Leaching characteristics and stabilization of heavy metals in tin-polymetallic tailings by sodium diethyl dithiocarbamate intercalated montmorillonite (DDTC-Mt)

Abstract

There are a large number of tailings left over by industrial development the world over and the tailings are harmful to the environment for a long time, so it is very important to study how to reduce environmental pollution from tailings. Here, the acid producing potential of three types of tin polymetallic tailings from the same locality with different degrees of weathering and the forms of heavy metals that exist in these tailings were studied. The effects of pH of simulated acid rain, temperature and time on the leaching of heavy metals from the different tailings were investigated along with their leaching characteristics. In addition, stabilization mechanism of heavy metals was analyzed from the kinetic and microscopic aspects. The potential application of sodium diethyldithiocarbamate intercalated montmorillonite (DDTC-Mt) was studied for stabilizing tin polymetallic tailings. The leaching of heavy metals in tailings is mainly due to the oxidation of tailings, which in turn is closely related to the acid producing potential of tailings and the existing forms of heavy metals in them. The stabilization of heavy metals by DDTC-Mt is mainly due to coordination between DDTC and heavy metals in the interlayer of montmorillonite. DDTC-Mt revealed a superior stabilization property in remediation of heavy metals from tin-polymetallic tailings with high acid producing potential by enhancing the stability of heavy metals in tailings, for example, the stabilization rates of Mn and Zn were 89.11% and 93.89%, respectively.