Abstract In Brazil, 65% of the electric power production comes from hydroelectric power plants (HPPs). In some cases, these power plants divert the course of rivers, resulting in regions impacted by the absence of water, which are known as reduced fow sections (RFS). These sections are regulated by legislation and aim to maintain the minimum fow necessary to preserve the fauna, flora, fish, and human consumption in the region. Depending on the time of year, this minimum flow, also known as ecological flow (residual flow), can reach significant values, resulting in the interruption of power generation in these HPPs. This article presents a study case of two hydroelectric power plants located in different Brazilian states. The objective of this study is to explore the feasibility of implementing auxiliary generator groups that can operate uninterruptedly at different drop heights while ensuring the preservation of residual flow during low flow periods or taking advantage of the overflow flow by spillways during high flow periods. This auxiliary system would use the same set of structures and transmission systems as the main power plant, minimizing environmental impacts and implementation costs, allowing this solution to be implemented in HPPs that face this type of problem in Brazil. The results obtained indicate that HPPs with larger reservoirs have a greater ability to maintain residual flows with minimal generation loss and that run-of-the-river power plants are the most impacted by the maintenance of residual flow. Brazil 65 . (HPPs) cases rivers water RFS. RFS (RFS) fauna flora fish region year , flow) values states plant costs runoftheriver run river 6 (HPPs (RFS

Abstract In the county of Pedra Lavrada - PB, various mineral occurrences of pegmatite are observed with prominence at Alto Dois Irmãos - PB, where quartz, feldspar and mica are mined. The understanding of mineral constituents is fundamental to define their industrial employment and to implement improvements in the beneficiation process. The proposal of this research is the detailed characterization and proof of that part of the ore (quartz) considered waste, presenting low poisoning (Fe2O3) and high silica (SiO2) content, to enable its industrial use. Besides that, to minimize the environmental impact through the reuse of this waste, and to determine the correct utilization of the milling equipment. For the pegmatite characterization, done were density determination tests, mineralogical identification by X-ray diffraction (XRD), chemical analysis by fluorescents X-rays and morphological analysis by scanning electron microscopy (SEM/EDS). Then tests were done for the Work Index (WI) calculous and consequently the empirical determination of the dimensions (LxD) of the pebble mill. The sterile presented a medium density of 2.66g/cm³, majority chemical composition of silicon and oxygen and quartz as the main mineralogical stage, indicating that this material has high purity. The. The Work Index (WI) was 15.9 kwh/t showing that this material can be considered resistant to breaking in the grinding process. The necessary energy to the milling was defined in 11.52 kwh/st, that corresponds to 57.28 HP. This power allowed the mill selection with diammeter and length of 1.83m, that provides the production maximization and the energy saving. PB mined process (quartz waste Fe2O3 FeO Fe O (Fe2O3 SiO2 SiO (SiO2 content use equipment Xray X ray XRD, XRD , (XRD) Xrays rays SEM/EDS. SEMEDS SEM/EDS . SEM EDS (SEM/EDS) WI (WI LxD (LxD 266gcm³ gcm 2 66g cm³ g cm 2.66g/cm³ stage purity 159 15 9 15. kwht kwh t 1152 11 52 11.5 kwhst st kwh/st 5728 57 28 57.2 HP 183m m 1 83m 1.83m saving Fe2O (Fe2O (SiO (XRD (SEM/EDS 266gcm 2.66g/cm 115 5 11. 572 57.

