Experimental investigation of dewatering silty tailings using electrokinetic method

Abstract

Mining and using underground resources demand high water usage, producing significant waste with environmental risks. Methods like electrokinetics prove effective in accelerating dewatering and stabilizing structures. This research provides the results of experimental investigation on dewatering silty tailings obtained from Sungun Tailings Dam (East Azerbaijan, Iran) using the electrokinetic water recovery method. Previous studies primarily examined the electrokinetic process in steady-state flow and saturated soil, with limited exploration of unsaturated soil parameters. In this research, the electrokinetic process in steady-state flow was initially investigated, and the saturated electro-osmotic permeability was determined. Subsequently, experiments were conducted in non-steady-state flow and unsaturated conditions, measuring the influential parameters with soil moisture sensors and tensiometers. Results show that decreasing sample moisture through electro-osmotic flow increases negative pore water pressure. Tailings' electrical conductivity is more influenced by moisture content, with a steeper reduction slope concerning volumetric moisture reduction over time. pH assessments show soil acidity at anode side and alkalinity on the cathode side. Higher applied voltage increasing maximum power consumption. Importantly, the results caution against assuming that higher applied voltage improves the electro-osmotic process, as it may lead to issues such as deep sample cracking; void space creation, interrupted electrical flow, and energy loss.