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Nowadays, electronics industry is the leading sector in developing new technologies. These new technologies lead to cheaper products increasing the consumption. The lifetime of such products is relatively short and soon it becomes waste, known as electronic waste. Cell phone is a common electronic waste. This waste represents an interesting raw material, because it contains large amount of base metals, considerable amount of valuable metals and also those dangerous. In this work, the electronic waste was submitted to mechanical processing: initially the devices were separated into two categories, as year of release (2002) and disassembled manually. The printed circuit boards were milled below 1 mm and then submitted to density and magnetic separation processes. The fractions obtained during the mechanical processing were characterized by chemical analysis. Using mechanical processing it was possible to obtain metal fractions of 80 wt%. A leaching test was carried out to determine if a waste needs to be managed as a hazardous; so that, cell phone waste must be considered in the category of hazardous residue because the lead concentration was above the limit established by Brazilian Standards

The objective of this work was the evaluation of wear resistance of Ti-6Al-4V alloy after plasma immersion ion implantation (PIII) in different immersion times. The goal of this process was the modification of surface properties of the alloy to obtain better tribology properties. In this process, atoms can be injected on the material´s surface changing the mechanical properties in the region near the surface independently of thermodynamics variables, as solubility and difusivity. The samples were submitted to 120 e 180 minutes of implantation at 250°C in the three samples for each condition. The wear analyses were made by pin-on-disk process, where the lost volumes and wear coefficients were compared in the samples. It was observed the decreasing of attrite coefficient and the lost volume of the material during wear test. The implanted sample by 180 minutes has showed the wear coefficient 35.12% lower in comparison of the sample without treatment, and 11.09% lower in comparison of implanted sample by 120 minutes. It can be observed that the sample implanted by 180 minutes showed lower wear coefficient.

Self-reducing tests were carried out under isothermal and non-isothermal condition in a muffle furnace, aiming to assess the reduction and melting of a self-reducing blend of mill scale and petroleum coke (85-15% in weight). The products obtained were analyzed by mass loss and wet analysis. Further investigations for the products from the non-isothermal condition were done by X-ray diffraction, nude eye inspection and carbon analyzer. It was observed that mass loss fraction and metallization degree are directly related and both increase with time and temperature. In the non-isothermal maximum mass loss was achieved in 8 minutes, reaching metallization degrees above 90%. It was observed that the reduction of iron oxide occurs mainly in solid state and the smelting of the samples is directly related to the iron carburization process. Thus, the use of self-reducing mixtures shows a possible way to recycle mill scale.

The effect of cooling rate on the occurrence of retained austenite in a low carbon Si-Mn steel, used for welding electrodes, is measured here by combining the sectioning of Jominy test samples with the measurement of retained austenite by X-ray diffraction. It was observed that the amount of retained austenite increases from zero, as the cooling rate is less than 0.8°C/s, and the structure is mostly ferrite, to a maximum of 6%, where the quantity of bainite is also maximum. This information guides the post-rolling cooling cycle when welding grade is been rolled. The hard phases proportionality with the amount of retained austenite allows, then, the use of X-ray diffraction as an end of the line equipment for quality control, and also permits simplification of heat treatment before wire drawing.

Aluminum cans with an organic coating are used in Brazil as packaging for carbonated beverages (soft drinks, beer), which act as electrolyte solutions. These electrolytes, in contact with the inner metal can, initiate a corrosion process of aluminum. The presence of metallic ions can change the flavor of the beverage, compromising the product quality. This work aims to evaluate the corrosion resistance of aluminum in beer environment using the technique of Electrochemical Impedance Spectroscopy (EIS). The Scanning Electron Microscopy (SEM) and the Energy Dispersive Spectroscopy (EDS) were used to evaluate the metal surface. Two batches with different coating thickness were analyzed for the same date of manufacture. The electrolyte resistance and the aluminum charge transfer resistance in beer varied depending on the batch analyzed.