Abstract Nowadays, despite the implementation of new wind farms in Brazil, it still is difficult to form partnerships with companies in the sector, which significantly contributes to the gap in information provided by national literature and the lack of knowledge about the mechanical behavior of wind turbines subjected to transient wind effects. Therefore, through a Research and Development Project to optimize and improve modeling in wind systems, the Brazilian electric power company Eletrobras Furnas aims to facilitate the construction of smaller wind turbines to supply energy to regions far from the Brazilian coast that do not have high generation potential due to the incidence of low-speed winds. Two relevant aspects directly linked to the performance of this kind of structures are: (i) determining their natural frequency and (ii) ensuring that this frequency does not coincide with any external vibration frequency that the structure may experience in its lifetime. Wind turbines are complex systems with many degrees of freedom and their own frequencies associated with the respective mode shapes in which they naturally vibrate. These frequencies are inversely related to the mass and directly related to the stiffness of the structure. Thus, through numerical modeling using the Finite Element Method, the present article aims to list some of the main factors that can affect the prediction of the natural frequency of a real-scale wind turbine prototype and to evaluate its dynamic behavior, considering its rotor revolution frequency, its blade passing frequency and the wind characteristics of its operating area. Nowadays Brazil sector effects Therefore lowspeed low speed winds i (i ii (ii lifetime vibrate Thus Method realscale real scale area

Abstract Cornstarch is one of the most used depressants in mineral flotation operations. However, corn is a costly input for the Brazilian mineral industry, since its main destination is to serve the animal and human food market and exports. In this study, sorghum and millet, two cheaper starch sources, were tested in order to reduce the mining dependence on corn. A simplex lattice design mixture {3,4} was used to evaluate the best proportion of corn, millet, and sorghum flours to be used as a pyrochlore depressant in relation to the industrially adopted cornstarch (Stargill 6172 supplied by Cargill). Flotation tests were carried out on a bench scale Denver flotation cell. All tests were performed in triplicate in a single rougher stage. The results found suggest that sorghum flour was a stronger pyrochlore depressant compared to corn and millet flours, with an average Nb2O5 content of 1.72 ± 0.05% and recovery of 80.75 ± 4.10%. These values were close to the ones found with Stargill 6172 (1.32 ± 0.02 and 80.95 ± 1.13%, Nb2O5 content and recovery, respectively), the industrially adopted depressant. The marked price and the easiness in the production of the flour in relation to the extraction of starches makes the sorghum flour a potential pyrochlore depressant, replacing the industrially used cornstarch. operations However industry exports study sources 3,4 34 3 4 {3,4 617 Cargill. Cargill . Cargill) cell stage NbO Nb O Nb2O 172 1 72 1.7 005 0 05 0.05 8075 80 75 80.7 410 10 4.10% 1.32 132 32 (1.3 002 02 0.0 8095 95 80.9 113 13 1.13% respectively, respectively , respectively) 3, {3, 61 17 7 1. 00 807 8 80. 41 4.10 1.3 (1. 0. 809 9 11 1.13 {3 6 4.1 (1 1.1 { 4. (

Abstract A kitagohaite grain, measuring approximately 1.0 mm, was retrieved from an alluvial gold gravity concentrate from the southeastern Quadrilátero Ferrífero (QFe), Mariana, Brazil. The grain exhibits a cubic structure, whitish-steel-gray, and has a metallic luster. It is composed of Wt. 94.42% Pt and 5.56% Cu (n=9), yielding the empirical formula Pt6.78Cu1.22. This groundbreaking discovery marks the first documented occurrence of kitagohaite in South America. This hydrothermal deposition of kitagohaite indicates that its mineralization is constrained to temperatures <500º C, as inferred by the stability of synthetic Pt7Cu. 10 1 0 1. mm QFe, QFe , (QFe) Mariana Brazil structure whitishsteelgray, whitishsteelgray whitish steel gray, gray whitish-steel-gray luster Wt 9442 94 42 94.42 556 5 56 5.56 n=9, n9 n n=9 9 (n=9) Pt678Cu122 PtCu Pt6 78Cu1 22 Pt6.78Cu1.22 America 500º º C Pt7Cu (QFe 944 4 94.4 55 5.5 n= (n=9 Pt678Cu12 78Cu 2 Pt6.78Cu1.2 94. 5. (n= Pt678Cu1 Pt6.78Cu1. (n Pt678Cu Pt6.78Cu1 Pt6.78Cu

