Hematite Pellets Research Articles

Microwave drying characteristics and kinetics of hematite pellets

Microwave drying characteristics and kinetics of hematite pellets were investigated based on evaluation of the effects of initial mass, microwave power and pellet size during the drying process. The results showed the average drying rate increased with initial mass from 50 g to 80 g and microwave power from 600 W to 1000 W. However, it decreased with increasing pellet size from 10–12 mm to 14–16 mm. The process was successively controlled by external diffusion, internal diffusion, and chemical reaction. The Verma model was the most suitable kinetic model for describing the process. The effective diffusion coefficient of moisture ranged from 6.61 × 10−7 m2/s to 9.98 × 10−7 m2/s. The activation energy for the microwave drying process was only 2.83 W/g.

High efficiency filtration and optimization of pelletizing performance of fine hematite concentrate using sulfuric acid filter aid: Behavior and mechanism

Following the application of anionic reverse flotation to fine low-grade hematite ore, a significant challenge emerges with elevated slurry viscosity and heightened moisture content in the resulting filter cakes. To address the challenge of dewatering during the filtration process of fine hematite concentrate, the impact of sulfuric acid filter aid dosage and filtration temperature on the filtration performance of hematite concentrate was systematically investigated in this study. In addition, the effect of sulfuric acid filter aid on the preparation of hematite pellets was also studied. The results revealed a significant decrease from 1.10 × 1010 1/m2 to 5.7 × 109 1/m2 in the specific resistance of the hematite filter cake when the sulfuric acid dosage was 1.2 g/kg and the filtration temperature was 20 °C. The mechanism underlying the enhancement of filtration performance of fine hematite concentrate by sulfuric acid was summarized. Sulfuric acid compressed the double electric layer on the surface of hematite concentrate particles, reducing the surface zeta potential and causing the aggregation of fine particles into larger ones. This led to an increase in filter cake porosity and compression of the hydration film thickness on particle surfaces, facilitating easier removal of filtrate from the filter cake. The appropriate dosage of bentonite for pelletizing was not significantly affected by sulfuric acid filter aid. Sulfuric acid improved the porosity, drying rate, and burst temperature of hematite green pellets. While the compressive strength of preheated pellets from sulfuric acid-assisted filtration of hematite concentrate showed a slight decrease, the compressive strength of roasted pellets was significantly increased.

Green Ironmaking at Higher H2 Pressure: Reduction Kinetics and Microstructure Formation During Hydrogen-Based Direct Reduction of Hematite Pellets

Hydrogen-based direct reduction (HyDR) of iron ores has attracted immense attention and is considered a forerunner technology for sustainable ironmaking. It has a high potential to mitigate CO2 emissions in the steel industry, which accounts today for ~ 8–10% of all global CO2 emissions. Direct reduction produces highly porous sponge iron via natural-gas-based or gasified-coal-based reducing agents that contain hydrogen and organic molecules. Commercial technologies usually operate at elevated pressure, e.g., the MIDREX process at 2 bar and the HyL/Energiron process at 6–8 bar. However, the impact of H2 pressure on reduction kinetics and microstructure evolution of hematite pellets during hydrogen-based direct reduction has not been well understood. Here, we present a study about the influence of H2 pressure on the reduction kinetics of hematite pellets with pure H2 at 700 °C at various pressures, i.e., 1, 10, and 100 bar under static gas exposure, and 1.3 and 50 bar under dynamic gas exposure. The microstructure of the reduced pellets was characterized by combining X-ray diffraction and scanning electron microscopy equipped with electron backscatter diffraction. The results provide new insights into the critical role of H2 pressure in the hydrogen-based direct reduction process and establish a direction for future furnace design and process optimization.Graphical

Reduction kinetics of hematite powder using argon/hydrogen plasma with prospects for near net shaping of sustainable iron

Direct reduction of iron ore using hydrogen plasma is being explored as a potential solution to decarbonize the iron and steel sector. The current state-of-the-art demonstrated reduction of hematite pellets via hydrogen plasma using Ar + 10% H2 but had slow reduction kinetics, requiring 30 minutes of plasma exposure for complete reduction. Here we show that using hematite in a powder form, easily obtainable from beneficiated ore, results in 10× faster kinetics using plasma generated from Ar + 2% H2 shielding gas compared to the current state-of-the art. The increased kinetics using powders and a dilute hydrogen concentration can enable the use of advanced manufacturing techniques like blown powder directed energy deposition using a plasma tungsten arc welding torch to manufacture near net shape components directly from the ore concentrates. This ore to part approach will also reduce the emissions associated with downstream processes like rolling, forging, and machining, thereby further aiding in the sectorial decarbonization efforts.

