Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 880, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2023.163209
Keywords
Mine backfill; Magnesium-coal slag; Mining cementitious material; Resource utilization; Synergistic effects
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This study investigates the feasibility of using solid waste modified magnesia slag (MMS), coal gasification slag (CGS), and desulfurized gypsum (DG) as magnesium-coal slag based cementitious materials (MCC) for mining cementitious materials in synergy with coal gangue to prepare backfill materials. The results show the existence of synergistic effect among MMS, CGS, and DG in a ternary system, and the optimal dosing of each raw material is determined. The backfill material prepared by MCC in collaboration with coal gangue meets the preliminary feasibility for mine backfill. This research is of great importance for the comprehensive utilization of bulk solid waste, reducing backfill costs, and enhancing the economic and ecological interests of mines.
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.
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