The use of alternative raw materials is essential for establishing a circular economy in the mineral and ironmaking sectors. Therefore, this study investigates the potential of lime sludge as fluxing material during pelletization and proposes an alternative route for the usage of waste. The pellets were manufactured with different binary basicity values (CaO/SiO2) (0.15-0.45) and bentonite (0.5-0.7 wt%) and fixed carbon (0.5-1.1 wt%) contents. The results demonstrated that lime sludge has significant potential for application in pelletization. Pellet quality was evaluated using drop number, mechanical strength, tumble index, porosity, and kinetic analyses. Pellets with the optimal composition using lime sludge withstood 3.6 drops/pellet, a tumble test of 1.57 wt.%, and a mechanical strength test of 214.83 kgf/pellet and exhibited a porosity of 31.28%. Lime sludge did not influence the reducibility of the iron-ore pellets. In the temperature range of 800-900 °C, the reaction was controlled by diffusion, with Ea between 179.89 and 233.10 kJ/mol.

Abstract Over the last decades, the capability of a desulfurizing mixture to remove sulfur has been widely studied. The hot metal desulfurization efficiency represents the percentage of sulfur removed from the bath and the development of parameters that predict the process efficiency is fundamental for selecting the best desulfurization mixture without the need for experimental tests. Therefore, this research aims to develop a new parameter to predict the hot metal desulfurization mixture efficiency, which was called the desulfurization factor (FDeS). Desulfurizing mixtures from CaO-Fluorspar and CaO-Sodalite systems were used for this purpose. The phases present in the heating of the mixtures at 1400°C as well as the liquid and solid percentage were determined by ThelmoCalc software. These data were used in the desulfurization factor construction. Experiments were carried out in an electric resistance furnace with mechanical stirring. Different mixtures from these systems were added in molten hot metal at 1400°C. Sampling was made to measure the sulfur content variation with time. It was possible to apply the desulfurization factor to the proposed mixtures and to determine the influence of the solid and liquid phases on the desulfurization efficiency.

Abstract Production cost reduction for the Electric Arc Furnace (EAF) technology is strongly dependent on the efficiency of the electrical energy being introduced into the metal bath. Besides EAF technology, the slag foaming process is currently applied to some other equipment for steel production aiming to save energy, productivity improvements, enhance the refractory service life and inhibit steel re-oxidation. In this way, this study involved the recycling options of Crushed MgO-C spent refractories removed from the EAF without complex and costly beneficiation, with emphasis on its application as a slag conditioner, since its composition presents high MgO content. The experiments were performed in a laboratory induction furnace and the temperature was controlled at 1700°C.The initial height of the slag was recorded and foaming briquettes added into the furnace. The experiments were carried out for 30 minutes. When the foaming process was finalized, an aliquot from the slag was collected to be analyzed by chemical analysis. Then, the metal with slag was tapped into a mold. The results indicated that the best viscosity was 0.39poise. The maximum height of foam formation was observed for a binary basicity greater than 1.2. The concentration of MgO in the slag is close to the saturation point.

The aim of this work was to study the use of slags to desulfurize cast iron. It was proposed to use alumina instead of fluorspar. In addition, marble waste was used instead of lime. Simulations applying Thermo-Calc® software were carried out in order to obtain the theoretical phases using thermodynamic data. Then, a comparison between theoretical data and experimental tests were performed. Cast iron was melted in induction furnace at 1550ºC. Slags composed mainly for CaO and Al2O3 were used to desulfurize cast iron. The results showed that the desulphurization reaction was favored when the liquid phase was increased. Furthermore, it was found that cast iron desulfurization occurs by top slag mechanism. Furthermore, the desulfurization tests showed a decrease up to 90.10% in the sulfur content to the mixture containing conventional lime and 87.25% to the mixture RMF15. The slags obtained from marble waste contained MgO, which it interfered negatively in the desulfurization yield. In addition, increasing the CaO particle diameter improved the desulfurization process. The desulphurization process more favored to particle size of 500-1000 µm.

