Andre Carlos Silva

Abstract:

Mining is a complex activity, necessary for economic extraction of mineral goods from the Earth's crust, causing changes to the environment, often irreversible, through extraction activities and mineral processing. Mineral processing involves stages of comminution, granulometric classification and separation (physical and/or chemical) to obtain mineral concentrates and generate tailings that often has larger volumes than the concentrate produced itself. Ores such as iron, phosphate and gold generate tailings that reach, respectively, 40, 75 and 97% by volume of all ore fed on mineral processing plants. Not always the tailings are inert, as in gold mineral processing. Commonly all this material generated is sent to tailings dams. These structures are deployed according to economic factors analysis, such as the initial total cost, the environmental impacts generated for different locals if it has different impacts, and the material disposal according to its constructive method. Dams require large confined areas between valleys, which were used to support the material storage. Those areas need to be deforested and, in some cases, coated with substances that will prevent the material deposited seepage. Such regions will become unusable after the closure of the disposal of tailings for hundreds (or even thousands) of years. Accidents can occur when tailings dams are not monitored and/or constructed properly, compromising the mineral enterprise and its sustainability. Minas Gerais is the largest mining state of Brazil, responsible for extracting more than 160 million tons of iron ore per year, accounts for 29% of all mineral production in the country. Its responsible for the production of 53% metallic minerals and for about 50% of all the gold produced in the country. Only in this state more than 64 tailings dams had its security considered dubious due to lack of information, surveys and control structures reports in the last years. Therefore, this paper shows the advantages of other tailings disposal methods, such as mineral paste and dry disposal. Worldwide, significant gains are being achieved with those techniques adoption, which proved to be economically viable, demystifying the premise of being a more expensive method than the conventional and seeking to complete the sustainability to continue the disposal in tailings dams.