Drill-Holes and Blast-Holes

Serge Antoine Séguret (1) , Sebastian de La Fuente (2)

1 GEOSCIENCES - Centre de Géosciences
2 Codelco

The following is a geostatistical study of copper measurements on samples from diamond drill-holes and blast-holes. Both measurements are formally compared, leading to a model where a blast-hole can be considered a regularization of the drill information up to a nugget effect characteristic of the blast-holes. This formal link makes it possible to build a cokriging system that takes into account the different supports and leads to a block model based on blast and drill-holes. The model is tested on a realistic simulation where the true block grades, which are known, are compared to their estimate obtained by:-Kriging using only drill-holes;-Kriging using only blast-holes;-Cokriging using drill and blast-holes together. A preliminary conclusion is that the best estimates are obtained when only blasts or alternatively, blast and drill-holes are used; there is no significant difference between the two, which is due to the great amount of blast information. This result justifies the usual practice of basing short-term planning on blasts only. But another conclusion may be drawn when kriging is compared to a moving average (another common practice), both based on blasts: depending on the number of data used in the neighborhood, the moving average produces a strong conditional bias. As a byproduct, we also show how it is possible to filter the blast error by kriging and to make a deconvolution to estimate point support values using blast measurements .

Mots clés: mining; geostatistics; blast-holes; drill-holes; supports; regularization

Domaines: Mathématiques appliquées; Sciences de la Terre

Serge Antoine Séguret, Sebastian de La Fuente. Drill-Holes and Blast-Holes. Geostat 2016, Sep 2016, valencia, Spain. ⟨hal-01410191⟩