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

Abstract

Abstract: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.

Toward the Implementation of Circular Economy Strategies: An Overview of the Current Situation in Mineral Processing

“…Another example of repurposing is the use of the reject brine of desalination process in mineral processing. Studies have shown that the leaching of caliche using reject brine is technically feasible and delivers similar results than using seawater (Ordóñez et al 2015(Ordóñez et al , 2017. In another study, the use of reject brine in the leaching of pure chalcocite provides better results than the use of seawater (Torres et al 2020).…”

Optimization of the Heap Leaching Process through Changes in Modes of Operation and Discrete Event Simulation

“…Around 20% of the world's copper production is obtained by heap leaching. This process has been modeled by many authors; however, the validation, verification and implementation of these models are difficult since there is uncertainty about the operating conditions and parameters of the leaching model [24][25][26].…”

Bioleaching Modeling—A Review

“…In addition to copper oxides, heap leaching is applied to a wide range of minerals, including copper sulphide minerals, such as chalcocite [5][6][7], covelline [8][9][10], or chalcopyrite [11][12][13]. On the other Materials 2023, 16, 3812 2 of 23 hand, non-metallic minerals, such as saltpeter, can also undergo leaching processes [14,15]. Applications of leaching in such cases have been studied by various authors [16][17][18] who have modeled mineral leaching at both laboratory and industrial scales.…”