DEMIN - Departamento de Engenharia de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/510
Navegar
10 resultados
Resultados da Pesquisa
Item Variáveis de impacto no sequenciamento de lavra.(2022) Campos, Bárbara Isabela da Silva; Souza, Felipe Ribeiro; Lima, Hernani Mota deO planejamento de mina é desenvolvido considerando variáveis econômicas, teores, litologia, posição espacial. Estas variáveis são utilizadas para determinar o limite final de cava e sequenciamento das operações. Normalmente são amostradas exaustivamente somente as variáveis relacionadas ao teor. As demais variáveis são configuradas com valores médios. As técnicas de estatística multivariada permitem determinar as variáveis de maior impacto. Utilizando um modelo geológico de cobre e ouro será determinado a cava final e sequenciamento de lavra utilizando o algoritmo de Lerchs-Grossmann. O modelo de blocos resultante será avaliado quanto as variáveis fora do padrão da população. Foram padronizados e transformados em variáveis contínuas adequadamente os elementos da população. Será utilizado a técnica de análise de componentes principais para determinar as variáveis mais importantes do sequenciamento de lavra e cava final. O objetivo deste trabalho é determinar as variáveis mais influentes na determinação de cava final e sequenciamento de lavra. As ferramentas de planejamento de mina apenas apresentam o resultado final do planejamento. Não apontam as variáveis mais sensíveis. É importante determinar as variáveis em que uma pequena variação no valor é capaz de transformar um bloco minerado em estéril. O trabalho confirmou a importância das variáveis econômica relacionadas a função benefício, entretanto quantificou que o posicionamento espacial do bloco possui importância semelhante a algumas variáveis econômicas.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 Impacto econômico da lavra de barragens.(2020) Silva, Paulo Henrique Magalhães; Silva, Mateus dos Anjos; Souza, Felipe RibeiroAlguns acidentes ocasionados pela mineração estão relacionados à disposição dos rejeitos do processo de mineração. Atualmente há um grande debate sobre o melhor método de descomissionar barragens já existentes e armazenar os novos rejeitos. Baseado na análise de custo este projeto foi elaborado com o objetivo de medir a queda no valor do NPV de um empreendimento de mineração de ferro que optou por utilizar o material existente na barragem junto com o material extraído da mina em seu processo de beneficiamento. Utilizando o software NPV Scheduler, que utiliza como princípio de funcionamento o algoritmo de Lerchs e Grossmann, foram produzidos alguns cenários nos modos Single e Multi Mine, os quais foram comparados. Considerando um cenário ideal no ponto de vista econômico para determinar a queda nos lucros causados pelo descomissionamento. Após problemas durante a montagem dos cenários como a geração incorreta de pushbacks e a estacionalização de massas, resolvidos usando alguns cálculos manuais e aplicação de técnicas conhecidas como o Pré Stripping, foi possível definir o impacto econômico gerado pela barragem.Item Comparativo dos modelos de capex para mineração.(2020) Queiroz, Guilherme Garcia Oliveira; Souza, Felipe Ribeiro; Campos, Bárbara Isabela da SilvaEstimar corretamente os custos de empreendimentos mineiros nas fases iniciais é importante para determinar a possibilidade de continuidade de pesquisa do depósito mineral. Diante da escassez e de uma padronização dos métodos de estimativa de custos das operações desses empreendimentos são utilizadas equações baseadas em regressão para a previsão dos custos e, com isso, surgem diferenças entre os resultados. O presente estudo, portanto, compreende uma análise de diferentes modelos de estimativa com foco nos custos de capital, ou seja, aqueles associados à infraestrutura necessária para a abertura de uma mina a céu aberto – lavra e beneficiamento. Foram avaliadas duas metodologias objetivando determinar qual é mais assertivo. Para verificar a compatibilidade entre os métodos foi realizada simulações de Monte Carlo com base nos limites dos modelos analisados. O estudo foi capaz de determinar qual modelo subestima os custos, com risco de apontar a viabilidade econômica de projetos inviáveis a luz do custo real.Item Mine fleet cost evaluation : Dijkstra’s optimized path.(2019) Souza, Felipe Ribeiro; Câmara, Taís Renata; Torres, Vidal Félix Navarro; Nader, Beck; Galery, RobertoThe transport distance in a mining operation strongly influences a mine op- eration revenue and its operational cycle because it is a fundamental part of the total mining costs. Generally, the transport route is determined based on an engi- neer’s practical knowledge, which does not consider any mechanism to optimize the possible routes to be taken. In an attempt to establish a methodology for cal- culating the path that results in minimum costs to transport the mined block to its destination, the Dijkstra methodology is applied to a tree graph analysis, where the mining blocks are analysed as nodes of the tree. The transport cost is reflected as the arc of the graphs, which can use the Euclidean distance or the transport time for the calculation of the minimum path. The result obtained from the Di- jkstra algorithm provided a non-operational route; to overcome this problem, an adjustment was performed through non-parametric equations. In this manner, it was possible to determine the transport costs for each block of the model. The paths based on Euclidean distance and transport time showed a tendency to in- crease for deeper mining regions. Identifying areas of largest growth and correctly quantifying their values increase the efficiency of mining planning.Item Optimum mine production rate based on price uncertainty.(2019) Souza, Felipe Ribeiro; Câmara, Taís Renata; Torres, Vidal Félix Navarro; Nader, Beck; Galery, RobertoThe production rate of a mining operation has an important effect on the opera- tional cycle and gross profit, which are often evaluated based on engineering practices. Assessment of the economic performance of mine operations in mining engineering is of great importance because an incorrect production rate can result in significant financial losses. The production rate is composed of two bases: the cost estimation and the price scenario. Bureau of Mines studies performed on American mines indicated that processing costs can be estimated through the production rate. This article pro- poses to connect the model presented by the Bureau of Mines and queuing theory to describe the operational costs, which are used to develop a production optimization methodology. The proposed cost composition describes a production system to verify the law of diminishing returns and the economy of scale. Between these regions of the production curve, the optimum point was determined with mathematical precision.Item Analysis of the impacts of slope angle variation on slope stability and NPV via two different final pit definition techniques.