Avaliação da eficiência da flotação de minério de grafita utilizando coletor de biodiesel formado por transesterificação

Abstract

Graphite is one of the minerals with special properties that stand out in areas of Science, such as Materials Engineering. Its lubricating character, chemical inertness, thermal resistance, excellent cleavage shows its wide applicability. However, it is necessary to acquire high purity of carbon’s graphite flake in order to explore such characteristics for materials. Flotation is a technique used for this purpose and this work proposed to study an alternative collector reagent with a more sustainable bias to replace the standard hydrocarbon-base collector used, the kerosene. The study used graphite ore obtained from Salto da Divisa/MG region, in Bahia-Minas Province. From the granulometric analysis and characterization of the graphite ore by X-ray diffraction (XRD), X-ray fluorescence (XRF), morphological e punctual chemical analysis by scanning electronic microscope (SEM-EDS), determination of the graphitic carbon content (LECO-CSA05V), and characterization of the biodiesel collector reagent formulated by gas chromatography (GC-FID) and Furrier Transform infrared spectroscopy (FTIR), it was possible to submit such samples in flotation tests, comparing them in three different groups: concentrate by kerosene collector, without reagent, and with a biodiesel collector. In addition, mass and metallurgical recoveries by group were compared to complete the concentration study. It was concluded that the graphite samples used were within the standard particle size for the ore found in Salto da Divisa/MG, in addition to the characteristic mineral phases present. Furthermore, the formulation of biodiesel from soybean oil through the transesterification reaction was analyzed through GC-FID and FTIR. The metallurgical recovery using biodiesel collector for graphite’s flotation was 11% superior to the performance of the kerosene’s. XPS identified a greater presence of esters and carboxyls in the biodiesel concentrate, with higher electronegative response and favoring a more selective adsorption in hydrophobic sites at the mineral surface, with less interference from the hydration film formed by the hydrophilic groups of the oxidized graphite. In addition, the biodiesel has a greater presence of C=C groups in relation to kerosene, which stills corresponds to the main adsorption’s mechanism performed through the formation of hydrogen bonds at the hydrophobic sites of the solid-liquid interface.