Mechanistic insights and predictive modeling of silicate dissolution in gold tailings via alkaline hydrothermal treatment

Abstract

The significant accumulation of gold tailings (GT) presents a substantial environmental challenge, while existing pathways for their high-value utilization remain limited and lack theoretical underpinning. This study provides a comprehensive exploration of the separation and recovery of silicate components from GT via a hydrothermal treatment conducted under alkaline conditions. The effects of key parameters including GT/NaOH ratio, NaOH concentration, hydrothermal temperature, and hydrothermal time on silica extraction efficiency (SEE) and solid phase mineral composition were systematically investigated. The study elucidated the mechanism of silicate dissolution and zeolite formation. Furthermore, the optimal parameters for silicon extraction, determined using response surface methodology, are 4 hours, 202°C, 6.95 mol/L, and 1:3 g/mL, achieving a SEE of 70.619 %. Employing multivariate nonlinear regression, the study established a robust predictive model capable of forecasting SEE under various experimental conditions. The model demonstrated high predictive accuracy with minimal deviation at different parameters. Additionally, the zeolite materials obtained as byproducts of the hydrothermal process exhibited ion adsorption capabilities, with a maximum CEC of 1.475 meq/g. This research provides a critical theoretical foundation for the valorization of GT, highlighting its potential for high-value applications.