Reduction Of Ore Research Articles

Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel.

Iron making is the biggest single cause of global warming. The reduction of iron ores with carbon generates about 7% of the global carbon dioxide emissions to produce ≈1.85 billion tons of steel per year. This dramatic scenario fuels efforts to re-invent this sector by using renewable and carbon-free reductants and electricity. Here, the authors showhow to make sustainable steel by reducing solid iron oxides with hydrogen released from ammonia. Ammonia is an annually 180 million ton traded chemical energy carrier, with established transcontinental logistics and low liquefaction costs. It can be synthesized with green hydrogen and release hydrogen again through the reduction reaction. This advantage connects it with green iron making, for replacing fossil reductants. the authors show that ammonia-based reduction of iron oxide proceeds through an autocatalytic reaction, is kinetically as effective as hydrogen-based direct reduction, yields the same metallization, and can be industrially realized with existing technologies. The produced iron/iron nitride mixture can be subsequently melted in an electric arc furnace (or co-charged into a converter) to adjust the chemical composition to the target steel grades. A novel approach is thus presented to deploying intermittent renewable energy, mediated by green ammonia, for a disruptive technology transition toward sustainable iron making.

Carbothermal Reduction of Stainless Steel Dust and Laterite Nickel Ore: Slag Phase Behavior Regulation and Self-pulverization Control Mechanism

Stainless steel dust is a type of high basicity iron containing solid waste from the iron and steel smelting industry. In this study, the carbon-containing composite briquettes were prepared by adding low basicity laterite nickel ore and stainless steel dust, and the valuable metals Fe, Cr, and Ni were recovered by carbothermal reduction. The results show that the addition of laterite nickel ore into CBSL (carbon containing composite briquette of stainless steel dust and laterite nickel ore) effectively improves the recovery of metal Fe, Cr and Ni and the self-pulverization rate of reduction slag. The reduction temperature is 1450°C, the reduction time is 30 min, the FC/O (molar ratio of fixed carbon to oxygen) is 1.0, and the laterite nickel ore addition is 6%, the recoveries of metal Fe, Cr and Ni are 92.1%, 90.1% and 91.6%, respectively, and the self-pulverization rate of the reduction slag reaches 91.5%. The Ca2SiO4 phase content of the reduced slag at high temperature is 71.8%, and the reduced slag system is located in the orthosilicate Ca2SiO4 region of the phase diagram, which effectively improves metal recovery, enables efficient separation of the reduced product and reduces energy consumption for subsequent processing.

Laser-assisted reduction of iron ore using aluminum powder

This study reports on the laser-assisted reduction of iron ore waste using Al powder as a reducing agent. Due to climate change and the global warming situation, it has become of paramount importance to search for and/or develop green and sustainable processes for iron and steel production. In this regard, a new method for iron ore utilization is proposed in this work, investigating the possibility of iron ore waste reduction via metallothermic reaction with Al powder. Laser processing of iron ore fines was performed, focusing on the Fe2O3–Al interaction behavior and extent of the iron ore reduction. The reaction between the materials proceeded in a rather intense uncontrolled manner, which led to the formation of Fe-rich domains and alumina as two separate phases. In addition, a combination of Al2O3 and Fe2O3 melts, as well as transitional areas such as intermetallics, was observed, suggesting the occurrence of incomplete reduction reaction in isolated regions. The reduced iron droplets were prone to acquire a sphere-like shape and concentrated mainly near the surface of the Al2O3 melt or at the interface with the iron oxide. Scanning electron microscopy, energy-dispersive x-ray spectroscopy, and wavelength-dispersive x-ray spectroscopy analyses were employed to analyze the chemical composition, microstructure, and morphological appearances of the reaction products. High-speed imaging was used to study the process phenomena and observe differences in the movement behavior of the particles. Furthermore, the measurements acquired from x-ray computed microtomography revealed that approximately 2.4% of iron was reduced during the laser processing of Fe2O3–Al powder bed, most likely due to an insufficient reaction time or inappropriate equivalence ratio of the two components.

