INTL. SYMP. ON ADVANCED SUSTAINABLE IRON AND STEEL MAKING

The scarcity of coke has been long known to all the iron making units. Various attempts have been made to optimize the requirement of coke by developing alternative route for iron making, and alternative methods to meet the thermal requirement of the blast furnace iron making process. Most popular among these developments has been the development of coal injection in the blast furnaces at the tuyere level. In order to sustain Blast furnace route of iron making, cost and productivity need to be improved. Tata Steel has been practicing injection of coal in the blast furnaces at its Jamshedpur works since 1991. This paper describes the enhancement of injection rate at FBF with existing facilities from 150 kg/thm to 195 kg/thm.

Nowadays, one of the most important global issues in the steelmaking industry is the benefits of recycling or provision of the particulate wastes generated by blast furnaces, LD / BOF converters, and electric arc furnaces. Transportation costs, disposal in appropriate places, and increasing environmental constraints are demanding steel companies for ways to avoid, minimize, and / or properly treat their residues. Several solid residues in the form of slags, powders, and sludges emerge from reactor steel plants, such as blast furnaces, electric arc furnaces, converters, and Basic Oxygen /Linz Donawitz - LD. The chemical composition of these residues depends on the load fed to these reactors. This waste may contain: Fe, C, Ca, Zn, Pb and others hazardous elements, which can be reused in a sustainable manner [1]. The LD Oxygen Converter is the most common process for the production of steel in the world. Institutions, such as United States Geological Survey (USGS) and World Steel Association, noted that the Basic Oxygen Furnace LD/BOF produced 40% of the total steel from the USA (USGS, 2014) and 70% of the total steel produced in the world (World Steel Association, 2014) [2]. However, the production of steel through LD converters also generates a large amount of gaseous discharge of emissions which are collected through gas cleaning systems. This waste can be of two types: powders (dry material - BOF OG) and sludges (wet material - BOFS). The production of BOF OG can vary between 0.75 and 24 kg/tLS based on European Commission (Remus et al., 2013). The generation of BOF OG on average is 18 kg/tlS (American Iron and Steel Institute, 2001). In 2015, world steel production reached 78.8 thousand tons in the USA and 1620 million tons in the world (World Steel Association, 2016). According to information from the World Steel Association, in 2013, 626 thousand tons of BOF OG were generated only in USA and around 20 million tons worldwide[3]. In Brazil, about 80% of crude steel production comes from LD converters. In addition, this country had the great advantage of owing ore deposits with high iron contents and low contents of contaminants. In terms of environmental performance, LD steelmaking gas is very rich in CO, and is more suitable for the process of self-power generation. It is also necessary to develop other more noble ways of using LD steel slag, as well as the treatment of sludges and emissions containing powders [4]. In Peru, previous studies on characterization of sludges in LD steelworks have not been reported or published specifically in continuous form, as it had been with the characterization and treatment of electric arc furnace dusts (EAFD). This fact makes it novel and relevant, and through this complete characterization of both fine and coarse sludge samples of LD steelwork, this project will attempt to predetermine a sequence of carbothermic self-reduction treatments that may or may not add up to coal fines collected from other sources, in order to obtain high grades of iron metallization and controlled extraction/separation mainly in the form of vapor from metals such as zinc and lead [5, 6]. Therefore, the sludges of LD steelworks are important for their significant iron contents as well as its low phosphorus content, which can be reinserted into the production system for reuse [7]. Therefore, this waste accumulated by the Peruvian steel industry (especially the old sediments of LD converter) will tend to be reused in the steel plant itself, to give an added value to this material that until now is constituted as an environmental liability of considerable economic value. The experimental methodology in this work comprised the characterization of materials from a sludge site, mainly the coarse and fine sludges generated at a primary wet LD dedusting system. It is for this purpose, that the following were utilized: chemical analysis, Atomic Absorption, X-Ray Diffraction, Optical Microscopy-OM and Scanning Electron Microscopy-SEM, Scanning Thermal Analysis-STA, Differential Scanning Calorimeter-DSC, Thermogravimetric Analysis-TGA, Diferential Thermogravimetric Analysis-DTG, and physical properties such as specific gravity and average particle size. From these characterizations, the following technological routes were suggested: a) the production of coarse/fine residues composite briquettes, to be used as burden in ironmaking reactors; b) the production of coarse/fine self-reducing briquettes, complemented by a carbon resource in their composition, to be used as an alternative cooling material for the liquid steel temperature control and as burden in reactors demanding fast iron metallization.

