Abstract Fluorspar (CaF2) is the most used flux in hot metal desulfurizing mixtures. However, its use can cause refractory wear and environmental contamination, prompting research efforts to develop alternative desulfurizing mixtures. This study aims to investigate the replacement desulfurizing mixtures containing fluorspar by other desulfurizing mixtures containing a new flux developed without fluorspar named MIX. The influence of varying the mass of these desulfurizing mixtures, temperature, and stirring of the system on the efficiency of hot metal desulfurization was also studied. The desulfurization experiments were carried out in an electric resistance furnace, at a temperature of 1370°C. Hot metal samples were taken to measure the change in sulfur content in the experiments. FactSage 8.0 software, was used to determine the phases present in the desulfurizing mixtures, and these phases were correlated with the hot metal desulfurization efficiency. The efficiency of the desulfurizing mixtures was also correlated with the Desulfurization Factor. The results showed that desulfurizing mixtures containing fiuorspar are the most efficient mixtures. However, fluorspar-free desulfurizing mixtures containing MIX can achieve similar efficiencies with increases in mass, temperature, and system stirring. The results also showed that the most efficient desulfurizing mixtures are those with higher percentages of solid CaO and lower percentages of the solid phases 3CaO.SiO2 and CaS and, consequently, a higher Desulfurization Factor.

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.

RESUMO A durabilidade natural da madeira é essencial para a definição de seu uso, e essa propriedade pode ser potencializada com o tratamento químico adequado da madeira. Assim, o objetivo deste trabalho foi avaliar a resistência da madeira de Jacaranda copaia modificada quimicamente por acetilação a cupins e fungos apodrecedores. Cinco tratamentos experimentais foram avaliados: acetilação por 2, 4, 6 e 8 horas e um controle (não acetilado). A acetilação foi realizada por imersão das amostras de madeira em anidrido acético a 90°C. Amostras acetiladas e controle foram submetidas à ação de cupins xilófagos (Nasutitermes sp.) e fungos apodrecedores (Gloeophyllum trabeum e Trametes versicolor). O processo de acetilação aumentou significativamente a resistência da madeira de Jacaranda copaia ao ataque dos organismos xilófagos. Não houve perda de massa após exposição aos cupins da madeira em nenhum dos tratamentos de acetilação, enquanto na madeira controle a perda de massa foi de 9,5%. Em relação aos fungos em decomposição, ocorreu perda de massa em todos os tratamentos. Os tratamentos químicos mais eficientes foram os de acetilação por 6 e 8 horas, elevando a classe de resistência da madeira de Jacaranda copaia para altamente resistente.

ABSTRACT The natural durability of the wood is essential for the definition of its use, and this property can be enhanced with the proper chemical treatment of the wood. Thus, the objective of this study was to evaluate the resistance to termites and decay fungi of Jacaranda copaia wood chemically modified through acetylation. Five experimental treatments were assessed: acetylation for 2, 4, 6 and 8 hours and a control (non-acetylated). The acetylation was carried out by immersing wood samples in acetic anhydride at 90 °C. Acetylated and control samples were subjected to the action of xylophagous termites (Nasutitermes sp.) and decaying fungi (Gloeophyllum trabeum and Trametes versicolor). The acetylation process significantly increased the resistance of Jacaranda copaia wood to the attack of the xylophagous organisms. There was no mass loss after exposure to termites of the wood in any of the acetylation treatments, while in the control wood, mass loss was 9.5%. Regarding the decaying fungi, mass loss occurred in all treatments. Acetylation for 6 and 8 hours were the most efficient chemical treatments, increasing the resistance class of the Jacaranda copaia wood to highly resistant.

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 The objective of this study was to evaluate the efficiency of a preservative treatment with Chromated Copper Borate (CCB) in different concentrations and autoclave pressure time on the biological resistance of Eucalyptus urophylla x Eucalyptus grandis (called urograndis). Urograndis fence posts were submitted to industrial autoclaving in nine treatments as a function of CCB concentration and pressure time: 1.5% (30, 60 and 90 minutes); 2.0% (30, 60 and 90 minutes); and 2.5% (30, 60 and 90 minutes). Then the obtained specimens were submitted to an accelerated laboratory decay test. The industrial preservative treatment increased the resistance of the wood to decay and the concentration of 1.5% CCB and 30 minutes of autoclave pressure can be applied to treat urograndis wood without compromising its resistance to the attack of white-rot and brown-rot fungi.