The main iron ore processing plants in Brazil operate through reverse cationic flotation. Many studies have been conducted in order to improve flotation efficiency by optimization process variables. The pneumatic flotation cell stands out due to the simplicity to and to the intense contact particle/bubble promoted by the pulp feeding system. In this study, laboratory scale and pilot were conducted using a sample of itabirite iron ore. The objectives are evaluating the performance of this device using low grade iron ore, and drawing a comparison with laboratory scale tests on conventional flotation cell. The results indicate the potential application of pneumatic flotation cell to the ore tested. Adjustments in the feed particle size and process optimizations can be performed on the concentrate, reaching Fe and SiO2 grades used by the industry

In the present study, the characteristics of sintering of metal and overglaze in a single firing was verified. For that, it was collected 5 samples of overglaze from different glazing companies in the South region of Brazil, which were characterized by chemical analysis, coefficient of linear thermal expansion by dilatometry, and draining button (glaze melt flow) test. Then, the overglazes were applied in the as-received condition and after milling for 5 and 10 minutes; the powders were characterized by particle size distribution analysis. Overglaze layers mixed with gold powder were applied to ceramic plates with mass of 0.5 and 1.0 g, and sintering was performed at four different temperatures (800°C, 850°C, 900°C and 950°C) with 60 minutes firing cycle. Finally, the following tests were performed: visual analysis, light microscopy, colorimetry, and Mohs hardness. With the results of this work, samples with brightness and color characteristics close to the standard commercial product produced in multiple firings could be obtained. In the scratch resistance (Mohs hardness), the result was one point above the standard, indicating a better quality and durability of the material.

Iron ore exploited in Brazil can be classified into several lithological types which have distinct features. The progress of mining over time leads to scarcity of high grade iron ores, leading to the exploitation of poor, contaminated and compact ores. There is a growing trend of application of process flowsheets involving grinding to promote mineral liberation, essential condition for concentration processes. Several authors have correlated metamorphism processes of banded iron formations to mineralogical features observed on itabirites from the Iron Quadrangle, mainly the crystals size. This paper presents the implications of such variation in defining the mesh of grinding. Mineralogical characterization and grinding, desliming and flotation tests have been carried out with samples from two regions of the Iron Quadrangle subjected to different degrees of metamorphism. It was found a trend of reaching satisfactory liberation degree in coarser size for the itabirite of higher metamorphic degree, which has larger crystals. The flotation tests have confirmed the mineralogical findings.

Corrosion resistance and poor mechanical properties are both characteristics of AISI 316 austenitic stainless steel. Nitrogen supersaturated expanded austenite, or S-phase, promotes surface hardening of the alloy without the formation of undesirable that can reduce passivation properties. Mechanical characterization of this layer using instrumented microscratch tests gives an important set of empirical data useful for comprehension and modeling of tribological phenomena occurring in mechanical system. This work presents results from a series of instrumented microscratch tests performed on Low Temperature Plasma Nitrided (LTPN) AISI 316 stainless steel samples with an expanded austenite layer. The specimens were produced by 20 h active screen plasma nitriding treatment, done in direct current reactor at 400°C in an atmosphere containing three parts of nitrogen for one part of hydrogen (3N2 :1H2 ). The reduced friction coefficient (< 0,1) between the indenter and the expanded austenite layer observed in the initial stage of scratch test and the absence of adhesive failure along the test are also discussed.

The occurrence of dynamic recrystallization in the intermediate stands of the Finishing Mill of a Hot Strip Mill promotes substantial softening of the rolling stock, a situation that can cause operational problems and even scrapping of the strip. The aim of this work was to identify the specific process conditions that can lead to this situation, which was carried out through the application of a microstructural evolution model. It was verified, for the specific conditions of the Cubatão Works of Usiminas, that this problem generally occurs during the processing of thin hot coils, with a relatively low Nb content and under rolling temperatures slightly lower than the normal range.

Macaúba (Acrocomia Aculeata) is a palm tree typical of the Brazilian savanna with great socioeconomic interest due to its high capacity of vegetable oil production with high levels of fatty acids. This paper evaluated the technical viability of saponified macaúba’s nut oil (SMNO) as a collector in apatite’s micro flotation in Hallimond tube, being the oil chemically characterized and saponified before its utilization. Tests were performed varying the solution pH (8, 9 and 10) and collector concentration (2.5, 5.0, 7.5 e 10 mg/L). To compare the obtained results with SMNO the industrial collector Clariant’s Flotigan 5806 was used in the same tests conditions. Results shows that SMNO reached the highest recoveries rates of apatite in pH 8 and 9, particularly at the concentrations 7.5 and 10 mg/L. When compared to Flotigam 5806, the MNO showed lower recoveries at all pHs and concentrations tested.

The granite processing market is one of the most promising business areas of the mineral sector, with an average growth of the world production of about 6% per year. The granite extraction generates residues in the form of powder rock of 20-25 wt.% of the total benefited. The granite dust must be carefully managed since it can cause siltation of rivers and human health risks. This paper presents two routes for the final destination of this waste: the vitrification process aiming the production of fibers for thermo-acoustic insulation, and the magnetic separation in order to recover the steel grit. Results showed that the forms of treatments presented are economically and ecologically viable since they represent a cost reduction in the waste disposal, and also provide the production of new materials with commercial value.

