Planejamento de lavra em complexos mineiros: aplicação do whittletmmulti-mineem modelos simulados na Mina do Sossego

Abstract

The Sossego Mine Complex, Carajás Mineral District, Pará, Brazil, today with two operating open pits, has a long term mine planning consisting in final pit optmization and pushbacks definition, using the Lersch-Grossmann algorithm, available in Whittle Four-X™ software and an orebody model constructed by traditional estimation techniques. In addition, pit design, production scheduling and DCF analysis are carried out in a wide range of specific computer packages and spreadsheets. The traditional optimization, in a single block model, despite of the specific geology and technical characteristics of each deposit, already shows the profitable extraction in three independent open pits, Sequeirinho and Sossego, as informed above, and Pista, a small open pit in the west border of the deposit. Pit separation is mainly due to geographic location of it, witch optimization parameters are not distinct. The open pit optimization and production scheduling with multi-mine approach, based in a integrated block model with the three deposits properly identified, available in Whittle Four-X software, allowed analysis of impacts in optimization process, final pit design and mining sequencing, showing the importance of optimization with distinct parameters for each deposit of Sossego Mining Complex. For results evaluation between conventional (called single-mine) and multi-mine approach proposed, both optimization methods were carried out using a set of conditionally simulated models, created by stochastic simulation techniques using the sequential Gaussian simulation algorithm, available in IsatisTM software. Improvements and advantages of multi-mine approach were presented, regarding uncertainty and risk assessment of mining process. In addition, potential improvements in production scheduling are possible, with extra information control, important for a more robust and flexible long term mine planning.