Efficient solidification of Pb²⁺ by activated tungsten tailings and cement

Abstract

The preparation of cementing admixture from tailings and co-solidification of Pb²⁺ with cement is a green way to realize the resource utilization of tailings and treatment of the lead-containing wastewater. In this paper, the tungsten tailings were activated in different ways, and the mechanical properties of the tungsten tailings-cement solidified body with different activation systems and the solidification behavior of Pb²⁺ were studied. The phase and microstructure of the hydrated product were characterized by XRD, FT-IR, SEM and EDS. The results showed that the curing effect of Pb²⁺ was obviously different of different activation systems, and the curing effect of the solidified body of the ternary composite activation system (TCAS) was the best, second only to the pure cement system (PCS). Different activation methods have a significant impact on the mechanical properties of the solidified body. With the increase of the Pb²⁺ content, the compressive strength of the solidified body gradually decreased, the Pb²⁺ leaching concentration gradually increased; with the extension of the curing age, the compressive strength gradually increased, and the Pb²⁺ leaching concentration gradually decreased. In particular, the compressive strength of the 28d solidified body was 31.43 MPa and the leaching concentration of Pb²⁺ was only 0.38 mg/L when the Pb²⁺ content was 5%. The phase, microstructure and EDS results of the hydration products showed that Pb²⁺ was mainly solidified in the C-S-H gel.