Parametric study on hematite pellet direct reduction by hydrogen

This study investigates the intrinsic kinetics of hematite reduction to iron using hydrogen through the utilization of a computational fluid dynamics (CFD) coupled with a modified unreacted shrinking core model. The new mathematical model is developed to analyze the reduction process of a real pellet, taking into account the variation in porosity at different reaction rates. The impact of temperature, particle size, gas inlet velocity, and porosity on hydrogen-based direct reduction were investigated. The study reveals that size affects reduction degree at temperatures below 973 K, while it is independent of size at 1273 K. The optimal inlet velocity is 0.28 m∙s−1, and the time for complete reduction is over 3500 s and 800 s at 973 K and 1273 K, respectively. The numerical results align with experimental results. The study provides a solid foundation for dynamic modeling of reduction process but further work is needed for a realistic model.

Direct Reduction of Iron Ore Pellets by Using CO/CO2 and CO Gases

Gas‐based direct reduction in a shaft furnace is the dominant process in the world for production of direct reduced iron. As fresh reducing gas passes through the iron ore burden, it is diluted by the gas emitted from the reacted iron ores which decreases the reduction potential of the reducing gas. Previous reduction experiments mostly used single pellet which could not examine this phenomenon. In this study, hematite pellets arranged in multiple layers inside a molybdenum basket are reduced isothermally at 1173–1273 K using 50% CO + 50% CO2% and 100% CO gases under flow rates of 0.2–5.0 NL min−1 to simulate the dilution of CO by CO2 in the shaft. It is discovered that the reduction of pellets in the basket is highly uneven even in pure CO atmosphere. Pellets in the middle layer are reduced ≈2 times less than the pellets in the top and bottom layers. The top side of a pellet is also less reduced than the bottom side facing the gas inlet. During melting of incompletely reduced pellets at 1873 K, intensive interaction between the unreduced iron oxides and the alumina crucible was observed. Thus, smelting of incompletely reduced iron could potentially shorten the refractory lifetime.

Modeling the First Hydrogen Direct Reduction Pilot Reactor for Ironmaking in the USA Using Finite Element Analysis and Its Validation Using Pilot Plant Trial Data

Direct reduction of hematite pellets with hydrogen (H2) was used to produce directly reduced iron (DRI) in a pilot scale reactor at a pellet feed rate of 21.4 kg/h. At a steady state, operational parameters of the pilot plant (gas recycling rate and inlet temperature) along with key reactor output parameters, the pellet metallization, and the internal temperature profile of the reactor were reported for two scenarios with high recycle and low recycle rate of H2. Scenario 1, with a high recycle rate of 400 L/min H2 along with external heating of 870 °C, gave an average metallization of 91.8%, while Scenario 2, with low recycle rate of 100 L/min H2 and external heating of 850 °C gave a metallization of 67.8% due to the higher moles of H2 available for reduction and the external energy required for the endothermic reduction reaction in Scenario 1 as compared with Scenario 2. Finite element analysis was used to build a model of the shaft reactor, which was validated against the metallization and internal temperature profile data. The average metallization values predicted by the model were very close to the metallization values obtained from the pilot plant samples, with 90.9% average metallization for Scenario 1 and 65.6% average metallization for Scenario 2. The internal temperature profiles in the lower region of the reactor obtained from the model were very close to these pilot plant data, with a maximum difference of 52.7 °C and 67.6 °C for Scenarios 1 and 2, respectively. The pilot plant reactor model was used extensively in the commissioning of the pilot plant and to predict the startup outcomes for a given set of operating parameters.

Термічне розкладання гематитових котунів при нагріванні аргоновою плазмою

Термічне розкладання гематитових котунів при нагріванні аргоновою плазмою

A comprehensive random pore model kinetic study of hematite to iron reduction by hydrogen

The consistent growth of industrialization has intensified the need for Iron and steel. Thus, it is essential to improve the efficiency of iron manufacturing plants. This work studies the inherent kinetics of hematite reduction to Iron with H2 via a random pore model (RPM) as the most sophisticated non-catalytic gas–solid reaction model. In this regard, reduction tests were performed on a pure hematite pellet by changing the reduction temperature and H2 concentration. Then, kinetic parameters were calculated via an RPM based on the pellet's pore size distribution. Validations of the calculated kinetic parameters using other pure hematite pellets with different characteristics besides an industrial pellet proved the robustness of this inclusive approach. The activation energy for the H2 reduction was obtained at 40.87 kJ/mol. Also, the diffusion coefficient of oxygen ions through the iron product layer for the industrial pellet was measured at 2.83 × 10-17 m2/s.

