Soilless remediation of the fine carbonate-rich gold-copper mine tailings

Abstract

Soil remediation with minimum amendments is a good strategy for tailings disposal. Carbonate-rich gold-copper mine tailings occurring alongside the Yangzi River, China, were employed as the objective in this study. They showed the characteristics of fine particles and alkaline pH with high density and low nutrition. The amendments including bacterial fertilizer (BF), polymer, peat, straw, and compound fertilizer (CF) were used for soilless remediation on the tailings. Soil quality index (SQI) involved in tailing properties and growth characteristics of ryegrass was used to optimize the combination of amendments. The results showed that the optimum amendment combination was 0.2% BF + 0.6% CF + 0.2% polymer + 10% peat and 2% straw. Tailing nutrients such as soil organic matter (5.56%), available nitrogen (93.6 mg kg⁻¹), available phosphorus (51.7 mg kg⁻¹), available potassium (711 mg kg⁻¹), and ryegrass exhibited the highest germination rate and biomass level under the optimal improvement conditions. Additional environmental assessments revealed that soilless treatment of the tailings helped to convert Cu, Zn, and As into residual forms. These findings show a good strategy for tailings soil improvement and provide a promising perspective of the soilless remediation for fine carbonate-rich metal tailings.