Maximizing the pozzolanic potential of superfine iron tailings for low-carbon stabilization: Application of high-calcium geopolymer

Abstract

Superfine iron tailings (5–75 μm) are difficult to be reused with traditional binders. The reaction behavior of newly developed high-calcium geopolymer (ASF), the activation effect of the ASF on the pozzolanic potential of tailings, and the application effectiveness of the ASF-stabilized mixtures have been discussed. The results show that highly cross-linked calcium aluminosilicate hydrates were the main hydration products, and there were some crystal products, e.g., stratlingite, ettringite, and crystalline calcium silicate hydrate. The ASF can activate and release magnesium ions in superfine tailings to form magnesium-based products. Second, the cumulative pore volume of stabilized tailings was reduced by 24.4% with the dosage increase of ASF binder from 3% to 8%. Finally, the strength of 8% ASF-stabilized tailings increased from 1.83 MPa to 3.44 MPa (7 d to 28 d). The alkalinity of ASF-stabilized tailings was weaker than that of the cement-based counterpart (∼0.6), reducing environmental pressure during application.