The steel industry is recognized as an intensive energy consumption due to the units operation being carried out at high temperatures. The common energy sources usually come from fossil fuels such as coal, natural gas and oil. Thus, the environmental impact of the steel industry is recognized as one of the most important challenges to reduce the emissions that have been continuously imposed. In the integrated steel industry, the sinter plant is the responsible one to furnish high quality of raw materials for the blast furnace which produce pig iron for the subsequent processes of refining and steels elaboration. The sintering process is an intensive user of coal (approx 45 kg of coal per ton of sinter) and steelmaking by products. Several attempts have been made in order to substitute the coal by alternative energy sources, however further research and developments are demanded to attain the sinter product quality. The difficulties associated with the production of high quality sinter product are mainly attributed to the strict control of combustion phenomena with thermal energy release within the narrow sintering front which plays crucial role on the phase formation and thus, determines the final metallurgical and mechanical properties of the sinter. The biomass and bio-gas (synthetic gas produced from biomasses) are energy resources with low environment impact, however, radical modifications are usually required to produce reasonable sinter with compatible mechanical strength suitable to be used in large blast furnaces. In this paper, a new concept of sintering process is proposed. The new technology concept consist of combining the use of high reactivity of granular biomass produced from elephant grass and the modification of the sinter strand to adapt recirculation of the gas to increase the efficiency of drying and calcination zones. The research is carried out by using a comprehensive mathematical model based on transport equations of momentum, energy and chemical species for a multiphase system. The model is closed with additional equations for the rate of chemical reactions, phase interactions and heat exchange. The model is used to simulate the proposal of new sintering process concepts to determine new feasible technological industrial conditions. Based on the results obtained in this study, a reduction of 30 kg per ton of sinter product of fossil fuel is expected with reduction of 50% of the returned.

Reducing agents are considered to be the major portion of most metallurgical processes cost and their production causes severe environmental concerns. In addition, lower energy consumption, lower CO2 emission and waste recycling are driving the reduction metallurgy processes to develop "coke free, zero waste and green processes". In the present overview, attempts to explore the possible alternative reducing agents for metallurgical processes will be presented. The present discussion will be focusing on the following approaches;
1. Replacing expensive carbon bearing materials with relatively less expensive alternate fuels having carbon as well as significant amount of potential reducing constituents such as coal, waste plastic and biomass materials.
2. Producing agglomerates from cheaper raw materials (secondary resources) like carbon rich integrated steel industry wastes.
3. Enhancing the carbon utilization by using higher reactive materials.
The present essay is an attempt to explore the feasible utilization of different carbon bearing materials as reductants in metallurgical processes. Different carbon bearing materials is considered, namely, waste plastic materials, biomass, carbon rich iron and steel industry wastes.

Diluted, mild or flameless oxy-fuel combustion has shown in the past years huge success as an optimization tool for different high temperature applications. This innovative combustion technology has a lower flame temperature, more uniform temperature distribution and low concentrations of oxygen as well as nitrogen inside the furnace, leading to low fuel consumption and very low NOx levels. In this work, we analyze the optimization processes of different types of copper anode furnaces (fix, rotary) with Messer Oxipyr burners, which led to impressive savings and ecological improvements for the customers. A review of the available literature, on this topic, is also given.

This work focuses on the physical and geometrical aspect of the surface layers of AISI / SAE 3115 having undergone treatment by ball burnishing hard steel or diamond tip. The results show that the optimal effects of burnishing are directly linked to the shape and the material of the active portion of the device as well as the ability to plastic deformation of the material surface to be treated. And roughness is improved over 68% and the rate of consolidation is increased by 24%. Also modeling rational curves traction provides a hardening coefficient up to 0.29 in the presence of burnishing.

The removal of boron and phosphorus from metallurgical grade silicon by refining with Na2O-SiO2; Na2O-SiO2-CaF2 slags was studied. The study evaluated the effects of temperature (1550 A°C and 1650 A°C), basicity (2 and 6), time (0, 5 15, 30, 60 and 120 minutes) variables and ratio silicon/slag (4:1, 2:1: 1:1, 1:2). Assays were performed in induction furnace under argon and high-density graphite crucible. In boron removal assessment, ICP-OES analytical techniques were used in the analysis of the levels of boron in silicon, XRF analysis was used in the composition of the slag after testing and optical microscopy was used to quantify the silicon present in the slag after testing. From the results, it can be concluded that the removal of boron using slags containing sodium is possible under non-equilibrium conditions in approximately 30 minutes after total dissolution of the slag. It was found that the removal of boron is higher than 1650°C.

The application and viability of agglomerates composed of coal and iron ore, known worldwide as Fe-coke, have been recently proposed as an innovative alternative to the reduction of CO2 emissions and energy consumption in the blast furnace. The present study aimed to investigate the carbonization behavior of coal/iron ore briquettes produced with different coals and the quality of Fe-coke produced. Three coals with different ranks were selected and individually blended with iron ore (pellet feed) on the proportion coal/iron ore equal 2.33. Low amounts of charcoal and a molasses/CaO as binder were added to the mixtures. Briquettes were produced in a laboratorial roll-press machine and subjected to carbonization in a laboratorial furnace. It was also carried out pyrolysis experiments in a thermobalance with small briquettes pieces. Briquettes mechanical strength was characterized before and after carbonization through compression and tumbler tests. Wet analysis, X-ray diffraction and Mossbauer spectroscopy were carried out to determine the iron phases present throughout the carbonization process. The changes in briquettes morphology during carbonization were analyzed by optical and scanning microscopies. The thermogravimetric experiments allowed a detailed evaluation of mass loss due to coal pyrolisys and iron ore reduction reactions. Mechanical strength of Fe-coke briquettes showed a significant dependence on temperature and coal characteristics. In general, the strength of iron-coke briquettes was higher for samples produced with higher fluidity coals. Morphological characteristics revealed significant differences among the briquettes produced from different coals, where the coke matrix cohesion was better for samples produced with higher fluidity coals and contributed to explain the differences in mechanical strength of Fe-coke briquettes.

