DEMIN - Departamento de Engenharia de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/510
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Resultados da Pesquisa
Item Otimização da unidade mínima de lavra para o planejamento de curto prazo.(2023) Oliveira, Mariana Paula Rossini de; Souza, Felipe Ribeiro; Silva, José Margarida daNa mineração a céu aberto, no horizonte de curto prazo, é realizado a subdivisão dos planos de lavra em trimestral, mensal, semanal e diário da operação. Em um horizonte mensal, um planejador de curto prazo define as poligonais, que compreende os sucessivos avanços de lavra, satisfazendo parâmetros de qualidade e tonelagem de minério fixadas previamente pela usina. As poligonais, tradicionalmente, são projetadas sem uma devida abordagem sistemática. Logo, as interações realizadas para obter as especificações exigidas pela usina é limitada. Portanto, há uma demanda por estudos envolvendo técnicas de otimização de unidades mínimas de lavra, auxiliando o delineamento do minério, de modo a minimizar a variabilidade em teor e maximizar a recuperação da usina, além de fornecer base quanto a tomada de decisão diária pelo planejador de curto prazo. Esse artigo propõe a adaptação de dois algoritmos de otimização – Cone Flutuante e Stope Flutuante, tradicionalmente utilizados para a definição de cavas e realces subterrâneos. Foi atribuído um valor de dimensão igual a zero para os pilares de sustentação, aproximando o método de câmaras e pilares a um método de bancadas, para configurar um comportamento próximo a lavra em céu aberto. O estudo comprovou que ambas as metodologias apresentaram resultados satisfatórios. Apesar da necessidade de ajustes manuais, descartando blocos compartilhados, o Cone Flutuante mostrou ser um sistema mais seletivo, principalmente para teores de corte mais elevado.Item Predição de vibrações induzidas por desmontes de rochas por explosivos usando redes neurais artificiais.(2022) Zorzal, Caroline Belisário; Santos, Francisco Lledo dos; Silva, José Margarida da; Souza, Rafael de FreitasNa indústria mineral, o parâmetro mais utilizado para a quantificação e avaliação do potencial de danos das vibrações sísmicas geradas por desmonte de rochas é a velocidade de vibração de pico de partícula (VPP). Várias iniciativas foram tomadas, ao longo do tempo, com o intuito de estimar os níveis de VPP. Os rápidos avanços na tecnologia computacional fizeram com que sistemas inteligentes se tornassem ferramentas promissoras na estimativa dos resultados de desmonte de rochas. Nesse contexto, este estudo tem como objetivo avaliar as vibrações induzidas por desmontes de rochas por explosivos em uma mina do Quadrilátero Ferrífero por meio de redes neurais artificiais. O banco de dados foi dividido em amostras de treinamento (70%) e teste (30%) das redes. Considerando a importância da seleção de variáveis de entrada adequadas para o treinamento das redes, diferentes grupos de variáveis input foram analisados. A arquitetura que demonstrou melhor desempenho considerou a distância entre o ponto de monitoramento e detonação e a carga máxima por espera como variáveis input. A fim de comparar o desempenho da rede neural com o desempenho de modelos empíricos e de regressão múltipla, os mesmos dados foram utilizados. Por fim, o modelo de redes neurais se mostrou superior às equações empíricas e à regressão múltipla em termos do coeficiente de determinação (R²) e da raiz do erro quadrático médio (RMSE) para os dados medidos e preditos. Além disso, demonstrou-se a importância da seleção das variáveis de entrada adequadas para a estimação de VPP por meio de redes neurais.Item Effect of dynamic stress produced by rock blasting on the optimal dimensioning of room and pillars in horizontal layers.(2022) Cano Nunez, Alcides Eloy; Arroyo Ortiz, Carlos Enrique; Silva, José Margarida daAn optimal dimensioning of the room and pillars of the square or rectangular section is nding adequate transversal section support for the pillar; in that sense, all forces acting on the pillar must be evaluated. e pillar has its ends subjected to normal (σ) and shear stresses (τ). In addition, the pillar can also be subjected to dynamic stresses from the seismic waves generated by rock blasting. us, when calculating the dimensions of a mine pillar, the stresses imposed by seismic waves must be considered. e combination of lithostatic and dynamic stresses generated by blasting can a ect the pillar, generating regions, or areas that will exhibit the formation of cracks, microcracks, chipping, and other detrimental processes for its stability. In that regard, it is appropriate to assess the dynamic e ects of the energy delivered in each wave pulse so that these dynamic quantities can be included in the dimensioning of the pillars. is paper presents the physical and mathematical formulation describing the dimensioning issues of room and pillars and its solution using numerical modeling. e numerical modeling is performed using nonlinear mathematical programming and simulation with FLAC 3D (Fast Lagrangian Analysis of Continua in 3D). In this study, it was proven that the stress generated by the seismic wave represents a dynamic stress of nearly 5.5 MPa. 