Improving hydrogen-rich gas-based shaft furnace direct reduction of fired hematite pellets by modifying basicity

To improve the hydrogen-rich gas-based direct reduction to promote green ironmaking, the influence of basicity (CaO/SiO2) on the consolidation characteristics and hydrogen-rich reduction behaviors of hematite pellets was investigated. The results show that increasing the basicity of hematite pellets can improve their firing performance and reduction behaviors in hydrogen-rich gas. With the rise of pellets basicity from 0.02 to 0.40, the higher compressive strength of fired pellets and the shorter roasting time were achieved. The maximum RSI decreased from 23% to 17% during hydrogen-rich reduction, while the compressive strength increased from 500 to 1070 N/pellet. Mechanism analysis shows that the liquid phase with suitable viscosity not only facilitated the consolidation of hematite pellets, but also desynchronized the volume expansion of the inner and outer layers in the reduced pellets, leading to good resistance against reduction stress and the higher compressive strength of reduced pellets.

Kinetic Mechanism Development for the Direct Reduction of Single Hematite Pellets in H2/CO Atmospheres

Increasing interest in the direct reduction process of iron ore has revived investigations on gaseous and heterogeneous iron oxides’ kinetics. Despite extensive studies on the reduction of iron oxides with pure hydrogen or syngas, the development of a generic reduction mechanism for iron oxides is still lacking. The conventional shrinking core model hardly distinguishes between transport and reaction processes, leading to biases or even errors in the kinetic models. In the present study, a porous solid model, which solves mass balances of the individual gas‐phase species and solid ones assuming spherical symmetry, is used for developing a heterogeneous kinetic mechanism accounting for different iron oxidation stages (Fe2O3, Fe3O4, FeO). It also accounts for carbon accumulation and cementite formation to model the carburization phenomena when using carbon‐containing reducing agents like syngas. The proposed generic mechanism successfully reproduces 49 experimental data sets from the literature for single iron oxide pellets’ isothermal reduction with syngas of varying hydrogen content up to pure hydrogen without any adjustment of its parameters. The model predictions are in excellent agreement with the experimental data. Finally, the carburization kinetics are explained, and the factors (e.g., temperature, hydrogen content) affecting the carbon deposition are analyzed.

Physicochemical Aspects of Oxidative Consolidation Behavior of Manganese Ore Powders with Various Mn/Fe Mass Ratios for Pellet Preparation.

With the depletion of rich manganese ore resources, plentiful manganese ore powders with various Mn/Fe mass ratios are produced. The physicochemical aspects of oxidative consolidation behavior of manganese ores with various Mn/Fe mass ratios were investigated in this work to determine whether manganese ore powders with high iron content (Fe-Mn ore) can be prepared as high-quality pellets. Physicochemical properties of the pellets were investigated, including cold compression strength (CCS), phase transformation, microstructural evolution, Vickers hardness (HV), porosity, and lattice parameter. CCS testing indicated that the strength of roasted Fe-Mn ore pellets was observably lower than that of pure hematite or manganese ore pellets. Phase and morphology results showed that in Fe-Mn ore pellets, an Mn ferrite phase was generated between hematite and pyrolusite particles. However, newborn Mn ferrites and hematite had an obvious crystal boundary in the crystallographic particles. Moreover, poorly crystallized Mn ferrite particles were evident, along with Mn and Fe element concentration gradients, due to the inadequate diffusion of metal ions. This resulted in poor mechanical properties of the Fe-Mn ore pellets. A temperature over 1275 °C and a roasting time of 15 min is required for the oxidative consolidation of Fe-Mn ores. In such optimized cases, Mn, Fe, O, and Al elements were uniformly distributed in the well-crystallized Mn ferrite grains, which provided favorable mineralogy for the consolidation of Fe-Mn ore powders.

