title: An engineered cover system for mine tailings using a hardpan layer: a solidification/stabilization method for layer and field performance evaluation.
abstract: A cover system for mine tailings with a solidified layer (called an engineered hardpan) was developed in this study to reduce water infiltration, acid generation and sulfide oxidation. Hydrated lime and waterglass were used to produce calcium silicate, which can serve as a binder when constructing a hardpan layer. The compressive strength of each solidified/stabilized material was found to be sufficient in the lab, and the amounts of heavy metals were significantly reduced in chemical leaching tests. Various characteristics of tailings may affect the layer's mechanical strength early on, but a long curing period is capable of compensating for these effects. Heavy metals were stabilized as carbonate-bound phases and sulfide minerals were surrounded by calcium silicate matrix, thereby preventing further reaction. To evaluate the field performance of the system, a hardpan layer was installed on top of tailings on a pilot scale. Leachate with high salt content was generated in the tailings layer in the early stages of monitoring, but after approximately 6 months, the objective was achieved as the hardpan layer gradually stabilized. Notably, during the heavy rainfall season of the later monitoring stage, water infiltration was continuously prevented by the system.
authors.affiliation: Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources, Daejeon, Republic of Korea. jsahn@kigam.re.kr
authors.forename: Joo Sung
authors.initials: JS
authors.lastname: Ahn
authors.forename: Hocheol
authors.initials: H
authors.lastname: Song
authors.forename: Gil-Jae
authors.initials: GJ
authors.lastname: Yim
authors.forename: Sang Woo
authors.initials: SW
authors.lastname: Ji
authors.forename: Jae-Gon
authors.initials: JG
authors.lastname: Kim
mesh_terms: D003252:Construction Materials; D004553:Electric Conductivity; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D008906:Mining; D010865:Pilot Projects