Biopolymer-amended-kaolin as a Barrier for Tailing Disposal Facilities

Abstract

Abstract Mining waste in tailing storage facilities contains high ionic strength salts that pose a potential threat to the environment. Kaolin clays are receiving great interest recently for engineered barriers as minimal shrinkage cracks occur in these 1:1 clays. The present study evaluates the hydraulic, volume-change, diffusion, and retardation characteristics of kaolin clay and xanthan gum amended clay under the hydro-chemo-mechanical loading conditions pertinent to the mine storage applications. A biopolymer, Xanthan Gum, was explored to amend the kaolin for the application of barrier to address the environmental concern. The barrier design parameters for tailing disposal facilities such as diffusion and retardation characteristics, were evaluated using the through-diffusion experiment. Diffusion tests were conducted on the samples obtained from the hydraulic permeation tests under mechanical loading to simulate the field conditions. Theoretical concentration profiles for both kaolin and xanthan gum amended kaolin barriers were obtained by the numerical simulation of the advection-diffusion equation using the finite difference method. The xanthan gum improved the chemical compatibility, reduced the hydraulic infiltration rate, and reduced diffusion rates significantly. The results from the study suggested the suitability of xanthan gum amended kaolin barrier for attenuation of contaminants and as a sustainable alternative in tailing disposal facilities.