Liquid flow in heap leaching using the discrete liquid flow model and graph-based void search algorithm

Abstract

The liquid flow in many heap leaching processes is discontinuous in nature as it occurs either as droplets or rivulets or in combination. Therefore, it cannot be represented correctly using continuum-based models at very low liquid flow rates, such as in heap leaching, or in non-wetting conditions, where liquid flow is discrete in nature. Many researchers have modelled the liquid flow through the heap packing using continuum models. However, this directly contradicts the experimental observations made by various researchers. In the current study, liquid flow is considered discrete in nature as rivulets and droplets with their rupture and merging phenomena. A single vertical layer of particles is considered for the study. A novel void search algorithm is devised to detect the position, shape, and size of the voids in a heap. The liquid flow behaviour is studied in terms of particle size, tortuosity, liquid distribution, breakthrough time, and contact angle. The study shows that heap leaching processes can be modelled more accurately using Discrete Liquid Flow (DLF) theory by avoiding uncertain experimental parameters such as bed permeability. It is found that particle size in the heap structure has significant effect on the liquid-solid contact area, which is an important parameter to determine the efficiency of the leaching process at an industrial scale.