Abstract The aim of this paper is to analyze mixtures of basic oxygen furnace slag and granite waste in order to produce Portland cement. X-ray patterns were carried out in both the basic oxygen furnace slag and granite waste. Then, mixtures were prepared to obtain the binary basicity of 0.5, 0.9 and 1.2. The mixtures were melted at 1500ºC. Two cooling steps were performed. The first cooling step was accomplished inside the furnace in order to determine the phases formed during the melting step. The second cooling process was carried out in water in order to obtain an amorphous structure. Images via scanning electrons microscopy and EDS spectrum were obtained for the mixtures cooling in water. The results showed that basic oxygen furnace slag contains a higher percent of CaO. A binary basicity of 4.6 was determined. The granite waste appeared as mainly a quartz phase. During the slow cooling step, silicates (akermanite and gehlenite) were formed. On the fast cooling step, amorphous structures were obtained. In addition, images obtained via scanning electrons microscopy showed glass structures. EDS spectrum indicated that the glass structures were composed for calcium silicates. Thus, the results suggest that mixtures using basic oxygen furnace slag and granite waste presented characteristics desirable for Portland cement production.

Esse trabalho tem como objetivo o uso da termodinâmica computacional no estudo de dessulfuração de ferro-gusa com misturas de CaO-Fluorita e CaO-Sodalita. As experiências foram realizadas com a adição de diferentes misturas a partir desses sistemas em ferro-gusa a uma temperatura de 1,400ºC. Os resultados do teste foram analisados e comparados com os obtidos pelo programa de termodinâmica computacional THERMOCALC. Através deste software, foi calculado o teor de equilíbrio de enxofre do metal, as fases sólidas presentes e a quantidade de líquido em cada uma das misturas dessulfurantes utilizadas no processo na temperatura de 1,400ºC. A termodinâmica computacional provou ser uma ferramenta eficaz para estimar a capacidade de dessulfuração das misturas.

This work aims at the use of computational thermodynamics in the study of desulfurization of pig iron through CaO-Fluorspar and CaO-Sodalite mixtures. Experiments were performed with the addition of different mixtures from these systems in molten pig iron at a temperature of 1,400ºC. The test results were analyzed and compared with those obtained by the computational thermodynamics software program THERMOCALC. Through this software, were calculated the equilibrium sulfur content in the metal, solid phases, and the amount of liquid in each desulfurizing mixture used in the process at a temperature of 1,400ºC. The computational thermodynamics proved to be an effective tool in predicting the desulfurization capacity of the mixtures.

O objetivo desse trabalho é estudar a redução dos óxidos de ferro e zinco contidos na poeira de aciaria elétrica (PAE), na forma de briquete, por um banho de ferro-gusa líquido com elevado teor de silício. A poeira de aciaria foi caracterizada através das seguintes técnicas: análise química, análise granulométrica, difração de raios X, microscopia eletrônica de varredura (MEV) e análise de microrregiões por EDS. Os experimentos foram realizados em escala de laboratório em um forno tubular vertical, com um fluxo argônio. Periodicamente, foram retiradas amostras do banho para a verificação dos teores de silício do banho. Os óxidos de zinco, ferrita de zinco e outros óxidos foram reduzidos, volatilizados e coletados pelo sistema de limpeza de gás, montado na parte superior do forno. Foi possível obter picos no EDS, que identificaram uma composição de, aproximadamente, 55,00% de zinco, além de conseguir reduzir o FeO pelo silício e carbono do ferro-gusa.

The aim of this work was to study the iron oxides and zinc reduction of from Electric Arc Furnace Dusts (EAFD), added in the form of a briquette with high silicon content present in hot metal bath. The EAFD will be. This study has begun with the EAFD characterization by chemical analysis, particle size determination, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) microanalysis. This study utilized a bench-scale equipment to melt the reactants. During this process, a flow rate of inert gas was kept above the bath. Bath samples were collected periodically and the total silicon content in the hot metal was determined by chemical analysis. Zinc oxide, zinc ferrite and other oxides were reduced, volatized and collected by a gas cleaning system (baghouse) located on top of the oven. It was possible to find peaks in the EDS with a composition of approximately 55.00 % zinc and reduction the FeO by silicon and carbon of hot metal.

