Multiscale mechanical characterizations of ultrafine tailings mixed with incineration slag

Abstract

Adding a type of municipal solid waste (incinerator slag) into ultrafine tailings can effectively enhance the mechanical properties of tailings. With an aim to study the macro- and micro-mechanical properties of the tailings slag mixture (TSM), the strength parameters (internal friction angle, cohesion) and micro-mechanical properties with different slag contents were analyzed by geotechnical experiments and particle flow simulations, respectively. The macroscale experimental results demonstrated that the strength parameters of TSM were much higher than that of tailings. Strength parameters also showed non-linear-rising trends with increasing slag content. For the slag content of 40%, the maximum cohesiveness of TSM was determined at 65.2 kPa, and the corresponding friction angle was 39.9°C. Furthermore, the Particle Flow Code (PFC) micro-simulation software was used to analyze the micro-mechanical characteristics of the TSM at different slag contents. The microscale simulation outcomes indicated that the particle transport, particularly in their moving directions, became increasingly chaotic with an increase in the slag content; also, the slag particles significantly impacted the shear processing zone of the TSM. These experimental and numerical results brought more scientific insights into the shear failure mechanism of TSM.