Flotação de espodumênio, microclina, quartzo e muscovita com coletores aniônicos, catiônicos, anfotéricos e mistura de coletores

Abstract

The worldwide lithium consumption is chiefly associated with the industries such as primary aluminum, glass, ceramics and lubricants being distinguished however the increasing and strategical use of lithium in components of batteries, nuclear reactors, parts for the aeronautical industry and the manufacturing of pharmaceuticals. Production oflithium carbonate and lithium hydroxide, base of the chemical industry of lithium derivatives, is made exclusively by producers whose production comes from salt mines, exception to Brazil and China where lithium carbonate and lithium hydroxide are still produced from pegmatite minerals. The Brazilian production is practically restricted to thepegmatites of the north of Minas Gerais state and has the spodumene as the main mineral being mined. The production is also modest in relation to the world lithium industry. Flotation is not used in Brazil due mainly to the inherent difficulties associated to process selectivity during the separation of the spodumene from other silicates that occur in thepegmatites bodies. The flotation process is an alternative to add value to the current operation for the reason that the fines fraction, around minus 1 mm, originated from the gravitic beneficiation method being used, is currently discarded as tailings. The present work aimed at the investigation of the individual adsorption and coadsorption of anionic,cationic and amphoteric collectors as well as corn starch onto the surface of spodumene, microcline, muscovite and quartz. The investigation was performed with microflotation tests and zeta potential measurements. The results showed a concrete possibility of selective separation, through reverse flotation at pH 5.0, using primary amine acetate anddirect flotation with sulfonates at pH 1.85. The adsorption mechanisms for both amines and sulfonates was controlled by forces of electrostatic type. With regard to muscovite, it is estimated that cation exchange capacity, due the K+ ion dissolution from its basal plane, was a collaborative mechanism for the cationic reagents adsorption. The main result from the collectors mixture was the amine and sulfonate coadsorption that maximized the floatability of microcline and muscovite. The tests performed with sodium oleate and corn starch have just confirmed the industrial practices of using these reagents for spodumene flotation. Two tests were carried out with a mixture of the four investigated minerals, and the results demonstrated again the possibility of selective separation of the spodumene.