Uso de óleos vegetais amazônicos na flotação de minérios fosfáticos

Abstract

The target of this investigation was to evaluate the potential application of anionic collectors extracted from Amazon vegetable species in phosphate ores flotation. The composition in fatty acids of six vegetable oils abundant in the Amazon Forest (buriti, passion fruit, inaj brazil nut, crabwood and açaí) was determined by gas chromatography and correlated with their performance in flotation. The critical micelle concentration of the oils, after saponification, was determined by surface tension measurements. Microflotation experiments were performed in a modified Hallimond tube, with the use of as pure as possible apatite, calcite, and quartz samples. The electrophoretic mobilities of minerals in indifferent electrolyte (KCl) solution and in the presence of Amazon collector were measured as a tool to assist in understanding theadsorption mechanism of each collector onto the mineral surface. Using statistical design of experiments, bench scale flotation tests were performed with phosphate ore from Itataia, using as collectors (tested individually) saponified Amazon oils, starch as depressant and Flotanol D25 as frother. From the results it was concluded that: i) theoils from Amazon used in this investigation contain high levels of oleic acid; ii) oil extracted from passion fruit seed presents the largest content of linoleic acid; iii) the saponification method of vegetable oils used in this work was satisfactory; iv) the collectors present low values of critical micelle concentration; v) the adsorption mechanism of anionic collectors from Amazon in alkaline pH range is chemisorptions; vi) empirical equation obtained describe satisfactorily P2O5 recovery in the phosphateore concentrate, in the collector dosage and pulp pH ranges used in this work; vii) the analyses of these empirical equations indicated that the best results of P2O5 grade and recovery were achieved using collector dosage 1352.5g/t and the pH between 8.6-11.4; viii) the results showed that the use of fatty acids salts obtained by alkaline hydrolysis of vegetable oils from Amazon is an alternative to reagents currently used as collectors in the mineral industry.