Stabilization of an iron ore tailings by-product with perlite waste geopolymer

Abstract

In the field of engineering, sustainable solutions that can generate lower environmental impacts, either through material replacement or reuse, are increasingly sought after. In Brazil, in the geotechnical area, there is a demand to find solutions to avoid the disposal of tailings sludge destined for structures, following the recent dam ruptures of Fundao in 2015 and Corrego do Feijao in 2019. One of the recent investments is in the treatment of tailings, generating by-products. To improve the mechanical properties of these by-products, geopolymer utilization has been employed. Geopolymers are products resulting from reactions between aluminosilicate precursors and alkaline activators. The objective of this study is to evaluate the unconfined compressive strength of an iron ore tailings by-product stabilized with a geopolymer that utilizes perlite waste as a precursor and sodium hydroxide as an activator through a two-part alkali-activation process. Two molar concentrations of activators, 2M and 5M, and two sample compositions were evaluated: one with 20% geopolymer and 80% iron ore tailings by-product, and another with 30% and 70%. An increase in unconfined compressive strength was observed with higher concentrations of the activator solution and a greater percentage of geopolymer in material stabilization. Thus, it can be stated that the use of geopolymers in by-product stabilization is promising, but finding the optimal dosage and evaluating other variables such as curing time and temperature is necessary.