Corrosion performance of Zr-based coating on substrates obtained by zinc electrodeposition in an alkaline bath is compared to chromate coatings (Cr III and Cr VI). The “nano Zr” is a conversion coating formed by immersion in a hexafluorozirconic acid solution. Since the “nano Zr” coating is transparent, the addiction of a colorant provides color to the surface. In this case, the colorant, when applied after the conversion coating, conferred the yellow color to the surface. The coating produced improves the corrosion protection of the substrate. For this study the samples were analyzed by electrochemical impedance spectroscopy (EIS) and accelerated corrosion test in a humidity chamber. The results showed similar behaviors between the “nano Zr”, colorant and the chromate (Cr III) coating. Therefore this kind of conversion coating is a promising substitute for chromate coatings.

This study has investigated how different methods and time of complementary hydration affects the cold strength of self-reducing pellets. Identical pellets had been made by the addition of pellet feed, coal, cement and lime and have been subjected to hydration by water immersion or in a moist chamber for different periods. A group of non-hydrated pellets was used as reference for evaluation the effect of hydration. The pellets were then characterized by mechanical tests of compression and tumbling strength. The results have shown an increase in the mechanical properties of pellets and have proved that the hydration by moist chamber was the most efficient method.

The aim of this paper is characterize printed circuit board of computers and propose a hydrometallurgical route for silver recovery present in its composition. Initially, the printed circuit board was comminuted in both knife and hammer mills. The comminuted material was characterized by sieve analysis, chemical analysis by inductively coupled plasma optical emission spectrometry (ICP-OES) and loss on ignition. Leaching tests were conducted in sulfuric acid, sulfuric acid in an oxidizing medium and nitric acid. The results indicated that the printed circuit board is mainly composed of copper (19.42%). Silver content of 0.045% was found. The route for silver recovery was leaching in sulfuric acid at 75°C for 18 hours. Then, leaching in sulfuric acid at 75°C in an oxidizing medium for 6 hours and nitric acid leaching at room temperature for 2 hours. Through of this route, 96.6% of silver was recovered.

Nanostructured zinc oxide (ZnO) was obtained by combustion synthesis in solution using zinc nitrate and citric acid. Morphology, weight loss, phase transformation and crystallite size were characterized scanning electron microscopy (SEM), thermal gravimetric (TGA) and thermal differential (DTA) analysis, and X-ray diffraction (XRD). The photocatalytic activity was evaluated by the degradation of a solution of methyl orange. We investigated the influence of different fuel/oxidant molar ratios in the microstructure and in the photocatalytic activity of ZnO. The results showed a higher crystallinity and photocatalytic performance for the products obtained with disabilities fuel in the reaction.

The phenomenon of particle size degradation of minerals due to decreptation is presented as source of fines. In the present work, a study of iron ores decrepitation by employing a system of thermal pretreatment of iron ore was carried out reusing exhaust gases from a mini charcoal blast furnace located in the state of Minas Gerais. The experiments were carried out in two periods of seven days each one, where in the first period the pretreatment system was deactivated and in the second period was activated. The results showed an improvement in the burden permeability by the reduction of the granules decreptation when it was used the thermal pretreatment, reflecting in a increasing of production.

The mining activities have a large environmental influence on areas direct and indirectly affected by this activity. The Permanent Protection Areas (APPs) noteworthy in terms of degradation from mine extraction. Among the acid rocks that compose the geology of Paraí-RS, the lower acid section shows horizontal structure failed where the rock slabs are extracted to produce stone-cut. Initially, the mining activity areas were bounded by Google Earth on Paraí-RS. After that, a new bound was proposed for the lower acid section. The APPs were bounded according to the National Forest Code of 2012. Finally, the zoning of the lower acid section was defined with feasible exploration, excluding the APPs overlapping the areas. The basalt mining activity represents about 1% of the territory of the Paraí-RS. Slightly more than half of this activity was in areas with Title Mining of National Department of Mineral Production (DNPM). Paraí-RS area is covered by 22% of APPs. Slightly more than 15 hectares of these areas were degraded by mining activities. The feasible areas for mining activities exploration represent about 13% of the Paraí-RS territory.