Proper understanding and control of accumulation, drainage, and heat transfer of hot metal and slag in BF (Blast Furnace) hearth is essential for a stable and efficient blast furnace operation. Abnormal drainage behavior may lead to high liquid build up in the hearth. Operation problems are normally encountered if the liquid levels exceed a critical limit when hearth coke and deadman start to float. This not only causes sluggish or irregular descent of burden material, but also results in irregular casting intervals, damage to lining, low blast intake, and furnace pressurization. Similarly, hot metal temperature is an important parameter to be controlled in the BF operation; it should be kept at an optimal level to obtain desired product quality and a stable BF performance. Predicting hot metal temperature variation during the tapping process is extremely useful, since it gives a clear picture to the operator about the tapping operation and prevents any panic. At the same time, it allows the correction of process parameters in case of any major deviation. If the metal temperature is too high or too low, it may directly affect the process and cost efficiency of BF as well as BOF (Basic Oxygen Furnace) plants. Efforts have continuously been made for BF process optimization to improve its productivity, energy efficiency, environment, and product quality. The control of the hot metal / slag accumulation, drainage pattern, and tapping temperature is of great importance for optimizing the BF process and making it productive, energy efficient, and cost competent. Therefore, it is utmost important for furnace operators to understand the mechanisms governing the liquid flow, accumulation, drainage and heat transfer between various phases in BF hearth. As it's extremely difficult to carry out any direct measurement due to the hostile conditions in the hearth with chemically aggressive hot liquids, estimation, and simulation based on rules of physics and mathematical calculations, taking into account available operating parameters is the only viable solution. The objective here is to develop a mathematical model to simulate the variation in hot metal/slag accumulation and temperature during the taping of the furnace, based on: the computed drainage rate; production rate; mass balance; heat transfer between metal and slag, metal, and solids; slag; solids; as well as the various zones of metal and slag itself. [1,3,4]

In a previous publication at FLOGEN SIPS 2016, ORIEN Technology was introduced as a new technology that is compact, energy intensive and self-sufficient. It is also environmentally friendly with numerous advantages compared to the classical iron and steel production technologies.
In a subsequent paper at FLOGEN SIPS 2017, the basic physicochemical principles of this process were described. This included its special characteristics of direct liquid-state reduction of unique iron-ore cold-pressed briquettes which simultaneously achieve the reduction of iron ore out of the briquettes and convert it into steel. This process is performed in a single electric furnace unit and produces a unique iron melt of a special type in which the carbon exists in a non-equilibrium colloidal form that can be controlled to vary widely from 0.04% to 30%.
This paper describes various unique characteristics and advantages of this process in terms of energy saving, environmental protection, economy and steel quality.

Some metals, for example aluminium, and many rare-earths such as lanthanum and neodymium, are produced by electrowinning. Nowadays, the blast furnace is the typical process for iron and steel. However, through this process coal is needed, which generates pollution. It is possible to produce iron by igneous electrolysis, but there are also many problems. One of them is the high temperature of fusing iron, 1538°C. Thus, the process for iron is much more complicated than for aluminium, which melts at 660°C. Nevertheless, if electricity can be produced by renewable sources, such as solar and wind energy, iron production by molten oxide electrolysis can be economically feasible some moment in the future. Thus, the feasiblity of iron production by electrolysyis is directly related to the price of renewable energy. Solar and wind are intermittent sources, and energy storage is a big problem. But excess of energy produced on a windy day can be, for example, stored as a reduced metal, aluminium, or even steel. Excess solar energy produced during noon can also be stored as a reduced metal.

