Resistência e mineralogia de rejeito de mineração de ferro estabilizado com ligante álcali-ativado oriundo de cinza de bagaço de cana-de-açúcar e cal de casca de ovo

Abstract

The valorization of mining tailings may be achieved through stabilization with the addition of cementing agents, such as Portland cement, whose production implies high consumption of natural resources and electricity and emits greenhouse gases. In this context, alkali-activated binders from alkali-activation of industrial waste are a promising alternative. The present study evaluated the stabilization of iron ore tailing (IOT) with an alkali-activated binder (AAB) from sugar cane bagasse ash and eggshell lime. An experimental design was carried to analyze the unconfined compressive strength (UCS) of IOT-AAB mixtures, considering distinct binder and initial moisture contents, dry unit weight, temperature and curing time. The UCS results were correlated to the porosity/volumetric binder content index (η/Biv). The mineralogy of selected mixtures was also investigated. The UCS of IOT-AAB is significantly influenced by all evaluated factors, mainly by binder content and dry unit weight. A strength of 6.59 MPa was achieved after 28 days of curing at 40°C. The η/Biv0.28 index proved to be an adequate parameter to evaluate the stabilization of RMF, in which, by reducing the porosity and increasing the cement content, the strength of the RMF-LAA mixtures is increased. The mineralogy of the stabilized material showed tobermorite, indicating the formation of cementing gel.