The recovery of rare earth elements (REEs) through heap leach/in situ techniques from so-called ion adsorption clays (IACs) is attractive due to their inherent simplicity. However, the underlying mechanisms of these processes are poorly understood. In this study, the deportment of REEs in a typical IAC material has been investigated and was found to concentrate in the phyllo-layers of the clays, especially hallyosite, and was readily desorbed by various ion-exchange reagents indicating various potential routes to liberate them. Here we are reporting the use of seawater (0.5 M NaCl), spiked with various amounts of (NH4)2SO4, and found better extraction using a reagent mixture than NaCl on its own. Further, the leaching of REEs from a bed of clay material was investigated over time to understand the rate of transport through the stagnant material. Results indicate that REE release is likely to be controlled by diffusion through the clay material, while desorption in agitated systems is rapid. A degree of fractionation between different REEs can be observed during diffusion. Nonetheless, the successful operation of in situ leach operations for this type of material would depend primarily on how easily solution cocktails can be made to flow through the bed material.
|Title of host publication||Extraction 2018|
|Subtitle of host publication||Proceedings of the First Global Conference on Extractive Metallurgy|
|Editors||Boyd R Davis, Jaeheon Lee, Michael S Moats, Graeme Miller, Shijie Wang, Jochen Petersen, Dean Gregurek, Virginia S T Ciminelli, Joël Kapusta, Qian Xu, Thomas P Battle, Ronald Molnar, Mark E Schlesinger, Jeff Adams, Gerardo Raul Alvear Flores, Wenying Liu, Evgueni Jak, Niels Verbaan, Graeme Goodall, John Goode, Michael L Free, Ian M London, Edouard Asselin, Gisele Azimi, Alexandre Chagnes, Alex Forstner, David Dreisinger, Ronel Kappes, Matthew Jeffrey, Tarun Bhambhani|
|Place of Publication||Cham Switzerland|
|Number of pages||11|
|Publication status||Published - 19 Aug 2018|
|Name||The Minerals, Metals & Materials Series|