Impact of Iron Ore Pre-Reduction Degree on the Hydrogen Plasma Smelting Reduction Process

To counteract the rising greenhouse gas emissions, mainly CO2, the European steel industry needs to restructure the current process route for steel production. Globally, the blast furnace and the subsequent basic oxygen furnace are used in 73% of crude steel production, with a CO2 footprint of roughly 1.8 t CO2 per ton of produced steel. Hydrogen Plasma Smelting Reduction (HPSR) utilizes excited hydrogen states with the highest reduction potentials to combine the simultaneous reduction and smelting of iron ore fines. Due to the wide range of iron ore grades available worldwide, a series of hydrogen plasma experiments were conducted to determine how pre-reduced iron ore and iron-containing residues affect reduction behavior, hydrogen consumption, overall process time, and metal phase microstructure. It was discovered that, during the pre-melting phase under pure argon, wet ore increased electrode consumption and hematite achieved higher reduction levels, due to thermal decomposition. The reduction of magnetite ore yielded the highest reduction rate and subsequent hydrogen conversion rates. Both hematite and magnetite exhibited high utilization rates at first, but hematite underwent a kinetic change at a reduction degree of 80–85%, causing the reduction rate to decrease. In comparison to fluidized bed technology, it is possible to use magnetite directly, and the final phase of the reduction can move along more quickly due to higher temperatures, which reduces the overall process time and raises the average hydrogen utilization. A combination of both technologies can be considered advantageous for exhaust gas recycling.

Gasification and kinetic study on metallurgical cokes in CO2-N2-H2O and CO2-N2 atmosphere

ABSTRACT A high-temperature gas-solid reaction device was used to simulate the gasification of coke in a hydrogen-rich blast furnace, with the gasification reaction of water/anhydrous bulk cokes studied. CO2 and H2O effects on coke gasification kinetics were analyzed in CO2-N2-H2O and CO2-N2 with the experimental temperature of 1173–1523 K, the CO2 content of 15–60%, and the H2O content of 15%. Compared with those of CO2-N2, the gasification reaction rate and carbon conversion rate of cokes in the CO2-N2-H2O mixture were significantly higher. Carbon conversion rates of the CO2-N2-H2O mixture at different temperatures were about 30% higher than those of CO2-N2 on average, and the gasification reaction rate was about 50% higher on average. There were two temperature regions for gasifying cokes in CO2-N2-H2O and CO2-N2 mixtures. At 1,273 K, the gasification reaction is transformed into diffusion control, which is from chemical reaction control. The aggravation of coke gasification by H2O generated after hydrogen reduction of iron ores was mainly reflected at the lower temperature. Besides, the kinetic model analysis showed that random pore model was optimal in describing the gasification reaction of cokes in CO2-N2-H2O and CO2-N2, and the addition of H2O improved the gasification reaction’s activation energy.

Effect of raw material composition on combustion behavior of quasi‐particles in the iron ore sintering process

AbstractAs the basic unit of iron ore sintering bed, the combustion behavior of quasi‐particles significantly impacts the sintering process. Adding biomass char leads to the deterioration of sintering quality, which was originally for the reduction of carbon emission. In this study, the isothermal thermogravimetric platform was used to analyze the combustion behavior of quasi‐particles using different fuels and ores. The results show that the mass of quasi‐particles packed bed decreases rapidly with combustion, then rises slowly, and then tends to be stable. The quasi‐particle samples in the combustion process were quenched with liquid nitrogen, and the composition changes in the quasi‐particle combustion process were analyzed. The results show that the excessive mass loss is caused by the reduction of iron ore in the sintering atmosphere, which also means heat loss. Compared with the samples using coke, when the fuel is exhausted, the proportion of calcium ferrite in the samples using charcoal decreases by 10.94%, while the proportion of magnetite and FeO is 11.36% and 1.04% higher, respectively, which will further lead to the formation of calcium iron olivine and reduce the sinter strength. The addition of magnetic concentrate may help to reduce the heat loss caused by the reduction reactions, but it is necessary to optimize the sintering process.

