Análise técnico-econômica da mistura das farinhas milho, milheto e sorgo como depressor de nióbio da flotação de carbonatos
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Data
2021-04-23
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Universidade Federal de Goiás
Resumo
Flotation is an operation that promotes the selective separation of minerals with different superficial characteristics through the addition of chemical reagents. Cornstarch is the most widely used depressant reagent in the Brazilian mineral industry due to its wide applicability and market availability. This reagent is purchased by companies at relatively high prices, since corn production in this country is mainly intended to animal feed and human consumption, followed by exportation. The objective of this work was the formulation of an alternative depressant, based on the mixture of flours from two more sustainable botanical sources, sorghum (Sorghum bicolor (L.) Moench) and millet (Pennisetum glaucum (L.) R. Br), as a way of reducing dependence on cornstarch. The methodology consisted of obtaining, preparing and characterizing mineral, sorghum, and millet samples, followed by flotation tests and finishing with an economic analysis. Sorghum and millet grains went through stages of cleaning, drying, packaging, storage, grinding, and magnetic separation. Flours had their lipid content measured and the starches were extracted from them in order to characterize grains parameters and to determine the yield of this stage. The ore used came from Niobras, a company that extracts and process niobium ore in the city of Catalão, Brazil, and corresponded to the carbonate flotation feed. Samples of the ore were characterized by pycnometry, particle size analysis using laser diffraction, SEM and XRF. Bench flotation tests, in rougher stage, were performed in a Denver cell, following Niobras operational parameters. Lioflot® 502-A was used as collector and StargillTM 6172 (a cornstarch) was used as benchmark. The mixtures of the flours were proposed according to a mixtures simplex lattice design. The average extraction yield of sorghum and millet flours were 28.72 ± 6.70% and 26.62 ± 4.05%, respectively. The average lipid content of the sorghum and millet flours were 3.47 ± 0.002% and 7.62 ± 0.001%, respectively. The ternary mixtures had an average Nb2O5 metallurgical recovery similar in the sunken material (approximately 54%) in the flotation tests. The same metallurgical recovery was observed for the binary mixtures composed by 25% / 75% and 75% / 25% (sorghum / millet). In the other hand, the binary mixtures composed by the 50% / 50% stood out in relation to the afore mentioned results, with an average Nb2O5 metallurgical recovery of 63.54%. The highest Nb2O5 metallurgical recovery was obtained with sorghum flour (80.75%), similar to the results (80.95%) found using the depressant industrially adopted at Niobras, StargillTM 6172. Therefore, a lower dosage of sorghum flour could be a potential substitute for cornstarch in this stage of Niobium processing, obtaining a similar result of metallurgical recovery of medium Nb2O5 in the sunk material, as well as a result close to mass recovery and with a higher Nb2O5 grade.
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Palavras-chave
Flotação, Depressor, Sorgo, Milheto, Planejamento de misturas, Flotation, Depressant, Sorghum, Millet, Mixture design
Citação
SILVA, L. A. Análise técnico-econômica da mistura das farinhas milho, milheto e sorgo como depressor de nióbio da flotação de carbonatos. 2021.167 f. Dissertação (Mestrado em Gestão Organizacional) - Universidade Federal de Goiás, Catalão, 2021.