Ivo Eyer Cabral

Estimate of hourly productivity applied to elaboration and implementation of mining plans

In order to elaborate a mine plan, it is necessary to adopt hourly production parameters for the equipment available for its execution. This equipment should be in synchrony with the productive capacity of the operational units in the mine for: rock drilling, blasting, loading and transporting ore. This study deals with the estimate of hourly production indexes for loading and transport obtained by the use of multiple regressions. Using a management system database from an operating mine, equations were generated to explain the productive cycle of each of the loading machines and dump trucks. Knowing the behavior of the principle variables that exert influence on the production schedule, it was possible to estimate the index and to guarantee high feasibility for the mine plan, considering the indexes obtained were very close to those executed. The model design was created in a simple manner, using statistical concepts and computational tools, being supported by good correlation between the variables. This factor was decisive in obtaining good results in the execution of the studied mining plan.

Perspectives for use of hydraulic fracturing in oil and gas production

Hydraulic fracturing emerges currently, all over the world, as one of the more strategic techniques used by companies in the oil exploitation sector. This technique is characterized by its high productivity and profit in relation to conven tional methods of hydrocarbon exploitation. However, in many countries, as is the case of Brazil, there are several divergences considering the employment of this methodology. Many renowned researchers attest that there are several irreversible environmental impacts generated by the use of this methodology. Among the main environmental impacts are the risk of groundwater level contamination, the risk of surface subsidence, and the risk of the environment contamination with fluids used in the process of the oil and gas extraction.

Análise de sensibilidade na otimização econômica de uma cava

Uma das variaveis que torna um projeto de mineracao mais vulneravel a instabilidade economica e a variacao dos precos de venda dos minerios. Nesse trabalho, procedeu-se a uma analise de sensibilidade de cavas otimas em relacao a variacao do preco de venda de um bem mineral. Foi gerada uma serie de contornos de cavas otimas com diferente valor presente liquido (VPL) e diferentes quantidades de minerio e esteril, a partir da aplicacao de fatores de desconto sobre um preco de venda de minerio tomado como base. Analises desse tipo sao uteis para o estabelecimento do planejamento de producao de uma mina. Para esse estudo, foram utilizados dados da mina Morro da Mina da Rio Doce Manganes S.A. e, para a geracao das cavas otimizadas, utilizou-se o modulo Pit Optimiser do Gemcom Surpac 6.0.

Um modelo de programação matemática para otimizar a composição de lotes de minério de ferro da mina Cauê da CVRD

This work focuses on the problem of blending iron ore products, at the Caue mine stockyard, of Companhia Vale do Rio Doce, in the state of Minas Gerais, for the formation of lots. It consists in elaborating a linear goal programming model that seeks to determine the areas to recapture the stored ore in such a way that the blending of products be in conformity with the quality specification required by the customer. This work is a case study of an applied nature. The mathematical programming model was developed with the support of the optimization software LINGO 9.0 in conjunction with EXCEL 2000 spreadsheets, making it possible to handle and export data in formats used by the mining company. With the purpose of validating the implemented system, the results obtained by the system were compared with real data. These results proved that is possible to improve the composition of the product lots applying the proposed model.

Comparison between the application of the conventional mine planning and of the direct block scheduling on an open pit mine Project

Historically, since the 60s, traditional mine planning consists of several distinct stages: 1) Definition of the ultimate pit the portion of the blocks that results in the greatest total value; 2) Pushback selection based on the generation of nested pits, obtained with the change in the value of the ore price; 3) Long-term production scheduling. Although considered quite satisfactory, this methodology presents some flaws: The stages, even if considered individually optimal, may not be when put together. The opportunity cost is not considered and the cut-off is fixed. Due to the recent computational advances, a new technique has been growing and is more reliable: the direct block sequencing. In this methodology, the steps are consolidated into only one process, improving the economic results, reducing the total execution time and obtaining, in fact, an optimal planning. The aim of this work is to compare the results of the two planning methods applied in a database of a Brazilian iron ore mine and to show the real advantages and disadvantages of each one. To solve the direct block sequencing technique, Doppler was used, a tool developed by Delphos Mine Planning Laboratory, located at the University of Chile. The traditional methodology was executed through Whittle software. Lastly, a medium-term scheduling was performed using Deswik software.

Incorporation of geological uncertainty in pit optimization with geostatistics simulation

Risk mapping processes in mine planning and ore recovery are constantly used in the mining industry to increase decision making certainty based on the available information. However, it is not possible to predict the risk behavior in all of the project’s boundary conditions and small variations in some of these conditions can cause a great impact on its financial return. Among the countless uncertainties existing in a mining project (operational, costs, market change), many authors define the geological uncertainty as the most critical one, capable of influencing the success of the project. Measurement and evaluation of the geological uncertainty of a mine planning project is crucial because the calculated risk can be translated into a financial risk of the project. This article presents a possible way to consider the geological uncertainty in the pit optimization step by using sequential Gaussian simulation. The results obtained from the case study on a copper deposit results in a simple procedure with significant increase in reliability for the project.

Regression model utilization to estimate the mass recovery of a phosphate mine in Brazil

The construction of block models with an estimation of grades in situ is a common practice throughout resource evaluation. However, this information is not enough to understand the behavior of the ore in the beneficiation process. Geometallurgy proposes the addition of the ore´s metallurgical behavior in the block model, making it more dependable and adhering when it comes to production capacity, which generates financial earnings and brings risks down. Mass recovery is an important metallurgical variable for economic and mine planning. This is often underused, due to the lack of data, making it hard to use in the planning process. In order to achieve better use of the data available, the multiple regression analysis technique was used so as to develop a statistic model that would relate the mass recovery with the in situ grades, allowing that deposit regions with no available metallurgical information have an estimation of this variables values.

Multi-Criteria decision aid methodology applied to highway truck selection at a mining company

In all mining projects, transportation costs influence net profit, justifying economic feasibility studies before transport fleet acquisition or replacement. These studies can provide the best loading and hauling equipment combination to meet production demands at lower costs by evaluating the alternatives available in the market. When there is more than one solution with similar costs and technical specifications, decision-making technics were considered to be used. Herein is presented the case of selecting hauling trucks used to transport run of mine (ROM) ore at a bauxite mining company, located in the State of Minas Gerais, Brazil, using the Multi-Criteria Decision Aid methodology (MCDA).