Felipe Fardin Grillo

Analysis of pig iron desulfurization with mixtures from the CaO-Fluorspar and CaO-Sodalite system with the use of computational thermodynamics

Esse trabalho tem como objetivo o uso da termodinâmica computacional no estudo de dessulfuracao de ferro-gusa com misturas de CaO-Fluorita e CaO-Sodalita. As experiencias foram realizadas com a adicao 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. Atraves deste software, foi calculado o teor de equilibrio de enxofre do metal, as fases solidas presentes e a quantidade de liquido 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 dessulfuracao das misturas.

Caracterização e adição de poeira de aciaria elétrica em 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.

Characterization of mineral wools obtained from ornamental rock wastes

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 1450°C 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 800°C and determine the liquid and solid content at 1400, 1450 and 1500°C. 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 800°C.

Evaluation of recycled MgO-C bricks and dead-burned dolomite fines in setting slag foaming in the electric arc furnace

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.

ESTUDO DA ADIÇÃO DE POEIRA DE ACIARIA ELÉTRICA EM FERRO-GUSA LÍQUIDO

This research aims to study the process of incorporation of the mass in final hot metal and volatilization mass contained in the electric arc furnace dust (EAFD), by addition in hot metal at a temperature of 1,400°C; 1,450°C and 1,500°C altering experimental conditions such as the percentage of EAFD to be added and the percentage of silicon in hot metal. Previously, the EAFD was characterized using techniques of chemical analysis and size analysis. After characterization, the EAFD to be added to the hot metal was agglomerated in the form of briquettes. The achievement of fusion experiments in laboratory scale was placed in a vertical tubular furnace with temperature control. A flow of inert gas (argon) was maintained inside the furnace during the experiments. The result of the sample EAFD volatilized shows that there is an increase in the zinc concentration when compared with the concentration of zinc present in EAFD “as received”.

UTILIZAÇÃO DE ÓXIDO DE BORO COMO FLUXANTE DE ESCÓRIAS SINTÉTICAS DESSULFURANTES

The global steel industry is facing a period of oversupply, thus companies need to reduce costs by improving processes and/or by using alternative raw materials. This work focuses precisely about this topic and seeks to replace the fluorite by another source of slag flux. In this paper, boron oxide was added to synthetic slags at 1600°C in a steel bath. Tests were carried out using 3%, 5% and 7% of boron oxide in the composition of the slag. The fusion was performed under an argon inert atmosphere in an electrical furnace with molybdenum disilicide resistance. Steel samples were removed periodically each 5 minutes until 25 minutes of the experiment. These samples were analyzed by an infrared spectrometer. The results showed the technical feasibility of boron oxide application as a substituent of fluorite.

EVALUATION OF CAST IRON DESULFURIZATION WITH SYNTHETIC SLAGS

The aim of this work was to study the use of slags to desulfurization of cast iron. It was proposed to use alumina instead fluorspar. In addition, marble waste was used instead lime. Simulations applying Thermo-Calc software were performed in order to obtain the theoretical phases thermodynamic data. Then, a comparison between theoretical data and experimental tests were performed. The cast iron was melting in induction furnace at 1550°C. Slags composed mainly for CaO and Al2O3 were used to cast iron desulphurization. It was observed that increasing liquid phase, the desulphurization reaction was favored. Besides, it was found that cast iron desulfurization occurs by top slag mechanism.

The influence of tundish heating and purging on inclusion formation

Steel with high cleanliness requirements require an accurate control of the non-metallic inclusions, such as its quantity, morphology, chemical composition and size distribution. The continuous casting tundish has a fundamental role in steel cleanliness, avoiding its reoxidation by air and ladle slag that retain inclusions, as well as aiding the removal of those same inclusions along the continuous casting (Sahai, 2008). To perform the study, IF steel samples were collected in RH at the start, in the middle and at the end of the continuous casting of the tundishs first heat in three different conditions of tundish processing, alternating between heating and purging. These samples had their inclusions characterized by MEV/EDS using the ASCAT (Automated Steel Cleanliness Analysis Tool) technology. The results showed that more than 90% of the oxide inclusions generated in that type of steel are Al2O3 and AlTi. It was also observed that there is an increase of steel inclusions originating from RH in the tundish and that area fraction and average inclusionary density decreases along the continuous casting in two of the processing conditions.

Assessment of the Addition of Electric Arc Furnace Dust in Hot Metal at Temperature of 1,350 °C

This research aims to assess the incorporation of mass of the electric arc furnace dust (EAFD) by addition in hot metal produced in a local foundry (1.78% Si) at a temperature of 1,350°C. The EAFD is from a steel mill producer of long steel. The EAFD was added in the form of briquettes. Previously, the EAFD was characterized using the following techniques: chemical analysis, size analysis, X-ray diffraction, scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) microanalysis. The achievement of fusion experiments in laboratory scale, took place in a vertical tubular furnace with temperature control. The fusion experiments to assess the incorporation of the EAFD mass used alumina crucibles. A flow of inert gas (argon) was maintained inside the furnace during the experiments. After cooling the furnace to room temperature, it was done the pig iron and the slag were weighed to do a mass balance to assess the efficiency of the experiments.

Evaluation of the Addition of Electric Arc Furnace Dust in Hot Metal Changind the Type of the Crucible

This research aims to assess the incorporation of mass of the electric arc furnace dust (EAFD) by addition in hot metal (1.78% Si) at a temperature of 1,400°C changing the type of the crucible. The EAFD is from a steel mill producer of long steel. The EAFD will be added in the form of briquette. Previously, the EAFD is going to be characterized using the following techniques: chemical analysis, size analysis, X-ray diffraction, scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) microanalysis. The achievement of fusion experiments in laboratory scale, is going to take place in a vertical tubular furnace with temperature control. The fusion experiments to assess the incorporation of the EAFD mass are going to use three kinds of crucibles. After cooling the furnace to room temperature, it will be done the hot metal and the slag weighing to do a mass balance. A flow of inert gas (argon) is going to be maintained inside the furnace during the experiments.