Double reverse flotation of a very low grade sedimentary phosphate rock, rich in carbonate and silicate

In this study, reverse flotation was applied to recover phosphate from a very low grade (5.01% of P2O5) sedimentary ore. Sodium silicate, starch, tannic acid, aluminum sulfate, (Na,K)Tartarat, sodium tripolyphosphate, H3PO4, and H2SO4 were used as phosphate mineral depressants in acidic and alkaline conditions. Oleic acid and Armac-T were added as carbonate and silicate collectors respectively, while pine oil was used as a frother and fuel oil as modifier. It was demonstrated that aluminum sulfate and (Na,K) Tartarat work synergistically to depress phosphate minerals. An experimental protocol was devised to optimize the grade and recovery of phosphate using two different methods: anionic–cationic and cationic–anionic. Anionic–cationic method was found more effective.

► The flotation response of apatite and calcite using of fatty acid collectors were investigated.
► Several kinds of phosphate minerals depressant were also evaluated.
► Phosphoric and sulfuric acids successfully depressed sedimentary phosphate minerals.
► A mixture of (Na,K) Tartarat and aluminum sulfate had a maximum effect on phosphate mineral depression.
► Collector and depressant dosages were distinguished as the main influential factors.