Esse trabalho consiste na caracterização do resíduo de mármore, lama fina de aciaria e borra de alumínio, para averiguar a viabilidade técnica da utilização de tais resíduos na dessulfuração e desfosforação de ferro-gusa líquido. A caracterização desses resíduos foi feita através de análises químicas, granulométricas, difração de raios X e microscopia eletrônica de varredura (MEV) com micro análise por Espectroscopia por Energia Dispersiva de Raios X (EDS). A lama fina de aciaria apresenta um teor de FeO de 84,90%, o resíduo de mármore apresentou um teor de 61,5% de CaO e 33,9% de MgO e a borra de alumínio apresentou 36,5% de Al metálico e 62% de Al2O3. A granulometria do resíduo de mármore apresentou um tamanho de grão médio igual 42,810 µm. Já, na borra de alumínio, o tamanho médio foi de 101,803 µm. A lama fina de aciaria LD apresentou, em torno de 54,7% de sua granulometria, entre 0,15 e 0,075mm. Esses resultados apontam para a viabilidade técnica da utilização desses materiais na dessulfuração e desfosforação do ferro-gusa.

This paper involves the characterization of marble waste, steelmaking fine sludge and aluminum dross, to ascertain the technical feasibility of using these in the desulfurization and dephosphorization of hot metal. The characterization of these residues was done taking into consideration: chemical analysis, particle size, X-ray diffraction results and scanning electron microscopy (SEM) with Energy Dispersive Spectrometry (EDS) data analyses. The steelmaking fine sludge has a FeO content of 84.90%, the marble waste lodged content of 61.5% CaO and 33.9% MgO, and aluminum dross 36.5% of Al metal and 62% of Al2O3. The particle size of marble waste had of the average grain size equal to 42.8 µm, in aluminum dross the average size was 101.8 µm and steelmaking fine sludge showed around 54.7% of its grain size between 0.15 and 0.075 mm. These results indicate the feasibility of using these materials in the desulfurization and dephosphorization of hot metal.

Esse trabalho estuda a viabilidade técnica da fabricação de cimento com uma mistura de resíduo proveniente da serragem de blocos de granito e escória de aciaria LD. Para isso, foi preparada uma mistura desses materiais de modo que a relação %CaO / %SiO2 fosse 1,2. Essa mistura foi fundida e resfriada rapidamente em água. A amostra foi caracterizada e o difratograma de raios X mostrou um material amorfo e a presença das fases mineralógicas Akermanita e Gehlenita, as quais são consideradas como as fases mineralógicas ideais para a atividade hidráulica. Essa mistura foi adicionada ao clínquer para a fabricação de cimento. Com o cimento fabricado, foram feitos ensaios cujos resultados são apresentados e comparados com os valores obtidos para o cimento de alto-forno. Esses resultados indicam a viabilidade técnica da utilização da mistura na fabricação de cimento.

This article studies the technical feasibility of manufacturing cement agglomerated with granite block sawing waste and LD steel slag. The materials were mixed in order to maintain the relationship %CaO / %SiO2 of the mixture equal to 1:2. The mixture was melted and rapidly cooled in water. The sample was characterized and the X-ray diffractograms showed an amorphous material and the presence of mineral phases akermanite and gehlenite, which were considered ideal mineral phases for hydraulic activity. This mixture was added to clinker for cement production. The cement made with this mixture was tested for comparison with the blast furnace slag cement. These results indicate a technical feasibility for manufacturing cement with this mixture.

O objetivo desse trabalho é apresentar uma análise dinâmica da utilização de misturas à base de resíduo de mármore na dessulfuração de ferro-gusa. Na realização do trabalho, foram utilizados: resíduo de mármore, fluorita, cal e ferro-gusa. Foram elaboradas quatro diferentes misturas, que foram adicionadas em um banho de ferro-gusa a 1450ºC com composição conhecida. A quantidade de cada material foi calculada a partir de suas análises químicas e comparadas com uma mistura utilizada na indústria. Todas as quatro misturas foram utilizadas em experimentos com agitação promovida por um agitador mecânico. Amostras do banho foram retiradas através de amostradores a vácuo nos tempos de 5, 10, 15, 20 e 30 minutos e analisadas para verificar a variação de enxofre no banho com o tempo. Os resultados obtidos com as adições foram analisados segundo parâmetros termodinâmicos, sendo verificada a possibilidade de utilização do resíduo como agente dessulfurante.

