Vale announced recently it has started operations at a tailings filtration plant located at the Vargem Grande Complex — the first of four filtration plants to be installed at Vale’s sites in Minas Gerais, totaling $2.3 billion in investments between 2020 and 2024. In addition to reducing the company’s dependence on tailings dams, the startup is expected to facilitate an improvement in the average quality of Vale’s product portfolio with the use of wet processing on the site.
Vale said the second filtration plant at the Itabira Complex and the first at the Brucutu site will begin operations in 2022. The four tailings filtration plants will serve beneficiation plants that can process 64 million mt/y of iron ore.
The company said the startup of tailings filtration operations in Vargem Grande is another step in stabilizing its iron ore production and reaching a targeted 400 million mt/y of production capacity by the end of 2022.
Last year, Vale reported it started the Pico Block plant, a pilot project to fabricate construction products made from tailings. The company said the plant at the Pico mine, in Itabirito, Minas Gerais, is designed to foster the circular economy within local iron ore processing activities. After an initial test period, Vale estimated that annually 30,000 mt of tailings that would be otherwise disposed of in dams or piles will be transformed into millions of pre-molded products with a variety of applications in the civil construction industry.
Vale, which said it had been studying options for reusing and recycling tailings since 2014, also noted that tailings use in civil construction in place of natural sand is a “green” solution, citing a 2019 United Nations report that said sand is the world’s second-most heavily exploited resource after water, as it can be scarce and subject to illegal and predatory extraction. “Vale’s sandy tailings resulting from ore processing activities have a high silica content and a very low iron content, in addition to a high degree of chemical homogeneity and optimum grain-size uniformity,” said Rodrigo Dutra, executive manager for environmental licensing.
The company will invest approximately $4.5 million in technological research and development in the first two years of operation of the Pico Block plant, which will receive technical support from the Federal Center for Technological Education of Minas Gerais (CEFET-MG). No products will be sold during the R&D phase.
“The main advantage of being in a plant inside a mining unit is the ability to study the application of various wastes and validate the technology developed in the laboratory in the production environment, on an industrial scale. This model will enable the transfer of technology in a more efficient way, in an environment that drives innovation,” explained Augusto Bezerra, lead researcher of the project and professor at CEFET-MG.
Vale plans to replicate the block plant in other units in Minas Gerais once the R&D phase at the Pico mine is completed. The company also combines efforts with more than 30 organizations, including universities, research centers and Brazilian and foreign companies to develop solutions for reusing mining tailings in different industrial sectors.