A Collector Promoter for Apatite Flotation in the Serra do Salitre Complex

Abstract

The concern about enhancing the productivity of Salitre phosphate mines has led to an extensive research and development program on new reagents, aimed at the sustainable processing of the ore, with greater production of phosphate concentrate and, consequently, less waste disposal in the tailings dam. Flotation is the most widely applied technique for processing of phosphate rocks, using mainly fatty acids and their salts as collectors. In partnership with BASF Mining Solutions, a new collector system was developed based on soy oil fatty acid (SOFA) and BASF’s co-collector Lupromin® FP A 1210 Base (L.1210, a mix of synthetic surfactants). The laboratory scale flotation results showed that most effective performance was achieved with a ratio SOFA:L.1210 of 70:30, while in the industrial application the ideal proportion was 90:10. This difference in reagent ratio is directly related to the surface tension of the bulk, making the apatite more or less hydrophobic, directly affecting the flotation performance. These proportions were tested by comparing different reagent conditions and pH, while contact angle and surface tension studies provided a theoretical framework to indicate a more effective collector adsorption, allowing for further process optimization. Applying 10% of L.1210 on an industrial scale, a more stable industrial process was observed to the oscillations of the processing plant, corroborating that by using the collector promoter there is a significant performance increase in this circuit of the Serra do Salitre Complex, which increased, on an industrial scale, at least 7.1% in P2O5 recovery and reduced 12.5% of the collector dosage compared to the use of only fatty acid. In this study, it was possible to identify two main process conditions to further optimize the current reagent system applied in industrial scale: pH 9.5 with the mixture SOFA/L.1210 90/10 (θ = 75.8°); and pH 7.5 with SOFA/L.1210 70/30 (θ = 76.8°).