The furnace process for silicon production is constantly improved both with respect to health, safety and environmental aspects and with respect to process and quality control. The notion of a closed furnace has often been discussed as it may provide several advantages, such as improved Si recovery, reduction of electrode consumption and carbon requirements. Additionally; it may enable more efficient recovery of the energy contained in the flue gas. Such improvement requires a safe and effective way of transporting the flue gas, which entails mitigation strategies for clogging and fouling by dust and SiO condensate. This, in turn, calls for increased understanding for the conditions and mechanisms for condensation of SiO-gas. The current paper gives an overview about the ongoing activities related to the transport of process gasses from a closed Si-furnace. Initially, small scale experiments are carried out, where the properties of SiO-gas is fundamentally investigated in terms of condensation temperature in different gaseous environments. SiO-gas was generated at 1650 A°C according to 2SiO2(s) + SiC(s) = 3SiO(g) + CO(g). Deposition of condensates started to take place at 1650 A°C. Condensates of different colors were deposited in the upper part of the reactor. The most common type was brown colored and was the product of the following reaction 2SiO(g ) = SiO2(s) + Si(s). Characterization of the condensates is performed by electron microscopy, chemical analysis and particle size distribution.

The present work aimed to investigate the influence of charcoal addition of different particle sizes on metallurgical coke reactivity. Thus, an eucalyptus charcoal was added to a prime American medium volatile coking coal in three amounts (3, 5 and 8%) and in two different particle size ranges (below 1 mm and between 3 and 4 mm). Charges of the individual coal and coal/charcoal blends were carbonized in a laboratorial scale coke oven (1 kg). The reactivity of the produced bio-cokes and reference coke were examined and compared using thermal gravimetric analysis in a CO2 atmosphere. Morphological analyses via optical and scanning electronic microscopies using samples from before and after reactivity experiments were also carried out. Charcoal addition showed a tendency to increase coke reactivity and lower the temperature at which carbon gasification started. Morphological observations confirmed that charcoal particles tend to be preferentially consumed compared with the coke matrix. However, bio-cokes produced with charcoal addition up to 3% for both particle sizes and up to 5% for the coarser particle size had a similar behavior in terms of CO2-reactivity as the reference coke. The effects of charcoal addition on coke texture and CO2 surface area appeared to justify the differences in coke reactivity.

In this work, our task consists in optimizing the nitriding treatment at low-temperature of the steel 32CrMoV13 by the way of the mixtures of ammonia gas, nitrogen and hydrogen to improve the mechanical properties of the surface (good wear resistance, friction and corrosion) and of the diffusion layer of the nitrogen (good resistance to fatigue and good tenacity with heart). By limiting our work to the pure iron and to the alloys iron-chromium and iron-chromium-carbon, we have studied the various parameters which manage the nitriding: flow rate and composition of the gaseous phase, the interaction chromium-nitrogen and chromium-carbon by the help of experiments of nitriding realized in the laboratory by thermogravimetry. The acquired knowledge has been applied by the mastery of the growth of the ƒ×' combination layer on the ƒÑ diffusion layer in the case of the industrial steel 32CrMoV13.

Corrosion is one of the most serious degradation processes of materials, in particular of metals. It has a great impact upon economy, environment and society and its effect upon sustainability cannot be discarded. In the present presentation, we will examine the main consequences of corrosion upon sustainability, such as the exhaustion of natural resources (ores, energy producing materials, water) and environmental disasters resulting from failure of materials in service due to corrosion. The importance of research and development for the development of a sustainable industrial society will be stressed, concerning in particular to the development of corrosion resistant materials, coatings and corrosion control techniques.

JFE Steel Corporation developed a technology for injection of hydrogen-based gas fuel in sintering machines, Super-SINTER (Secondary-fuel Injection Technology for Energy Reduction). The technology makes it possible to greatly reduce CO2 emissions in the sintering process, and was successfully applied to a commercial sinter plant for the first time in the world.<br />In ordinary sintering process, after coke breeze is mixed with iron ore and limestone, raw materials are charged and sintered in sintering machine. In order to produce high strength and high reducibility sintered ore, it is necessary to keep the sintering temperature between 1,200 degrees and 1,400 degrees during sintering. In the temperature below 1,200 degrees, the strength of sintered ore decreases because raw materials do not melt enough. In the temperature over 1,400 degrees, the strength and reducibility decrease by increasing glassy silicate.<br />With Super-SINTER technology, it is possible to extend the optimum temperature zone by injecting a hydrogen-based gas fuel from the upper side of the charged raw materials as a partial substitute for coke breeze. As a result, the energy efficiency of the sintering process was greatly improved, and it has been achieved to reduce CO2 emissions by a maximum of approximately 60,000 tons/year.<br />Moreover, the new technology of hydrogen-based gas fuel injection with oxygen enrichment has been developed to furthermore improve Super-SINTER technology. This technology can extend the optimum temperature zone wider than ordinary Super-SINTER by increase of combustion rate of fuels with oxygen enrichment. As a result, sinter productivity with high quality was improved greatly.

Ironmaking is the major energy consuming and CO2-emmiting step in steel production. Direct reduction processes are an alternative to the traditional blast furnace because of the use of H2 in the reducing gases which generate less CO2. There are two main technologies for direct reduction of iron, Midrex and Energiron (or Hyl) which together are responsible for 80% of the production of direct reduced iron in the world. A review on the patents published by the two companies was performed in this work and it was possible to describe the functioning of both process, the developments over the years and to distinguish the differences. Both process are based on shaft furnaces where reducing gases flow in countercurrent to iron ore pellets heating them and reducing iron. The reducing gases are generated by catalytic reforming of methane. The reforming in Midrex is mainly by reaction with CO2 and in Energiron with H2O. There is a newer process version without a reformer, the Energiron Zero Reformer (ZR). In this process, natural gas is injected together with CO2 and H2O in the reduction reactor and the recently reduced iron works as catalyst for reforming reactions. The heat balance is compensated by the injection of oxygen that partially burns the combustible gases.

Sustainable development is widely regarded as a major social, economic and technical driver, and a key consideration in assessing the relative value and quality of any development. Spent refractories generation, disposal and recycling technologies are key points of environmental management systems of metallurgical and refractories industries. The demands from increasingly environmental regulations, improving working conditions, spiraling landfilling costs and future liability concerns are driving both producers and consumers of refractories towards a sustainable business model, where the increase in performance, thus decrease in consumption, and suitable treatment of any waste is paramount. To meet this need and provide a proper disposal of spent refractory material producers and refractories users must invest in more sustainable technology research and develop innovative methods of management, logistic and process. This study evaluated the main spent refractories recycling routes and technologies, focusing the evolution and the future of refractories recycling management, from local and global point of view.

