Pracaxi : novo coletor para flotação de xenotima

Abstract

Rare earth elements (REE) have played a key role in recent technological advancements, showing increasing interest in the commodity market since 2009, when production and export quotas were implemented by China, the world's largest producer. With the reduction in supply and rising prices, the world is experiencing a race for the processing of rare earth deposits not yet exploited. Xenotime, a heavy REE resource (YPO4), isfound mainly associated with quartz, a microclimate and albite in granitic rocks, as in the Brazilian deposit of Pitinga, located in the Amazon region. Flotation is the main concentration method for the processing of rare earths, although few studies have been published on the processing of xenotime ores, especially with regard to innovation in the use of reagents. The present work investigates the application of a new collector produced from pracaxi oil, an abundant Amazon oil found in Brazil, in the selective flotation between xenotime and its main gangue minerals. The study involved the synthesis and characterization of the collector, chemical, mineralogical and surface characterization of minerals, as well as evaluations of adsorption and flotability of the collector via microflotation, zeta potential and surface tension tests and XRD, WDXRF, ICP-MS, FTIR and XPS analyses. The pracaxi collector, which is composed mainly of oleic (56.2%), linoleic (14.1%) and behenic acids(10.6%), showed great potential for xenotime flotation at basic pH (pH 9.0), with selectivity of up to 90% in relation to the gangue minerals. The increase in the negative xenotime surface charge (zeta potential) and the presence of a 1545 cm-1 band in the FTIR data indicate that the interaction between the collector and the mineral is chemical in nature. The low dosages required by the pracaxi collector (5mg/L), when compared to traditional collectors, indicate the synergistic effect between the different fatty acid salts in its composition. The presence of Fe in the structure of the silicates, acting as an activator, may be responsible for the flotability of these minerals, which may be a relevant point in the application of the reagent, depending on the mineralogy of the ore.