FLOGEN Technologies Inc. has implemented and commissioned FLOGEN CONTOP, a Design/Decision-Making/Control/Optimization/Automation System at various blast furnaces of pig iron producers in Brazil.
The system makes instantaneously a complete optimization of all raw materials including limestone, silica, air and oxygen volumes in order to achieve specific targets according to the needs of the company. The main achievements of the implementation of the FLOGEN CONTOP system were the increase of the pig iron production by about 10%, the decrease of total consumption of charcoal (breeze and fines) by about 5%, the increase of fines injected through the tuyeres, a better control of pig iron and slag temperatures, minimization of silica addition (less charcoal consumption), a better control of pig iron composition (mainly Si and P), and complete mass and energy balance.
The CONTOP system was also used to determine the annual procurement strategies and different scenarios and to determine raw material cost-based scenarios regarding productivity, fuel consumption and to develop specific useful scenarios for this purpose.
CONTOP increased productivity and reduced cost up to the highest designed limit of the technology. CONTOP also changed the way of operating from a reactive wait-the-lab-results-approach to a proactive forecast-and-act approach.

In the production of silicon, quartz is reduced with carbon in an arc furnace. During the selection of a plant site, key considerations include availability of high quality quartz, source of carbon such as charcoal and or low ash high reactivity bituminous coal, and wood chips. Quartz quality requires adequate thermal strength and impurities namely alumina, iron oxide and titanium. High alumina levels in quartz not only impact the silicon production but also require creative refining. The supplies of low ash coal suitable for silicon production are limited. Such coals are available in United States and to some extent in Europe. Charcoal is widely used in South America but not so in Europe and USA.
The furnace operating strategy depends on the raw material type, and size of the furnace. The operating strategy with coal and charcoal based raw material mix is discussed and recommendations are made for operating variables namely, furnace operating resistance and electrode current to complement the raw material mix. The size of raw materials and the fines content also has a significant impact on process efficiency. The furnace size also impacts process efficiency requiring attention to details with increasing furnace size. Typically the furnace efficiency drops as the furnace size exceeds 20 MW load.
Silicon refining process is a function of tap temperature, tap chemistry (with respect to Al and Ca), silicon flow rate, tap weight and the amount of slag from the tap hole. Taking into account the refining conditions, the refining strategy is discussed to increase in specification product and at the same time reduce scull losses and improve ladle life.

Coke is a fuel with few impurities and high carbon content. It is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Coke is the most important factor in blast furnace iron making, which provides heat, reactants, and mechanical support to burden, and accounts for more than 50% of hot metal production cost alone. In modern blast furnace operational practices significant efforts are made to decrease the costly coke consumption mainly by introducing cheaper coals in pulverized form through tuyeres. This alters the in-furnace aerodynamics, reduction conditions, burden distribution and demands on raw material, particularly coke, quality. Therefore coke quality such as its hot and cold strength, reactivity, composition, size fraction and granulometry etc. exerts great influence on the performance of blast furnaces. With increasing productivity & pulverized coal injection, the quality requirement becomes more and more stringent. This is due to the fact that ascending injection rates cause descend in coke unit per charge and the function of coke from being thermal, chemical and mechanical equally shifts to become predominantly mechanical. Hence, in order to maintain stable operation with higher rates of performance, it is important to have lowest possible degradation of coke during its travel from top to bottom of the furnace. This in turn demands proper understanding of the conditions coke has to face in the BF (i.e. effect of alkali, lime, other oxides, char/dust & reactions with surrounding gases) and mechanisms of fines generation & consumption in the blast furnace.
In this work, a study on the role of coke and its functions in traditional as well as modern high PCI furnace operations, has been made. The mechanisms inducing and affecting coke degradation have been investigated and correlated with the actual experience from one of the best blast furnaces operating in the world.