Facing energy crisis and global warming, the use of new energy sources such as sustainable ones has become imperative. In this context, CEMIG GT Company, ONDATEC Company and the Federal University of Ouro Preto, invested in a project under the Program (R&D) CEMIG/ANEEL for power generation. The objective of this work was to compare the energetic potential of waste gases (non-condensable gases-NCG) and liquid (condensable gases-CG) of a biomass pyrolysis plant by microwave to produce charcoal and the pilot plant that originated it. Therefore, the ONDATEC made the necessary improvements and built the Unit for energy and charcoal production (UPEC-250) by microwave with production capacity of 250 kg per hour. The pyrolysis process was in a continuous mode and in two stages: the biomass drying and the pyrolysis itself. As a result, charcoal, pyrolysis gas (NCG) and bio-oil (CG) were produced. According to the results obtained for the CG and the NCG, it was found a generation potential of 2.24 MWh of electric energy produced by one ton of charcoal, which can be a good alternative to relieve the production chain of charcoal and pig iron.

Carbon composite iron ore agglomerates have been studied for years as partial substitutes of coke and sinter in blast furnaces because of their high reduction rates. In recent years, the development of the Carbon Composite Iron Ore Hot Briquette (CCB) addressed the problem of poor mechanical strength at high temperatures. This paper tests an alternative method for manufacturing self-reducing briquettes and evaluates their physical properties and kinetic behavior during reduction. The method for manufacturing self-reducing briquettes consists of pressing a mixture of fine particles of coal and pellet feed iron ore in a laboratorial briquetting machine followed by a heat treatment. The briquettes showed an average compressive strength of 58 kgf and apparent activation energy for reduction of 306 kJ/mol.

The use of biomass in processes of iron ore reduction contributes to lowering the CO2 emissions, which is one of the main issues in the ironmaking industry. An alternative to nowadays technologies is the development of coal-charcoal composite materials that have similar properties of those found in metallurgical coke. This paper presents an evaluation of the compressive strength and CO2 reactivity of coal-charcoal composite briquettes. Coal-charcoal composite briquettes were manufactured with addictions of 5, 10 and 15 wt% of charcoal, with both coal and charcoal presenting particle size less than 0,150 mm. The briquettes were obtained by pressing the coal-charcoal mixture in a cylindrical die followed by a heat treatment of 1100°C for 8 hours. The briquettes were evaluated by their compressive strength and CO2 reactivity. The CO2 reactivity tests were carried out under different temperatures and CO2 flows. It was found out that the briquettes produced with additions between 10 and 15 wt% of charcoal showed the best compressive strength results. The CO2 reactivity showed a slight increase for additions above 5 wt% of charcoal in comparison with briquettes of coal (without the addiction of charcoal) that went through the same heat treatment.

Industrial stiff vacuum extrusion briquettes (BREX) producing line can efficiently provide for the small-scale blast furnace (BF) operation with 100% briquetted charge. Physical and metallurgical properties of the BREX are being investigated. A new effect of the non-linear strengthening of the BREX bonded with the combined Portland cement and Bentonite binder is described. The application of this combined binder results in the local maximum of the cold compressive strength of the BREX on third day of strengthening. The hot strength mechanism of the BREX is being explained. The results of the industrial operation of the small-scale BF with 100 % BREX in burden are analyzed. The consumption of coke in the BF at 100% of BREX does not exceed 500 kg/t compared to 680 kg/t for the smelting without BREX.<br />
KEY WORDS: extrusion briquette (BREX); stiff vacuum extrusion; small-scale blast furnace; coke rate; hot strength.

Dust, or airborne particulate matter, constitutes a health, safety and environmental challenge for most metal producers. This paper evaluates the potential of commercially available dust measurement devices for use in the ferroalloy industry. Two main locations were chosen for the measurements: a roof exhaust opening at a manganese alloy production site and a tapping area at a silicon alloy production site. A number of instruments and measurements techniques was employed at both sites, including two different optical transmission devices, a laser photometer, gravimetric filters and an electrical low pressure impactor (ELPITM). The results generated by the different methods have been compared and evaluated. The correlations between the different techniques are generally good. Certain optical instruments need calibration for the specific dust types of each plant, which may be done using the results obtained by the gravimetric filters. For the estimation of fugitive dust emissions, the results obtained by the long-range optical dust measurement devices may be combined with anemometer results (wind speed and direction) to estimate the total amount of fugitive emissions escaping from each exhaust opening. With the correct choice and placement of such instruments, it is possible for a metallurgical plant to greatly improve the accuracy of the emission estimates for environmental reports and emission control. This study also evaluates two stationary point samplers with respect to the indoor air quality measurements. Such instruments are valuable for the scientific understanding of the fume formation and characteristics, since they allow real-time, size-fractionated collection with particle size distribution and subsequent chemical analysis of the particulate matter.

Dust, fume or airborne particulate matter, constitutes a health, safety and environmental challenge for most metal producers, including the ferromanganese alloy industry. To decrease the oxide dust generation of industrial metallurgical processes, more fundamental knowledge about the fume formation mechanisms is necessary. In this study, the active oxidation of a ferromanganese alloy and the resulting fume formation has been investigated. A liquid medium carbon grade ferromanganese alloy was held at different temperatures in the range 1400-1700A°C, while the surface was exposed to an impinging air jet. The resulting fume was multi-coloured and rich in either MnO, MnOx-FeOy or Mn3O4 depending on the deposition temperatures; the Fe/Mn average ratio also varied (0.009 - 0.023) with deposition temperature. Most of the particles were spheres of various dimensions but cubic particles and whiskers were also observed and protoparticle diameter increased with temperature. There were also amorphous phases present in the fume. Silicon, calcium and magnesium were the most common impurity elements with traces of K, Na, Zn, Ni, Cu and P. The use of a graphite crucible most likely had a significant effect on the chemistry and kinetics of the fuming process. The carbon presence led to formation of CO (g) and a corresponding oxygen deficit in the atmosphere above the liquid metal which seem to have prevented full oxidation to Mn3O4. In these experiments, the Mn vapour formed MnO fume as a first oxidation step, which was then stabilized (quenched) in the off-gas cooler. The flux (molar amount/time unit) of fume produced was one order of magnitude greater than for other ferroalloys, such as Si and SiMn. This may, according to previous studies and theories, be attributed to the formation of an oxide (MnO) mist in the boundary layer.

