Computer simulation of fluid motion in a porous bed using a volume of fluid method: Application in heap leaching S.M. Mousavi a,b, * , A. Jafari b , S. Yaghmaei a , M. Vossoughi a , P. Sarkomaa b a Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran b Department of Energy and Environmental Engineering, Lappeenranta University of Technology, Lappeenranta, Finland Received 8 January 2006; accepted 25 April 2006 Available online 30 June 2006 Abstract Heap leaching is a process extensively used by the mining industry to recover metals from low-grade ores and large quantities of sub- marginal material resources. Understanding flow through a packed particle bed is important to enhance the performance of heap leach- ing with respect to design and operating considerations. Complex fluid behavior in porous media, such as film flow, fragmentation, coalescence of droplets, and rivulet flow with or without meandering, has been widely observed in laboratory experiments. In this study, to provide detailed information of momentum and mass transfer phenomena in a granular bed direct numerical simulations (DNS) were performed. In this case the liquid–gas flow through a granular bed was considered comprised of monosized, spherical, solid particles arranged randomly in a cylindrical container. The volume of fluid (VOF) method was used to compute velocity field as well as liquid volume fraction distributions in the container. The results obtained suggest that the liquid phase distribution in the bed is mainly con- trolled by surface tension and particle induced turbulence appears to have insignificant effects. These results allow us to obtain a better understanding of the fundamental physics governing unsaturated fluid flow. This finding seems to have a significant impact in the design of efficient multi-phase reactors for heap leaching and bioleaching processes. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Porous bed; Direct numerical simulations; Volume of fluid; Heap leaching 1. Introduction Hydrometallurgical processes are increasingly applied worldwide, particularly for the recovery of metals from low-grade sulfide ores which are otherwise wasted. Depending upon the characteristics of the deposit and the ore, the technology is applied in different ways: heap leach- ing, in situ leaching and in place mineral processing opera- tions (Mousavi et al., 2005, in press). Currently, heap leaching finds important applications in the recovery of copper and gold from their ores because of its low cost, short construction time, operational simplicity, good performance, and environmental advantages. Col- umn and heap leaching have many analogies with down flow trickle-bed catalytic reactors for which the hydrody- namics has received enormous attention for more than four decades. The liquid phase hydrodynamics in column and heap leaching, however, in spite of their economic impor- tance as a metal recovery and cleanup method, has been the object of only a very few systematic studies and was not completely elucidated yet. Phenomenological mathe- matical models for heap and column leaching, taking into account the fluid flow throughout the porous bed and the reaction that takes place in the solid particles, can be used to the design and optimization of these processes (de And- rade Lima, 2006; Petersen and Dixon, 2002; Sheikhzadeh et al., 2005). A porous medium is defined as a matrix of solid parti- cles with interconnected void spaces. The solid matrix is 0892-6875/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.mineng.2006.04.016 * Corresponding author. Address: Department of Chemical and Petro- leum Engineering, Sharif University of Technology, Tehran, Iran. Tel.: +98 21 66165494; fax: +98 21 66005417. E-mail address: Mousavi@chemeng.sharif.edu (S.M. Mousavi). This article is also available online at: www.elsevier.com/locate/mineng Minerals Engineering 19 (2006) 1077–1083