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Minerals 2017, 7(10), 180;

Heap Leaching of Caliche Ore. Modeling of a Multicomponent System with Particle Size Distribution

Mining Technological and Scientific Research Center (CICITEM), Antofagasta 1240000, Chile
Department of Chemical and Mineral Process Engineering, Universidad de Antofagasta, Antofagasta 1240000, Chile
Department of Chemical Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden
Author to whom correspondence should be addressed.
Received: 3 August 2017 / Revised: 10 September 2017 / Accepted: 20 September 2017 / Published: 26 September 2017
(This article belongs to the Special Issue Heap Leaching: The State-of-the-Art)
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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. When it occurs and unlike most other leachable ores, the particle size diminishes. The leaching modeling of several soluble species of caliche has been recently addressed; however, one of the main assumptions is the idealization that the heap is composed of particles of the same size. The present work aims to complement the 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. These two water-soluble species have different solubilities and dissolution rates and the conceptual model considers that both species are dissolved at the particle surface. When the most soluble species is being depleted, the particle collapses, leaving a remaining fraction of the less soluble species together with insoluble material. The less soluble species is now being dissolved from the collapsed material. This article also includes the experimental verification of the conceptual model using data obtained from column leaching tests conducted for this purpose, focusing on the dissolution of two soluble species: Nitrate and Magnesium. View Full-Text
Keywords: heap leaching; modeling; caliche; PSD; multicomponent system; particle size decreasing heap leaching; modeling; caliche; PSD; multicomponent system; particle size decreasing

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Ordóñez, J.I.; Condori, A.; Moreno, L.; Cisternas, L.A. Heap Leaching of Caliche Ore. Modeling of a Multicomponent System with Particle Size Distribution. Minerals 2017, 7, 180.

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