There are three different main opportunities on process improvement in industry, to obtain more profitable and sustainable results: the conceptual design phase of a new project, the optimization of an existing equipment and the troubleshooting on non-conformities. The manufactured products and industrial processes exhibit a great number of physical phenomena. Many of those phenomena closely relates to Physics of Fluids and associated solutions.
That engineering technique pays attention to the correction on the cause of non-conformities due to physical phenomena but never on its effects, reaching the intimacy of such processes, avoiding tedious and expensive trials and errors procedures.
The methodology employed consists on studying the physical phenomena, that govern all the fluid flow which occurs in a physical process, that operate in a market product or industrial process, regarding to one of the three opportunities of improvements. An extensive review of up-to-date data basis publications, on similar phenomena and associated mathematical model, present in advanced technologies such as Aeronautics, Space and Defense, as well as basic principles books [1 to 5] provide the scientific basis for the search on a suitable solution.
The final solution takes advantage on the understanding and correction of details present in fluid flow during CFD computer simulation of the physical processes, which involves its geometric characteristics and operational condition.
The following industrial sectors are using solutions provided by FEMTO: aeronautics, space, defense, appliances, energy, aluminum, oil and gas, pulp and paper, sugar and alcohol, food, petrochemical, plastics, personal products, health and glass, among many others.
The present work will explore several solution examples that improved both market products and industrial processes indicating the qualitative or quantitative gain obtained using mathematical modeling and high performance CFD simulation.

Presently, the production and consumption of DRI are continuously increasing, as a consequence of a specific condition of the NG market, generated for the economic impact assigned to the shale gas extraction technology. Considering this context, DRI can thus effectively improve the BF, EAF and LD converters' productivity and, consequently their competitiveness. In this work, the results of a cooperative research between PUC-Rio University and a Brazilian mining company are presented. Laboratory-scale simulation tests, using RD commercial pellets and typical industrial operational parameters of a bench market RD shaft furnace, were conducted and planned using statistical and factorial analysis. In the simulated experiments, the following three regions of the DR shaft furnace were considered: Reduction, Transition, and Cooling zones. Basically, three stages were considered in the research development: step one, which analyzed the reactions and equations concerning pellet metallization and carbon precipitation; step two, where the experiments focused essentially on the definition of the carburization kinetic equations occurring in the Transition and Cooling zones; and finally step three, which aimed to develop the "METCARB" computational program, conceived to mathematically simulate the metallization and carbon reactions along the height of the furnace. At last, an industrial case was presented in order to compare to the "METCARB" outputs.

Mechanical characterization of construction materials is a fundamental step to enabling reliable design. Globally, many standards in the field of mechanical characterization have been developed. With improving FEM simulations and material models, the local properties and anisotropies become very interesting, as they can be implemented in FEM simulations. However, data on local properties should be provided based on so fan no-standard miniaturized specimens providing information for specific locations/orientation to feed material models. With specimens downsizing there are consequently many issues, such as geometrical similarity between standard and miniaturized specimens and probably the main one, the microstructure. As the miniaturized specimens for engineering applications should still be related to bulk material behavior, some critical number of grains should be within the volume of the specimens gauge section in order to represent polycrystal behavior. This paper deals with the investigation of grain size influence on tensile behavior determined with the use on miniaturized tensile specimens with gauge section thickness of 0.5mm. Tensile tests are a very basic test in the field of mechanical properties characterization, and specimens downsizing can be seen in many papers nowadays, eg. (1-2). It has been proven that the performance of miniaturized tensile tests in comparison to standard ones is very good. In order to set the boundaries up to which it is possible to go regarding the specimens cross section and maintain comparability with standard sized specimens, the grain size influence is investigated here. Two steels with several different grains sizes are investigated here. Various grain sizes were obtained by heat treatment, resulting in a wide range of the grain sizes. Tensile tests of standard specimens and miniaturized ones are carried out on the investigated heats of steels for comparison. The results obtained here point out that very good performance of miniaturized tensile tests in terms of providing information on "bulk" material behavior can be achieved, even with very few grains over the specimen's thickness.

