Resumo em Inglês:

Abstract Mining projects are often budgeted in millions of dollars, making it of interest to the investor to measure a project’s uncertainties and risks, which include the changes in the commodity price. The simulation of asset prices is valid because it enables displaying, with a degree of certainty, the future behavior of a financial asset. One of the most commonly used mathematical forecast models is the Geometric Brownian Motion (GBM) model. This article aims at simulating the forecast price of an iron ore commodity with the GBM method based on the historical price series and comparing it to other forecast approaches used in the financial market. The results of this study indicate that the model has limitations, which should be considered. However, it is an overall good tool to support the economic evaluation of a project, if performed along with other approaches.

Resumo em Inglês:

Abstract Mine planning is dependent on the natural lithologic features and on the definition of their limits. The geological model is constantly updated during the life of the mine, based on all the information collected so far, plus the knowledge developed from the exploration stage up to the mine closure. As the mine progresses, the amount of available data increases, as well as the experience of the geological modeller and mine planner who deliver the short, medium, and long-term plans. This classical approach can benefit from the automation of the geological mapping on the mining faces and outcrops, improving the speed of repetitious work and avoiding exposure to intrinsic dangers like mining equipment, falling rocks, high wall proximity, among others. The use of photogrammetry to keep up with surface mining activities boarded in UAVs is a reality and the automated lithological classification using machine learning techniques is a low-cost evolution that might present accuracies above 90% of the contact zones and lithologies based on the automated dense point cloud classification when compared to the manual (or reality) classified model.

Resumo em Inglês:

Abstract The aim of the study was to analyze the impact on the strip ratio (SR) through varying haul road geometric parameters in two types of deposits, namely one with a steeper dip and a second one with a more equidimensional horizontal behavior. The SRs and the overall slope angle were compared with a base scenario, where the results show an increase in the SR when: (a) the width of the haul roads was increased; (b) the longitudinal grade of the road was decreased; and (c) switchbacks were added. The increase in the longitudinal grade of 2% was considered the best-case scenario, resulting in 1.08% decrease in the SR for the horizontal deposit and in a 4.15% decrease for the vertical one. It was also noticed that the SR variations are inversely proportional to the overall slope angle variations, illustrating the important role that the geometric design of the haul roads has in the return on capital.

Resumo em Inglês:

Abstract As defined in PNSB - Law 12.334/2010 (Brasil, 2010), the DNPM, which manages the Brazilian mineral resources, is also responsible for overseeing the safety management of tailings dams in the country. The purpose of this article is to present the actions carried out in this context by the Department since the enactment of the Law in 2010, such as: elaboration of infra-legal regulatory instruments, training of civil servants, inspection actions throughout the country, seminars and lectures at mining companies and the organized civil society in general, among others, with the primary purpose of monitoring the implementation of the law instruments by mining companies, such as PSB and PAEBM, in order to avoid / mitigate accidents related to these structures.

Resumo em Inglês:

Abstract Mine closure is the set of all activities that follow the end of the productive phase of a mine, characterizing itself as the process of returning an area transformed by mining into a new condition of sustainability, considering the potential future and the best possible reclamation of the area impacted. However, such an understanding was not conceivable during the Colonial Period, a time when gold mining took place in the Ouro Preto Hill, among others, and nearly 200 years after the end of the gold rush, negative and positive impacts are revealed by the human interaction and the urban occupation on those mined areas. Through both geographic information data of eighteenth-century mining traces and a socioeconomic study involving six tourist gold mines, this article describes how overcoming paradigms involving underground mines have resulted in business opportunities, setting a success example of Mine Closure and future use of the area, showing an alternative way to handle the current abandoned mines.

Resumo em Inglês:

Abstract Tailings dam safety is a frequent subject of discussion during mining project development. However, due to recent accidents with these structures, this issue has become even more prominent. A highlighted point is the risk management, which can be defined as the identification, analysis and maintenance of risks at acceptable levels during the design, construction and operation phases. Therefore, this article aims to present the direct application of ISO 31000: Risk Management applied to the safety management of tailings dams. Although not widespread, this standard brings guidelines and principles for the safety management of dams that will contribute to manage the risks associated with these structures in a systematic and effective way.

Resumo em Inglês:

Abstract This article proposes a procedure to elaborate a map that presents the potential risk of failure occurrence in the operational slopes of open pit mines. First, it is necessary to collect the available geological-geotechnical data and perform a field mapping, in order to verify and validate the most representative parameters and to characterize the discontinuity families of the rock mass. Then, the mine should be sectorized, considering all the data collected, the geometry of the operational slopes and its development until the final pit. The next step will be to define and to evaluate which failure modes have greater or lesser potential to occur in the pit and to assign weights to them. In this study, the weathering, planar failure, and plane circular failure potentials were evaluated. As a result, it is possible to develop a map with the susceptibility level of the sectors. This map will help make technical and managerial decisions in order to reduce the risk level of the sectors and to promote an increase in the operational safety of the mine.

Resumo em Inglês:

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.

Resumo em Inglês:

Abstract Presented herein are the economic viability results when applying the analysis techniques for investments to replace mobile equipment. Due to the high cost involved in these exchanges, an economic model was designed based on Life Cycle Cost analysis and through the Equivalent Annual Uniform Cost method, evaluating and comparing the best option: to maintain or replace the equipment, and to define when is the best time for this replacement. This methodology, besides defining the best moment of replacement, is also applicable for defining the moment of the equipment purchases because this methodology allows cost annualization and consequently, it is possible to compare equipment with different life times. This means, they allow the choice of the best financial option for the company.