Novel 3D analysis of reduction behavior of single iron-oxide particle in CO-CO2 gas atmosphere

The production of steel, which is achieved by the reduction of iron ores mainly through indirect reduction reactions in a blast furnace, is gradually increasing worldwide. Because the reducing gas diffuses three-dimensionally, irregular particle shapes influence the reduction through differences in the diffusion length. The analysis of actual irregularly shaped iron-ore particles using existing models is difficult because they are primarily effective for 1D systems. Therefore, a novel reduction model based on the 3D diffusion equation that accommodates irregular particle shapes and 3D systems was developed in this study. The established model was validated by reproducing experimental conditions and comparing the quantified effective diffusivity and chemical reaction rate constant using the shrinking core model. In addition, the model was used to investigate the reducing behavior of an actual sintered-ore particle and the effects of particle sphericity and macro pore content. The sintered-ore particle had a higher reduction rate than that of a spherical equivalent with the same volume because sections of the surface with shorter diffusion lengths facilitated the gas diffusion. Additionally, the particle sphericity was determined to be inversely proportional to the reduction rate because the rate of gas diffusion into the particle depended on the diffusion length. With respect to porous particles, the gas was found to readily diffuse into the particles through pores, leading to a higher reduction rate for higher pore numbers. Overall, the gas diffusion was confirmed to drive the reduction reaction.

Reduction Kinetics of Compact Hematite with Hydrogen from 600 to 1050 °C

Reduction of iron ores with hydrogen is a solution to replace fossil fuels. For this reason, it is important to discuss previous discrepancies. Some previous studies suggest a rate minimum with respect to temperature. Our research work indicates that a rate minimum can be avoided. Thermogravimetric isothermal reduction experiments were carried out from 600 to 1050 °C with pure reagent ferric oxide and hydrogen using a tubular furnace. The morphology and chemical composition of the initial sample, consisting of particulate hematite (Fe2O3), and the final product, consisting of metallic iron (Fe°), was defined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The reduction rate for the conversion from hematite to magnetite (Fe2O3 to Fe3O4) was the highest, around 5 %/min, decreasing to around 2–5%/min for the second stage of conversion from magnetite to wüstite (Fe3O4 to FeO). This reduction rate remains almost constant from about 20–80% reduction, decreasing to 0.3–1%/min for the completion of reduction from wüstite to metallic iron (FeO to Fe°). The reduction controlling mechanism was evaluated based on the calculated apparent activation energy and fitting the experimental data to one gas-solid reaction equation. Under the experimental conditions in this work, the reduction rate of pure hematite with hydrogen linearly increased with temperatures from 600 to 1000 °C, without a rate minimum in this temperature range. Above 1000 °C, the reduction rate decreased due to sintering phenomena. This result suggests a maximum reduction temperature of 1000 °C using pure hematite and hydrogen as the reducing gas. The reduction controlling mechanisms identified using hydrogen as a reducing gas were chemical reaction for the conversion from hematite to wüstite and diffusion control for the final reduction from wüstite to metallic iron. Since the reduction rate from wüstite to metallic iron is the one that affects the overall rate of reduction, overall changes in porosity were also evaluated. Finally, the reduction of wüstite is schematically described.

Cost effective decarbonisation of blast furnace – basic oxygen furnace steel production through thermochemical sector coupling

We present here a first-principles study of the sector coupling between a thermochemical carbon dioxide (CO2) splitting cycle and existing blast furnace – basic oxygen furnace (BF-BOF) steel making for cost-effective decarbonisation. A double perovskite, Ba2Ca0.66Nb0.34FeO6, is proposed for the thermochemical splitting of CO2, a viable candidate due to its low reaction temperatures, high carbon monoxide (CO) yields, and 100% selectivity towards CO. The CO produced by the TC cycle replaces expensive metallurgical coke for the reduction of iron ore to metallic iron in the blast furnace (BF). The CO2 produced from the BF is used in the TC cycle to produce more CO, therefore creating a closed carbon loop, allowing for the decoupling of steel production from greenhouse gas emissions. Techno-economic analysis of the implementation of this system in UK BF-BOFs could reduce steel sector emissions by 88% while increasing the cost-competitiveness of UK steel on the global market through cost reduction. After five years, this system would save the UK steel industry £1.28 billion while reducing UK-wide emissions by 2.9%. Implementation of this system in the world's BF-BOFs could allow the steel sector to decarbonise in line with the Paris Climate Agreement to limit warming to 1.5 °C.