Understanding the behaviour of softening layer is very important to the control and optimization of the blast furnace operation, because the softening layer has a strong influence on the gas flow in the blast furnace. Futhermore, location and shape of softening and melting layer has a heavy relation to the wearness of refractories. For these reasons, prediction of the softening layer is considered to be an important subject for different sizes of blast furnace. In this study, mathematical modelling has been conducted. The first step of the simulation is the prediction of the solid flow, such as large or small sintered ore cokes using VOF (Volume of Fluid) model; the second step is evaluating the permeability of the burden distribution; and finally, the distribution of gas, heat transfer, and reaction between solid and gas phase are simulated using multi-domain coupling. The layered materials were explicitly considered not an averaged value such as Lo/Lc. Basically, different softening layers may relate to different burden distributions at the furnace top. In addition, the profile and productivity of blast furnace are strongly linked to the location and shape of softening layer. To understand and to evaluate the effects of the blast furnace size on softening layer shape and location, simulation approaches have been conducted with #1(1,660m3), #2(2,550m3), #4 (5,600m3) blast furnace in Pohang, South Korea. As the size of the blast furnace increases, the shape of softening layer changes from reverse-V to L or W. With reverse-V shape of softening layer, coke slits are vertically spread and it is able to distribute the reducing gas uniformly. However, the distribution of gas worsens with L and W shape of softening layer, because of thick coke slits at the lower and wall side softening layer.

Oxygen combustion technologies are lowering the production costs of many processes, since energy costs are continuously raising. Oxygen is used more and more in combustion systems technologies, like oxygen burners, oxygen lancing, or oxygen enrichment, in order to increase the capacity or conserve energy in particular furnaces, Oxyfuel is used to provide discrete oxygen rich areas in a furnace to allow complete combustion separately from a reducing zone or lower the emission volumes. This article analyzes the possibilities and the advantages of oxygen application in different furnaces used for steel production, based on Messer results and literature review.

The exhaustion of natural resources (quantity and quality) and CO₂ emission controls are becoming increasingly important in the steel industry. Several steel engineers studied various means to decrease the reducing agent at blast furnace for reduction of CO₂ emissions [1]. For example, the injection of waste plastics [2] and carbon neutral materials, such as biomass, into the blast furnace is a better alternative [3, 4]. In particular, biomass has the novel advantage of producing no CO₂ emissions, due to being carbon neutral. Production of carbon composite iron ore agglomerates that have good reducibility and strength is becoming one of the most important subjects [5].
Carbon composite iron oxide pellets using semi-char or semi-charcoal were produced from the measured results of the carbonization gas release behavior. The carbonization was done under a rising temperature condition, until arriving at a maximum carbonization temperature Tc,max to release some volatile matter (V.M.). Starting point of reduction of carbon composite pellet using semi-charcoal produced at Tc,max = 823 K under the rising temperature condition was observed at the reduction temperature TR = 833 K, only a little higher than Tc,max, which was the aimed phenomena for semi-charcoal composite pellet.
As Tc,max increases, the emitted carbonization gas volume increases, the residual V.M. decreases and, as a whole, the total heat value of the carbonization gas tends to increase monotonically.
The effect of the particle size of the semi-charcoal on the reduction rate was studied. When TR is higher than Tc,max, the reduction rate increases, as the particle size decreases. When TR is equal to Tc,max, there is no effect.
With decreasing Tc,max, the activation energy E a of semi-charcoal decreases. The maximum carbonization temperature Tc,max may be optimized for reactivity (1/E a) of semi-charcoal and the total carbonization gas volume or the heat value.

The Norwegian ferro-alloy industry is a world leader in sustainable production of ferro-silicon, silicon, and manganese alloys. Even if the industry is currently operating with very low specific energy consumption, there is a considerable amount of energy available in the off-gas from the submerged arc furnaces, both in terms latent heat and unconverted chemical energy. For FeMn production, the off-gas also contains mineral rich particles which are contaminated by tar and polycyclic aromatic hydrocarbon (PAH) components. The dust particles are currently removed from the off-gas and deposited as a wet sludge waste stream.
Results from recent experimental validation are presented for a new concept for off-gas processing, which enables an increased energy recovery and can facilitate future material recovery through production of tar and PAH free mineral dust. New results from a techno-economic evaluation of the concept will be presented, including ideas for material recovery from the currently unutilized waste stream. The overall objective is a maximized energy recovery and simultaneously prepare for a comprehensive reduction of waste streams.