Consolidation mechanism of fluxed hematite pellets

Consolidation mechanism of fluxed hematite pellets

Green steel at its crossroads: Hybrid hydrogen-based reduction of iron ores

Iron- and steelmaking cause ∼7% of the global CO2 emissions, due to the use of carbon for the reduction of iron ores. Replacing carbon by hydrogen as the reductant offers a pathway to massively reduce these emissions. However, the production of hydrogen using renewable energy will remain as one of the bottlenecks at least during the next two decades, because making the gigantic annual crude steel production of 1.8 billion tons sustainable requires a minimum stoichiometric amount of ∼97 million tons of green hydrogen per year. Another fundamental aspect to render the ironmaking sector more sustainable lies in an optimal utilization of green hydrogen and energy, thus reducing efforts for costly in-process hydrogen recycling. We therefore demonstrate here how the efficiency in hydrogen and energy consumption during iron ore reduction can be dramatically improved by the knowledge-based combination of two technologies: partially reducing the ore at low temperature via solid-state direct reduction (DR) to a kinetically defined degree, and subsequently melting and completely transforming it to iron under a reducing plasma (i.e. via hydrogen plasma reduction, HPR). Results suggest that an optimal transition point between these two technologies occurs where their efficiency in hydrogen utilization is equal. We found that the reduction of hematite through magnetite into wüstite via DR is clean and efficient, but it gets sluggish and inefficient when iron forms at the outermost layers of the iron ore pellets. Conversely, HPR starts violent and unstable with arc delocalization, but proceeds smoothly and efficiently when processing semi-reduced oxides, an effect which might be related to the material's high electrical conductivity. We performed hybrid reduction experiments by partially reducing hematite pellets via DR at 700 °C to 38% global reduction (using a standard thermogravimetry system) and subsequently transferring them to HPR, conducted with a lean gas mixture of Ar-10%H2 in an arc-melting furnace, to achieve full conversion into liquid iron. This hybrid approach allows to exploit the specific characteristics and kinetically favourable regimes of both technologies, while simultaneously showing the potential to keep the consumption of energy and hydrogen low and improve both, process stability and furnace longevity by limiting its overexposure to plasma radiation.

Phase equilibria analysis of hematite pellets during induration

In order to study the change of each phase and the influence of single oxide during the consolidation of pellets. A systematic thermodynamic calculation was carried out through the phase diagram to study the influence of five oxides (CaO, SiO2, Fe2O3, Al2O3 and MgO) on the phase equilibrium of the hematite pellet system. The results show that the content of CaO has the most significant effect on the content of liquid phase and SPINA. There are critical values for the influence of SiO2 and CaO on the Ca3Fe2Si3O12 phase, which are 3.5% and 3.0%, respectively. Through in-situ heating experiments, XRD-Rietveld and SEM-EDS, the macro morphology and phase composition of the hardened samples were compared and analyzed. Finally, a multiple regression model is used to predict the liquid content of hematite pellets, which is effective in predicting the phase component.

Modelling of heat transfer in a straight grate pellet induration reactor complemented with plant scale experiments

ABSTRACT Straight grate furnaces are widely used for induration of hematite pellets where typically 1%–2% carbon is added to the green mix to help in generating heat by combustion. The quality of the pellets in such reactor varies from top to bottom of the bed as different layers of pellets are exposed to varying thermal and gaseous environments. The thermal evolution (as a function of time) at a specific location in a moving pallet car was studied through plant scale experiments. Subsequently, these experimental temperature measurements were supplemented with a 1-D heat transfer model of the pellet bed. It was observed, from simulation results, that peak temperature faced by the pellets in top layer and bottom layer of the pellet bed differed by 105°C. The effect of bed height and grate velocity on the pellet bed thermal profile was studied using the model. With increase in production rate through increase in grate velocity and bed height, this difference further intensified. These findings can provide insight to plant operator to optimise production rate.

Pelletization of hematite and synthesized magnetite concentrate from a banded hematite quartzite ore: A comparison study

A compressive pelletization study, for the utilization of an Indian Banded Hematite Quartzite ore, is presented in this communication. Iron ore concentrates have been generated utilizing the conventional beneficiation process and also by the approach of reduction roasting-magnetic separation. The Fe contents of the hematite and the synthesized magnetite concentrate were found to be 64.22 and 63.80%, respectively. The influence of different factors on the respective physical, chemical, and metallurgical properties of the fired pellets, generated through both the routes, have been compared. The pellets prepared from the synthesized magnetite attain the threshold Cold Crushing Strength (CCS) of 50 kg/pellet at a lower temperature of 1050 °C in comparison to hematite pellets (1100 °C). Also, the threshold CCS of 250 kg/pellet is attained by synthesized magnetite pellets at a lower temperature of 1250 °C compared to hematite pellets (1360 °C). The fired synthesized magnetite pellets also achieve the desired metallurgical properties i.e., Reduction Degradation Index (RDI), Reducibility Index (RI), and Swelling Index (SI) at par with the hematite pellets. Moreover, unlike the hematite pellets, the synthesized magnetite pellets do not need the addition of external carbon during the pellet making.