The Effect of Mechanochemical Activation on Carbothermic Reduction of Pyrolusite Ore

The Effect of Mechanochemical Activation on Carbothermic Reduction of Pyrolusite Ore

Ironmaking Using Municipal Solid Waste (MSW) as Reducing Agent: A Preliminary Investigation on MSW Decomposition and Ore Reduction Behavior

Ironmaking Using Municipal Solid Waste (MSW) as Reducing Agent: A Preliminary Investigation on MSW Decomposition and Ore Reduction Behavior

Review on the chemical reduction modelling of hematite iron ore to magnetite in fluidized bed reactor

Abstract Steel production is considered as one of the major backbones of many economies. Though blast furnace is the primary route of steel production, the industries are willing to alternatives technologies such as the high temperature-controlled conversion of hematite to magnetite. The geological and mineralogical characteristics of the low-grade iron ores possess difficulties in their conventional enrichment. The literature concludes the advantages of high-temperature conversion in terms of easiness in downstream operations caused by decreased hardness and increased magnetic susceptibility of magnetite. The modelling work has been primarily focused on the direct reduction of iron ore to metallic iron. The present compilation discusses the scientific and engineering developments on the reduction-roasting of iron-ore followed by the CFD–DEM modelling and simulation work performed to reduce iron ore to magnetite. It provides a comprehensive review of the experimental and industrial progress done in the area.

Industrial practice and CFD investigation of a multi-chamber fluidized bed reactor for MnO2 ore reduction

The multi-chamber fluidized bed reactor (MCFBR) is beneficial to the higher solids conversion rate, but the complex configuration needs special methodology for the rational design and smooth operation. In this study, an actual plant data of MCFBR for the reduction of MnO2 ore were analyzed, which indicated that the recovery rate of Mn was confirmed to be kept above 95% normally. To investigate the multi-chamber fluidized bed hydrodynamics and reaction characteristics, the 3D computational fluid dynamics (CFD) numeration coupled with structure-based transfer model and multi-chamber calculation method was established. The effect of mesoscale structure on the prediction of multi-chamber reaction process was evaluated as well. The simulation results showed that the model was able to calculate the gas–solid reaction behavior more accurately than the traditional model without taking mesoscale structure into account. The computed tanks-in-series number of 2.0 is less than the actual chamber number of 4.0 for the wide gap between the vertical baffle and the side wall. The quantitative effects of partition configuration, fluidized structure, and operating condition on the solids conversion rate were estimated as well.

Improvement of the current methodology for calculating the parameters of drilling and blasting on the explosive force

Purpose. Improvement of the current methodology for calculating the parameters of drilling and blasting (D&B) by determining the explosive force by the degree of realization of the detonation velocity for all types of industrial explosives (IE). The methodology of research. To solve the problem, a systematic approach was used, including an analysis of the current industry methodology for calculating the parameters of D&B in underground ore mining using IE, improvement of the power-law dependence of the calculation of the line of least resistance (LLR) of charges by determining the coefficient of explosive force of the IE, taking into account the degree of implementation of the burning rate, as well as approbation of the improved technique in the conditions of the operating iron ore mine. Findings. According to the methodology for determining the coefficient of explosive force of explosives (EX) according to the degree of implementation of the burning rate and according to the results of experimental studies of the change in the burning rate of the bulk emulsion explosive (EE) Ukrainit-PP-2, an improvement is proposed for the current industry methodology for calculating the parameters of D&B for the mines of the Kriviy Rig basin and the Private Joint Stock Society "Zaporozhye iron ore plant" (PJSS "ZIOP"). This made it possible, in the conditions of the experimental block of the mine "Yubileinaya" of the PJSS "Sukhaya Balka", using the bulk EE Ukrainit-PP-2, to increase the LLR and the distance between the borehole bottom up to 17%, and to obtain good results of ore reduction. The originality. The well-known power-law dependence of the determination of the LLR of borehole for rock breaking has been improved through the refinement of the coefficient of explosive force of the IE, which takes into account the degree of realization of the burning rate EX. Practical implications. The results of the research have improved the power-law dependence of the calculation of the LLR on the explosive force, taking into account the degree of implementation of the burning rate, the use of which will allow rationalizing the parameters of the D&B when breaking the ore mass using all types of IE.

