Column experiments to study the interaction between acid mine drainage and rock and Portland cement

Abstract

Interaction between Portland cement, rock (siliceous limestone) and acid mine drainage (AMD) from the Iberian Pyrite Belt (IPB) was studied by means of column experiments at laboratory scale. Synthetic acidic solutions (pH = 2) containing sulfate, Fe(II), Al, Mg and minor elements such as divalent cations (Cd, Zn, Cu, Ni and Cd) and an anion As(V) were injected. The interaction was dominated by the dissolution of calcite (main rock phase) and portlandite (one of the main phases of cement). Dissolution of these phases increased the pH up to ≈ 12 as portlandite dissolved and up to ≈ 6 when calcite dissolved. This change in pH resulted in (1) the precipitation of gypsum, aragonite, schwertmannite, brucite and Feand Al-amorphous phases and (2) the precipitation of Cd, Ni and Zn hydroxides and the adsorption of Cu and As(V) on iron hydroxides.