Enhancing Arsenic Solidification/Stabilisation Efficiency of Metallurgical Slag-Based Green Mining Fill and Its Structure Analysis

To dispose of arsenic-containing tailings with low carbon and high efficiency, sodium sulphate (Na2SO4), hydroxide (NaOH), calcium nitrate Ca(NO3)2 Ca(OH)2 were independently added to metallurgical slag-based binder (MSB) solidification/stabilisation (S/S)-treated (MSTs) enhance the MST arsenic S/S performance. Results showed that only could increase unconfined compressive strength from 16.3 20.49 MPa decrease leachate As concentration 31 ?g/L below 10 ?g/L. Na3AsO4·12H2O NaAsO2 used prepare pure MSB paste for mechanism analysis. The results microstructure analyses specific surface area amorphous properties calcium–sodium aluminosilicate hydrate facilitated adsorption or solid-solution formation As(V) As(III). formed an inner-sphere complex in ettringite, whereas As(III) outer-sphere complex, relatively larger size charge compared SO42? restrict substitution inside channels without affecting ettringite structure under loading As(V). promoted hydration reaction MSBs a Ca–As(V) precipitate solubility, Ca4(OH)2(AsO4)2·4H2O (Ksp = 10?27.49) Ca5(AsO4)3(OH) 10?40.12). This work is beneficial application cement-free process.