Transfer the Sulfate Environment into a Beneficial Factor: Performance Enhancement and Mechanism of Electrolytic Manganese Residue-Based Mine Filling Materials

This paper presents a dual-benefit method for green and sustainable mine construction through developing filling materials using solid waste. In practical engineering applications, there are sulfate ions in mine water, which leads to performance degradation in traditional cement-based filling materials. In this paper, electrolytic manganese slag-based mine filling materials (EBFMs) were developed by utilizing electrolytic manganese residue (EMR), fly ash (FA), phosphorus slag (PS), and quicklime (QL). The effects of EMR content on the basic performance and the sulfate resistance of EBFM in a 5 wt.% Na2SO4 solution at different stages of erosion were extensively discussed. The results showed that when the content of EMR was 25 wt.%, EBFM showed the best basic performance and sulfate resistance among all groups. After sulfate erosion, the compressive strength increased and the porosity decreased, and the mass of the samples increased. The EBFM exhibited superior sulfate corrosion resistance at the lowest porosity (4.14%) and the highest mass change rate (5.82%) after 90 days of sulfate erosion. The corrosion resistance coefficient stabilized between 1.23 and 1.24 after 30 days of erosion. In a sulfate environment, sulfate ions contribute to promoting hydration reactions to form more hydration products, which make a denser structure. The Fe-AFt (ferrous ettringite) formed during hydration demonstrates superior stability, representing a key factor for better sulfate resistance. The EBFM transformed the presence of sulfate ions in mine water (a typically adverse condition) into a beneficial factor that enhanced the materials’ performance, thereby exhibiting excellent sulfate resistance.