Abstract The flotation mechanism of galena with xanthate as the collector is generally explained based on the mixed potential of the pulp, in which an anodic electron transfer reaction from the collector to the mineral is combined with an O2 cathodic reduction. Sodium sulphide, often used as a mineral activator, strongly influences the pulp's mixed potential, and depending on the dosage applied, it can become a galena depressor reagent. In this way, the current study assesses galena flotability in the absence of collector, as well as in the presence of the collector potassium amyl xanthate (PAX) and sodium sulphide. The effect of an extremely cathodic potential was also studied through the addition of hydrogen peroxide. In addition, the effect of different stages in the oxidation of the galena surface on the flotability was investigated. Moreover, the zeta potential was measured and contact angle (wettability) tests were carried out. The contact angle measurements were taken for a distilled water, PAX solution and for a mixture of PAX and sodium sulphide solution on the oxidized and non-oxidized surface of galena. All the results showed that galena could be floated in all the PAX concentrations tested. It was observed that a moderate oxidation in the galena surface may contribute to an improvement of its flotation with PAX. However, extremely anodic and cathodic potentials cause flotability close to zero. The zeta potential results showed that sodium sulphide affected the interaction between PAX and galena. The measurements of the contact angle corroborated the results obtained in the microflotation tests. pulp O reduction activator pulps s applied reagent way (PAX peroxide investigated Moreover wettability (wettability out water nonoxidized non tested However zero

Abstract Recent events involving iron ore tailings dam collapses have emphasized the need for developing alternative ways of depositing tailings. This study aims to evaluate the effects of using three hydroxamates and a sulfosuccinamate as collectors in the direct flotation of iron ore tailings, using a bench flotation. The best result obtained on bench flotation was tested in a pneumatic cell. The sample used in this study (10.8% of Fe) consists of quartz and hematite. The Aero® 6494 Promoter hydroxamate showed the highest selectivity among the analyzed reagents, reaching 64.31% of Fe in the final product of the test with the < 150 µm sample. The possibility of using these reagents as constituents of a mixed collector with dodecylamine was also investigated. In this case, the Aero® 845 Promoter sulfosuccinamate yielded the best results, with 62.84% of Fe and 59.01% of metallurgical recovery of Fe. The synergistic effect between the two reagents might be explained by the stability of the monolayer formed by the intercalation of the ions from the dodecylamine and the Aero® 845 Promoter, which reduces the electrostatic repulsion between ions of the same species This mixed collector was tested in a pneumatic cell. However, it had a lower performance in terms of Fe metallurgical recovery than in a bench-scale cell test, mainly for the finest particles, due to the greater control of the process’s variables in the bench cell. 10.8% 108 10 8 (10.8 hematite Aero 649 6431 64 31 64.31 15 investigated case 84 results 6284 62 62.84 5901 59 01 59.01 However benchscale scale particles processs process s 10.8 1 (10. 643 6 3 64.3 628 62.8 590 5 0 59.0 10. (10 64. 62. 59. (1 (

Abstract A continuous increase in levels of atmospheric pollution and emission restrictions has forced scientists and engineers to adopt new strategies to improve and develop internal combustion engines. One strategy is based on the development of new simulation methodologies using computational fluid dynamic (CFD) techniques, proposed in the present article. In this study,the dynamic loop methodology with ANSYS Fluent code is proposed to perform the numerical simulation ofa four-stroke spark ignition engine. The complexity of the real case was first simplified with three-dimensional CAD geometry, which was then discretized in ANSYS Meshing, whereby a hybrid mesh was created using prismatic and tetrahedral elements. Simulations for in-cylinder analyses were performed in cold flow and employing common flow parameters, such as swirl and tumble. The mesh quality results were classified as good or excellent, being higher than 0.79 for orthogonal quality criteria and lower than 0.36 for skewness criteria. Turbulent effects were introduced concerning the opening and closing of the valves. It was found that the turbulence increases during the intake stroke up to 90°, and during the power stroke, wherein the of the piston bowl, had a great contributionthat can be seen from the swirl and tumble profile for the engine cycle. In the case of the turbulence intensity, a sharp increase was registered during the admission step up to 90°, at which point the turbulence intensity was 4.0. It canbe concluded that this is an innovative approach, capable of simulating the engine motion profile in cold flow. engines CFD (CFD techniques article studythe study fourstroke four threedimensional three dimensional geometry Meshing elements incylinder cylinder parameters excellent 079 0 79 0.7 036 36 0.3 valves 90 90° bowl cycle 40 4 4.0 approach 07 7 0. 03 3 9 4.

