稻壳灰对污染尾砂典型重金属的稳定化

Stabilizing Heavy Metal Using Rice Husk Ash in Mine Tailings

矿山开采引起的废弃物堆积、滑坡及渗漏问题愈发严重。基于“以废治废”的理念和策略,本研究旨在提出一种绿色、高效的方法以稳定尾砂中的重金属。为了更好地评价稳定化尾砂的稳定性能,通过向铅锌矿尾砂中加入不同掺量的稻壳灰(RHA)(1%、5%、7%、10%和15%),并在室温下养护7 d、14 d、21 d和28 d,测定稳定后尾砂的浸出毒性和形态含量。结果表明,RHA的添加有利于调节尾砂的pH。相关性结果显示,pH与Cd呈显著负相关(p<0.01),与Pb呈正相关(p<0.05),与Zn无明显的相关性,与Pb、Zn相比,Cd受酸碱度的影响最大。RHA对Pb、Zn和Cd的稳定效果依次为Pb>Cd>Zn,Pb、Zn和Cd的最佳去除率分别达到99.94%、83.03%和95.70%。稳定后浸出液中Cd的浓度低于地表水IV级水质标准(GB 3838-2002),弱酸提取态Pb、Zn和Cd的含量分别下降了96.68%、65.53%和69.47%,有效降低了Pb、Zn和Cd对生态环境和人体的直接毒性和潜在风险。

The problems of waste accumulation,landslides and seepage caused by mining are becoming increasingly serious.Based on the concept of"treating waste with waste",this study aims to propose a green and efficient method to stabilize heavy metals in mine tailings.To better evaluate the stability of the treated tailings,different contents of rice husk ash(RHA)(1%,5%,7%,10%and 15%)were added to lead(Pb)-zinc(Zn)tailings and cured at room temperature for 7 d,14 d,21 d and 28 d to determine the Pb,Zn and cadmium(Cd)leachability and speciation in tailings.The results reveal that RHA addition was beneficial in regulating the pH value of the tailings.The correlation analysis shows that the pH was significantly,negatively correlated with Cd(p<0.01),positively correlated with Pb(p<0.05),but not significantly correlated with Zn.Compared to Pb and Zn,Cd was most remarkably affected by pH.RHA stabilized Pb,Zn and Cd in the order of Pb>Cd>Zn,with the best removal rates of 99.94%,83.03%and 95.70%for Pb,Zn and Cd.The concentration of Cd in the leachate after stabilization was lower than the level IV water quality standard of surface water(CB 3838-2002).The contents of weak acid extractable Pb,Zn and Cd decreased by 96.68%,65.53%and 69.47%.Therefore,stabilization using rice husk ash may effectively reduce the direct toxicity and potential risks of Pb,Zn and Cd in mine tailings to the ecosystems and human beings.