Rates of gaseous reduction of commercial sinter with CO-CO2-N2 or H2-H2O-N2 gas mixture were measured under single particle and fixed bed situation at a constant temperature. By these data analyses using the unreacted-core shrinking (UCS) models for one and three interface(s), rate parameters; namely chemical reaction rate constants and intra-particle effective diffusivities in the models were evaluated. Fixed bed packed with the sinter was also reduced under rising temperature conditions with stepwise gas concentration change, which was roughly simulated as in a blast furnace. The reduction rate was analyzed by using UCS model for three interfaces with the pre-determined rate parameter values; the comparison between the experimental reduction curve and the computed one showed rough agreement but not so precise and this discrepancy was considered by the existence of quaternary calcium ferrite (abbreviated by CF), which is reported the complex crystalline mineral produced from Fe2O3, CaO, SiO2 and Al2O3. In all the previous analyses for reduction reaction of iron oxides in a blast furnace, sinter was treated as pure iron oxides (hematite and magnetite); the existence of CF was disregarded.
Afterward, final fractional reduction of sinter in hematite to magnetite stage was found out to be about 70 % at lower reduction temperatures, which was caused by the irreducibility of CF in this region and verified with XRD analysis. By changing reduction temperature and reducing gas composition, we determined the border line between CF (= 'Fe2O3') and 'Fe3O4'. Equilibrium relations for 'Fe3O4' / 'FeO' and 'FeO' / 'Fe' were reported by Prof. Maeda, et al, where 'Fe2O3', 'Fe3O4', 'FeO' and 'Fe' designate hematite, magnetite, wustite and iron stages of CF, respectively.
Reduction steps for CF can be written as:
CF (= 'Fe2O3') a†’ 'Fe3O4' a†’ 'FeO' a†’ 'Fe',
which are much the same as those for pure iron oxides. However, a reported variation of gas composition with temperature measured in a blast furnace shows that the gas composition in the thermal reserve zone is only a little higher than the wustite/iron equilibrium, the reduction potential of which is less than 'FeO' / 'Fe' equilibrium and hence 'FeO' cannot be reduced to 'Fe'. Therefore, gaseous reduction model for sinter has been developed in consideration of CF reaction process; UCS model for six interfaces has been proposed to take into account reaction processes of CF as well as pure iron oxides. Trial comparison of the calculated reduction curve with our previously reported experimental data mentioned above under simulated blast furnace conditions has shown rather reasonable agreement. The present model will play an important role in analyzing the reduction rate of sinter, in which CF is existing or even intentionally increasing to suppress the bad effect of SiO2.

A very important application of magnetic materials is on the thin films for magnetic recording. Miniaturization requires phases with high crystalline anisotropy as PtFe, PtCo or Nd2Fe14B. Perpendicular magnetic recording (PMR) with textured thin films are among the possibilities for improving the areal recording density. The relationship between magnetic properties and nanostructures can be studied with the Stoner-Wohlfarth model, which predicts that a sharp (00l) texture can result in improved squareness of the hysteresis loop.
Texture effects in hard nanocrystalline materials or thin films can be evaluated with the Stoner-Wohlfarth (SW) model, since the particles are single domain size and non-interacting. The texture can be introduced in the SW hysteresis by means of an experimental distribution measured by X-Ray diffraction, or theoretically by using distribution functions as Gaussian, Cauchy or Pearson VII. Any symmetrical distribution function can be used for uniaxial texture description, since it represents well the experimental texture data.

The iron and steel making industry is one of the most intensive energy consuming in the industrial sector. In iron-making blast furnace, the energy cost is about 50% of the total coal. Moreover, the CO2 emission is accounted to be more than 70% of the total emission of the integrated steel plants. Using climate-neutral biomass in the blast furnace as a replacement for fossil carbon is expected to significantly reduce the consumed energy and have large positive effect on the environmental objectives of reducing CO2 emission. The present work is an attempt to efficiently utilize carbon containing biomass in the blast furnace. Thermogravimertic analysis is used to study the devolatilization and reduction behavior of biomass-iron oxide self-reducing mixtures. The reaction progress was tracked by online monitoring of the mass loss with time. Moreover, the evolved gases were continuously analyzed by means of quadruple mass spectroscopy.

Non-ferrous metal, whether primary production from primary sources or industrial waste recycling brings with it a burden on the environment. One very important load is the excessive production of carbon dioxide and waste water production containing heavy metals. These two environmental problems are closely linked. This article briefly describes the method of using carbon dioxide arising from industrial processes for the preparation of biomass needed for subsequent removal of heavy metals from wastewater. In this particular case, we use special nanotechnology based material to improve the process and the quality of recovered biomass. The results are very promising. During the first step of the process, we increase biomass production by 30% and also reduce the cost of the whole biomass preparation process. These results are very useful for future application in the next steps. With this technology improvement, we can now produce more biosorbent based materials and after that we use it as a source to bioreactor for heavy metals removal procedure.

Production data of high efficiency of thermal neutralization of anode gases of aluminum electrolyzers with self-baking anodes in insulated burners is presented. The design of insulated chamber with aerodynamics effect of expansion for thermal destruction of anode gases in the existing flue pipe on the longitudinal side of the anode is elaborated. A new construction of gas collection bell with a combustion chamber and with adjustable air supply has been worked out. Heat insulation of combustion chambers and adjustable air supply allow reducing the quantity of harmful things in the waste gases of aluminum production.<br />Key words: insulated burners, thermal neutralization, anode gases, electrolyzers, gas collection bell, adjustable air supply.

ThyssenKrupp CSA Blast Furnaces are 3000mA³ class furnaces that have a unique profile configuration, which imposes different understandings of hearth conditions. Although the constant effort for gas flow and process heat balance stabilization, variations in the Blast Furnace operation are frequent, commonly related to hot metal and slag tapping cycles. Thereby control the liquid flow in the hearth has great influence on transport phenomena and fluctuations on the burden descent and the unusual liquid flow should be evaluated in order to control temperatures and wear. The understanding of these effects is very important to the BF performance and life spam. The coke particle size distribution shows a significant influence on the liquid flow line. Therefore, measures to change the philosophy of burden distribution were taken with a focus on control of peripheral flow. This paper shows a brief review of hearth phenomena and the results noticed at TKCSAA's Blast Furnaces.

