“…For instance, in this way Pérez-López et al (2007a) recently showed in labexperiments how the addition of a cover of fly ash (a strongly alkaline low-cost material from coal combustion) on a pyritic sludge tailing dam from the IPB favoured acid neutralization, metal retention in solution, and therefore, the improvement of the quality of the leachates. Under these conditions, Fe-precipitation as ferrihydrite forming a coating on the pyrite surfaces may also prevent the interaction between oxidizing agents and the pyrite grains, halting pyrite oxidation.…”