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A Screening Study on Phosphate Depressants for Beneficiating Florida Phosphate Minerals



Numerous phosphate depressants were evaluated for both the phosphate/silica and phosphate/dolomite systems. Starch was found to be most suitable form floating fine silica from phosphate, while sodium tripolyphosphate (STPP) proved to be more efficient for separating coarse silica from coarse phosphate. It was also concluded that STPP was the most effective depressant for separating dolomite from phosphate. Based on those findings, an all-cationic flotation process was developed for Florida siliceous phosphates. A reverse Crago process was also developed, which involves floating fine silica with an amine and a polymer, followed by fatty acid flotation. More than a dozen of polymers were tested as slime “blinder” in floating silica from phosphate.