In this work, the influence of the binders on the mechanical properties at high temperatures and on the reduction process of the chromite self-reducing pellets were studied.
Compression strength was evaluated at room temperature after submitting them to the temperatures of 1173, 1273, 1373, 1473 and 1573. Bentonite, hydrated lime, molasses, carboxymethyl cellulose (CMC) and sodium silicate were tested with different contents.
Initially, all the materials (chromite, ferrosilicon, petroleum coke and binder) were characterized by chemical analysis and particle size. After this, the materials were agglomerated as 15 pellets (P1 to P15). The compression strength was measured for green pellets, during curing period for 28 days, after drying and after submitting at high temperatures profiles. Decrepitation tests were also done. After reduction experiments, at 1773K, the products obtained (slag and metal) were analyzed by SEM and EDS. The best performance was obtained by the pellet P15 (4% sodium silicate as binder): it reached a compression strength of 5 kg-f/pellet (dry pellet) and of 15 and 15.5 kg-f/pellet, after heat treatment at 1173 and 1273K, respectively. None of tested pellets presented decrepitation. The pellet P15 achieved unitary reaction fraction, after 10 minutes at 1773K. It was observed slag formation after 3.5 minutes, harming the reaction CO/Chromite.
Keywords: Ferrochromium, Self-reduction, Self-reducing pellets, Chromite.

The interaction between metal and refractory in vacuum induction melting furnaces has been extensively studied. It is interesting that depending on the type of metal or alloy that is melt, then the behaviour of the interaction is different. The present paper shows that the behaviour of liquid Nickel is different from liquid Iron when they are processed in an Alumina refractory. Additionally, thermodynamic analysis was carried out in a commercial software in order to explain those differences. The results showed that Iron interacts with the silica in the alumina while Nickel interacts with the alumina itself changing dramatically the rate of interaction.

An overview of the state-of-art of Neodymium reduction is given. Neodymium has found large application in magnets of the Nd-Fe-B type. Calciothermic reduction is industrially used for other rare earths, but is not suitable for neodymium. The industrial production of metallic neodymium is by means of molten salts. It is discussed in the present study why fluorides are advantageous over chlorides. Special attention is given for Neodymium-Dysprosium and Neodymium-Praseodyimium because these alloys are very relevant for magnet production. A model able to simulate the metallic reduction of neodymium is in development. The model takes into account magnetohydrodynamics. Processing variables as cell size, current of operation and cathode consumption can be evaluated with the model.

Examples of non-traditional pyrometallurgical processes applied to metals, slags and concentrates are presented, focusing on products valorization, environmental friendly processes and valuable metals production. Niobium concentrate can be refined by selective carbothermic reduction. Niobium powder or niobium sub-oxides powders can be produced by metalothemic or hydrogen reduction. High pure silicon can be produced by plasma, vacuum, reactive gases, slag and controlled solidification treatments. Titaniferous slag can be produced by titanium ore reduction in self-reducing pellets. Steelmaking slags can be valorized by molten slag treatment and appropriated cooling rates. Fundamental aspects of these processes from thermodynamic and kinetic point of view are highlighted showing the huge potential of pyrometallurgy for metallurgical industries.

In the last more than four thousand years, the iron making technology has come a long way. The transition from bloom in bloomeries to molten iron produced in blast furnaces was the first major step in advancing iron making technology. An average modern blast furnace has an inner volume of about 3500 m3 and produces about 8000 t of hot metal per day thus consuming about 12000 t of iron bearing material and 4000 t of coke per day. On the contrary alternative, iron making processes like DRI making can utilize non-coking coal without use of coke. There is, however, a continuous endeavour to develop several alternative processes for iron making. These iron making systems are beset with process complexities mainly in finding the proper raw materials comprising both iron ore and matching reducing agents. So the experience of the operators and the engineers still have a dependence of ironmaking processes on the performance characteristics of iron bearing minerals and reducing agents. Kenya has, in recent years, discovered significant reserves of iron ore and coal. It is, therefore, expedient to determine as to whether these iron making raw materials could economically be utilised in some of the iron making processes, including the blast furnace. The paper seeks to examine the performance characteristics of Kenyan iron making raw materials under conditions simulating some of the essential features of blast furnace and directly reduced iron making processes. It also discusses various aspects of alternative iron making processes vis-a vis the physico-chemical properties of Kenyan iron ore for an energy efficient and environmentally benign production units both for directly reduced iron and liquid hot metal operations.

The increasing demand for new technologies in the ironmaking/steelmaking field has been motivating several studies towards pelletizing process improvement. Within this context, the coal adding technique, aiming the iron ore self-reduction, constitutes a promising approach for optimizing this process, besides the environmental engagement. This paper aims the metallurgical and mechanical characterization of iron ore pellets incorporating biomass coal obtained from sugarcane straw burning in their composition. With this purpose, three experimental procedures are of concern as follows. Firstly, the volume growth of the pellets is measured using a dilatometer, which heats the samples up to high different temperatures, ranging from 1373 to 1633 K. Then, each sample is cooled back to room temperature and undergoes a microstructural characterization, with the aid of a scanning electron microscope. At last, the compressive mechanical strength of the pellets is evaluated, using a strength-testing machine. The results indicate that the coal adding - rich in Carbon - reduces the necessary temperature for sintering, decreasing the heat input and, consequently, lowering costs. This behavior is due to the fact that Carbon reacts with Oxygen arising from gas for lower temperatures compared to the conventional pure iron ore pellets.

Highly metalized and virtually free of impurities, ore-based iron metallics (OBM) are ideal supplements to steel scrap for making various grades of steel products in the most economical way. OBM is the collective term for metallic charge materials made by processing iron oxides. These include pig iron, hot briquetted iron (HBI), direct reduced iron (DRI), and iron nuggets. OBM, especially pig iron and HBI, are often shipped considerable distances from where they are produced to be used in a variety of melting vessels.<br />This presentation will introduce the physical and chemical characteristics of OBM and will show where merchant pig iron and HBI, the two most widely traded OBM, are produced. HBI, a physically enhanced form of DRI created particularly for the merchant market, will be described in some detail in order to better understand its similarities and differences with DRI and how each is best used.<br />A review of the benefits of using OBM and a few words about the International Iron Metallics Association (IIMA) will be included in the presentation.

