Effects Of Curing Agents On Heavy Metals Stabilization In The Tested Soils And Reasearch Of Modified Curing Agents

The stabilization of Pb, Cd, Cu, and Zn in contaminated soil of Hunan typical mine area (Hengyang) was studied by using six kinds of curing agents (zeolite, limestone, diatomite, hydroxyl-apatite, bentonite and sepiolite), and some effective curing agents were picked out. Zeolite and bentonite were modified through three methods, and six kinds of modified curing agents were prepared. The stabilization of soil Pb, Cd, Cu, Zn of curing agents and modified curing agents was studied. Finally, the practical addition of curing agents were fixed, and the stabilization of soil Pb, Cd, Cu, Zn in experimental base (Zhuzhou) was studied by applying five kinds of curing agents (zeolite, bentonite, limestone, hydroxyl-apatite, modified bentonite) at a single addition. The main results of the experiments were as follows:(1) Zeolite, limestone, and hydroxyl-apatite could effectively reduce exchangeable contents and leaching solution contents of Pb and Cd in Hengyang soil. Zeolite showed the best effects on reducing exchangeable soil Pb and Cd by48.7%and56.2%, and on reducing leaching solution contents of Pb and Cd by37.1%and30.1%, respectively. Zeolite and limestone could reduce exchangeable Cu effectively in the soil, and the reduction reached68.1%and85.2%. Bentonite could reduce leaching solution contents of Cu effectively and the reduction reached66.5%. Limestone had good effects on stabilization of Zn in the soil.(2) Bentonite modified by sulfuric acid had the best effects on stabilization of heavy metals among six modified curing agents. It was better than natural bentonite on stabilization of Pb and Zn in the soil. Compared with natural bentonite, the Bentonite modified by sulfuric acid reduced exchangeable Pb or Zn by8.4%or23.1%in the soil from Hengyang, and reduced leaching solution contents of Pb or Zn by12.6or49.9%, respectively, at the addition of8g-kg-1.(3) Six curing agents had the best effects on stabilization of heavy metals in the soil at the maximum addition of8g-kg-1or16g’kg-1. Bentonite modified by sulfuric acid, bentonite, zeolite, limestone, and hydroxyl-apatite all had effects, to some degree, on stabilization of heavy metals in Zhuzhou soil at the addition of8g·kg-1. Limestone could reduce exchangeable contents of soil Pb, Cd, Cu, Zn by59.3%, 91.7%,32.6%,92.9%, and reduce leaching solution contents of Pb, Cd, Cu, Zn by94.8%,59.2%,18.2%,13.8%. Zeolite could reduce exchangeable contents of soil Pb, Cd, Cu, Zn by26.4%,40.1%,49.0%,12.2%, and reduce leaching solution contents of Pb, Cd, Cu, Zn by17.3%,17.7%,29.3%,11.2%. Comprehensive considering, limestone had good effects on the stabilization of Zn and Cd, and zeolite had good effects on the stabilization of Cu in the soil.