Lately, due to the incidents that occurred in tailings dams in recent years, the Brazilian mineral industry is committed to closure upstream raised dams and, in addition, for the new Tailings Storage Facilities, dry stacking of filtered tailings has emerged as a safer alternative to traditional slurry disposal in ponds. Both structures as a particular characteristic: embankments of iron ore tailings with several meters high and partiality saturated. Considering that, it is essential the understanding of the unsaturated behavior of the tailings for a safe removal and de-characterization of upstream dams and, also, for monitoring the performance of filtered tailings dry stacks. Dielectrics techniques are widely used to measure water content in soil, however, the capacitance probes must be calibrated for each soil type. Iron ore tailings have in their constitution iron minerals such as hematite, magnetite and goethite, those minerals show capacitance influence and could varieties the response of the sensor causing a wrong measure of water content. Thus, it is demonstrated in this work, calibrations curves for Frequency Domain Refractometry (FDR) considering iron ore tailings.