Comparative study among rock mass classification systems in a Porphyry deposit

• Published in: Boletiín de ciencias de la tierra 2018-01 (43), p.34
• Main Authors: Santiago Perez Rodriguez, Manuel, Edwin Fabian Garcia-Aristizabal, Vega-Posada, Carlos Alberto, Montoya-Dominguez, Juan, Noriega, Pablo, Jhon Alfonso, Cajicáca, Leonardo
• Format: Article
• Language: Spanish
• Subjects: Aquifers; Classification; Comparative studies; Core drilling; Geotechnology; Mineral resources; Minerals; Rocks; Weights & measures
• ISSN: 0120-3630; 2357-3740
• DOI: 10.15446/rbct.n43.67217

The Porphyry deposits are the largest mineral resources in the world. During the exploration phase, with the extraction of drilling cores, it is possible to obtain geotechnical information from the rock mass. This information allows the classification of rock mass by means of empirical classification systems such as Rock Mass Rating (RMR), Mining Rock Mass Rating (MRMR) and Q index. In Porphyry deposits, the rock mass is affected by the presence of hydrothermal alterations; this implies that the rock may exhibit variations in its geomechanical properties depending on the hydrothermal alteration present. In this research, 6292 drilled meters with geotechnical information were considered. With this information, a classification of the rock mas was made by the aforementioned systems. Once the deposit was classified, a comparison was made between the classification systems mentioned. Comparison was based on the lithologies and hydrothermal alterations present in the deposit by means of descriptive statistics (average values, box plot diagrams, linear regressions). a comparison was made between the aforementioned classification systems with respect to the dominant hydrothermal alterations present in the reservoir. The results showed that in the porphyry deposit, the analysis by hydrothermal alteration allows differentiating a poor to regular behavior (Sericíte alteration) from a good behavior (Potassium Alteration).