Blast Furnace Flue Dust as a Potential Carbon Additive in Hematite Ore Pellet

ABSTRACT Coke or anthracite coal is traditionally used as the carbon source in the hematite ore pellet for providing in-situ heat and enhancing diffusion bonding and slag bonding. Blast furnace flue dust (BFD) is a waste material, which contains a significant quantity of carbon may be another possible option of carbon source. However, the feasibility of using this material for the preparation of blast furnace quality pellet from hematite ore needs to be studied. In the present study, the burning characteristics of BFD in pellet have been studied and compared with that of coke fines. The characteristics of the pellets prepared with the above two carbon sources have been compared to assess the feasibility of using BFD as a carbon source in the hematite pellet. While 1% C level in BFD-added pellet shows the optimum result, 1.5% C level in coke-added pellet shows that. All properties of pellets improve significantly by the addition of carbon in form of either BFD or coke both in acidic and basic conditions. Induration temperature could be reduced by 50–75 K in both cases. However, better pellet properties in terms of cold crushing strength (277 kg/pellet) and reducibility index (81%) have been observed in using BFD. This study optimizes the process parameters to utilize the BFD as a carbon additive in hematite pellet both in acidic and basic condition replacing coke fines and establishes that BFD is a potential carbon source to achieve better pellet properties without any adverse effect.

Effect of the reaction of ammonia gas on the swelling of metallic iron and its oxides during nitriding processes

In order to study the relationship and effect of nitrogen gas in the reducing gases used in the reducibility tests of iron oxides, under isothermal conditions, a test scheme was executed using ammonia gas, such that its decomposition of the gas in the reactor produced a mixture of H2 and N2 gases. Furthermore, the addition of 6% NH3 in a 28% H2 and 68% N2 gas stream was planned to obtain a gas composition of 70% N2 and 30% H2. This would allow comparing the reducibility curves between both conditions, assuming that the possible difference between both conditions to compare the volume changes of the reduced samples. The difference to be studied will be based on the estimation and comparison of the rate of formation of metallic iron in the stages of reduction of Hematite / Magnetite / Wustite (FeO), as well as the effects of nitrogen absorbed by the fresh metallic iron produced, or present. in iron catalysts to produce ammonia, from the reducing gas mixture, on the volume change of the samples. Likewise, the catastrophic volume changes caused by nitrogen are compared by comparing sources of this gas in solid carbonaceous reducers.
 Keywords: Gaseous Reduction, Direct Reduced Iron, isothermal tests.
 References
 [1]O. Dam G. “The Influence of Nitrogen on the Swelling Mechanism of Iron Oxides During Reduction”. Univ. of London. PhD Thesis 1983.
 [2]J. Bogde. “Thermoelectric Power Measurements in Wustite. Univ. of Michigan”. 1976.
 [3]O. Dam G. y J. Jeffes. “Model for the Assessment of Chemical Composition of reduced iron ores from single measurements. Ironmaking and Steelmaking”. Vol. 14, N`5. 1987.
 [4]M. Yang. “Nitriding-Fundamentals, modelling and process optimization”. Tesis PhD. Worcester Polytech Institute. 2012.
 [5]EL Kasabgy. T and W-K. LU. “The Influence of Calcia and Magnesia in Wustite on the Kinetics of Metallization and Iron Whisker Formation”. Metallurgical 1980 American Society for Metals and the Metallurgical Society of AIME Volume 11b, pp. 410-414. 1980.
 [6]“Srikar Potnuru Studies nn the Physical Properties and Reduction Swelling Behavior of Fired Haematite Iton ore Pellets”. MSc Thesis. Department of Metallurgical and Materials Engineering National Institute Of Technology, Rourkela May 2012.
 [7]R. Agarwal, S. Hembram. “To Study the Reduction and Swelling Behavior Iron Ore Pellets”. BSc. Department of Metallurgical and Materials Engineering National Institute Of Technology, Rourkela May 2013.
 [8]C. Seaton., J. Foster. and J. Velasco. “Structural Changes Occurring during Reduction of Hematite and Magnetite Pellets Containing Coal Char”. Transactions ISIJ, Vol. 23, 1983, pp.
 [10]C. Bozco. “Interaction of Nitrogen with Iron Surfaces”. Journal of Catalysis 49. pp16-41. 1977.
 [11]L. Darken y R. Gurry. “Physical Chemistry of Metals”. Mc Graw hIll . 1953.
 [12]H. Weirdt and Z. Zwell, Trans. AIME. 229. 142. 1969.
 [13]J. Schulten. Trans. Soc. Faraday. 53, 1363, 1957.
 [14]E. Barret y C. Wood. Bureau of Mines R-I 3229. 1934