There is a great diversity of minerals containing manganese. The important ones are psilomelane (Ba,H₂O)₂Mn₅O₁₀) pyrolusite (MnO₂), criptomelane (K(Mn⁺⁺⁺⁺,Mn⁺⁺)₈O₁₆), rhodochrosite (MnCO₃) and some ore with high content of iron oxides. For ferro-manganese production, the accepted reduction steps are gas/solid reaction to reduce higher oxides to lower ones (MnO₂> MnO and Fe₂O3>FeO) and at temperatures higher than around 1000°C gas/solid, solid/solid, liquid/solid and liquid/liquid reactions. The liquid/liquid and metal/slag reactions are the predominant ones at conventional Smelting Electric Furnace, for effective reduction of MnO>Mn at temperatures (~>1300°C) and it involves slag formation, dissolution of MnO in the slag, reduction of Mn++ in slag by carbon embebeded by slag or by slag/metal reaction by carbon dissolved in liquid Fe-Mn(MnxCy). The result is low production rate due to slow reactions. This paper analyzes some important effects from the characteristics of the manganese ores for ferromanganese production, such as: gangue and mineral compositions regarding the components that may form liquid phase during high temperature processing, impairing the rate of reduction of manganese ore-carbon composite. It may conclude that ores with high manganese content and low content of silica, iron oxide, (and others which may form liquid phase-slag at temperatures around 1350/1400°C) are prone to having better reduction behavior and consequently higher productivity and lower energy consumption.

Steel mill dust nowadays is a well-known secondary resource for zinc. Most of the companies treating this dust operate the established waelz process. However, even though it is known as best
available technology, it finally only recovers zinc and does not create any value out of the other metals contained in the dust such as lead, iron etc. Moreover, the waelz process generates huge amounts of new residues which become more and more difficult to landfill.
The often promoted concept of circular economy also requires a more efficient use of different resources to avoid the loss of raw materials.
With this even the waelz kiln operators have started to think about utilization of the resulting slags and an optimized use of the produced zinc concentrate which also includes lead. Beside this, new developments try to offer better solutions especially regarding the realization of zero waste strategies.
This paper discusses different options for a multi-metal recovery out of steel mill dust from the technical as well as economical point of view. Special emphasis is put on a development done at the University of Leoben. This so called 2sDR-process (two-step-dust-recycling) tries to combine two general aims, the recovery of different metals and the generation of a high quality zinc product and is currently undergoing the upscaling process to a pilot plant size.

Brazil produces important volumes of pig iron from domestic ores using various extraction technologies, and also has important current and potential capacities to produce pig iron in a sustainable way. In this paper, a detailed overview of the pig iron production in Brazil is carried out from the point of view of plant locations, their capacity and characteristics, the type of products and their specifications as well as the thermo-reduction agent used. Special attention is given to Minas Gerais and Espirito Santo states, which are the most important for pig iron production in the Brazilian Federation. A distinct part of the paper is an analysis of the use of charcoal as a thermo-reduction agent in the extraction technologies that produce pig iron, and its advantages compared to the use of metallurgical coke in terms of sustainability. The sustainability programs are specifically discussed, along with the current stimulus and barriers for the pig iron industry.

Foundries in Slovakia use imported pig iron, sorelmetal, and steel scrap for production of cast iron. There are more than 100% of price differences in these components. Composition of raw materials can greatly influence the costs of castings. The quality of a cast iron, usually expessed by values of mechanical properties (Rm, HB, E0), is closely related to its chemical composition (content of C, Si, Mn, P, S), eventually other monitored elements such as alloying elements (Cr, Ni, Cu, ...), and in some cases, pollutants (Pb, Sn, As, Sb, ...). The chemical composition is simply determined by the degree of saturation (Sc) or by the carbon equivalent (CE). Other factors that impact the quality of cast iron are the metallurgical conditions of production (melting and treatment) of cast iron, and the solidification speed in mould. Beside ordinary quality evaluation of cast iron, i. e. determination of Rm, HB, eventually chemical composition, or other required properties, in practice the quality criteria of grey iron are used. This is a comparison of the mechanical properties of produced grey iron with optimal values determined for the same degree of saturation (Sc). An important component of raw material is return material. Influence of raw material on cast iron properties with lamellar graphite (EN-GJL250) made from different percentages of charge material was examined in operating conditions of two Slovak foundries.