To examine in detail the special features of the structure of the T-x-y diagrams with the immiscibility of the liquids, which are given in the literature sometimes with the inaccuracies or even with the errors, the 3-dimensional (3D) computer models of T-x-y diagrams are designed. Some of them are formed either by binary systems with monotectics or have monotectic transformations in the ternary system (without the immiscibility in the binary systems). There are diagrams with the co-existence of three liquid phases, and also diagrams with the sintectic uni- or invariant transformation. They all are included in the electronic Reference book, which contains 3D models of the diagrams T-x-y: 1) with the continuous series of solid solutions; 2) with the uni- and invariant transformations, given by one, two or three binary solubility gaps of eutectic and peritectic type; 3) with the binary and ternary compounds; 4) with the allotropy of components in different temperature intervals; 5) with the immiscibility.
The diagrams of the topology, not described before, but discovered in real systems, are included also in the Reference book. Each computer model is the template of phase diagram, which is converted into the model of the real system if to introduce experimental parameters (concentrations and temperatures of binary and ternary invariant points, and also characteristics of lines and surfaces curvature).
For instance, the subsystem Cu-Cu2S is characterized by the co-existence of two immiscible alloys in the presence of the compound Cu2S: L1=L2+R4.
The invariant monotectic reaction L1=L2+A1+R4 takes a place in the ternary subsystem Fe-FeS-Cu2S-Cu at 1074 C, and the immiscibility gap intersects the curve of the co-crystallization of the compound Cu2S and the intermediate polymorphous modification of iron gamma-Fe. Furthermore, another two invariant reactions L+gamma-Fe=Cu+Cu2S at 1070 C and L=gamma-Fe+FeS+Cu2S at 914 C take a place in the subsystem. The main innovation in 3D models consists of the construction of pseudo-fold on the solidus surface of the gamma-Fe modification. It is the directing of two ruled surfaces, it does not influence the smoothness of solidus and liquidus and solidus surfaces are topologically equivalent thanks to it.
The work was partially supported by the Russian Foundation for Basic Research (projects 14-08-00453 and 14-08-31468).

In many metal producing processes, a prereduction unit that will pre-reduce the iron and dry the raw materials will reduce the electrical consumption per ton of alloy. This is a technology often used in industrial HCFeCr production. This paper presents a theoretical analysis of the effect of different pretreatment steps on energy consumption in HCFeCr production with use of Jaccurici ore from Ferbasa. The actual steps are drying, preheating, evaporation of crystalline bound water and prereduction of iron and chromium oxides. By heating the raw materials to 600 °C and evaporating the water, the savings in energy consumption can be more than 20%. Preheating and prereduction require energy and the choice of energy source will affect the environmental footprint. Various means of preheating are discussed. To be sustainable, energy sources that are not otherwise used must be utilised. CO-gas from HCFeCr-production with Jaccurici ore has an energy content of more than 2000 kWh/ ton of alloy and is a possible energy source for pretreatment of the ores.<br />Heating and prereduction will change the physical properties of the raw materials and may, through this, further affect final reduction to alloy and thus chromium losses to slag. Prereduction of Jaccurici ore and its effect of further reduction are discussed based on results from small scale experiments with Jaccurici ore.

In the present day, rare-earths relevance has increased. Market and applications of rare-earths are discussed in detail. Praseodymium, Neodymium, Dysprosium and Terbium are in high demand for magnet fabrication. High-Efficiency Wind turbines for energy production require a large amount of these elements. The Europium price has decreased recently. Europium is usually in high demand due to its use in TV and computer screens. However, the replacement from CFLB - compact fluorescent ligh bulbs - to LED light bulbs reduced the need of Europium. There is significant oversupply of Cerium. Research and development should focus on new Cerium applications. Lanthanum has large applications in catalysis and batteries. Rare-earths can be extracted as byproduct of existing mines, for example phosphat mines that produce fertilizers. Heavy rare-earths as Dy and Tb can be obtained as byproduct of tin mines. As the price of rare-earth concentrate is very low, research should focus on more economic methods for rare earth oxide separation.

In this work, pyrometallurgical techniques were used to recover a portion of iron present in iron oxide form in slag of LD steelmaking process. Various reducing additions were tested in molten slag in pot, resulting in a significant recovery of iron with low phosphorus and sulfur content that enables reuse of this material as scrap in production and refining pig iron.

In this work, the reaction between an equimolar synthetic zinc ferrite sample and a mixture of CO - CO2 gases was studied to evaluate the effects of temperature and CO content. The temperature ranged from 1073 to 1373K, and the gas mixtures from 50% to 100% of CO. These tests were supported by physical, chemical, structural and microscopic characterizations of both, initial zinc ferrite generated in laboratory and the remained after reaction. It was observed that the temperature and CO content were the main factors affecting the zinc ferrite reduction. The maximum reductions indexes obtained in these experiments were 85%, for 100% CO at 1373K, in 105 min, and 52%, for 50% CO at 1373K, elapsed 105 min. The Apparent Activation Energies obtained in this study were 55.60 and 91.71 kJ/mol, for 100%CO and 50% CO-50% CO2, respectively.

The self-reducing pellets are a mixture of powdered iron ore and reducer. They possess kinetic advantages compared to traditional pellets. One of the disadvantages is the cold low mechanical strength and during thermal processing. In the papermaking industry, there are cellulose residues which are difficult to use in the paper production process. These fibers can reinforce the mechanical strength of the pellets and also serve as an aid in the reduction process. In the experimental part, pellets with 13% of Portland cement (standard sample) and pellets with the same amount of cement but with additions of 1, 2 and 5% dried and milling paper pulp will be produced. A cure time of 30 days in humid environment will be observed. Cold compression tests will be carried out. After heat treatment at 950 A° C falls test, cold and hot abrasion tests were performed. The reduction curves for each of the employed mixtures, as well as analysis by optical and electron microscopy (SEM) will be plotted.

