Conference Dates

April 29-May 4, 2018


Flotation represents, at present, the technology capable of efficiently concentrate the minerals of interest, separating them from other gangue minerals. The flotation process is based on interactions between minerals (solid phase), water (liquid phase), and air (gas phase). However, it depends on physical forces driving the system. If mineral particles do not have enough momentum during the collision with the air bubble no attachment between them occurs, and consequently no flotation. Impeller rotation speed is undoubtedly a factor that changes the hydrodynamic conditions of the flotation system playing a vital role on it. It supplies the flotation system with air by suction, produces bubbles on the base of the cell, and stirs the pulp. By keeping the mineral particles in movement, the impeller rotation avoid fast sedimentation of the particles and gives the energy required for the particles attach themselves to the bubble. Although the impeller rotation has very high importance to the flotation, it also has a negative action on the system since it is one of the greater producer of turbulence in the flotation cell. The better understand the influence of the impeller rotation speed in the phosphate rock flotation experiments using a Denver cell with 3.0L cell were carried out using phosphate rock from Copebras/CMOC mine, a magmatic deposit situated in Ouvidor/GO/Brazil. Cornstarch (600 g/t) supplied by Cargill was used as depressant and Lioflot 502-A (500 g/t), a mix of fatty acids, supplied by Miracema-Nuodex was used as collector. The conditioning time was three minutes for the depressant and two minutes for the collector and flotation time was five minutes. The pH was kept at 9 with hydrochloric acid and sodium hydroxide, both at 1%. Five different impeller speeds were tested (1000, 1150, 1300, 1450, and 1600 RPM). All tests were performed in triplicate at room temperature and using tap water. Samples of the feed, concentrate and tailings were analyzed at Copebras S/A laboratory using an X-ray Fluorescence spectrometer AXIOX MAX series DY 5001 from PANalytical. Results show that an increasing in the impeller speed until 1450 RPM produces a reduction in the P2O5 content in the concentrate. Above this value the P2O5 content raises with the impeller speed. The higher grade obtained was around 34% of P2O5 at 1600 RPM.

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