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Mining waste

Home built with waste material from iron ore mining, which would otherwise end up in a dam

UFMGHome built with waste material from iron ore mining, which would otherwise end up in a damUFMG

Researchers from the Federal University of Minas Gerais (UFMG) presented proposals about what to do with waste rock like that which caused the accident at the Samarco-owned dam in Mariana, Minas Gerais – even before the environmental problem struck the region’s residents and the Doce River. In 2015, prior to the environmental disaster, the researchers, led by professors Evandro da Gama and Abdias Gomes, successfully built a 46-square-meter house using products derived from iron ore waste rock and tailings.  Waste rock is what remains after processing iron ore, while tailings are rocks that are associated with itabirite, the mineral that contains the ore. Both types of waste are held in dams. “Except for roofing tiles, glass, flooring, and doors, everything can be made from leftover mining material,” says Gama. “We developed a calcination furnace called Flex, which calcinates the powder and transforms it into microparticles that will later be transformed into sand, blocks, beams, stone, and cement for construction purposes,” the researcher explains. Gama coordinates the Geotechnologies and Geomaterials Laboratory at the UFMG’s Center for Sustainable Production in Pedro Leopoldo, Minas Gerais. He guarantees that the large dams used to hold the waste products generated not only by iron ore mining but also in the mining of bauxite, gold, phosphate, and limestone would become unnecessary if waste rock and tailings were put to this use. Another advantage is that processing the waste material and then using it for construction purposes produces cooler homes whose walls absorb less water.