For more than two centuries now the gas-solid smelting mode has been the dominant way to produce Iron from its ores, in the Blast-Furnace process. The main reason for this long lasting dominance was that iron-ores were found in nature as stones. By mid XX Century, stones got scarce so fine iron-ores had to be used. Because of the very nature of Blast-Furnaces smelting mode, fine iron-ores should be made into lump form to suit the size requirements of the Blast-Furnace burden. Producing artificial stones, thru high temperature sintering of fine iron-ores became common practice, followed soon by pelletizing of finer fractions usually resulting from concentration of poorer iron-ore reserves. The consequence of attaching to the historical smelting mode was that more capital and energy intensive steps had to be added to the road to steel. Nonetheless, in the other hand, charge preparation was key to improve the efficiency of Blast-Furnaces and thus sinter and pellets became classical burden materials. But the gas-solid mode is inherently a slow process since it implies the penetration of the reducing gas molecules into the solid stones of the charge. A high residence time results, what translates into the need of high stacks for the burden, hence the need for high strength coke. Coking plants, thus became part of the integrated complexes, adding even more capital and energy intensive units. In our century, the need to reduce CAPEX and OPEX in Steelmaking and an urge to abate its impact on the environment became clear. <br />This paper deals with the basics of Self-Reduction smelting mode and how and why it will change Iron making forever and for the best. Starting by a review of the well established cold bonded Self-Reduction agglomerates production ways and proceeding to a detailed thermo-chemistry analysis behind the extremely fast smelting capabilities of the built-in reactions within them, the paper proceeds to an explanation on why such simple reasons can slash CAPEX, OPEX and emissions in Iron making to unprecedented levels and, just as important, how and why existing Blast-Furnaces can be retrofit to accommodate to the self-reduction mode of reactions. Follows an in depth reflection on the raw-materials and supply chain opportunities the self-reduction mode brings about, when new logistics friendly products, out of this simple innovative mode, shall impact the Iron-Units supply chain and the very structure of the Mining and Steel business worldwide. <br />Keywords: Ironmaking

The present work originates from a cooperative research program linking PUC-Rio University and a Brazilian integrated steelwork company, dealing with the use of self-reducing agglomerates. Aiming the utilization of residues generated in the integrated steelmaking plant, several types of self-reducing briquettes were formulated. In this communication, a set of results obtained through two routes are presented: firstly, the briquettes solid reduction and their correspondent metallization, monitoring the composition of the exhaust gases in a CO gas line. Secondly, using a properly prepared and instrumented induction furnace, investigating the metallization degree and the effect on the melting steel temperature, after adding the briquettes into the induction reactor. The results showed the sustainability nature and the technical viability of both methods, i.e, the solid state recycling route and the use of composite briquettes as an alternative cooling material for steel baths.

The steelmaking industry in semi-integrated plants produces steel from ferrous scrap, using electric arc furnaces (EAF). Besides steel, this operation generates several solid wastes or by-products with low value. Among these wastes, there are some with high iron content, mainly composed of iron oxides, e.g mill scale and EAF dust, which increase the interest on recycling them in the plant where they originate. However, nowadays in Brazil most steelmaking solid wastes go to industrial landfills or for co-processing in cement industry. In light of that, the objective of the present work is to look for a solution to mill scale recycling, generated in semi-integrated steelmaking plants, inside its own productive process. Therefore, the proposed solution was to develop self-reducing briquette produced with mill scale and charcoal fines as reducing agent, aiming to use these briquettes as a minor part of electric arc furnace charge. Mill scale and charcoal fines were collected and characterized. The components were blend and molasses/CaO was used as binder. Self-reducing briquettes were made in an industrial rolling press machine. The briquettes were subjected to reduction tests carried out in laboratory scale, at temperatures of 1100, 1200 and 1260°C. The behaviour of briquettes in high temperatures was also qualitatively evaluated. The performance of briquettes and the results indicate the potential use of these self-reducing briquettes as part of electric arc furnaces charge.

A possible method of reducing the amount of the scarce and expensive alloying element dysprosium in the alloys used for magnet production is the addition of dysprosium by means of diffusion, from a dysprosium rich surface layer. In this study, the optimum parameters for dysprosium diffusion are discussed. The kinetics indicate that high temperatures of the order of 900oC are more suitable for this process. Models based on the Fick 2nd law are discussed. Some situations admit analytical solutions for the Fick equations.

Currently, the process of reduction of iron ore in blast furnaces has presented some disadvantages which are unwanted by environmental agencies. Some solutions for optimization of the process would be: using reducing sources with less carbon than coal; reducing raw materials and increasing the consumption of scraps and to reduce the energy demand of the reactor. A suitable proposal is the increasing for direct reduction processes, such as Midrex and Hyl. Aiming to solve these problems, the present work consisted to analyze the energetic profile of the shaft reactor and to suggest any changes in the feed charge, using computational simulation. A part of the feed charge used in reactor of type Midrex shaft was replaced by self-reducing pellets composed by BOF dust, pellet feed and biomass of elephant grass.<br />The thermogravimetric runs performed in TGA-DSC allowed estimating the kinetic constants for the different reactions for mixtures containing 15, 20 and 30% of carbon. At 1100°C it was found the biggest constant for step FeO Fe, 0,0258s-1. Simulation results showed a good agreement about the energetic reduction of the Midrex furnace and contributed to comprehend better the phenomena occur in shaft furnace suiting it to partial substitution of the current charge by self-reducing pellets.

