Experimental study on the stabilization and anti-seepage treatment of lead and zinc elements in heavy metal tailings pond using cement slurry containing heavy metal stabilizing agent

The release of heavy metal elements in heavy metal tailings ponds not only causes environmental pollution but also poses potential hazards to human health. Therefore, it is of great significance to stabilize heavy metals and apply anti-seepage treatment to tailings ponds. In this paper, the tailings in the Shenxiandong lead-zinc tailings pond in Yunnan Province, Southwest China, were analyzed. The adsorption effects of different natural stabilizing agents on lead (Pb) and zinc (Zn) in tailings were investigated. Orthogonal and modification experiments were used to identify the most effective stabilizing agent. This agent was then combined with a high-pressure rotary jet cement slurry to investigate the properties of the resulting consolidation body and its effect on heavy metal solidification. The results show that the tailings are more likely to release heavy metal elements into the environment. The results of the orthogonal experiments show that the stabilizing agent CCA, which is a combination of fly ash, attapulgite, and Na-bentonite in a 2:1:2 ratio, effectively adsorbs Pb and Zn elements in the tailings. The stabilizing agent CCAPT is created by modifying CCA with 7% H3PO4 at pH of 12 and heat treating at 200 °C. CCAPT demonstrates a 97.2% improvement in stabilization efficiency for Pb and a 94.1% improvement for Zn compared to CCA. The combination of CCAPT and cement slurry resulted in a 25.6% increase in compressive strength and a 29.5% decrease in permeability coefficient compared to the cement slurry formed consolidation body. The core-flooding experiment shows that the residual leachate after consolidation of “5% CCAPT + cementitious slurry” contains only 35.6 μg/L of Pb and 29.2 μg/L of Zn. These concentrations are significantly lower than the national emission requirements. This study presents an experimental foundation for further investigation into the use of high-pressure jet grouting technology to seal tailings ponds.