The objective of this paper is to present an analysis of the use of residual marble mixtures in the pig iron desulfurization process. The study involved the use of: marble waste, fluorspar, lime, and hot metal. Four mixtures were made and added to a liquid hot metal - with known chemical composition - at a temperature of 1450ºC. The mass of each element was calculated from its chemical analysis and compared with an industrial mixture. All of the four mixtures used in the experiments were stirred by a mechanical stirrer. Samples were collected by vacuum sampling for times of 5, 10, 15, 20, and 30 minutes, and analysis was performed to check sulfur variation in the bath with time. The results were analyzed and they verified that it was possible to use marble waste as a desulfurizer.

Um dos pré-requisitos para o processo de tixoconformação de ligas, é que estas apresentem microestruturas globulares. Esse trabalho utilizou o método da deformação seguido por recristalização com o objetivo de determinar a deformação e o tempo mínimos necessários para completa globularização de duas novas ligas de Al no estado semi-sólido (ESS). Buscou-se, também, encontrar a deformação necessária para um máximo refinamento microestrutural. As ligas foram fundidas a partir de sucatas de latas de alumínio, acrescentando-se Si, até atingir 3,5% (Al3,5Si), e Cu para a outra liga, até atingir-se 4% (Al4Cu). As novas ligas foram laminadas com deformações variando de 5 a 30% e levadas ao ESS com tempo de encharque variando de 1 a 60 minutos. As microestruturas foram caracterizadas por microscopia ótica. Os resultados mostram que a deformação mínima, para promover total globularização, está entre 5 e 10%. Quanto maior a deformação mais refinada é a microestrutura, porém, a partir de aproximadamente 20%, é necessário melhorar as condições de conformação para impedir a formação de trincas.

One of the prerequisites for thixoforming processing of alloys is a globular microstructure. This study used a deformation followed by recrystallization methodology in order to determine the minimum deformation and time needed to complete particle globularization of two new aluminum alloys in semi solid state (SSS). The required deformation for a maximum microstructural refinement was also researched. The alloys were cast from aluminum can scraps, adding up to 3.5% Si (Al3,5Si) and the other alloy up to 4% Cu (Al4Cu). The new alloys were rolled with deformations ranging from 5 to 30% and taken to the semisolid state SSS with soaking time ranging from 10 to 60 minutes. The microstructures were characterized by optical microscopy. The results show that the minimum deformation to promote entire globularization is between 5 and 10%. The increase of the total strain refines the microstructure; however, from about 20% of strain, it is necessary to improve the conformation conditioning to prevent the formation of cracks.

As fibras cerâmicas se caracterizam por ser um material leve, com alto grau de pureza, baixo armazenamento de calor, baixa condutividade térmica, resistência a choque térmico e alta resistência à corrosão em altas temperaturas. Essas características levam a uma grande procura das indústrias mínero-metalúrgicas e de outros setores para revestimentos de distribuidores, muflas, fornos de aquecimentos, entre outros. Após utilização no processo, por perderem sua capacidade de isolamento, os resíduos gerados precisam de destinação. Esse trabalho enfoca, especificamente, resíduos de lã cerâmica e lã de vidro. Pelo fato de a composição das fibras cerâmicas ser rica em sílica e alumina, efetuou-se uma investigação acerca da atividade pozolânica das mesmas com a cal e o cimento, especificamente CPV ARI, CPII E32 e CPIII 32RS, para avaliação da perspectiva de reciclagem em possível incorporação no concreto.

Ceramic fibers are characterized by their light weight, high degree of purity, low heat storage, low thermal conductivity, thermal shock resistance and superior corrosion resistance in high-temperature environments. Such characteristics make them ideal in the coating of distributors, mufflers, heating ovens, inter alia, as highly demanded by the mining and metallurgical industries, among others. After use in the process of industrial production, generated waste will lose its insulation capacity and thus requires disposal. The present work focuses specifically on ceramic and glass wools. Due to the fact that ceramic fibers are aluminosilicate rich, we carried out an investigation relating to their pozzolanic activity with lime and cement, CPV ARI, CPII E32 and CPIII 32RS specifically, aiming at an evaluation of their recycling prospect for incorporation into concrete.