Abstract This article presents a formulation for the optimization problem that minimizes the CO2 emission of pile caps with variations of geometry and pile position. The problem is defined by the design variables: concrete pile cap dimensions, rebar ratio, concrete compressive strength, the number of piles, the diameter, and length. The environmental impact was chosen as the objective function, taking CO2 emission as the main parameter. The design procedure was based on the ABNT NBR 6118:2014 (2014), and by the formulation proposed by Blévot & Frémy (1967). Also, the soil structure interaction between the cap and the piles was considered in the optimization problem. The problem was implemented using MATLAB (2016) and solved via a Genetic Algorithm native to the program. Results obtained from numerical examples were compared with structural designs solutions located in the Grande Vitória metropolitan area, Espírito Santo, Brazil and validated with a commercial software. The analyses indicate that design optimizations of pile caps considering the compressive strength of concrete, the diameter and length of piles and the optimal geometry of the pile caps may lead to significant reductions of material consumption, and consequently, a reduction of environmental impacts. CO position variables dimensions ratio function parameter 61182014 6118 2014 6118:201 2014, , (2014) 1967. 1967 . (1967) Also 2016 (2016 program area Santo software consumption consequently impacts 6118201 611 201 6118:20 (2014 196 (1967 (201 611820 61 20 6118:2 19 (196 (20 61182 6 2 6118: 1 (19 (2 (1 (

Abstract Improving a technical work environment encourages creativity and enhances research efforts. The conception of a modular ventilation laboratory aims at free construction and assembly of the air circuit in different shapes, sizes, and operational variations. The modules allow the development of academic experiences, automatic data acquisition from sensors, data analysis, and verification of concepts related to ventilation in underground mines. The modular ventilation laboratory uses a teaching methodology based on a playful and low-cost way to teach engineering, mainly underground mine ventilation. The aim of this work is essentially to propose the creation of a modular underground mine ventilation laboratory to facilitate engineering teaching and allow the simulation of real situations. The Plan-Do-Check-Act (PDCA) methodology was used to develop a framework for building the modular educational ventilation laboratory. This methodology encompasses project planning and studying, applying the Ventsim® software, and the design of a teaching laboratory with sensors and microcontrollers using the Internet of Things (IoT). The results involve the construction of a physical project with PVC (polyvinyl chloride) pipes and connections and electronic circuits. The project presents the main parameters monitored in underground mines and foresees the simulation of scenarios, aiming to facilitate an understanding of the concepts of fluid mechanics and mining ventilation. The conclusions indicate that using simulation in pedagogical practices develops several activities that contribute to innumerable learning and expands the network of constructive meanings as a learning strategy. efforts shapes sizes variations experiences analysis lowcost low cost situations PlanDoCheckAct Plan Do Check Act PDCA (PDCA studying Ventsim software IoT. IoT . (IoT) polyvinyl chloride circuits scenarios strategy (IoT

Abstract This study evaluated the mechanical properties and the chemical and thermal characteristics of low-density polyethylene (LDPE) nanocomposites reinforced with graphene oxide for manufacturing via 3D printing. LDPE nanocomposites with different graphene oxide (GO) loadings (0.5% and 1.5%) were processed by a single-screw extruder. To characterize the pre-injected material, Fourier transform infrared spectroscopy (FTIR) and thermal characterization with thermogravimetry (TGA) were used. The injected material was also characterized with mechanical impact and traction tests. The results showed that incorporating GO into the polymeric matrix added hydroxyl groups to the matrix structure, with a 39.13% increase in Young's modulus for LDPE-1.5%wtGO samples. Mechanical tests of 3D printed samples showed that, with an increase in the amount of GO in the polymer matrix, the composite loses ductility, enabling its use in 3D printing technologies and thus encouraging new studies on printed materials for various applications. lowdensity low density (LDPE D (GO 0.5% 05 0 5 (0.5 1.5% 15 1 singlescrew single screw extruder preinjected pre FTIR (FTIR TGA (TGA used structure 3913 39 13 39.13 Youngs Young s LDPE1.5%wtGO LDPE15wtGO LDPEwtGO 1.5%wtGO wtGO ductility applications 0.5 (0. 1.5 391 3 39.1 LDPE1 15wtGO 0. (0 1. 39. (