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.

Abstract Phosphate capability (CP) and phosphorus partition ratio (LP) are usually used to evaluate the thermodynamic efficiency of dephosphorization slags with different compositions in hot metal pretreatment. However, these parameters are only useful in equilibrium conditions, and they are not accurate when they are used to evaluate slag efficiency in industrial processes. The current study evaluated the hot metal dephosphorization efficiency of different synthetic slags in experimental tests at 1400ºC. This evaluation was made by using CP and LP, and by the computational thermodynamic software FactSage 6.4. This software allows to calculate the amount of liquid and solid present in the slag, which directly affects kinetic reactions. Therefore, even the computational thermodynamic software calculations are from considering the equilibrium, which in these cases can be used to explain the kinetic behavior of the processes. The obtained results allow concluding that CP and LP are valid, but only when they are used for equilibrium calculations; and that they should not be used to measure slag efficiency in industrial processes. A parameter named Dephosphorization Factor (FDeP) was developed based on data determined by computational thermodynamics. It was developed to be related to the dephosphorization efficiency. The results obtained in the current study allow to conclude that the initial synthetic slags, which presented higher CaO activity value, higher liquid quantity and FeO activity, will be the most efficient ones. And allow to conclude too, that the higher the factor, the greater the slag dephosphorization 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.

As micro e pequenas empresas (MPEs) exercem papel importante para a promoção social, lastro de estabilidade política e força propulsora de desenvolvimento, e destacam-se na geração de empregos e distribuição de renda de um país, logo, deve-se estimular a continuidade dessas empresas. Por essa razão, mostra-se importante conhecer os aspectos que auxiliariam em tal continuidade. A existência de características comportamentais empreendedoras nos proprietários de empresas seria um facilitador da longevidade empresarial. Entretanto, são incipientes trabalhos que revelam a presença dessas características em proprietários de MPEs. Portanto, este artigo teve por objetivo central identificar se a presença de características comportamentais (CCEs) nos proprietários de MPEs do Vale do Mucuri e Jequitinhonha/MG é determinante para a longevidade dessas empresas. O estudo é empírico-descritivo, em que se utilizou questionário estruturado na coleta de dados, obtendo-se o retorno de 283 respondentes, sendo analisados por meio de estatísticas descritivas e análise discriminante. A amostra foi segmentada em três grupos de empreendedores categorizados pela longevidade das empresas, para aferir uma possível diferença quanto à presença das características, de acordo com a idade das empresas. Constatou-se que as únicas características que divergiram na discriminação dos três grupos de longevidade foram "Ser independente/autoconfiança" e "Relacionamento pessoal e liderança". Conclui-se que, a partir da percepção dos empreendedores, a presença da maioria das CCEs não estaria diretamente associada à longevidade das empresas, entretanto, pode colaborar para a longevidade das empresas, caso sejam refletidas nas ações dos seus proprietários. Logo, esta pesquisa fortaleceu os resultados de Petry e Nascimento (2009), uma vez que, tanto aqueles achados quanto as constatações pertinentes às empresas da mesorregião, se alinharam ao retratar que, mesmo as CCEs sendo sugeridas pela teoria como elementos bastante associados à longevidade, esse efeito não foi confirmado pelos testes empíricos. Ainda assim, os gestores devem cultivá-las, pois a literatura sugere que podem contribuir para o aperfeiçoamento das empresas.

Small Business (EB) play an important role for social promotion, ballast political stability and driving force of development, and stand out in job generation and income distribution of a country, therefore, should be encouraged to continue these companies. In this context, appears to be important to know the aspects that would assist in such continuity. The existence of behavioral traits in entrepreneurial business owners would be a facilitator of the same longevity. However, they are incipient works that reveal the presence of these characteristics in a MSE owners. From this, this paper had the main objective to identify the presence of behavioral characteristics attributed to successful entrepreneurs in the MSE owners do Vale do Mucuri and Jequitinhonha/MG. The study is empirical-descriptive, which used a structured questionnaire to collect data, obtaining the return of 283 respondents and analyzed using descriptive statistics and discriminant analysis. The sample was divided into three groups of entrepreneurs categorized by the longevity of companies, to assess a possible difference in the presence of the characteristics, according to the same age. We found that the unique characteristics that differed in the discrimination of the three groups were longevity "Being independent / self" and "Personal relationship and leadership." We conclude that, from the perception of entrepreneurs, the presence of most of CCE’s would not be directly associated with longevity of the businesses, however, can contribute to the longevity thereof, if reflected in the actions of their owners. Therefore, this research has strengthened the results of Petry and Nascimento (2009), since both those findings as relevant to enterprises of Mesoregion findings, lined in portraying that even the CCE’s being suggested by the theory as elements rather associated with longevity, this effect was not confirmed by empirical tests. Still, managers should cultivate them, because the literature suggests that they can contribute to the improvement of enterprises.