Efecto de la descomposición de gas de amoniaco (NH3) sobre el hinchamiento de óxidos de hierro durante reducción

Con el objeto de estudiar la relación y efecto del gas nitrógeno en los gases reductores utilizados en los ensayos de reducibilidad de óxidos de hierro, en condiciones isotérmicas, se ejecutó un esquema de ensayos utilizando gas amoniaco, tal que la descomposición del gas en el reactor produjera un gas de H2 y N2. Además, se planifico la adición de 6% de NH3 en una corriente de gas 28% H2 y 68% N2 para obtener una composición de gas de 70% N2 y 30% H2. Esto permitiría la reinterpretación de los datos de laboratorio para comparar las curvas d reducibilidad entre ambas condiciones, asumiendo que la posible diferencia entre ambas condiciones a comparar los cambios de volumen de las muestras reducidas. La diferencia a estudiar se basará en la estimación y comparación de la velocidad de formación de hierro metálico en las etapas de reducción de hematita/magnetita/wustita (FeO), así como los efectos del nitrógeno absorbido por el hierro metálico fresco producido, partir de la mezcla de gas reductor, sobre el cambio de volumen de las muestras. Así mismo se comparan empíricamente los cambios catastróficos de volumen causados por el nitrógeno comparando fuentes de este gas en reductores carbonosos sólidos.
 Palabras clave: reducción gaseosa, hierro de reducción directa (HRD), catálisis, catalizador de hierro, amoniaco, hinchamiento, absorción, nitruración. ensayos isotérmicos, nitrógeno en carbón.
 Referencias
 [1]O.G. Dam . The Influence of Nitrogen on the Swelling Mechanism of Iron Oxides During Reduction. Univ. of London. PhD Thesis 1983.
 [2]J.D Bogde.- Thermoelectric Power Measurements in Wustite. Univ. of Michigan. 1976.
 [3]O.G. Dam y J. Jeffes. Model for the Assessment of Chemical Composition of reduced iron ores from single measurements. Ironmaking and Steelmaking. 1987. Vol. 14, N`5.
 [4]M. Yang. Nitriding-Fundamentals, modelling and process optimization. Tesis PhD. Worcester PolytechInstitute. 2012.
 [5]T. EL Kasabgy y W-K. LU. (1980). The Influence of Calcia and Magnesia in Wustite on the Kinetics of Metallization and Iron Whisker Formation. Metallurgical 1980 American Society for Metals and the Metallurgical Society of AIME Volume 11b, September 1980, pp. 410-414.
 [6]Srikar Potnuru Studies nn the Physical Properties and Reduction Swelling Behavior of Fired Haematite Iton ore Pellets. MSc Thesis. Department of Metallurgical and Materials Engineering National Institute Of Technology, Rourkela May 2012.
 [7]R.S Agarwal y S.S. Hembram. To Study the Reduction and Swelling Behavior Iron Ore Pellets. BSc. Department of Metallurgical and Materials Engineering National Institute Of Technology, Rourkela May 2013.
 [8]C.E. Seaton y J.S. Foster. and Velasco. Structural Changes Occurring during Reduction of Hematite and Magnetite Pellets Containing Coal Char. Transactions ISIJ, Vol. 23, 1983, pp.
 [10]C. Bozco. et.al. Interaction of Nitrogen with Iron Surfaces. Journal of Catalysis 49. 1977.
 [11]L.S. Darken y R.W. Gurry, Physical Chemistry of Metals. Mc Graw hIll . 1953.
 [12]H. A. Weirdt, y Z .Zwell. Trans. AIME. 229. 142. 1969.
 [13]J.J.S.Schulten. et al. Trans. Soc. Faraday. 53, 1363, 1957.
 [14]E.G.Barret y C.F. Wood. Bureau of Mines R-I 3229. 1934.