Heavy metal immobilisation and particle cementation of tailings by biomineralisation

Abstract

Tailings are the wastes remaining after mineral beneficiation. Leaching of heavy metals in tailings can pollute the environment and poor mechanical properties of tailings can lead to the collapse of tailings dams or reduced capacity of tailings ponds. Usually, treatments of tailings to reduce heavy metal pollution and improve soil mechanical properties are undertaken separately. In this study, microbially induced mineralisation (MIM) technology was used to treat a tailing that resulted in simultaneous immobilisation of heavy metals and the cementation of soil particles. The tailing was taken from Hunan, China, and contained large amounts of arsenic and molybdenum. The microorganism used in the experiments was Sporosarcina pasteurii. The results showed that molybdenum content was reduced by about 98% after MIM treatments, but the arsenic content was only slightly less than that in the reference group. The P-wave velocity and the uniaxial compressive strength of the treated tailing were also greatly improved in two groups of samples.