Biopolymer Stabilization of Mine Tailings

A feasibility study was performed on using xanthan gum and guar gum, two biopolymers that are naturally occurring and inexpensive, to stabilize mine tailings (MT). The simple fall cone method was adopted to evaluate the liquid limit and undrained shear strength of sun-dried MT mixed with xanthan gum or guar gum solutions at different concentrations. Environmental scanning electron microscopy (ESEM) imaging was also conducted to study the microstructure of the biopolymer-MT system. The results indicate that the inclusion of xanthan gum or guar gum increases both the liquid limit and the undrained shear strength of the MT, higher biopolymer concentrations leading to greater increases. The increase of the liquid limit and undrained shear strength of the MT mixed with a biopolymer solution is mainly attributable to the high viscosity of the biopolymer pore fluid and the bonding between the biopolymer and the MT particles. Guar gum is more effective than xanthan gum in increasing the liquid limit and undrained shear strength of the MT, because the guar gum solution is more viscous than the xanthan gum solution at the same concentration, the guar gum-MT particle bonding is stronger than the xanthan gum-MT particle bonding, and guar gum causes a lower degree of aggregation of MT particles than xanthan gum. By comparing the undrained shear strength data with empirical equations in the literature, two new equations were proposed for predicting the undrained shear strength of the MT mixed with a biopolymer for water contents near the liquid limit, based on the liquid limit and water content, and the liquidity index, respectively. (C) 2013 American Society of Civil Engineers.