'Dimensioned pillars considering wave stresses allows it to recover an average 1.6% less when it is compared with pillars only under overlying rock mass'.Item Development of a low-cost device for monitoring ventilation parameters (temperature, humidity and pressure) in underground environments to increase operational safety using IoT.(2022) Santos, Rita de Cássia Pedrosa; Silva, José Margarida da; Albergaria Junior, Walter; Pinto, Cláudio Lúcio Lopes; Oliveira, Michel Melo; Mazzinghy, Douglas BatistaThe important role of ventilation in underground mines is to ensure safety and adequate environmental conditions in all accessible areas of a mine. This research aims to develop lowcost solutions for monitoring ventilation parameters in underground mines using the Internet of Things (IoT). A comparison between standard measuring equipment and a new low-cost wearable monitoring device prototype was performed, and the variables measured in an underground mine were pressure, temperature, and relative humidity. The results in all surveys indicate that the wearable monitoring device prototype can properly be used for continuous monitoring of the underground environment. The standard measurement devices for underground mines should continuously be used by mining companies as requested by local legislation. The low-cost wearable monitoring device developed should be viewed as a redundant measurement device for operators’ safety. The constant innovations in technology can support mining operators in anticipating problems, improving productivity, ensuring safety, and meeting standards at low investments.Item Benefícios na utilização da frota elétrica para ventilação de mina subterrânea.(2021) Costa, Leandro de Vilhena; Silva, José Margarida daO desenvolvimento de equipamentos elétricos permitiu a utilização de uma energia mais limpa em minas subterrâneas. A recente aplicação dessa tecnologia em carregadeiras LHD e caminhões viabilizou sua aplicação em minas no Canadá e na Suécia. Além de eliminar as emissões de poluentes, estima-se que a utilização da frota elétrica apresente um potencial de redução de aproximadamente 40% na demanda por ventilação devido a zero emissão de gases e da menor emissão de calor dos veículos elétricos. Entretanto, há poucos estudos técnicos e de aplicação na prática. Apesar dos benefícios ambientais, financeiros e de saúde ocupacional, observa-se a preferência pela tecnologia a diesel dificultando a expansão da frota elétrica em todo mundo. Nesse contexto, este artigo busca analisar para uma mina de ouro, localizada na região central de Minas Gerais, aplicação da tecnologia elétrica atualmente disponível para mineração e quantificar qual o potencial impacto sobre sistemas de ventilação com a substituição de 100% da frota diesel pela elétrica. Outra questão seria avaliar o potencial impacto que a adoção de frota elétrica representaria em uma mina nas condições brasileiras, respeitando as normas regulatórias vigentes.Item Diagnosis of the production cycle in the small shaft sinking.(2022) Luz, José Aurélio Medeiros da; Silva, José Margarida da; Neuppmann, Pedro HenriqueShaft sinking is a classic activity in underground mines. In shafts with small cross-section or in mines with low mechanization indices it is common to use hand pneumatic drills and blasting by explosive gelatin in cartridges, employing natural draft or flexible ducts with axial fans for gases and fumes exhaustion, muck removal by hand shoveling into hoistable dumping buckets. System of this type has been studied here, consisting of a rectangular cross- section shaft (3.7 m x 2.0 m), with final depth of 94 m, excavated in order to obtain samples for a pilot-scale mineral processing testwork, before the open pit mine’s industrial startup. The shaft had a concrete collar and its walls were supported by wooden sets spaced 1.5 m and 25 mm thick wooden planks as liners. This shaft has been excavated in schist rocks belonging to the metamorphosed hydrothermal deposit of copper and gold located in Chapada (municipality of Mara Rosa, Brazil). Daily production worksheets covering one month campaign were statistically analyzed, encompassing the entire cycle of mining operations, namely drilling, charging and blasting, fumes exhaustion, mucking, wall and face trimming and scaling, and assemblage of support system. Operation downtimes were also quantified. Statistical analysis of productivity indices allowed the detection of critical points of the operation and the establishment reference for similar mining operations.Item Determination of young’s modulus by specific vibration of basalt and diabase.