Abstract
The heap leaching process has been widely used for recovering different metals since its first application at the end of the 1960s. In Chile, copper production via heap leaching has accounted for between 30 and 40% of annual copper production over the past 10 years. This level of production has been achieved through and supported by the use of a mathematical relation, known as the leaching ratio (LR) or irrigation ratio (IR), which relates operational parameters with metal extraction in a heap leaching operation. This ratio has been used to develop leaching column tests, to scale up results from the laboratory to industrial operations, to design new heap leaching plants, and in metallurgical control and production estimation. In spite of the widespread industrial use of this relation, few scientific studies mention it. This is due to its simplicity and basic theoretical foundations. This disparity between industrial practice and scientific research could lead to operational decisions which lack substantial theoretical support, and to scientific studies which have limited industrial impact. Against this background, several questions arise about the use of the LR: What are the constraints on the use of the LR? Are there practical advantages with respect to reported kinetic models? What is the main reason that industry prefers the use of the LR over kinetic models, which enjoy greater theoretical support? In order to guide its future use, this paper describes the leaching ratio and its current uses and limitations, through a literature review and case studies.
Similar content being viewed by others
References
Petersen J (2016) Heap leaching as a key technology for recovery of values from low-grade ores – a brief overview. Hydrometallurgy 165:206–212. https://doi.org/10.1016/j.hydromet.2015.09.001
Ghorbani Y, Franzidis JP, Petersen J (2016) Heap leaching technology – current state, innovations and future directions: a review. Min Proc Ext Met Rev 37(N 2):73–119. https://doi.org/10.1080/08827508.2015.1115990
Ilankoon IMSK, Tang Y, Ghorbani Y, Northey S, Yellishetty M, Deng X, McBride D (2018) The current state and future directions of percolation leaching in the Chinese mining industry: challenges and opportunities. Min Eng 125:2016–2222. https://doi.org/10.1016/j.mineng.2018.06.006
Thenepalli T, Chilakala R, Habte L, Quang-Tuan L, Sik-Kim C (2019) A brief note on the heap leaching technologies for the recovery of valuable metals. Sustainability 11:3347. https://doi.org/10.3390/su11123347
Cochilco (2018). Yearbook: Copper and other mineral statistics (1998–2017). https://www.cochilco.cl/Lists/Anuario/Attachments/18/AnuarioCochilco2017final.pdf (accessed 31 October 2018)
Vidal-Astudillo J (2013). Análisis de Procesos Mineros VI Versión MGM. http://www.enm.ucn.cl/intranet_enm_ucn/claroline1107/programas/APM_001/document/01-Revisi%C3%B3n_General_%C3%93xidos_Encuentro_Peer_Review_Enero_2013.pdf (accessed 09 November 2018)
Aldana J (2011). Procesamiento de Mineral Oxidado de Baja Ley de Cobre – Proyecto Antucoya, Chile. 6th International Seminar on Copper Hydrometallurgy, HydroCopper 2011, July 6–8, 2011, Viña del Mar, Chile. https://docplayer.es/10211834-Procesamiento-de-mineral-oxidado-de-baja-ley-de-cobre-proyecto-antucoya-chile.html (accessed 09 November 2018)
Figuera A, Silva P, Arriagada F, Peralta R (2015). Copper Production Model for San Francisco Dump Leaching Operation. 7th International Seminar on Process Hydrometallurgy, HydroProcess 2015, July 22–24, 2015, Antofagasta, Chile
Carvajal-Gutiérrez C (2012). Caracterización de un Mineral Oxidado Sector Veta-Blanca, El Soldado, Angloamerican Chile. Thesis, Extractive Metallurgy Engineering, Pontificia Universidad Católica de Valparaiso. http://opac.pucv.cl/pucv_txt/txt-3000/UCF3107_01.pdf (accessed 09 November 2018)
