Abstract Biomass was the first material used as a fuel by humanity, being replaced by fossil fuels after the industrial revolution. With the growing of environment discursions and the effects of CO2 emissions, biomass has been gaining strength as a potential alternative to fossil fuels, especially for steelmaking, which is responsible for about 5 to 10% of all CO2 emitted. It is known that biomass, compared to fossil fossils, has a higher volatile content, high moisture and lower calorific value. On the other hand, it has a higher hydrogen content and lower sulfur content (important for the steel industry), in addition it is considered neutral in CO2 emissions. Torrefaction, heating biomass at a temperature between 200-280°C in an oxygen free atmosphere, is an interesting treatment to adapt biomasses for use in the steelmaking processes, mainly in the pulverized material injection into the blast furnace. PCI is an extremely important process for the production of iron in the blast furnace, due to its ability to reduce coke consumption and optimize the operation of the reactor. This article comes with the purpose of presenting a bibliographic review about PCI technique, torrefaction process, biomasses and its applicability in the steel industry. In addition, an economic and environmental analysis of the possible use of biomass in steelmaking processes will be presented. Results shows that the use of torrefied biomass in the injection process is interesting, generating savings of 10 dollars and reduction of 264kg in CO2 emissions per ton of hot metal, with a replacement of 50% of the coal used by biomass.

Abstract The present research is dedicated to analyzing the addition of sawdust biomass, which is a carbonaceous raw material that may be used in coal blends for the production of metallurgical coke, preserving the required quality, with lower cost. The quality of metallurgical coke may be determined by the efficiency of its chemical, physical and thermal functions inside the blast furnace. For the production of hot metal, any modification in the constituents of the raw materials may have a direct influence on the blast furnace productivity and in the final quality of steel. From the thermal degradation analyzes such as coke reactivity index (CRI) and coke strength reaction (CSR), cold resistance (DI) and immediate analyzes, it may define the quality of metallurgical coke produced with biomass aiming at relating the parameters that interfere in the particularities of the material function in the blast furnace. Some results show that it is possible to use 2% of eucalyptus sawdust in the coal mixture.

RESUMO O compósito WC-10%Co também conhecido como Metal Duro de Carbeto de Tungstênico (WC) com Cobalto (Co) é um dos materiais mais produzidas pela indústria fabricante de metal duro, entretanto busca-se o melhor entendimento sobre o efeito de parâmetros de processo sobre as suas características estruturais, especialmente no que diz respeito à formação de fases metaestáveis – fases η. Neste trabalho, usamos o método de Rietveld aliado a difração de raios X (DRX), a microscopia eletrônica de varredura (MEV) e o Brunauer – Emmett – Teller (BET) para investigar a estrutura das matérias-primas utilizadas na produção de metal duro. Os tamanhos das partículas assim como as morfologias identificadas para os pós de WC e Co são reflexos do seu processo de fabricação que, introduzem tensões residuais para o pó de WC, a baixa cristalinidade e significante parcela de amorfo para o pó de Co. Estas características foram identificadas com a difração de raios X em comparação com o padrão de difração obtido e os bancos de dados cristalográficos. Após o processo de mistura dos pós foram quantificadas as fases e identificados os efeitos desse processo sobre as células unitárias de cada fase. Este trabalho mostra que a rota de caracterização empregada, com o uso do método de Rietveld, é eficiente para analisar a estrutura desses materiais durante seu processamento. Foi possível observar que o processo de mistura utilizando equipamento de moagem de alta energia promove alteração na densidade das células unitárias do WC “empurrando” átomos de Co para dentro de sua estrutura. Isso pode vir a acelerar o processo de dissolução de grande parte das partículas de WC durante a sinterização, contribuindo para a formação acentuada das fases metaestáveis eta – η, prejudicando o equilíbrio entre as propriedades mecânicas de dureza e tenacidade à fratura tornando a ferramenta ou peça muito dura e pouco tenaz.

ABSTRACT The composite WC-10% Co is one of the materials most produced by the hardmetal fabrication industry. However, a better understanding of the effect of process parameters on their structural characteristics is sought, especially with respect to the formation of metastable phases - η. In this work, we used the Rietveld Method with X - Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Brunauer - Emmett - Teller (BET) to investigate the structure of the raw materials used in the production of hardmetal. The particle sizes as well as the identified morphologies for the WC and Co powders are reflections of their manufacturing process, which introduce residual stresses for WC powder, low crystallinity and a significant amorphous portion for Co powder. These characteristics were identified with XRD in comparison to the obtained diffraction pattern and crystallographic databases. After the powder mixing process, the phases were quantified and the effects of this process were identified on the unit cells of each phase. This work shows that the characterization route using the Rietveld Method is efficient to analyze the structure of these materials during their processing. It was observed that the mixing process using high energy milling equipment promotes a change in the density of WC unit cells by “pushing” Co atoms into their structure. This may accelerate the dissolution process of most WC particles during sintering. And contribute to the accentuated formation of metastable phases eta – η, damaging the balance between the mechanical properties of hardness and fracture toughness making the tool or piece very hard and not very tenacious.