(2020) Quaglio, Osvail André; Silva, José Margarida da; Rodovalho, Edmo da Cunha; Costa, Leandro de VilhenaThe elasticity is an important parameter for the evaluation of the mechanical behavior of a rock mass and a fundamental factor in the definition of the resistance characteristics, stability, and blastability in rock blasts, and it is an important parameter for the blastability equations like the Kuz–Ram method. +is paper presents a comparison of the Uniaxial Compression Method (UCM) and the Impulse Excitation Technique (IET) in determining Young’s modulus. +e IET is a static and nondestructive dynamic method of characterizing mechanical parameters of materials, while the UCM is a quasistatic and destructive method. We determined Young’s modulus of samples from nine basalt and diabase mines used as aggregates in the construction industry. Young’s modulus was determined by the acoustic response due to longitudinal oscillations caused by a mechanical impulse (IET) in the Sonelastic equipment and the stress-strain curve (UCM). Young’s modulus values showed high repeatability and agreed with those reported in the literature for the same material. +e work shows that the solnelastic is an innovate equipment and elucidated advantages of IET in comparison to the UCM such as shorter execution time, greater safety, and a lower cost ranging from 11.5% to 22.5% of the UCM.Item Strategies used to control the costs of underground ventilation in some Brazilian mines.(2020) Costa, Leandro de Vilhena; Silva, José Margarida daIn an underground mine, the ventilation is responsible for 25% to 50% of its electrical energy consumption. In countries such as South Africa, United States and Canada researchers have started to achieve a significant reduction in energy consumption without neglecting aspects of the quantity and quality of air required for the best performance of the system, in compliance with safety standards and worker comfort. In Brazil, on demand this ventilation application began in 2013 at the Ipueira mine (Bahia, controlled by Ferbasa company), and was soon after applied by the Cuiabá, Córrego do Sitio I and Lamego mines; all three mines administered by Anglo Gold Ashanti. Each mine adopted frequency inverters for the main ventilation, whereby the fan rotation is adjusted according to demand and speed drivers. This measure resulted in the saving of thousands of reais, since the flow is proportional to the velocity, the pressure is proportional to the square of the velocity, and the power is proportional to the cubed velocity. Therefore, a reduction of 20% in the flow will save about 50% of the energy required. The Cuiabá mine presents the most modern and automated system in the country. The fans are controlled and monitored through a control room. In addition, sensors scattered in the mine, control the required flow rate. The Lamego mine has a similar but simpler system. This article proposes to discuss the application and improvement of the process of ventilation on demand in Brazilian mines where this system is applied.Item Influence of rock blast advance direction on boulder generation : a case study.(2020) Quaglio, Osvail André; Silva, José Margarida da; Rodovalho, Edmo da Cunha; Magalhães, Ana Olivia Barufi Franco de; Pereira, Thaís GontijoIn quarries, rock blasting is important for mining and transportation, being the first step in the comminution. Discontinuities present in a rock mass can interrupt the propagation of the shock wave and evacuate gases, thereby reducing the efficiency of the explosives. Differences in the orientation of joint sets and the advancing direction of the mine produce different fragmentation results. In this study, the blastability of a rock mass was evaluated as a function of mining advance direction relative to the direction of the main joint set using particle size curves generated by photo-analysis. The data were analysed for each bench, and the optimal direction of advance was determined as the one to generate the smallest boulders. The particle size curves reveal optimal fragmentation when the mining direction is orthogonal to the main joint set, reducing the number of boulders by 64.40%.Item Cost-saving electrical energy consumption in underground ventilation by the use of ventilation on demand.(2020) Costa, Leandro de Vilhena; Silva, José Margarida daElectricity is one of the biggest expenses associated with underground mining and ventilation often accounts for 50% of the total electricity use. Ventilation on demand is not widely used in Brazil, but the Ipueira, Cuiaba, and Corrego do Sitio I mines reported savings of 26%, 30%, and 21%, respectively, following its application. Frequency inverters are used to control the rotation of the main fans during shift changes. The Cuiaba mine has a control room and fans are monitored online using wireless scattered sensors. Data from field studies were compared to other foreign mines. The results showed that the application of this technique, even in an experimental way, can reduce electricity consumption significantly. Despite the energy savings that can be achieved by providing air only when/where it is needed, the costs of automation, software, and infrastructure mean that it is not practical to apply this technique at a more advanced level.