Immobilization forms of ZnO in the solidification/stabilization (S/S) of a zinc mine tailing through geopolymerization

Solidification/stabilization (S/S) of a zinc mine tailing through geopolymerization has been studied. The mechanical property and microstructure of the mine tailings based-geopolymers were investigated through compressive strength measurements, FTIR, NMR and SEM characterizations. The stabilization of zinc in the geopolymers was analyzed through toxicity characteristic leaching procedure (TCLP) and the immobilization forms were characterized through XPS. With the content of metakaolin in raw materials increased from 0 to 50%, the amount of geopolymer gel in the binders and the compressive strength of geopolymer increased. As a ratio of metakaolin to mine tailings of 1:1, the mine tailings promoted the formation of silica-rich gel and the compressive strength of geopolymer was 30.1 MPa which was similar to pure metakaolin-based geopolymer. The immobilization efficiency of Zn in the geopolymers is correlated to their mechanical property. Zinc is immobilized in the geopolymers through physical encapsulation and adsorption of the leached Zn2+ by geopolymer gel. (C) 2019 The Authors. Published by Elsevier B.V.