Reactive flotation as a sustainable alternative for removing carbonate gang present in phosphate ore

ABSTRACT

The concentration of carbonate-rich phosphate ores through conventional flotation is difficult due to the similarities in their surface properties. Thus, the reactive flotation based on the retention of carbon dioxide produced by carbonates in an acid medium arises. Given the current demands of new concentration techniques, this work investigated the reactive flotation of silica-carbonated phosphate ore. For that, samples from the granulometric ranges, –10# +20# (–1.70 mm +0.84 mm) and –20# +65# (–0.84 mm +0.210 mm) were used during the process. Through factorial design tests, the reagents employed were sulfuric and phosphoric acids and polymer polyvinyl alcohol (PVA). Phosphoric acid favored the reduction of the CaO/P₂O₅ ratio and the increase of the P₂O₅ grade. The best result was the one that provided an increase of about 30% in the P₂O₅ grade (12.3 to 16%) in the range –20# +65#, when using 10% (v/v) phosphoric acid and 0.5% (m/v) PVA. Although it was possible to reach, in some tests, the industrial parameter for the CaO/P₂O₅ ratio (less than 1.6), the same did not occur for the MgO contents (less than 1%). The results are promising however, new studies with more sustainable alternatives are extremely necessary nowadays.

Keywords:
Reactive Flotation; Phosphate; Carbonate; Carbon dioxide