Tapia-Godoy J (2016). Evaluación Alternativas de Procesamiento Línea Hidrometalurgia División Salvador-Codelco. Master Thesis, Industrial Engineering, University of Chile. http://repositorio.uchile.cl/bitstream/handle/2250/141072/Evaluacion-alternativas-de-procesamiento-linea-hidrometalurgia-Division-Salvador-Codelco-Chile.pdf?sequence=1 (accessed 09 November 2018)
Avendaño C (2013). Técnicas Mejoradas de Lixiviación Minerales de Cobre en Pilas. 5th International Seminar on Process Hydrometallurgy, Hydroprocess 2013, Short course, July 9, 2013, Santiago, Chile. http://www.terral.cl/wp-content/uploads/Tecnicas_Lixiviaci%C3%B3n_en_Pilas_HIDROPROCESS.2013.pdf (accessed 09 November 2018)
Lancaster T, Walsh D (1997). The Development of the Aeration of Copper Sulphide Ore at Girilambone. IBZ Biomine ‘97 Conference, Sydney, Australia, Australian Mineral Foundation
Torres MA, Meruane GE, Graber TA, Gutiérrez PC, Taboada ME (2013) Recovery of nitrates from leaching solutions using seawater. Hydrometallurgy 133:100–105. https://doi.org/10.1016/j.hydromet.2012.12.008
van Staden PJ, Kolesnikov AV, Petersen J (2017) Comparative assessment of heap leach production data – 1. A procedure for deriving the batch leach curve. Miner Eng 101:47–57. https://doi.org/10.1016/j.mineng.2016.11.009
van Staden PJ, Huynh TD, Kiel MK, Clark RI, Petersen J (2017) Comparative assessment of heap leach production data – 2. Heap leaching kinetics of Kipoi HMS floats material, laboratory vs. commercial scale. Miner Eng 101:58–70. https://doi.org/10.1016/j.mineng.2016.11.015
Menacho JM (2017). Scale Up of Hydrodynamic and Metallurgical Response in Heap Leaching Operations. 9th International Seminar on Process Hydrometallurgy/International Conference on Metal Solvent Extraction, Hydroprocess/ICMSE 2017, June 21–23, 2017, Santiago, Chile. http://www.drm.cl/wp-content/uploads/2017/07/JORGE-MENACHO-Scale-Up-Hydrodynamic-22-06-2017.pdf (accessed 09 November 2018)
Ilankoon IMSK, Neethling SJ (2013) The effect of particle porosity on liquid holdup in heap leaching. Min Eng 45:73–80. https://doi.org/10.1016/j.mineng.2013.01.016
Levenspiel O (1999) Chemical reaction engineering, 3rd edn. Wiley, New York
Botz MM, Marsden JO (2019) Heap leach production modeling: a spreadsheet-based technique. Min Metall Explor 36:1041–1052. https://doi.org/10.1007/s42461-019-00129-0
Dixon DG, Hendrix JL (1993) A mathematical model for heap leaching of one or more solid reactants from porous ore pellets. Metall Tran B 24B:1087–1102. https://doi.org/10.1007/BF02661000
Ogbonna N, Petersen J, Dixon DG (2005). HeapSim-Unravelling the mathematics of heap bioleaching, in: M. and P. Canadian Institute of Mining (Ed.), Proc. 35th Annu. Hydrometall. Conf., Quebec
Petersen J, Dixon DG (2007) Modeling and optimisation of heap bioleach processes. In: Rawlings DE, Johnson DB (eds) Biomining. Springer Verlag, Berlin. ISBN: 978-3-540-34909-9, pp 153–176
Petersen J, Dixon DG (2007) Principles, mechanisms and dynamics of chalcocite heap bioleaching. In: Donati E, Sand W (eds) Microbial processing of metal sulfides. Springer Verlag, Berlin. ISBN: 978-1-4020-5588-1, pp 193–218
Marsden JO, Botz MM (2017) Heap leach modeling – a review of approaches to metal production forecasting. Miner Metall Proc 34(2):53–64. https://doi.org/10.19150/mmp.7505
McBride D, Cross M, Gebhardt JE (2012) Heap leach modeling employing CFD technology: a ‘process’ heap model. Miner Eng 33:72–79. https://doi.org/10.1016/j.mineng.2011.10.003
McBride D, Gebhardt JE, Croft N, Cross M (2018) Heap leaching: modelling and forecasting using CFD technology. Minerals 8:9. https://doi.org/10.3390/min8010009