The generation of basic oxygen furnace dust is a problem that companies found in the steel industry. In this way, studies are important to obtain, or at least indicate a way to recycle this waste. The direct reduction can be an alternative, once this method produces rich in iron. Thus, the goal of this paper is study the kinetic of reduction of basic oxygen furnace dust pellet using a mixture containing hydrogen and argon. Thereby, the mechanism and apparent activation energy that involve the reduction can be found out. The kinetic analysis was carried out applying the Forced Stepwise Isothermal Analysis method. The temperatures used in the test were between 500°C to 1,100°C. The results showed that reduction occurred in three steps. In the first step, nucleation was the control mechanism. It was found an apparent activation energy about 24kJ/mol in this step. In the second and third stage, the control mechanism was diffusion. In the second step, the apparent activation energy was 54.9 kJ/mol, while in the third step the apparent activation energy was 80.7 kJ/mol.

Chalcopyrite leaching by ferric iron is considered a slow process with low copper recovery; a phenomenon ascribed to the passivation of the mineral surface during leaching. Thus, the current study investigated the leaching kinetics of a high purity chalcopyrite sample in the presence of ferric sulfate as oxidant. The effects of the stirring rate, temperature, Eh and Fe3+ concentration on copper extraction were assessed. The leaching data could be described by the shirking core model (SCM) for particles of unchanging size and indicated diffusion in the ash layer as the rate-controlling step with a high activation energy (103.9±6.5kJ/mol); likely an outcome of neglecting the effect of particle size distribution (PSD) on the kinetics equations. Both the application of the quasi-steady-state assumption to solid-liquid systems and the effect of the particle size distribution on the interpretation of kinetics data are also discussed.

Continuous casting is a solidification process, in which the knowledge about its variables is very important in order to produce steel with good quality. The tundish distributes the steel coming from the ladle to the metallurgical mold as the traditional function, besides, it also has some other important functions. Because of its importance in the process, this work aim to carry out studies on the steel flow in the tundish with two different configurations, with and without inert gas injection. A Computational Fluid Dynamic (CFD) software were used to make the mathematical simulations making possible to note the difference in terms of the Residence Time Distribution curves (RTD curves), levels of turbulence and velocity profiles with or without inert gas injection

The use of solar energy is growing sharply in the past years. The most used material for solar cells is high-purity silicon produced by refining low-purity silicon. With the increasing demand for photovoltaic components, new refining processes have been investigated. Carbon is one of the impurities to be removed and one possible removing technique is based on the settling of silicon carbide particles. Settling tests were carried out at 1,500°C during one and six hours. Results show that differences in settling time do not affect carbon removal significantly and that the carbon contents after settling are still higher than that required by standards for solar grade silicon (43 ppm). Results from this work and from literature show that settling is not a feasible processing step for carbon removal to the level needed for photovoltaic applications.

The need for microalloyed steels resistant to harsh environments in oil and gas fields, such as pre-salt which contain considerable amounts of hydrogen sulfide (H2 S) and carbon dioxide (CO2 ), requires that all sectors involved in petroleum industry know the factors that influence the processes of corrosion and failures by hydrogen in pipelines and components fabricated with microalloyed steels. This text was prepared from a collection of selected publications and research done at the Electrochemical Processes Laboratory of Metallurgical and Materials Engineering Department, Polytechnic School, São Paulo University. This document does not intend to be a complete or exhaustive review of the literature, but rather to address the main scientific and technological factors associated with failures by hydrogen in the presence of wet hydrogen sulfide (H2 S), particularly, when related to the Hydrogen Induced Cracking (HIC) phenomenon. This complex phenomenon that involves several successive stages, HIC phenomena were discussed in terms of environmental and metallurgical variables. The HIC starts with the process of corrosion of steel, therefore must be considered the corrosive media (H2 S presence) effect. Moreover, it is necessary to know the interactions of compounds present in the electrolyte with the metal surface, and how they affect the hydrogen adsorption and absorption into steel. The following stages are hydrogen diffusion, trapping and metal cracking, directly related to the chemical composition and the microstructure, factors that depend strongly on the manufacture of steel. The purpose of this paper is to provide the scientific information about the failures caused by hydrogen and challenge for the Oil and Gas Pipeline Industry.

There are concerns about the use of Nb microalloyed steels in the normalizing rolling of plate steels, as this thermomechanical treatment is finished at a temperature range where Nb(CN) precipitation can promote partial recrystallization of austenite. The aim of this work was to verify the effectiveness of Nb in retarding austenite recrystallization and to determine conditions under which Nb microalloyed steels can be processed through normalizing rolling fulfilling, as much as possible, the metallurgical recommendations proposed to this thermomechanical treatment, mainly the full austenite recrystallization between consecutive rolling passes.