Esse trabalho estuda a viabilidade técnica do aproveitamento de resíduo proveniente do corte de granito para ajustar a basicidade (relação CaO/SiO2) da escória de aciaria LD, visando a sua utilização na fabricação de cimento Portland. Para isso, foram realizadas a caracterização química dos resíduos e a sua mistura e fusão, a fim de se obter uma relação CaO/SiO2 em torno de 0,9 e 1,2. As misturas fundidas foram resfriadas em água e ao forno. Nas amostras resfriadas em água, após uma análise por difratometria de raios X, constatou-se que estas se apresentaram, predominantemente, amorfas. Para as amostras resfriadas ao forno, que se apresentaram cristalinas, observou-se a presença das fases mineralógicas Akermanita e Gehlenita, as quais são consideradas como as fases mineralógicas ideais para a atividade hidráulica das escórias. Esses resultados permitem concluir que o ajuste da basicidade da escória de aciaria LD através da adição de resíduo de granito mostrou-se eficiente, indicando a sua viabilidade técnica para a fabricação de cimento Portland.

This study focuses on the technical feasibility of the utilization of waste from the cutting of granite to adjust the chemical composition of slag from steelworks LD, targeting the addition of clinker Portland cement. For this, chemical characterization of the waste, its mixture and fusion was performed, obtaining a CaO/SiO2 relationship of around 0.9 to 1.2 for the steelworks slag. We selected samples of the waste, mixed, melted and cooled in water and in the oven. Samples cooled in water, after examining with X-ray difractrograms, had been predominantly amorphous. For samples cooled in the furnace, which had vitreous, there was the presence of mineralogical phases Akermanita and Gehlenita, which is considered as the ideal stage for the mineral water activity of the slag. The adjustment of the chemical composition of the slag from steel works by the addition of waste granite was efficient, transforming the waste into a product that is the same as blast furnace slag and can be used in the manufacture of cement.

Esse trabalho apresenta os resultados obtidos com a confecção de briquetes a partir da granalha de aço presente no resíduo de rochas ornamentais. A granalha recuperada através de separação magnética foi caracterizada pelo método titulométrico, EDS (Espectrometria por Dispersão de Elétrons) e difração de raios X. O tamanho e a distribuição das partículas foram obtidos por microscopia eletrônica de varredura e análise granulométrica. O concentrado ferroso recuperado apresentou teor de 93% de ferro metálico. Os briquetes apresentaram resistência a verde para força até 1,02 kN e a seco para a força máxima de 3,59 kN.

This paper presents the results obtained with the production of briquettes from the steel grit found in the residue of ornamental rocks. The grit recovered by magnetic separation was characterized by titrimetric analysis, EDS (Electron Dispersive Spectroscopy) and X-ray diffraction for the analysis of iron concentration in the residue. The size and distribution of particles were obtained by the granulometric analysis method and scanning electron microscopy (SEM). The process resulted in a concentrate containing 93% metallic iron. The maximum load before fracture of the green briquettes was 1.02kN and of the dry briquettes was 3.59kN.

Esse trabalho tem os objetivos de caracterizar o resíduo de manta cerâmica, gerado no lingotamento contínuo dos aços, devido à diminuição da sua capacidade de isolamento térmico, e de estudar a viabilidade técnica da utilização desse resíduo na fabricação de argamassa. O resíduo foi submetido à análise química, difração de raios X e MEV e utilizado na preparação de argamassa. Foram feitas dosagens de 0%, 2%, e 6% em massa do resíduo, em substituição ao cimento, e realizado o ensaio de índice de consistência e compressão na argamassa. Dessa maneira, obtiveram-se resultados em três argamassas distintas. Os resultados indicam um aumento na resistência à compressão com adição do resíduo, em comparação com a argamassa-padrão, e o índice de consistência apresentou alterações pouco consideráveis.

The goal of this study is to characterize the waste of ceramic blankets used in the thermal insulation of the continuous casting machine, which was generated due to the decrease in the capacity of thermal insulation. It also investigated the technical feasibility of the use of this waste as raw material to produce mortar. The waste was characterized by chemical analysis, X-ray diffraction, and SEM. Proportions of 0%, 2%, and 6% of the mass of the waste were used in substitution of cement in the production of mortar samples. Samples were tested to obtain the consistency index and mortar compression tests. The results indicate an increase in the compression resistance with the addition of waste in comparison with standard mortar. The consistency index was not affected by the additions.