Abstract The Brazilian ferroalloy industry faces a highly competitive scenario in the foreign market. Among the key factors to determine the price of its products, electric energy stands out as one of the main inputs. So, the possibility of energy being unavailable or having high prices causes a direct impact in the ferroalloy chain. On the other hand, the renewable energy market, especially the solar photovoltaic (SPV) energy shows extensive growth due to technological advances and recent regulation. Connecting both contexts, this study investigates a way to apply the great moment of the SPV energy sector to the ferroalloys industry. Firstly, the ferroalloy sector data was searched in order to develop a model of ferroalloy production by using the average data of production and electric energy consumption, called model-ferroalloy. So an SPV power plant was estimated to supply its electric energy demand. It was considered in four different scenarios according to current law and its economic viability verified. From these studies, the viability of implementing solar photovoltaic energy to ferroalloys industry was determined. The levelized cost of energy (LCOE) comparative shows that SPV energy has a lower price than conventional sources, no matter if it is in the free or regulated energy market. Furthermore, the necessary investment, according to the results found, has good attractiveness in the financial market point of view.

Abstract Coal blend bulk density is an important property in the coking process. Some variables, such as moisture and particle size, which are controlled or measured in the coal beneficiation process in steel mills, exert a strong influence on this feature. This study aims to understand the density variation of coal blends by the influence of moisture and particle size when using dry and wet bases. The investigations showed that higher density can be reached when drying the coal blend or even with excess of moisture by an agglomeration process. However, for a coal blend of lower moisture content, such as 4%, the better effects on the coking process are evident. Changes on the density from particle size require care, since they can fall in a region of high density achieved by larger particles or in a region with excess coal fines, where either or both can compromise the coke quality.

Abstract The injection of pulverized materials is a technique used in most of the blast furnaces in the world to reduce coke and charcoal consumption. In addition, injection is one of the main variables of the blast furnace heat control. Coal is the most used material for the injection, but some industries have been attempting to use other materials, usually mixtures, in order to reduce the total dependence on it. The quality of the injected material influences some operational parameters, such as the permeability, the heat control, and also the quality of the hot metal produced. Due to these factors, the strategy and quality of these materials should be planned and evaluated using quality indicators to achieve good production, with low cost and environmental impact. In this context, there is a large number of researches on different materials, especially waste from iron and steelmaking processes, among others. Herein, some quality indicators of different materials tested on industrial and laboratory scales were analyzed compared, and the feasibility of using new materials injected into the blast furnace was discussed.

Abstract Pulverized coal injection (PCI) into blast furnace tuyeres is widely used by integrated steel mills worldwide to reduce the consumption of coke and costs. High injection rates are desirable. The big challenge is to achieve them with cheaper and lower quality raw materials, without losing the quality of the hot metal and the productivity of the blast furnace. An increase in the injection rate leads to improved fuel selection. Thus, it is important to have knowledge of the injected fuel quality variables that affect the burning efficiency and the replacement rate of the coke into the furnace, as well as the quality of the hot metal and the stability of the furnace. In this context, the present study is based on the chemical characterization and combustibility behavior of four fuels: Australian coal (CMA), North-American coal (CMN), charcoal fines (MCV) and green petroleum coke (CVP) and fuel blends. Results of chemical analysis show that the CMA, CMN, MVC and CVP are within the ranges of acceptable values in the PCI process for the ash and sulfur contents. The order of combustibility by thermogravimetric analysis was MCV>CMN>CMA>CVP. However, the combustion rate obtained by the simulator test, performed under extreme conditions of short residence time and high temperature, presented a different order of combustion rate of MCV>CVP>CMA>CMN, which may be related to the mineral on char. The blend that presented the best burning efficiency was obtained for the composition containing 20%MCV+80%CVP, followed by blends containing 80 and 90% of CMA, respectively.