Las micro y pequeñas empresas (MPE) juegan un papel importante para la promoción social, la estabilidad política y el lastre motor del desarrollo, y se destacan en la generación de empleo y distribución del ingreso de un país, por lo tanto, deben ser alentados a continuar estas empresas. En este contexto, parece ser importante conocer los aspectos que ayudarían a tal continuidad. La existencia de rasgos de comportamiento de los dueños de negocios empresariales sería un facilitador de la misma longevidad. Sin embargo, son incipientes obras que revelan la presencia de estas características en unos propietarios de MPE. De esto, el presente trabajo tuvo como objetivo principal identificar la presencia de características de comportamiento atribuido a los empresarios de éxito en los propietarios de MPE do Vale do Mucuri y Jequitinhonha/MG. El estudio es empírico-descriptivo, que utilizó un cuestionario estructurado para recabar datos, obtener la devolución de 283 entrevistados y analizados mediante estadística descriptiva y análisis discriminante. La muestra se dividió en tres grupos de empresarios clasificados por la longevidad de las empresas, para evaluar una posible diferencia en la presencia de las características, de acuerdo con la misma edad. Se encontró que las características únicas que diferían en la discriminación de los tres grupos fueron longevidad "Ser independiente / yo" y "relación personal y el liderazgo." Se concluye que, desde la percepción de los empresarios, la presencia de la mayoría de los CCE de que no estaría asociado directamente con la longevidad de las empresas, sin embargo, puede contribuir a la longevidad de las empresas, si se refleja en las acciones de sus propietarios. Por lo tanto, esta investigación ha fortalecido los resultados de Petry y Nascimento (2009), ya que tanto los resultados como la correspondiente a las empresas de hallazgos mesorregión, forrados en retratar que incluso el CCE de que se han sugerido por la teoría como elementos más asociados con la longevidad, este efecto no fue confirmado por pruebas empíricas. Aún así, los gerentes deben cultivarlas, porque la literatura sugiere que ellos pueden contribuir a la mejora de las empresas.

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.

Este artigo teve por objetivo identificar a relação entre a longevidade de micro e pequenas empresas situadas na microrregião de Teófilo Otoni/MG, e as características comportamentais atribuídas aos empreendedores. No estudo utilizou-se questionário estruturado na coleta de dados, obtendo-se o retorno de 283 respondentes, sendo analisados por meio de estatísticas descritivas e análise discriminante. A amostra foi segmentada em três grupos de empreendedores categorizados pela longevidade das empresas, para aferir uma possível diferença quanto à presença das características empreendendoras. Constatou-se que, a presença dessas características estaria associada à longevidade dos empreendimentos, destacando-se a variável “ser independente/autoconfiança”, pois os resultados da análise discriminante apontam influência desta no tempo de existência das empresas. Esperava-se encontrar diferenças entre grupos, a partir da função discriminante, o que não ocorreu. Contudo, nos diversos estágios de maturidade dessas MPE’s, as características podem contribuir para o desempenho das empresas, se estiverem presentes nas ações de seus Administradores.

We aimed to identify the relationship between longevity of micro and small enterprises located in the microregion of Teófilo Otoni/MG, and the behavioral characteristics attributed to successful entrepreneurs. The study is empirical-descriptive, structured questionnaire was used in data collection, obtaining the return of 283 respondents, were analyzed using descriptive statistics and discriminant analysis. The sample was divided in three groups of entrepreneurs categorized by the longevity of enterprises, to assess a possible difference in the presence of the characteristics, according to age them. It was found that the presence of these characteristics would be associated with longevity, highlighting the variable "be independent/self-confidence", since than the results of discriminant analysis indicate the influence from this in the age of these enterprises. It was expected to find differences between groups, from the discriminant function, which had not occured. However, in various stages of maturity these small business, the characteristics can contribute to enterprises' performance, if present in the actions of their managers, even those in that informal structures are more present, their managers have low schooling, and that the region produces little economic wealth.

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.