Stabilization of soft soils using electrochemical mineral precipitation: Application to overburden dumps

¹ Department of Civil and Environmental Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110016
² Geomechanics and Porous Media (G2MP), University of Pau & Pays Adour (UPPA), Anglet, France-64600
³ Natural Resources Division, Tata Steel Limited, Jamshedpur, Jharkhand, India- 831001

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Mine overburden dumps (MOBD) are generally unstable due to poor compaction, high permeability, and a lack of internal cohesion, posing a significant risk of slope failure and environmental hazard. Therefore, developing an effective stabilization technique for MOBD is vital to ensure long-term safety and sustainable mining operations. One promising approach is the use of electrodeposition, which reduces permeability and enhances mechanical stability by inducing mineral precipitation within the pore spaces. When an electrical potential (EP) is applied across the MOBD, it drives the electrolysis of chemical compounds and the migration of ions toward the electrodes, leading to the formation of stable, insoluble compounds such as carbonates or silicate minerals. In this context, laboratory experiments were performed using calcium chloride and sodium metasilicate as wetting fluid in the MOBD sample. The EPs of 1 V, 3 V, and 5 V were selected to determine the efficacy of mineral precipitation at different potentials. Post-treatment characterization using scanning electron microscopy (SEM) confirmed the formation of calcium silicate hydrate as the primary electrodeposit across all voltages. However, the uniformity and extent of electrodeposition vary with the magnitude of EP: low voltage results in uniform electrodeposits, whereas high voltage leads to non-uniform electrodeposits. Moreover, an increase in strength of up to 70% was immediately measured via a penetration test for the treated samples. In conclusion, this study demonstrates the potential of electrodeposition in stabilizing MOBD.