Rodrigo de Lemos Peroni

Topographic modelling using UAVs compared with traditional survey methods in mining

The current developments with unmanned aerial vehicles (‘UAVs’) are revolutionizing many fields in civil applications, such as agriculture, environmental and visual inspections. The mining industry can also benefit from UAVs in many aspects, and the reconciliation through topographic control is an example. In comparison with traditional topography and maybe modern techniques such as laser scanning, aerial photogrammetry is cheaper, provides faster data acquisition and processing, and generates several high-quality products and impressive level of details in the outputs. However, despite the quality of the software currently available, there is an uncertainty intrinsic to the surfaces acquired by photogrammetry and this discrepancy needs to be assessed in order to validate the techniques applied. To understand the uncertainty, different surfaces were generated by UAVs for a small open pit quarry in southern Brazil. Wellestablished topographic surveying methodologies were used for geolocation support and comparison, namely the RTK (real-time kinetic) global navigation satellite system (GNSS) (here called conventional method) and laser scanning. The results showed consistency between the UAV surfaces with a few outliers in when vegetation, water and mobile objects during the flight missions. In comparison with the laser-scanned surface, the UAV results were less erratic surrounding the RTK points, showing that surfaces generated by photogrammetry can be a simpler and quicker alternative for mining reconciliation, presenting low uncertainty when compared to conventional methods.

Controlling operational dilution in open-pit mining

ABSTRACT Dilution and ore loss are important factors that can affect costs and profitability of a mining operation by lowering the quantity of mineral or metal that can be produced from each ton of processed ore. When discussing open-pit mining, dilution and ore loss are sometimes assumed as fixed factors in geostatistical block models and cut-off grade calculations, without considering specific particularities of the deposit and operation. This paper proposes to quantify the dilution caused by operational inefficiency through identifying the ore blocks that are a part of the short-term plans and mapping their neighbourhood, considering the nature of the contacts and the differences in grades. This technique enables the operational dilution to be calculated. It is applicable for operations using mechanical excavation and/or blasting. The results demonstrate that operational dilution can be measured and controlled to improve the tonnage and grade reconciliation between planning and production.

Quantifying dilution caused by execution efficiency

In open pit mining, dilution is not always a factor systematically analyzed and calculated. Often it is only an adjusted number, for example, calculated or even empirically determined for a certain operational condition perpetuating along time in the form of a constant applied to calculating reserves or mine planning in attendance of audit requirements. Dilution and loss are factors that should be always considered for tonnage and grade estimates. These factors are always associated and can be determined considering several particularities of the deposit and the operation itself. In this study, a methodology was determined to identify blocks adjacent to the blocks previously planned to be mined. Thus, it is possible to estimate the dilution caused by poor operating efficiency, taking into account the inability of the equipment to perfectly remove each block, respecting its limits. Mining dilution is defined as the incorporation of waste material to ore due to the operational incapacity to efficiently separate the materials during the mining process, considering the physical processes, and the operating and geometric configurations of the mining with the equipment available.

Proposal of an environmental sustainability index for open-pit mines using landscape fragmentation indicators

The perception of the environmental impacts caused by economic activities is subjective and usually negatively affects the image of an extractive sector such as mining. In order to avoid this, the environmental impact assessment must be supported by clear and well-selected environmental indicators. An index of sustainability was created to demonstrate that open-pit mining is comparable to other economic activities. The index is composed by of environmental indicators like water and energy consumption combined with an indicator of landscape fragmentation, using remote sensing data and geoprocessing. A comparative study considering a ten-year period was carried out with the biggest iron ore mine in Brazil, N5W, and the largest Brazilian soybean producer, the Sorriso County, in the Mato Grosso State to illustrate the methodology.

Impact in long-term planning of optimization algorithms and mineral deposit geometry

The main objective of mine planning is to determine ore quantity and quality distribution along a time sequence, i.e., scheduling the ore necessary to make the project technically and economically feasible. These temporal sequences are fundamental for the financial success of a mining activity and currently this optimal sequence can be obtained through various mining software. Most studies in mine planning present the final pit calculated by only one algorithm chosen by the mining engineer or simply by availability. Besides, technical constraints and geometrical aspects can be imposed promoting differences on the results of the project. There are many algorithms implemented in various commercial software for the ultimate pit calculation. One of the purposes of this work is to check the effectiveness of the algorithms that obtained greater recognition within the mineral industry and if there are differences related to the type of mineralization and deposit where they are applied. The comparison is performed using two commercial software, and two different algorithms to determine if differences can be observed from the different mineralization types. The implementation of the two algorithms in three-dimensional block models estimated and analyzed for three types of deposits: a massive disseminated copper orebody, a large igneous phosphate deposit and a subvertical gold vein type.

Análise da variabilidade de teores e sua incorporação no planejamento de lavra

This study presents the results obtained using geostatistical simulation techniques combined with pit optimization and sequencing to assess the grade uncertainty impact in mine planning and reserve assessment. Traditional approaches use an estimated model by geostatistical methods (Ordinary Kriging, Indicator Kriging) or even classical methods of estimation (IPD, polygons, moving average). In the same manner, to evaluate mining projects, analyses considering economical sensitivity aspects were made, disregarding the uncertainty of the geological model. This study demonstrates that grade estimation can have a relevant impact on the uncertainty over mining projects, even in the open pit design, i.e. in the feasibility study.