Abstract In order to increase competitiveness in the steel industry through reduction of the cost of coal mixtures and increase in the quality productivity of coke in the oven, this research was developed with the aim of increasing the bulk density through briquetting of low power coking coal using tar as a binding material. Initially an industrial scale double roller press was used to manufacture briquettes in the ellipsoid format. The physical properties of the briquettes were analyzed in relation to variation of the amount of tar and the curing time of briquettes. Through the process of coal briquetting using low amounts of tar, it is possible to obtain a fuel of greater density, greater use of soft coals, uniform granulometry and easy handling. The increase in the apparent density of coal through briquetting may reach 42.5%. The success achieved in these tests, through these briquettes, with good chemical and physical characteristics represents ease of production as well as economic gain and low investment when compared to other processes of charge densification in coke ovens.

Abstract The induration furnace is one of the most important devices in the pellet production system. It is responsible for ensuring the quality of pellets produced, since a high level of thermal energy is necessary to reach the physical properties needed. Therefore, the refractory lining performance is important to guarantee the quality of pellets and to avoid thermal losses. Minor failures in the refractory lining may result in serious damage, if it not previously identified and repaired. This article was written to explain a preventive technique to identify and repair such minor issues with the refractory lining before escalation. The use of this technique in the proper frequency may result in furnace life cycle extension.

The use of scrap tires in the coal blends is an alternative to reduction of coke production costs as well as mitigates the impact caused by tire accumulation in the environment. Tests were carried out on a pilot scale, with coal blends and waste tire in 4 levels and 3 particle sizes, in order to assess the impact on the produced coke quality, especially on the Strength after Reaction with CO2 - CSR and Drum Index (DI150-15). In addition, it evaluated the mechanical resistance to compression, punctual chemical composition by Energy Dispersive Spectroscopy (EDS) analysis beyond the carbonaceous matrix-tire interface by SEM microscopy. The results from the coking tests showed that addition of up to 3% of the average ground tire (20-30mm) with steel mesh, raised either as CSR DI150-15, making feasible added also from a technical point of view.

Ao contrário dos processos convencionais, onde são utilizados coque e hematita nos altos-fornos, combustíveis e minérios de ferro alternativos podem ser utilizados nos processos de fusão-redução, como carvão vegetal e finos de minérios de ferro a fim de produzir ferro esponja. . O uso dessas matérias-primas alternativas, através desses processos, pode amenizar os impactos ambientais e reduzir os custos de processos. Os conceitos da razão teórica de consumo de gás, a energia da redução do minério de ferro e os valores calóricos efetivos foram introduzidos primeiro. A razão de consumo de gás, na prática, e o consumo de gás, como unidade de redução na fusão-redução foram discutidos e calculados. A relação de carvão consumido e a variação da redução do minério de ferro no leito fluidizado também foram discutidos. A influência da pós-combustão no consumo de carvão no banho de minério no forno, como consumo de energia em diferentes combinações de quatro equipamentos foram calculados e discutidos.

In contrast, conventional processes use coke and hematite/sinter in the blast furnace, in SR processes, other alternative fuels and iron ore sources, like charcoal and fine iron ores, can be used to produce sponge iron. The use of these alternative sources, by SR processes, can reduce environmental impacts and lower production costs. At first, the concepts of the theoretical gas utilization ratio, the smelting heat of the iron ore and the effective calorific value of coal were introduced. Then, the reason for gas utilization ratio and its performance in the shaft as a reducer in the smelting process are discussed and calculated. The relationship between coal consumption and iron ore reduction in the fluidized bed are also discussed. Finally, the influence of post-combustion on coal consumption in an iron bath furnace are calculated and discussed.

A necessidade de aplicarmos as diretrizes ambientais no contexto produtivo de qualquer empresa é hoje uma realidade no cenário mundial. O beneficiamento e a comercialização de resíduos, em diversos seguimentos industriais, têm levado as organizações a uma nova ideologia sobre a questão do gerenciamento desses materiais, sendo que a geração de receita, através da reciclagem, tem contribuído para a expansão dessa prática. Carepa é um co-produto oriundo da oxidação da superfície do aço, quando submetido ao gradiente térmico ou à simples ação do tempo. No ramo siderúrgico, provém, basicamente, das operações de lingotamento contínuo e laminação. Carepas são óxidos de ferro, cuja disposição, em pátios de resíduos deve ser realizada, seguindo-se as normas ambientais pertinentes, visto que podem ser classificados como resíduos perigosos (Classe I, NBR 10004:2004). Entretanto há poucos estudos no sentido de se viabilizar sua reciclagem, agregando valor ao co-produto em questão. Nesse sentido, operações unitárias de secagem, peneiramento e briquetagem foram adotadas no processamento desse material. Caracterizações físicas e químicas permitiram investigar suas propriedades e potencialidades industriais, de forma a adequar os parâmetros ambientais, econômicos e produtivos às necessidades das empresas.