The Direct Reduction processes are one of the most consolidated ironmaking technologies, particularly the DR shaft furnaces process, which amounts to more than 65% of the world DRI production. An important aspect is their low gaseous emission impact as compared with other ironmaking technologies, due to their top gas recycling feature, aiming to generate the reductant gases CO and H2 throughout the catalyzed reforming reactions between Natural Gas and CO2 or steam. Another significant technological aspect refers to the DRI carburization, which also plays a key role on the carbon process footprint, due to the electrical energy abatement on the further EAF steelmaking refining step. In this context, both the gas recycling and DRI carburization confer an undeniable sustainability differential to the DR shaft furnace process. The present communication deals with these issues, focusing the cooperative research programs between PUC-Rio University / Iron & Steelmaking Group and steelwork companies, ranging from experimental laboratories to applied mathematical models.
KEYWORDS: Direct Reduction; Ironmaking; DRI Carburization; Mathematical Models

The use of metallurgical slags in cement production depends on the phases presented in such slags, which are affected by changes in slag composition and in its cooling rate during solidification. In this work, slags with different compositions were melted and solidified in different conditions. The objective is to determine process conditions for obtaining phases that are known for their good cementations properties, such as amorphous phases and tri and di-calcium silicates.
Samples were characterized by quantitative X-ray diffraction for determination and quantification of phases and X-ray fluorescence for chemical composition. The microstructure of the samples was observed in SEM-EDS and the composition of each phase was also measured. The solidification of the slags was simulated in the FactSage thermodynamic software to analyze the solidification path and compare equilibrium and obtained results.
Slags with high amorphous phase were obtained for low basicity (CaO/SiO2 = 1.25) and Al2O3 content of 11% for cooling rates higher than 4oC/s . The phases formed in slags with higher basicity (1.4 and 3.8) are less influenced by cooling rate, and different silicates are obtained such as larnite, merwinite, monticellite, akerminate and gehlenite. For slags with basicity of 3.8 the phase RO, that is a solid solution of FeO, MgO, CaO and MnO, and free lime were observed. Both phases can cause expansion during cement hydration.

Metallurgical industries are one of the most intensive energy sector in the industrial activity. Most of the metallurgical processing is pyrometallurgical with intensive energy consumption and some of them are in big scale, such as iron & steel, aluminum, nickel, copper and zinc. Only these metallurgical industries represent around 8% of the total world energy demand. Most of the energy source is based on mineral coal with large impact for environment. In addition, the energy cost in these industries could be very high (higher than 70% of variable costs, for Ni and around 35-45% for iron). Sustainability of these industries relies on improving energy efficient use; recover of waste energy, alternative processes with lower energy consumption and alternative energy sources with lower environmental and economic impact. Recently, many alternatives are ongoing subjects for R&D and industrial implementation, but it deserves more reflection and efforts.

Carbothermic self-reduction of iron ore is known as a fast and reliable method to perform the solid state reduction of iron oxides by carbonaceous materials. Industrial processes already employ this technology, like Fastmet, ITmK3 and Tecnored, and the use of self-reduction agglomerates in the blast furnace has been proposed by some authors. On the other hand, the use of concentrated solar energy to perform several different processes has been extensively studied in recent years. In the present paper, some process routes that combine carbothermic self-reduction of iron ore and concentrated solar energy are analyzed. The proposed routes can easily incorporate different raw materials, like biomass, and some new technologies, like chemical looping combustion and solar hydrogen production, in order to achieve iron and energy production with low carbon consumption and low CO2 production.

Samarco is a Brazilian mining company, which produces iron ore pellets of high quality for the global steel industry. The production process is fully integrated and performed in two industrial units. The mixing step has a paramount importance so as to ensure the quality and final physical chemistry of fired pellets. In this study, a deep investigation was performed regarding the influence of the mixing stage over agglomeration process. The main objective was to evaluate the influence of the mixing process in the physical and chemical quality of the fired pellets. Based on that, a design of experiment (including different mixing times, binders, mixers, etc) was performed in order to find out the best set of parameters which will consequently impact the quality of the final product. The pellet feed and all the raw material (coal, limestone and binder) were collected in the industrial plant. Based on the experiment, pilot-scale tests were conducted to simulate the mixing, agglomeration and firing step (Pot Grate). The mixing efficiency was defined statistically comparing the values of chemical results of the material collected at different points of the samples. This mix was agglomerated in pilot disc, where the green pellet characteristics were compared. The firing stage was also carried out with the green balls, in order to get the best set of parameters. The information obtained from the study provided the best way of operation of mixers and generated information for future investment projects at Samarco.
Keywords: mixing, mixers, balling, pelletizing.

Ferrosilicon is produced by the carbothermic reduction of iron and silicon oxides in submerged arc furnace. The ferrosilicon smelting process is essentially a slag-free process. Iron and silicon are mainly end up in the liquid metal product and the alloy contains usually over 95% Fe and Si. The other impurity elements existing in the charge materials are distributed between the metal product and the furnace off-gas. There are always certain amounts of Al, Ti, Mn, Ca, Mg, P, B, ... impurities in ferrosilicon. The removal of impurities from ferrosilicon may be necessary for improving the quality of the product to fulfill the required specification for steel makers. Vacuum refining is a process candidate for treatment of molten ferrosilicon in which the volatile impurities are evaporated at the melt surface. In the present study, the behavior of different elements under moderate vacuum conditions at elevated temperatures is studied through the application of the vacuum-induction melting technique. It is indicated that impurities, such as P, Al, Mn and Cu can be removed significantly under vacuum. In contrast, the vacuum removal of Ti and B is impossible. Moreover, the mass transfer coefficients for the evaporation of the volatile elements from the melt are determined and they are compared with theoretical values.

Vanadium (V) and Niobium (Nb) are added in small quantities (0.01-0.1wt%) in High Strength Low-Alloy (HSLA) steels, or micro-alloyed steels, to obtain the desired mechanical properties through ferrite grain refinement and precipitation strengthening mechanisms by forming of the V(C,N) and Nb(C,N) particles.
During Submerged Arc Welding (SAW) of HSLA steels, or micro-alloyed steels, a considerable content of these micro-alloyed elements from the base metal (BM) passes through (dissolved) into the weld metal (WM) and during cooling of the weld pool, it occurs the formation of new precipitates (reprecipitation) of these micro-alloyed elements with different content of vanadium and niobium, whose acting effect in the microstructure and mechanical properties of the weld metal (WM) and heat affected zone (HAZ) is very complex and yet unclear.
The objective of this study was to determine the content distribution of vanadium (V) and niobium (Nb) across the welded joint during Submerged Arc Welding (SAW) of spiral line pipes. Three types of micro-alloyed steel were used, single micro-alloying with vanadium (V), single micro-alloying with niobium (Nb) and double micro-alloying with vanadium and niobium (V+Nb). The chemical compositions of the samples were determined using an Electron Probe Micro-analyzer (EPMA), JXA8900RL, Fa.JEOL.
The results of this research indicated that the content distribution of vanadium (V) and niobium (Nb) across the welded joint during Submerged Arc Welding (SAW) is inhomogeneous and with the decreasing tendency toward the weld metal (WM).

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