The Use of Iron Ore Tailings in the Iron Quadrangle of Minas Gerais, Brazil

The Iron Quadrangle of Minas Gerais comprises 7,000 km2 and accounts for about 60% of Brazil's iron ore production. The rocks explored in this region are banded iron formations. The processing of this rock to produce the iron ore concentrate generates large quantities of tailings that were being stored in dams. After the ruptures of the dams in 2015 (Mariana–MG) and 2019 (Brumadinho–MG), dam storage became very difficult. Other storage destinations for tailings are now being considered, including dry storage in piles and the use of tailings as a raw material for other manufacturing chains, such as civil construction and road paving. Due to the fine particle size of the tailings, the use of Portland cement to manufacture products for civil construction is limited. However, alkali-activated cement should play an important role, due to their ability to incorporate fine grained materials. Although alkali activated mortars made with the tailings have good characteristics, their cost is very high, especially when sodium silicate prices are elevated. In this study, sodium silicate synthesis from the tailings, alternative calcined clays, the use of the overburden and other aluminosilicate sources are being investigated with a view to reducing the manufacturing cost. Keywords: Iron ore tailings, Alkali-activated, Building Material