YANG Chengya1 , HAN Zhiwei 1,2 , ZHU Jiwei 1
(1. Resource and Environmental Engineering College, Guizhou University, Guiyang 550025, China;
2. Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guiyang 550025, China)
Abstract: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 (GB 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.
Key words: lead-zinc tailings; heavy metal; speciation distribution; leaching toxicity; stabilization; rice hush ash
EARTH AND ENVIRONMENT： Vol. 51, No. 5, Tot No.355 2023
