduction, transition, and cooling), and the model is two-dimensional (cylindrical geometry for the upper sections and conical geometry for the lower one), to correctly describe the lateral gas feed and cooling gas outlet. This model relies on a detailed description of the main physical–chemical and thermal phenomena, using a multi-scale approach. The moving bed is assumed to be comprised of pellets of grains and crystallites. We also take into account eight heterogeneous and two homogeneous chemical reactions. The local mass, energy, and momentum balances are numerically solved, using the finite volume method. This model was successfully validated by simulating the shaft furnaces of two direct reduction plants of different capacities. The calculated results reveal the detailed interior behavior of the shaft furnace operation. Eight different zones can be distinguished, according to their predominant thermal and reaction characteristics. An important finding is the presence of a central zone of lesser temperature and conversion.

Thermodynamic study of reduction process of Bapy deposit iron ore concentrate by coal of Karazhyra deposit

2021 ◽  
Vol 77 (3) ◽  
pp. 262-271
Author(s):  
I. A. Rybenko ◽  
B. A. Edil’baev ◽  
O. I. Nokhrina ◽  
I. D. Rozhikhina ◽  
E. V. Protopopov ◽  
...  
Keyword(s):  
Gas Phase ◽  
Iron Ore ◽  
Iron Reduction ◽  
Direct Reduction ◽  
Reduction Process ◽  
Reducing Agent ◽  
Coal Consumption ◽  
Oxidative Potential ◽  
Reduction Of Iron ◽  
Iron Ore Concentrate

In modern ferrous metallurgy, direct reduction of iron from iron ore materials is becoming increasingly common. In order to assess the feasibility of using a particular technology, it is necessary to obtain information on the reduction processes of iron oxides. Taking into consideration that experimental research is usually expensive, a computational experiment is optimal, which allows to draw conclusions about the behavior of the studied objects on the basis of modeling high-temperature processes in complex thermodynamic systems with physicochemical transformations under equilibrium and non-equilibrium conditions. As a modeling tool, the Terra software complex created at the Moscow State Technical University named after N. E. Bauman was used. As a result of thermodynamic studies boundaries of redox processes are identified and optimal temperature and consumption of reducing agent were determined, which provide maximum degree of iron reduction. The results of simulation of iron reduction process from iron ore concentrate obtained during concentration of iron ore of Bapy deposit, by coal of Karazhyra deposit (Kazakhstan) are presented. Dependencies of composition and volume of gas phase, formed as a result of volatile coal components emission in the process of heating, degree of iron reduction at various coal consumption rates on the temperature was established. It was found that the complete reduction of iron occurs at a coal consumption of 25 kg/100 kg of concentrate and a temperature of 1013 K, and the further increase in the consumption of the reducing agent leads only to a change in the ratio of CO and SO2 in the gas phase towards a decrease in the oxidative potential and an increase in the temperature of completion of the reducing process.

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