Subsurface potash mining at the Cabanasses anticline vicinity overcomes major technical challenges. Ore concentrates in currently folded layers, originally embedded horizontally in the upper Eocene-Oligocene period, at the Catalan Basin. In general, potash ores of the Catalan basin are halokinetic deposits. White carnallite is a low-grade potash variety of carnallite, rich in Mg and Cl compared to red carnallite. It roughly tops a main ore seam at the mine. The main problem and risk evolve from its petrophysical character. It disintegrates during the drilling procedure, so retrieving samples for robust identification is virtually impossible considering current drilling methods. Several reserve blocks have already been abandoned due to its massive occurrences. Survey exploration drillings executed before mining operations should assist in detection of the material and should prevent losses of mining resources.
Here we present subsurface mapping and analysis the of the white carnallite and associated foliated carnallite beds to predict the extent and to minimize mining risks. Based on 2d and 3d seismic reflection surveys, vertical drills and sub-horizontal survey core drills we spatially assess the problem.
Preliminary observations confirm a geological structural control of the white carnallite. Occurrences overlap elevated positions of the top (ceiling) seam B surface. Structural datasets are integrated with geochemical analysis. Work is done together with the local geology team both in active mining sectors and in the larger scope of the mine. A robust and reliable methodology is being developed to detect the white carnallite in underground survey drillings. An attempt is being made to predict expected zones of occurrence and prevent financial losses and accidents. Definition of key horizons and structures of white carnallite are regularly integrated into mining plans.