Kinetic study in selective reduction of limonitic and saprolitic nickel ore

ABSTRACT Saprolite and limonite have different behaviour in the carbothermic reduction process due to the differences in their atomic structures. This work investigates the kinetic study of these two different kinds of lateritic nickel ores. Nickel ore, coal, sodium sulfate, and calcium oxide were mixed, then pelletised into 10–15 mm diameters. The pellets were reduced with a non-isothermal condition using a muffle furnace at 950–1150 °C for 5–120 min. The reduced pellets were crushed into less than 74 µm prior to the wet magnetic separation process to obtain concentrates (ferronickel) and tailings (impurities). The result showed that the reduction rate for both lateritic nickel ores increased with the increase of reduction temperature and holding time. The Ginstling-Brouhnstein model was appropriate to describe the diffusion mechanism of the reduction process of limonite and saprolite. The activation energy in the reduction of limonite was lower than in saprolite. It indicated that the iron and nickel in magnesium silicate in saprolite have lower reducibility than the oxide structure in limonite. Modifying basicity in nickel laterite with CaO addition could also reduce the activation energy.

Energy and emission analysis of flash ironmaking-powder generation coupling processes with various fuels

• The full-cycle flash ironmaking-power generation process was firstly investigated. • The sensitivity analysis provides optimum conditions during the different stages. • Direct use of biomass is not recommended with highest fuel ratio R f = 4.3. • Hydrogen was proved the most effective with the high exergy efficiency (48.6 %). • The chemical exergy in hot metal (31–34 MJ) helps improving the system efficiency. The flash ironmaking-power generation coupling (FIPG) process combines the latest entrained-flow bed ironmaking technology and efficient cycle power generation. Different fuels (hydrogen, methane, coal, and biomass) are adopted to produce the reducing gas components. In this study, the process simulation was established based on the Gibbs free energy minimize principle, and FIPG included the flash ironmaking coupling (FIC), settler heating (SH), and combined cycle power (CCP) processes. The sensitivity analysis determined the optimum conditions (fuel ratio R F , oxygen ratio R O , and replenished oxygen ratio R OF ), and we compared mass, energy, and exergy flows in different cases. In FIC, the optimized conditions determined using the crossing points of curves temperature T = 1350 °C and reduction degree X = 0.7 are (H 2 : R F = 0.16, R O = 2.11), (CH 4 : R F = 0.43, R O = 1.58) and (Coal: R F = 0.59, R O = 0.88). Due to the low heating value of biomass, its optimized R F is higher than others, even with a declined requirement ( X = 0.6) (Biomass: R F = 4.3, R O = 0.39). In SH, except that the SH-biomass requires more replenished fuel, the other three cases slightly differ due to the close first stage particle outputs. A suitable replenished oxygen/coal ratio ( R OR = 0.74) ensures the hot metal's high carburization rate and temperature with fewer fuel amounts. From the energy balance perspective, the fuels account for most heat expenditure, while the electricity produced by CCP accounts for most of the energy benefit. Meanwhile, chemical energy from iron is the third largest expenditure item, with a share ranging from 10.91 % to 21.71 %. Exergy analysis provided a detailed flow chart between processes, showing the highest exergy efficiency (48.6 %) in FIPG-H 2 and the lowest (43.0 %) in FIPG-biomass. Although the ore reduction consumes CO to generate the oxidation product CO 2 , the most significant CO 2 generation occurred in the CCP stage. The total CO 2 emissions per energy consumption unit are 71.55 Nm 3 /MW, 107.56 Nm 3 /MW, 138.49 Nm 3 /MW, and 148.63 Nm 3 /MW in FIPG-H 2 , FIPG-CH 4 , FIPG-coal, and FIPG-biomass.

