Influência da qualidade da água na flotação reversa de minério de ferro na unidade de Conceição do Mato Dentro da Anglo American

Abstract

Flotation concentration is one of the most used operation for concentrating iron ores. This separation method operates in an aqueous medium which has a great influence on the separation efficiency. Water availability has been increasingly problematic, both in terms of quantity and quality. The flotation of iron ore from Serra do Sapo, in the municipality of Conceição do Mato Dentro- Minas Gerais-Brazil, is carried out with a mix of waters, the majority of which are water recovered from thickeners, water recovered from the tailings dam and water collected from the Rio do Peixe. The ore has a friable characteristic, mostly composed of hematite and quartz. This study aims to understand the flotation behavior carried out with different water sources and to understand the main factors that influence concentration performance. Bench flotation tests were carried out using the pulp at pH 10.5, with dosages of 1450 g/t Fe of starch (3% starch stock solution) and 150g/ton of amine (1% amine stock solution). Four types of water sources were used separately in flotation, namely, deionized water, water from the Rio do Peixe, water from the overflow of the thickeners and water from the tailings dam. For these waters, the concentrations of Ca, Fe, K, Mg, Mn, Na, P, Si and Ti were analyzed, in addition to the concentration of total organic carbon, dissolved oxygen, DBO, COD, ORP, conductivity and turbidity. According to the results, the waters from the Rio do Peixe promoted better performance of the separation process compared to the water recovered from the thickeners and the tailings dam. The statistical model built with the experimental data indicates that conductivity, aluminum concentration and oxygen dissolved in the water used in flotation are the 3 most important factors that influence the Flotation Selectivity Index.