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 The large amount of dust generated in electric arc furnace aligned with its chemical composition makes this dust a potential source of iron in the direct reduction iron process. Thus, the aim of this research is to investigate the reduction of pellets produced with electric arc furnace dust using hydrogen as the reducing agent. The kinetic investigation was examined applying the differential method. In addition, the influence of reducing gas stream and temperature in the reduction process were investigated applying the Forced Stepwise Isothermal Analysis technique. The temperature studied varied from 500 to 1000°C with isothermals in each 50°C. The reducing gas was a mixture of 10% of hydrogen and 90% of argon. Then, the product characterization was carried out via scanning electron microscope and X-ray analysis. A thermogravimetric test showed a mass loss of 42 wt% due to the reduction of iron and zinc oxides. Besides this, the reduction occurred in three steps: 550-650°C, 700-800°C, 850-950°C. Between 550-650°C, the reduction was controlled by a nucleation mechanism with an Ea of 41.1 kJ/mol. In the second step (700-800°C), a mixed control between nucleation and diffusion was obtained with an Ea of 89.1 kJ/mol. Furthermore, a crust of iron was formed around the pellet, which hindered the reducing gas diffusion into the pellet. In the third stage (850-950°C), the formation of a sintered structure was noted, which decreased pore volume. The internal diffusion of reducing gases was determined as the controlling mechanism, with an Ea of 130.9 kJ/mol.

Fiberglass/thermoset matrix composite present important properties, such as specific mass and mechanical strength, aiming to replace some engineering materials. However, its mixture of different materials transforms them into an environmental problem, due to the complex recycling process. The highlight is meeting the demands of environmental pressures and for establishing recycling mechanisms, the proposal is to study physical recycling processes, focusing on the microwave-assisted pyrolysis process and also recovering fiberglass. The results were: humidity around 3 wt. %; the average loss of mass around 68 wt. %; the tensile strength is reduced by about 76 % when a composite with recycled fiberglass is laminated, as compared to the use of virgin fiberglass. This work establishing the physical recycling mechanism and route for composite materials, identifying the thermal degradation processes, for thus applying them to other materials, still considered environmental issues, technically and economically making these materials manufacturing processes viable, as well as establishing a recycling route.

Abstract The feasibility of using common chemicals to separate plastics from waste electrical and electronic equipment (WEEE) by froth flotation is investigated. Plastic waste is one of the WEEE polluters and a separation is necessary to recycle it. The most common plastics in electronic industries are acrylonitrile-butadiene-styrene (ABS) and high impact polystyrene (HIPS). These plastics are difficult to separate due to the similar specific weights and to both being repellent to water. Froth flotation allows for separating particles by the differences in their surface characteristics by selective wetting agents. The common chemicals are ethanol and acetic acid to depress the plastics. The process with 20% weight of ethanol was able to produce a recovery concentrate of HIPS with 98% and ABS with 96%. The process with 40% weight of acetic acid produces a recovery concentrate of HIPS with 96% and ABS with 83%.

Abstract The study aimed to characterize the mineral wools obtained from wastes of the cutting step of marble and granite, in order to evaluate the possibility of their use on an industrial scale. Mixtures of marble and/or granite wastes were prepared in order to reach the chemical composition of rock and glass wools. The batches were melted in an electric arc furnace in laboratory scale at 1450ºC and casted with water, in order to obtain a higher cooling rate. Characterization work was performed in batches that formed vitreous material, and with superior incorporation of the residues: 11.7% and 14.6% of marble waste with glass wool and rock wool, respectively; 78.3% and 91.6% of an association of marble and granite wastes with glass wool and rock wool, respectively. Computational thermodynamics was used in order to obtain the main phases at 800ºC and determine the liquid and solid content at 1400, 1450 and 1500ºC. In addition, the materials obtained were characterized via chemical analysis using X-ray fluorescence, DTA, X-ray diffraction and SEM. The results indicate that the marble and granite waste are composed mainly of CaO (34.7 wt.%) and SiO2 (66.3 wt.%), respectively. An amorphous crystalline structure was obtained in all tests, indicating that this material can be used as an insulation material. The crystallization temperatures were determined around 800ºC.

One of the most studied deleterious phases in stainless steels is the sigma phase, due to its high potential to decrease the toughness and corrosion resistance of these steels. Eight samples of as-received cold rolled UNS S32205 duplex stainless steel were submitted to isothermal heat treatments at 850 oC during 10, 15, 30, 60, 120, 180, 240, and 300 minutes in order to study the precipitation kinetics of the sigma and chi deleterious phases. Several complementary microstructural analysis techniques were used to determine the volume fraction of the intermetallic phases, including optical microscopy and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Evaluation was made of the kinetics of isothermal formation of sigma and chi phases in commercial duplex stainless steels (UNS S32205). The results indicated two different mechanisms for sigma phase precipitation: sigma phase formed from the chi phase for shorter isothermal heat treatment times, and sigma phase precipitated at the ferrite-austenite interface for longer isothermal heat treatment times, using a temperature of 850 oC. The phase transformation kinetics determined using the JMA equation indicated that chi phase precipitation caused faster sigma phase formation.

Steelmaking slag and residues from granite cuttings are industrial wastes with considerable production, however limited applications. This work studied an inertization and recovery process of such wastes as raw materials into production of rock wool (i.e. a thermo-acoustic insulator with growing market). Several batches were produced aiming the chemical proprieties of a currently marketed rock wool. Mixtures were casted at temperatures of 1400-1500 °C, then quenched in water and also poured into a Herty Viscosimeter. Produced materials with thickness smaller than 500µm were characterized by chemical analyses, XRD, SEM, EDS and DTA. ThermoCalc software was used to simulate the cooling curves of rock wools. Results showed that incorporation of wastes does not affect the main qualities of rock wool, the thermal insulation and prevention of fire spread. Raw material batches of rock wools may assimilate up to 66% of granite waste, or 53% steelmaking slag, or 70% combining both materials.