Barlett RW (1998) Solution mining: leaching and fluid recovery of materials, 2nd edn. Gordon and Breach Science Publishers, Amsterdam
Lizama HM (2004) A kinetic description of percolation bioleaching. Miner Eng 17:23–32. https://doi.org/10.1016/j.mineng.2003.09.012
Lizama HM, Harlamovs JR, McKay DJ, Dai Z (2005) Heap leaching kinetics are proportional to the irrigation rate divided by heap height. Miner Eng 18:623–630. https://doi.org/10.1016/j.mineng.2004.12.012
Sidborn M, Casas J, Martínez J, Moreno L (2003) Two-dimensional dynamic model of a copper sulphide ore bed. Hydrometallurgy 71:67–74. https://doi.org/10.1016/S0304-386X(03)00178-6
Ferrier RJ, Cai L, Lin Q, Gorman GJ, Neethling SJ (2016) Models for apparent reaction kinetics in heap leaching: a new semi-empirical approach and its comparison to shrinking core and other particle-scale models. Hydrometallurgy 166:22–33. https://doi.org/10.1016/j.hydromet.2016.08.007
Mellado ME, Cisternas LA, Gálvez ED (2009) An analytical model approach to heap leaching. Hydrometallurgy 95:33–38. https://doi.org/10.1016/j.hydromet.2008.04.009
Mellado ME, Gálvez ED, Cisternas LA (2011) On the optimization of flow rates on copper heap leaching operations. Int J Miner Process 101:75–80. https://doi.org/10.1016/j.minpro.2011.07.011
Mellado ME, Gálvez ED, Cisternas LA (2012) Stochastic analysis of heap leaching process via analytical models. Miner Eng 33:93–98. https://doi.org/10.1016/j.mineng.2011.09.006
Mellado ME, Cisternas LA, Lucay FA, Gálvez ED, Sepulveda FD (2018) A posteriori analysis of analytical models for heap leaching using uncertainty and global sensitivity analyses. Minerals 8(2):44. https://doi.org/10.3390/min8020044
Padilla GA, Cisternas LA, Cueto JY (2008) On the optimization of heap leaching. Miner Eng 21:673–678. https://doi.org/10.1016/j.mineng.2008.01.002
Ghorbani Y, Petersen J, Becker M, Mainza AN, Franzidis JP (2013) Investigation and modelling of the progression of zinc leaching from large sphalerite ore particles. Hydrometallurgy 131-132:8–23. https://doi.org/10.1016/j.hydromet.2012.10.004
Richards LA (1931) Capillary conduction of liquids through porous mediums. J Appl Phys 1:318–333. https://doi.org/10.1063/1.1745010
van Genuchten M (1980) A closed-form equation for predicting the hydraulic conductivity of unsaturated soils. Soil Sci Soc Am 44:891–898. https://doi.org/10.2136/sssaj1980.03615995004400050002x
Vargas T, Rojas F, Bahamondez C, Castro R, Ihle CF, Caraballo M, Widzyk-Capehart E (2017) Physical and chemical transformations of gangue materials during leaching of copper sulfides, and their influence on copper leaching kinetics. J S Afr I Min Metall 117:727–730 https://doi.org/10.17159/2411-9717/2017/v117n8a1
Crundwell FK (2013) The dissolution and leaching of minerals: mechanisms, myths and misunderstandings. Hydrometallurgy 139:132–148 https://doi.org/10.1016/j.hydromet.2013.08.003
Acknowledgements
The authors gratefully acknowledge the financial support of the National Commission for Scientific and Technological Research (CONICYT Chile) through the CONICYT-PIA Project AFB180004. Furthermore, the authors appreciate the critical review of Dr. Tomás Vargas.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of Interest
On behalf of all authors, the corresponding author states that there is no conflict of interest.
Additional information
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Estay, H., Díaz-Quezada, S. Deconstructing the Leaching Ratio. Mining, Metallurgy & Exploration 37, 1329–1337 (2020). https://doi.org/10.1007/s42461-020-00243-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s42461-020-00243-4