The concern to apply environmental rules within the productive context of any company is actually a reality in the worldwide scene. Waste improvement and commercialization in many industrial deals have led organizations to a new ideology about the managing of this material, where the increase of income generated by its recycling has much contributed to the expansion of this practice. Scale is a by-product, which arises from oxidation of the steel surface when it is submitted to a thermal gradient or simply to the action of time. In the metallurgical field, it basically derives from the operations of continuous casting and rolling. Scale are iron oxides whose disposal at wastes yards must be carried out following the pertinent environmental laws, since they can be classified as dangerous wastes (Class I, NBR 10004:2004). However, there are few studies towards its improvement so as to enhance the worth of the by-product in reference. In this context, drying, sieving and briquetting unit operations were employed on the material processing. Physical and chemical characterizations enabled investigation of their properties and prospective industrial applications, aiming to adapt the environmental, economical and processing parameters to the companies' requirements.

É bem conhecido o alto peso que o coque representa no custo final dos produtos, além do que as suas propriedades estão intimamente ligadas à performance dos altos-fornos. Portanto buscar uma qualidade do coque compatível com as necessidades do alto-forno e com o menor custo possível se transforma em uma tarefa difícil se não se dispuser de ferramentas que permitam uma correta seleção de carvões. O objetivo principal desse trabalho é desenvolver modelo de previsão para o DI - resistência mecânica do coque, através de análises estatísticas de dados industriais e coqueificação em escala-piloto. O modelo de previsão do DI representa 75,8% dos dados industriais, obtendo-se um aumento de precisão de 8,07 pontos percentuais em comparação com o modelo atual. Portanto o novo modelo desenvolvido mostrou-se adequado e pode ser usado como ferramenta para auxiliar a compra de carvões.

Coke has a major significance in the final cost of products. Besides, its properties are closely connected with the performance of blast furnaces. Therefore, seeking a type of coke compatible with the needs of the high furnace and at the lowest price may become a very hard task if it does not have the necessary tools available to accomplish a correct selection of coals. The main goal of this dissertation is to develop models for the prediction for DI - Coke Mechanics Strength and CSR - Coke Strength after Reaction, through of statistics analyses of industrial data and coking in pilot scale. The model for the prediction for DI represent 75,8% of industrial data, amounting to a precision improvement of 8,07% in comparison with the present model. Therefore, the new model has proved adequate and may be used as a tool to help the purchase of coals.

Alguns dados sobre a injeção de carvão pulverizado são mostrados bem como uma descrição do modelo de combustão de partículas com elevado gradiente térmico construído na Escola de Minas - UFOP. Usando misturas de três carvões, bem como pré-aquecimento de carvão, foi possível constatar que: o uso de misturas de mais de dois carvões bem como o seu pré-aquecimento podem ser duas técnicas a serem usadas em altos-fornos no sentido de melhorar ainda mais os rendimentos obtidos nos reatores que usam a técnica de injeção.

Some data about coal powder injection have been shown and one physical model, with high thermal gradient constructed at Escola de Minas-UFOP is described Using mixture of coal (3) and pre-heating of the coal some tests have been done, giving the conclusions below: pre heating of coal could be a good idea for improving the results obtained into the blast furnace, so mixture of more than two coals, not common practiced, could improve the combustion rate.

Esse artigo apresenta uma análise crítica da metodologia empregada para avaliação técnica rotineira de finos de minérios de ferro para sinterização, tanto por parte das siderúrgicas, quanto pelas minerações brasileiras, com base apenas no controle granulométrico e químico. Sugere-se a realização da caracterização mineralógica das partículas nucleantes, intermediárias e aderentes do sinter feed, visando à otimização do processo e à melhoria da qualidade intrínseca do produto, destacando os principais atributos que devem constituir a sua identidade microestrutural. Vislumbra-se, para os próximos anos, uma verdadeira revolução nos critérios que norteiam a análise técnica de minérios para os processos industriais de aglomeração.

This paper provides a critical analysis of the methodology used in Brazil for routine technical evaluation of iron ore fines used in the sintering process based uniquely on chemical and granulometric parameters. The mineralogical characterization of adherents, intermediates and nucleantes particles of sinter feed and the main attributes that should constitute its microstrutural identity have been highlighted. It should contribute a great deal to optimize the process parameters during the various stages of the sintering process as well as promote better intrinsic sinter quality. Based on these concepts, it is expected that in future years, significant criterias will be developed for technical analysis of iron ores fines used in agglomeration industry.