Este trabalho visa estudar e caracterizar o desempenho de aditivos retardantes de chama não bromados em copolímero de ABS. Foram estudadas combinações de retardantes de chama, como: o polifosfato de amônio (APP), a melamina, nanopartículas de dióxido de titânio e argila organicamente modificada com sal quaternário de fosfônio. Os materiais obtidos foram caracterizados por ensaios mecânicos (resistência ao impacto Izod e resistência à tração), análise termogravimétrica (TG), avaliação da morfologia e ensaio de retardância à chama. Os resultados obtidos indicaram uma redução de cerca de 48% na velocidade de propagação da chama dos compósitos com APP/melamina/TiO2/argila organofílica, em relação ao copolímero de ABS puro.

This work presents a study on alternative systems to substitute brominated flame retardants used in ABS. Combinations of flame retardants without bromine were studied: Ammonium polyphosphate, Melamine, Titanium dioxide Nanoparticles and phosphonium salt modified Organoclay. The composites obtained were characterized by mechanical tests (Izod Impact and Tensile strength), thermal analyses, scanning electron microscopy and Flame Retardancy tests. The results indicated that the Linear Burning Rate of ABS was reduced ca. 48% when the APP/MEL/OMMT/TiO2 system was used.

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.

A tradicional produção de açúcar, associada à crescente produção de etanol, faz da indústria sucroalcooleira um dos principais segmentos da economia brasileira. As indústrias brasileiras de açúcar e álcool processaram cerca de 630 milhões de toneladas de cana em 2009, gerando, aproximadamente, 142 milhões de toneladas de bagaço. Este trabalho apresenta uma possibilidade de destinação para o bagaço da cana através da queima controlada associada à síntese de nanotubos de carbono (CNTs), materiais que possuem inúmeras possibilidades de aplicações tecnológicas devido as suas excepcionais propriedades. Foi utilizado o processo de pirólise a 1000ºC associado a um sistema catalisador, visando à recuperação dos gases gerados como matéria-prima para a síntese dos CNTs. As emissões gasosas foram analisadas por cromatografia e os materiais produzidos foram caracterizados com o emprego de MEV, MET, TGA e espectroscopia Raman. Os resultados mostraram que o uso do catalisador resultou na diminuição das emissões gasosas. Nanotubos de carbono com comprimentos de 10 a 40 µm e diâmetros entre 20 e 50 nm foram produzidos.

The traditional sugar production associated with the growing ethanol production makes the sugarcane industry one of the main segments of the Brazilian economy; together the Brazilian industries of sugar and ethanol processed about 630 million tons of sugarcane in 2009, which generated approximately 142 million tons of bagasse. This work presents an economically and environmentally viable solution for the bagasse disposal through the controlled burn associated with the synthesis of carbon nanotubes (CNTs), materials that have a wide range of potential technological applications due to its exceptional properties. The pyrolysis process at 1000°C associated with a catalyst system were used to recover the generated gases as raw material for the synthesis of CNTs. Gaseous emissions were analyzed by chromatography and the produced materials were characterized with the use of SEM, TEM, TGA and Raman spectroscopy. Results showed that the catalyst application resulted in the reduction of gaseous emissions. Carbon nanotubes with lengths of 10-40 µm and diameters in the range of 20-50 nm were produced.

O objetivo da pesquisa é recuperar os principais metais presentes em um lote com uma mistura de diversos tipos de pilhas e de baterias descartadas após o uso, lote obtido em um posto de coleta. Para esse estudo, o resíduo das pilhas e das baterias foi moído, reduzido em forno elétrico, submetido à separação magnética e lixiviado. A composição química, após a lixiviação, foi reproduzida em uma solução sintética, que foi submetida à extração por solventes e reextração sendo que as soluções obtidas, após as reextrações, foram utilizadas como eletrólitos. Manganês, cobre, cobalto e níquel são recuperados na forma metálica após um tratamento que inclui as etapas pirometalúrgica, hidrometalúrgica e eletroquímica. Estudos anteriores definiram os parâmetros das etapas pirometalúrgica, lixiviação e extração por solventes que proporcionaram separação mais seletiva dos íons metálicos que se pretende recuperar. A contribuição do presente estudo é encontrar um processo que trate de todos os tipos de pilhas e de baterias juntos e recuperar seus metais mais importantes, evitando, assim, a etapa de separação prévia das baterias. Os filmes foram analisados quanto à sua espessura e composição.

The research aims to recover the major metals present in a lot with the mixture of several types of spent batteries, obtained from a collection station. For this study, battery residue was crushed, reduced in an electric furnace, and subjected to magnetic separation and leaching. The chemical composition after leaching was reproduced in a synthetic solution, which was subjected to extraction by solvents, and re-extracted. The stripped solutions were used as electrolytes. Manganese, copper, cobalt and nickel were recovered in metallic form after a treatment that included pyrometallurgical, hydrometallurgical and electrochemical steps. Previous studies have defined the parameters of the pyrometallurgical steps, leaching and liquid-liquid extraction which provided more selective separation of metallic ions than was intended to recover. The contribution of this study is to find a process that involves all batteries types and recovers the more important metals, eliminating the battery separation step. Films were analyzed as to their thickness and composition.

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.

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.