Análise qualitativa de resultados geoquímicos em amostras de furos gêmeos de sondagens rotativas diamantadas e sondagens rotopercussivas em circulação reversa em depósito de minério de ferro

Abstract

The choice of drilling method is a determining factor in mineral exploration, as it directly influences sample quality, execution time, and operational costs. This study compares the geochemical results obtained by diamond drill core sampling (DDH) and reverse circulation percussion drilling (RC) in a brownfield iron ore exploration campaign. The analysis was based on twin-hole data, using bivariate statistics, scatter plots, and boxplots to assess the correlation and variability between the methods. The results showed a moderate correlation between the methods with correlation coefficients (r) close to 0.78. However, it was observed that much of the differences in chemical grades were associated with lateral variability of the deposit, and not necessarily the drilling and sampling techniques. After excluding intervals with significant lithological differences, the correlation between the methods increased, reaching a coefficient of 0.95 for iron and alumina, while elements such as silica and loss on ignition (LOI) presented lower correlation. Additionally, boxplots were used to visualize the distribution of iron, alumina, silica, and LOI grades, allowing the identification of discrepancies, asymmetries, and possible outliers associated with each technique. This approach complemented the scatter plot analysis and helped interpret the influence of lithological variability on the results. The findings indicate that, when used correctly and within the same lithological context, both methods can provide reliable results, making RC drilling an economically viable alternative for exploration campaigns. However, strict control of geological variability and sample preparation is essential to ensure greater reliability in geochemical models.