Abstract Waste management and environmental aspects are progressively gathering attention in the mining industry. Mine planners must deal with increasingly complex tasks to balance between ore block schedules, waste disposal, operational cost and environmental reclamation. The mine incomes are generally related to mining and processing of the ore, thus most optimization researches regarding strategic mining usually focus mainly on ore extraction. Nevertheless, waste sequencing and disposal play an important role given that, in several situations in open pit mining, waste volumes are generally larger than ore volumes and must be moved to reach the buried and deeper ore bodies. In some cases, a significant percentage of operational costs is represented by waste haulage and disposal. Thus a careful planning strategy must be considered to minimize unnecessary expenses. Selecting locations for waste dumps is also a challenge. Many operational and technical aspects must be considered, not to mention the increasingly limiting environmental constraints. This definition can be very time consuming, and if it is not properly studied, may negatively impact the mine operation during its lifetime. This article investigates a new approach for mine waste management called the multi-stage dumping sequence (MSDS), suggesting the use of temporary waste dumps along the way to the final dump destination. Although this method requires material re-handling, which is considered a paradigm in mine industry, it certainly provides additional time to design and permit the final waste dump site and, if well planned, might even result in profit increases by reducing haulage distances in the first years of operation.

Abstract To optimize a mining project, it is necessary to deal with several technical aspects and constraints, such as orebody modelling, reserve estimation, blending strategy, optimal and operational pit designs, cost control, environmental issues, among others. In this sense, locating surface infrastructures is one of the most critical mine planning concerns, as approximating these facilities to the pit in order to reduce the operational costs, might interfere with future pit expansions in new favorable scenarios. In such cases, impacts on the project's net present value (NPV) are inevitable and must be technically dealt with, evaluating alternative scenarios to propose a strategy that increases profitability. The aim of this study is to evaluate, through NPV comparisons, different constrained scenarios, under geological uncertainty, determining the possibility of moving the constraints from their current position and/or defining priorities measuring the impact that each of them represents on the project's profitability. The methodology is applied to a phosphate mine, to determine the best alternative from a long-term mine planning perspective. The use of the hybrid pit approach, applied to a simulated grade model, allowed to identify the occurrence of probability zones within a mathematical pit, providing further information to support decision making regarding infrastructure relocation.

Abstract One of the basic factors in mine operational optimization is knowledge regarding mineral deposit features, which allows to predict its behavior. This could be achieved by conditional geostatistical simulation, which allows to evaluate deposit variability (uncertainty band) and its impacts on project economics. However, a large number of realizations could be computationally expensive when applied in a transfer function. The transfer function that was used in this study was the NPV net present value. Hence, there arises a necessity to reduce the number of realizations obtained by conditional geostatistical simulation in order to make the process more dynamic and yet maintain the uncertainty band. This study made use of machine-learning techniques, such as multidimensional scaling and hierarchical cluster analysis to reduce the number of realizations, based on the Euclidean distance between simulation grids. This approach was tested, generating 100 realizations by the sequential Gaussian simulation method in a database. Proving that similar uncertainty analysis results can be obtained from a smaller number of simulations previously selected by the methodology described in this study, when compared to all simulations.

O treinamento de força tem sido referido como uma importante ferramenta para o incremento e a manutenção da saúde. Os exercícios que compõem um programa de treino podem ser executados em condição unilateral ou bilateral. Alguns estudos têm apresentado valores mais reduzidos de produção de força e sinal eletromiográfico em condições bilaterais do que o somatório desses valores em condições unilaterais. Essa diferença na produção de força, bem como no sinal eletromiográfico é denominada déficit bilateral. O objetivo do presente estudo foi avaliar a produção de força e a atividade eletromiográfica dos músculos reto da coxa e vasto lateral no exercício de extensão isométrica de joelhos, nas condições unilateral e bilateral. A amostra foi constituída de 10 indivíduos do sexo masculino, com idades entre 18 e 30 anos, não praticantes de treinamento de força. Foram registrados os valores de força e atividade elétrica com a utilização de uma célula de carga e eletrodos de superfície, respectivamente, no teste isométrico de extensão de joelhos (120º). Os resultados apontaram valores maiores (p<0,05) para a produção de força e sinal eletromiográfico na condição unilateral do exercício, reportando um déficit bilateral tanto na força como na atividade eletromiográfica. Estes resultados sugerem que o treino unilateral promove maior estímulo muscular, constituindo-se como uma importante estratégia a ser utilizada na prescrição dos exercícios de força.

Strength training has been reported as an important tool for enhancing and maintaining health. Resistance exercises can be executed unilaterally or bilaterally. Some studies have reported lower strength and electromyography (EMG) signal values in bilateral conditions than the sum of these values in unilateral conditions. This difference in strength and EMG is called the bilateral deficit. The aim of this study was to evaluate the strength and EMG activity of the rectus femoris and vastus lateralis during unilateral and bilateral isometric knee extension. The sample consisted of 10 non-resistance trained males aged 18 to 30 years. Strength and EMG were recorded through use of a load cell and surface electrodes, respectively. A 120º knee extension was used for the isometric knee extension test. The results showed significantly higher values for strength and EMG signal (p <0.05) in unilateral conditions, as well as bilateral deficit in both strength and EMG signal. These results suggest that unilateral training promotes greater muscle stimulation, and can thus represent an important strategy to be used in the prescription of strength training exercises.