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    SURFACE CHEMISTRY OF THE ELECTROFLOTATION OF HEMATITE FROM AN ITABIRITIC ORE USING A GROUND-BREAKING BIOSURFACTANT EXTRACTED FROM A HYDROFOBIC STRAIN
    Matheus Silva1; Carolina Simões1; Ronald Rojas Hacha2; Antonio Gutierrez Merma3; Mauricio Leonardo Torem4;
    1PONTIFICAL CATHOLIC UNIVERSITY OF RIO DE JANEIRO, Rio de Janeiro, Brazil; 2PONTIFICAL CATHOLIC UNIVERSITY OF RIO DE JANEIRO, Rio de Janeiro, Peru; 3VALE INSTITUTE OF TECHNOLOGY, Rio de Janeiro, Brazil; 4PONTIFICAL CATHOLIC U. OF RIO DE JANEIRO, Rio de Janeiro, Brazil;
    PAPER: 30/Mineral/Regular (Oral) OL
    SCHEDULED: 11:30/Wed. 29 Nov. 2023/Sunflower



    ABSTRACT:
    Electroflotation is a potencial and suitable procedure to be well-thought-out alternative for the mineral processing development. This electrochemical technique is capable of float fine particles, using micro-bubbles oxygen and hydrogen with diameters smaller than 100 μm generated from the electrolysis of aqueous solutions [1,2,3]. Another important factor that has been studied is the use of a biorreagent in the concentration of minerals [4]. Research in biotechnology indicates that biosurfactants can be used to replace chemical surfactants because they offer functional characteristics, such as negative electric charge and hydrophobicity, and have low toxicity and higher degradation capacity than surfactants [5]. In this way the aim of this work was to evaluate the electroflotation of fines particles of an itabiritic iron ore using a biosurfactant extracted from Rhodococcus opacus strain. The tests were carried out with an iron ore in a specific particle size range of -38 + 20 μm containing 77,12% Fe2O3 and 22,65% SiO2. The assays were conducted in a modified Partridge-Smith binary electroflotation cell. The parameters used in these tests were iron ore mass (1g), agitation (500 rpm), conditioning time (5 min), flotation time (10 min), electrolyte concentration (Na2SO4 - 0.20 mol/L) and current density around 16mA/cm2. Moreover, the pH and biosurfactant concentration were respectively in the range of 3 to 11 and 50 to 800mg/L. The results of the interaction study indicated a possible interaction of the biosurfactant with hematite. After conditioning of the hematite with the biosurfactant, the spectrum (FTIR) showed characteristic functional groups of the biosurfactant (NH, CH2, C=O, COO and PO2-). The measurements of zeta potential suggest a possible electrostatic interaction between the hematite and the biosurfactant, by shifting the isoelectric point from 5.3 to 3.5. Contact angle measurements suggest that after interaction, hematite may have become more hydrophobic, changing the contact angle from 40° to 60°. According to the surface tension analysis, a reduction in surface tension from 71 mN/m to 40 mN/m was demonstrated in the presence of 25 mg/L biosurfactant. The electroflotation experiments validated an encouraging form of hematite recovery. The best results occurred at pH 3, this behavior can be attributed to electrostatic interactions that occur in this pH range. The increase of the biosurfactant concentration favored metallurgical recovery and the iron grade, this behavior remained up to 300 mg/L, above this value occurred a decline probably caused by the formation of micelles. The maximum metallurgical recovery was 80% and the iron content 59%.

    References:
    [1] HACHA, R. R., MERMA, A. G., COUTO, H. J. B., TOREM, M. L. Measurement and analysis of H<sub>2</sub> and O<sub>2</sub> bubbles diameter produced by electroflotation processes in a modified Partridge-Smith cell. Powder Technology, 342, 308-320, 2019.

    [2] FARROKHPAY, S. et al. Flotation of fine particles in the presence of combined microbubbles and conventional bubbles. Minerals Engineering, v. 155, p. 106439-106445, ago. 2020

    [3] LIU, An; FAN, Pan-Pan; HAN, Feng; HAN, Hua; LI, Zhi-Hong; WANG, Huai-Fa; FAN, Min-Qiang. Effect of electroflotation on quartz and magnetite and its utilization on the reverse flotation of magnetic separation concentrate. Minerals Engineering, [S.L.], v. 175, p. 107292, jan. 2022

    [4] DWYER, R. et al. Bioflotation and biofloculation review: microorganisms relevant for mineral beneficiation. Minerals Processing and Extractive Metallurgy, 121 (2). p. 65-71, 2012.

    [5] CAMARATE, M. C., MERMA, A. G., HACHA, R. R., TOREM, M. L. Selective bioflocculation of ultrafine hematite particles from quartz using a biosurfactant extracted from Candida stellata yeast. Separation Science and Technology, 57(1), 36-47, 2022.