Heap Leaching of Caliche Ore Modeling of

Caliche is a mineral exploited in northern Chile, from which iodine and nitrate salts (saltpeter) are obtained. This ore is the most important source of iodine in the world and is processed mainly by heap leaching using water as a leaching agent. Heap leaching of caliche ore is carried out by the stacking of ROM (Run-Of-Mine) material, where the particle size distribution covers a wide range, from a few millimeters up to several decimeters, even diameters about 1 m. During the leaching, the multiple soluble species of caliche, which can reach total fractions larger than 40%, are dissolved at different rates, mainly controlled by their solubilities. The present work aims to complement previously formulated phenomenological models for caliche ore leaching, through a model that considers the simultaneous dissolution of two species from caliche with three different particle sizes. The article includes the experimental verification of the conceptual model using data obtained from column leaching tests conducted for this purpose, focusing on the effects of particle size on dissolution rates, thereby addressing shortcomings in prior models.