Adobes produzidos a partir do rejeito de mineração e da lignina kraft

Abstract

One of the bases of the Brazilian economy is mining, which generates millions of tons of waste annually in the process. This waste is deposited in containment dams, becoming a potential risk. In 2015, in the city of Mariana-MG, what would become known as the biggest environmental disaster in the history of Brazil occurred, which was the rupture of the Fundão dam. Then, in 2019, another tailings dam broke, this time in Brumadinho-MG. Thus, studies aimed at a more appropriate destination for mining waste are of great importance. The objective of this work was to evaluate the use of waste in the production of adobes and its stabilization with Kraft lignin (KL), which is a natural, renewable and hydrophobic organic polymer. Adobes were made with 0%, 0.5%, 1%, 2%, 4% and 8% KL in the matrix, in relation to the dry mass of the waste. After molding, the adobes were kept in an environment protected from the weather until completely dry. For mechanical properties, adobes with 2% LK stood out with a rupture modulus of 0.64 MPa and an elastic modulus of 75.5 MPa. The treatment without lignin had the highest compressive strength, which was 1.20 MPa, followed by adobe with 2% LK, with a compressive strength of 1 MPa. For the property of water absorption, in general, all adobes with LK obtained better results than the control treatment, especially the adobes with 2%, 4% and 8% of LK, with values of 3.8% of water absorption. water. For the mass loss test (erodibility), the adobes with 4% KL had the lowest loss: 0.23 g. In the contact angle test, adobes with 4% KL were the most hydrophobic, with an angle of 87.3°. In this way, the tailings from the dam failure have the potential for the production of adobes, which are mainly used in fence walls. In addition, it can be stated that the adobes with Kraft lignin were cohesive and resistant to the impacts of water droplets on their surface, showing the binding and stabilizing effect of Kraft lignin in mining waste.