Zeolitic tuffs for acid mine drainage (AMD) treatment in Ecuador: breakthrough curves for Mn 2+ , Cd 2+ , Cr 3+ , Zn 2+ , and Al 3+

Abstract

Zeolitic tuff constitutes a technical and economical feasible alternative to manage acidic waters in initial phases of generation. A study of cation exchange with two zeolitic tuffs from Ecuador and one from Cuba has been conducted using breakthrough curve methodology. Cations Mn²⁺, Cd²⁺, Cr³⁺, Zn²⁺, and Al³⁺ have been chosen owing to their presence in underground water in exploration activities (decline development) in Fruta del Norte (Ecuador). Zeolites characterized by X-ray diffraction and thermal stability after heating overnight as heulandites show a similar exchange behavior for the five cations studied. The clinoptilolite sample Tasajeras shows a relevant cation exchange performance expressed in the important increment of spatial time to reach the breakthrough point in comparison with heulandite samples. The maximum length of unused beds was found for Cr³⁺ and Zn²⁺ cations showing, therefore, a lower adsorption performance in relation with Mn²⁺ and Cd²⁺. A final disposal method of metal-loaded zeolites with cement is proposed.

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