Determinação da relação farinha/NaOH na gelatinização de depressores à luz da microscopia óptica e a sua influência nos testes de flotação mineral

Starches are depressant reagents used in mineral flotation in order to confer selectivity to the process. For this, they need to be previously gelatinized, with the alkaline method being the most used technique in the mineral industry. In Brazil, NaOH is used as alkali and the flour/NaOH ratio is a parameter analyzed in this process. Although they are important, studies on this topic are scarce in the literature. That said, the work consisted in determining the ideal flour/ NaOH ratio for the gelatinization of depressants based on corn, sorghum and millet and in proving the effectiveness of the process under optical microscopy with polarized light. Subsequently, flotation tests with niobium ore using corn, millet and sorghum flours and their respective mixtures as depressants were carried out and the results were compared with industrial corn starch. The results showed that the new proposed depressants used smaller amounts of NaOH to be gelatinized in relation to corn starch. The optical microscopy stage confirmed the disruption of Maltese crosses for all flours, indicating complete gelatinization. The best pyrochlore depressant was sorghum flour and the results showed statistical similarity with corn starch.