Comparative analysis of the resource classification techniques: case study of the Conceicao Mine, Brazil

The major international codes recognise that resource classification involves the interaction of numerous qualitative and quantitative criteria. However, the difficulty in quantifying the degree of uncertainty associated with the estimation of mineral resources has led to the creation of a large suite of methods, terms, and definitions, with almost every mining company having its own set of standards. Traditional methods used to evaluate resources, such as, the number of samples used to interpolate a block, or the position of samples surrounding this block, do not take into account the spatial continuity of the grades; and some approaches based on geostatistical methods are unable to provide a measure of the error associated with their estimates. Because they do not provide an error assessment, these methods are inappropriate to assess the local or global uncertainty associated with an estimate. Posed with these problems, some of the widely applied techniques for mineral resource classification were assembled in a software package, and a comparative study was conducted at the Conceicao Mine (Iron Ore Quadrangle, Brazil), allowing a comparison among the parameters affecting mineral inventory assessment. The results showed the specific limitations of each classification system, the influence in selecting their key parameters, and the empirical nature of the traditional methods that are mainly subjective.