Assessing the influence of geological stress induced damage and initial pH levels on the metal leaching behaviors of cemented paste backfill

• Published in: Construction & building materials 2023-08, Vol.393, p.131958, Article 131958
• Main Authors: Deng, Xuejie, Huang, Yanli, Feng, Jianye, Zheng, Tongda, Jia, Ning, de Wit, Benjamin
• Format: Article
• Language: English
• Subjects: Cemented paste backfill; Geological stress induced damage; Initial pH; Leaching behavior; Metallic elements
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.131958

•The stress-induced damage of cemented paste backfill (CPB) is defined.•The influence of damage and initial pH on the metal leaching behavior is presented.•The pH and conductivity of the leachate increase with the increasing damage of CPB.•The release process of metallic elements in CPB is divided into three stages.•The release rate of metallic elements is described by Kinetic equations. Cemented paste backfill (CPB) is generally considered environmentally friendly when used in mining operations. However, the combination of geological stresses and groundwater seepage in an underground environment may cause the metallic elements contained in CPB to escape confined areas and potentially pollute the external environment. In this paper, geological stress-induced damage to CPB and the initial pH levels of the surrounding environment are assessed to determine their influences on the metal leaching behavior of CPB. Research methods used in the analysis include component characterization, static leaching tests, and kinetic theory analysis. The research results show that: as damage to CPB increased, both the pH and conductivity of the leachate increased, while the concentration of metallic elements in the leachate also increased except for aluminum (Al). Different metallic elements showed various leaching behaviors as the initial pH of the leaching solution increased. The release process of metallic elements from CPB can be segmented into three separate stages: the surface release stage, the internal release stage, and the adsorption and precipitation stage. Kinetic equations are obtained to describe the release rate of metallic elements. The leaching process is a dynamic equilibrium system formed by the release, absorption, and precipitation of metallic elements in the leachate. This research provides data for the evaluation of environmental effects on CPB.