Abstract: The risk of acidic wastewater and heavy metal contamination from the storage of copper sulfide tailings poses a significant challenge for mining operations. This study selected four remediation materials,shell-based CaCO₃,expanded  vermiculite,zeolite,and biochar,to systematically evaluate their effects on leachate pH regulation and the transformation and mobility of heavy metals (Cr,Cu,Pb,Ni,Cd) under simulated field conditions using laboratory column leaching experiments. The aim was to provide a scientific basis and technical options for mitigating contamination from tailings storage. The results showed that:① All four materials increased the pH of the leachate and soil to varying degrees. Shell-based CaCO3 acted most rapidly and stably,raising soil pH to around 8. 0;Biochar and expanded vermiculite exhibited a slow-release effect,while zeolite had a relatively weaker impact. The optimal application rates (by dry soil weight) for improving soil pH were 15%,15%,10%,and 10%,respectively. ② Compared with the control group (CK),biochar significantly enhanced the immobilization of Cr,Cu,Pb,and Ni,with the total fixed amounts increasing by up to 338. 5%,106. 6%,34. 8%,and 271. 1%,respectively,as the application rate increased. The application of 10% shell-based CaCO3 increased the fixation of Cu and Pb by 30. 5% and 130. 9%,respectively,while 10% zeolite increased Pb fixation by 50. 1%. ③ BCR sequential extraction results indicated that all treatments material reduced the proportions of the acid-soluble and reducible fractions while increasing the residual fraction. Shellbased CaCO₃ and biochar were the most effective in enhancing the binding intensity (I_R) of heavy metals and reducing their migration factor (M_f). Correlation analysis further confirmed that soil pH was positively correlated with the contents and residual fraction of Cd and Pb,and negatively correlated with the acid-soluble fraction of Cd,Cr,Cu,Pb,and Ni,indicating that increasing pH is a key mechanism promoting heavy metal stabilization and reducing mobility. In conclusion,all four materials enhanced the adsorption and immobilization of heavy metals in copper sulfide tailings by elevating soil pH,thereby significantly reducing their mobility and bioavailability. Shell-based CaCO3 and biochar demonstrate strong potential for ecological remediation of tailings storage sites and are recommended as core materials for engineering applications and further development.