Two-Phase Liquid-Solid Hydrodynamics of Inclined Fluidized Beds

Although many fluidized systems are not vertically oriented, little research has been done on fluidization within inclined channels. The fluidization of the gravitational force and the tensile force may be substantially opposing in the vertical system. The theory of gravitational field fluidization, which is related to industrial fluidization processes like coal gasification, iron ore reduction, and catalytic cracking and calls for the use of standing tubes or angled risers, has to be developed in order to encompass various orientations. Without underlying theories, engineers must rely on vertical fluidization equations to build these sloping systems. A significant barrier to improving the design and optimization of new solid circulation systems is the tendency of fluidization. Based on historical developments and theoretical progress, the study presents an overview of recent advancements of liquid-solid fluidized beds in inclined columns. The fluidized bed is investigated as a whole by looking at the governing factors.

Pelletization and sintering of New Zealand titanomagnetite ironsand

Direct reduction (DR) of iron ore with hydrogen is a potential route for near-zero CO2 steelmaking, but vertical shaft DR reactors require that iron ore fines must first be pelletized. This study reports an investigation of the pelletization and subsequent sintering behaviour of titanomagnetite (TTM) ironsand, which is the main iron ore feedstock for New Zealand’s steel industry. Initially green pellets were bound with bentonite and carboxymethyl-cellulose (Peridur), using an average ironsand particle size of 65 µm. The compressive strength of these pellets after sintering at 1200 °C in air for 2 hr was measured to be 976 N, meeting the expected feedstock requirements for a shaft reactor. This strength was attributed to interparticle bonding arising from extensive recrystallisation of titanohematite grains from oxidation of TTM, as well as the formation of a liquid bonding phase due to melting and diffusion of the binders. Building on these results, alternative binders were then explored in order to lower the required sintering temperature. A combination of both organic and inorganic binders was found to deliver optimum performance, wherein carboxymethyl-cellulose based binders provided strength in the green pellets, whilst inorganic binders, such as calcium borate or ground glass, promoted high sintered strengths.

Thermodynamic analysis and experimental verification of the direct reduction of iron ores with hydrogen at elevated temperature

Thermodynamic analysis and experimental verification of the direct reduction of iron ores with hydrogen at elevated temperature

Decarbonization scenarios for the iron and steel industry in context of a sectoral carbon budget: Germany as a case study

CO2 emissions from global steel production may jeopardize climate goals of 1.5 °C unless current steel production practices will be rapidly decarbonized. At present, primary iron and steel production is still heavily dependent on fossil fuels, primarily coke. This study aims to determine which decarbonization pathways can achieve the strongest emission reductions of the iron and steel industry in Germany by 2050. Moreover, we estimate whether the German iron and steel industry will be able to stay within its sectoral carbon budgets for a 1.5 °C or 1.75 °C target. We developed three decarbonization scenarios for German steel production: an electrification, coal-exit, and a carbon capture and storage (CCS) scenario. They describe a phase-out of coal-fired production plants and an introduction of electricity-based, low-carbon iron production technologies, i.e. hydrogen-based direct reduction and electrowinning of iron ore. The scenarios consider the age and lifetimes of existing coal-based furnaces, the maturity of emerging technologies, and increasing recycling shares. Based on specific energy requirements and reaction-related emissions per technology, we calculated future CO2 emissions of future steel production in Germany. We found that under the decarbonization scenarios, annual CO2 emissions decrease by up to 83% in 2050 relative to 2020. The reductions of cumulative emissions by 2050 range from 24% (360 Mt CO2) under the electrification scenario up to the maximum of 46% (677 Mt CO2) under the CCS scenario compared to a reference scenario. This clearly demonstrates that the technology pathway matters. Nevertheless, the German steel sector will exceed its sectoral CO2 budget for a 1.5 °C warming scenario between 2023 and 2037. Thus, drastic measures are required very soon to sufficiently limit future CO2 emissions from German steel production, such as, a rapid decarbonization of the electricity mix, the construction of a hydrogen and CCS infrastructure, or early shutdowns of current coal-based furnaces.