Abstract Most of the dams registered on the National Information System on Dam Safety (SNISB of Brazil) do not have enough information to assess whether they fit into the National Dam Safety Policy (PNSB), or to assess their safety conditions. According to the National Agency of Waters (ANA, 2021b), there are currently 122 dams with some important structural problems indicated by their inspectors in 23 states. Therefore, this article proposes a methodology for identifying faults in dam safety activities. The method applies to all types of existing dams. The proposed methodology comprises ten stages that, according to the progress of the steps, are defined by three levels of completeness of the information. Tables were developed with the objective of being a verification guide for these ten stages. This research applied the proposed methodology to two dams in Paraná, Brazil. The first is the Iraí dam, located in the metropolitan region of Curitiba, and the second is the Jordan River Derivation dam, located in Reserva do Iguaçu. The example of the Iraí dam could complete all stages of the proposed methodology. For the Jordan River Derivation dam, stages 1 to 5 of the proposed methodology were carried out. The application of the proposed methodology intends to become a useful tool, especially for inspectors, aiming at a more effective registration process, accelerating the completion of the SNISB. SNISB Brazil PNSB, PNSB , (PNSB) conditions ANA, ANA (ANA 2021b, 2021b b 2021b) 12 2 states Therefore activities that steps Paraná Curitiba Iguaçu out tool process (PNSB

Abstract The transport capacity of the slurry pipelines is related to the internal roughness of the pipe. Thus, the application of corrosion protection methods is of fundamental importance, both in the operational phase and in times of temporary shutdown. In addition, corrosion also affects the service life of the duct. The studied pipeline was hibernated with nitrogen using the ABNT NBR 15280-2 standard as a reference and remained hibernated for 3.5 years. Chemical, mineralogical, and microstructural analyses were carried out on samples of materials removed from the pipeline interior during the hibernation period. The most striking phase found was magnetite, with botrioidal morphology, formed by the oxidation of steel in the pipeline. After reactivation, the pipeline was inspected by smart pigs with ultrasound and MFL technologies. It was found that the corroded regions are more concentrated in the initial kilometers of the sections, where important depths of corrosion were also observed, as well as higher rates of corrosion and erosion, which show the influence of the operational phase in the development of the pipeline corrosive process and wear. Thus, the application of the nitrogen hibernation process in long-distance pipelines proved to be feasible for long periods of time. However, improvements are suggested in this article to make the process more robust. pipe Thus importance shutdown addition duct 152802 15280 2 15280- 35 3 5 3. years Chemical mineralogical period magnetite morphology reactivation technologies sections observed erosion wear longdistance distance time However robust 1528 152 15 1

Abstract Process simulations can be used to improve grinding circuit performance, which efficiently reduces operating costs. The population balance model (PBM) is widely accepted for grinding modeling because it can reproduce breakage events in tumbling mills, as described by Austin et al. (1984). In this study, a pseudo-dynamic model is introduced, integrating the PBM with the Monte Carlo Method to stochastically simulate variables in an industrial grinding circuit. This integrated approach enabled circuit simulations over a period of 2 hours, representing the operational variables as seen in historical data. Model validation showed a correlation of 0.74 in the product size distribution when comparing simulated outcomes with the original population. performance costs (PBM mills al 1984. 1984 . (1984) study pseudodynamic pseudo dynamic introduced hours data 074 0 74 0.7 198 (1984 07 7 0. 19 (198 1 (19 (1 (