(2020) Chaves, Leonardo Soares; Carvalho, Luiz Alberto de; Souza, Felipe Ribeiro; Nader, Alizeibek Saleimen; Arroyo Ortiz, Carlos Enrique; Torres, Vidal Félix Navarro; Câmara, Taís Renata; Napa Garcia, Gian Franco; Valadão, George Eduardo SalesThe traditionally and widely used Lerchs-Grossmann algorithm presents well-known limitations that newer propositions attempt to overcome. The direct block schedule (DBS) methodology, which has gained relevance with computational advances, obtains the final pit as a natural result of production sequencing, different from Lerchs-Grossmann-based algorithms. This process flow applies constraints in the final pit definition stage attempting to provide a more realistic result and to minimize risks. Slope instability is a common and inherent risk to open pit mining and may affect the project's net present value (NPV). A study of the impacts of slope angle variations on safety indexes and final pit NPV provides an auxiliary tool for the overall slope angle definition process. This article presents a case study in which the effects of variations of the overall slope angle on the safety factor (SF) and project NPV were analyzed. A total of 25 pits were generated by each studied final pit definition methodology, and each pit had the sections with the varied slope angles analyzed in the stability assessment, resulting in a total of 150 slopes analyzed. A comparison between the results obtained by the two different methodologies implemented in commercial software is presented. The results show no relationship between the NPV and the overall slope angle using the DBS methodology. An analysis of the results for each geotechnical sector obtained by the traditional methodology was conducted and may contribute to the trade-off analysis between the best slope angle to achieve a reasonable SF and the maximum NPV.Item Direct stockpile scheduling : mathematical formulation.(2018) Souza, Felipe Ribeiro; Chaves, Leonardo Soares; Burgarelli, Hudson Rodrigues; Nader, Alizeibek Saleimen; Arroyo Ortiz, Carlos Enrique; Alberto, LuizIn a mining context, production scheduling’s main objective is to determine the best mining sequence of blocks to achieve the largest net present value and to maximize ore reserve exploitation. Stockpiling and blending procedures may represent very helpful alternatives for mine planning to ensure the ore quality and amount required by the processing plant. In order to satisfy industrial requirements of grades and tones, reducing stockpile fluctuations may represent a very important tool especially for medium and short term mine planning. Classical linear programing has been widely used to model blending problems at the mining industry, however this formulation allows only one objective formulation. The current work describes a system based on goal programing able to reach blending constraints desired by short/medium term planning. The proposed formulation achieves the best schedule scenario, ensuring cost constrains are respected. Hence, this study aims to provide support for both short and long term mine planning.Item Classical and stochastic mine planning techniques, state of the art and trends.(2018) Torres, Vidal Félix Navarro; Nader, Beck; Arroyo Ortiz, Carlos Enrique; Souza, Felipe Ribeiro; Burgarelli, Hudson Rodrigues; Chaves, Leonardo Soares; Carvalho, Luiz Alberto de; Câmara, Taís Renata; Fernandes, Eunírio Zanetti; Galery, RobertoDetermination of the best possible ultimate pit for an open pit mine is a fundamental subject that has undergone a highly evolutionary process, reviewed in this study, since the correct choice carries substantial economic impact for the industry. The correct choice can be very beneficial for project analysis, whereas an incorrect choice has the potential to mask huge financial and economic future losses that could render a project unfeasible. The advent of computers in the 1960s allowed sophisticated analysis for the selection of the best ultimate pit determination, under specific modifying factors such as economic, social, environmental, and political, but only in deterministic situations, i.e., when the problem and variables for the ultimate pit determinations were considered deterministically and almost always based on average values. Techniques such as the Lerchs– Grossman algorithm and mixed-integer programming are among many standard tools now used by the mineral industry. Geological uncertainty and the associated risks as well as the need to consider the appropriate time to mine a block during a mine operation have a significant impact on the net present value of the resulting ultimate pits. Stochastic aspects embed a probabilistic component that varies in time and are now under intense investigation by researchers, who are creating algorithms that can be experimented with and tested in real mine situations. One can expect that once these algorithms demonstrate their efficiency and superior results, they will readily dominate the industry.Item Direct block scheduling under marketing uncertainties.(2018) Burgarelli, Hudson Rodrigues; Souza, Felipe Ribeiro; Nader, Alizeibek Saleimen; Torres, Vidal Félix Navarro; Câmara, Taís Renata; Arroyo Ortiz, Carlos Enrique; Galery, RobertoMineral projects are composed of geological, operational and market uncertainties, and reducing these uncertainties is one of the objectives of engineering. Most surveys assess the impact of geological and operational uncertainties on the mining planning. The objective of this work is to study the impact of market uncertainty on the mineral activity. The influence of iron ore price simulation on mining sequencing will be evaluated. The price of iron ore has random behavior that is best represented by the Geometric Brownian Movement system. This study analyzed the historical series of iron ore in order to determine the percentage volatility and drift. Traditionally, a constant and deterministic price is used for the ore mined in all periods of a mineral project. The direct block scheduling methodology was adopted because it is able to apply the appropriate financial discount factor to the simulated probabilistic price. The proposed methodology was able to quantify the market uncertainty.