Primary resources nowadays show decreasing qualities regarding metal content and impurities. The alternative, to go for secondary raw materials like scraps and follow circular economy strategies, suffers from the often low availability of relevant scraps.
In parallel the question, how limited Europe is in allowing new technologies to utilize possible metal resources, becomes important.
In this context, a relatively new metal resource, by-products from metallurgical industry, have to be considered.
Due to the long history of Europe in metal industry, huge amounts of such materials are available. Nevertheless, also in this case the question emerges, if Europe is able to cope with its limits to use this potential metal source in an appropriate way.
The University of Leoben tries to realize an optimized use of various by-products combined with the development of a certification system, similar to procedures used in primary metallurgy to allow a better evaluation of by-products.

In July of 1967, an unexpected landing of a Vale's helicopter was the cause of the discovery of the minerals in the province of Carajas. The mines of Carajas, located in the Para State, are today among the biggest iron ore deposits in the world, that contain also manganese, copper and gold minerals. In 1985, Vale made its first transportation of iron ore through the railroad of Estrada de Ferro Carajas and exported it by shipping it out from the port of Ponta da Madeira.
Aided by the incentives given by the Brazilian Government and Vale to develop this region of Brazil, many companies from Minas Gerais state came to Para and Maranhao states and started producing pig iron using mini Blast Furnaces, Vale granulated iron ore, and charcoal made out of the sawmill wood residues that were previously exported. These factors created perfect conditions for pig iron production. As a result, the installed capacity reached more than 5 million tons of pig iron per year, and the production reached its peak between 2006-2008.
Today, less than 30 years later, only one company is producing pig iron for export, while only two others are producing pig iron to use solely in their own steel plants without selling it in the market. The questions of what happened with this boom and bust, and what should be done to remedy this situation remains unanswered. Did the pig iron production using Mini Blast Furnaces that was dominant in this area became unfeasible with high Capex and Opex? Can the production of pig iron resume in a feasible way? Can this be done through a new, more feasible technology that might able to replace the mini blast furnaces with lower Capex and Opex? In the latter case, what should be done with existing Eucalyptus forests planted by the pig iron producers to produce charcoal for mini blast furnaces? And in general: what does the future look like for this region of Brazil? This paper responds to these questions and proposes some solutions which are submitted for a wider discussion.

For obtaining clean steel, it is important to remove nonmetallic inclusions from molten steel by agglomeration or dispersion of particles. Cold model experiments were carried out by using polymethymethacrylate (PMMA) particles of 2.8m in mean diameter and 3.0 mol/L KCl solution as solid and liquid phases, respectively, and compared with the calculated results of newly developed mathematical models. Three kinds of mixing practices were examined: mechanical stirring by an impeller, gas blowing, and ultrasonic irradiation.
The PMMA agglomeration rate of impeller mixing explained by a turbulence agglomeration model was larger than that of gas blowing at the same energy input rate. By introducing a breakup model where the adhered particles on the bubbles were divided on the free liquid surface, the calculated results agreed well with the experiment. The ultrasonic irradiation promoted the dispersion of agglomerated particles, and the dispersion rate increased with the decreasing ultrasonic irradiation frequency and increasing electric power. However, as for impeller mixing, the dispersion proceeded at higher rotation speed and agglomeration occurred at lower speed. Based on the experimental results, mathematical models for ultrasonic irradiation and impeller mixing were developed, and the calculation of the temporal change in total number of particles agreed well with the experiment.

Viena Siderurgica, which is celebrating its 30th anniversary of operations in November 2018, is the largest pig iron producer and exporter in Brazil, with an achieved production of 401,917 MT in 2017 and an expected production over 500,000 MT in 2018.
The key factor of the company's success is the continuous investment in three sustainable directions: (a) biomass production, forestation, and reforestation, and its equal consumption of the forest for charcoal production in order to achieve a zero CO₂ balance ; (b) sinter plants that use the fines of iron ores and coke in order to minimise waste and increase productivity; and (c) power plants in order to effectively use the heat produced in the blast furnaces to produce electric energy that inputs in the public electric grid. The story of the company proves that investing in sustainability is also a key to survival and market success.