Investigating the synergistic effects of magnesia-coal slag based solid waste cementitious materials and its basic characteristics as a backfill material

Pan Yang; Lang Liu; Yonglu Suo; Huisheng Qu; Geng Xie; Caixin Zhang; Shunchun Deng; Yin Lv

doi:10.1016/j.scitotenv.2023.163209

Investigating the synergistic effects of magnesia-coal slag based solid waste cementitious materials and its basic characteristics as a backfill material

Sci Total Environ. 2023 Jul 1:880:163209. doi: 10.1016/j.scitotenv.2023.163209. Epub 2023 Mar 30.

Authors

Pan Yang¹, Lang Liu², Yonglu Suo³, Huisheng Qu⁴, Geng Xie⁴, Caixin Zhang⁵, Shunchun Deng⁶, Yin Lv⁷

Affiliations

¹ Energy School, Xi'an University of Science and Technology, Xi'an 710054, China. Electronic address: YangPan@xust.edu.cn.
² Energy School, Xi'an University of Science and Technology, Xi'an 710054, China; Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi'an 710054, China. Electronic address: liulang@xust.edu.cn.
³ Energy School, Xi'an University of Science and Technology, Xi'an 710054, China; Key Laboratory of Western Mines and Hazards Prevention, Ministry of Education of China, Xi'an 710054, China.
⁴ Energy School, Xi'an University of Science and Technology, Xi'an 710054, China.
⁵ Energy School, Xi'an University of Science and Technology, Xi'an 710054, China. Electronic address: zhangcaixin@stu.xust.edu.cn.
⁶ Energy School, Xi'an University of Science and Technology, Xi'an 710054, China. Electronic address: Dengshunchun@stu.xust.edu.cn.
⁷ Energy School, Xi'an University of Science and Technology, Xi'an 710054, China. Electronic address: 21203226082@stu.xust.edu.cn.

PMID: 37001664
DOI: 10.1016/j.scitotenv.2023.163209

Abstract

Applying solid waste resources as backfill material can reduce both the cost of backfill and the environmental problems caused by solid waste landfills. In this paper, the synergistic reaction effects of solid waste modified magnesia slag (MMS), coal gasification slag (CGS), and desulfurized gypsum (DG) as magnesium-coal slag based cementitious materials (MCC) and their preliminary feasibility as mining cementitious materials in synergy with coal gangue for the preparation of backfill materials are investigated. The results show that the order of the compressive strength of the cementitious systems is ternary system > binary system > monolithic system, which proves the existence of synergistic effect among MMS, CGS, and DG and determines the optimal dosing of each raw material in the ternary system. At early ages, the physical effect of CGS and the chemical effect of DG in the ternary system can promote the hydration reaction of MMS, but the synergistic effect between the three is weak; At later ages, a synergistic effect occurred among silica-aluminate depolymerization in CGS, dissolved sulfate from DG and hydration products from MMS, which promoted the production of more hydration products calcium-silicate(aluminum)-hydrate (C-S(A)-H) and AFt, and improved the compressive strength. In addition, the strength, fluidity and leaching of the backfill material prepared by MCC in collaboration with coal gangue can meet the preliminary feasibility for mine backfill. In the present work, the full solid waste MCC is developed to completely replace cement and use it to prepare backfill materials, which is of great importance to the comprehensive utilization of bulk solid waste, the reduction of backfill costs, and the enhancement of the economic and ecological interests of mines.

Keywords: Magnesium-coal slag; Mine backfill; Mining cementitious material; Resource utilization; Synergistic effects.