Chemical Papers

, Volume 72, Issue 10, pp 2641–2646 | Cite as

Role of calcium ions and their interaction with depressants in phosphate flotation

  • S. E. El-Mofty
  • A. A. El-Midany
Original Paper


The commonly utilized flotation scheme in phosphate industry is reverse flotation using fatty acids in acidic media adjusted by H2SO4. The acidity of the flotation pulp results in presence of different ionic species that play a crucial role in modifying the minerals’ surfaces. Therefore, the flotation of pure phosphate was investigated in presence of H2SO4 for pH adjustment and potassium oleate, potassium dihydrogen phosphate, potassium oxalate, calcium nitrate and potassium sulfate. The reason behind using these chemical reagents is to study the effect of different ionic species on the phosphate flotation. Flotation results as well as thermodynamic analysis indicated that the formation of aqueous calcium/phosphate complexes (i.e., CaHPO4(aq)) on hydroxyapatite surface is the most significant species in depressing phosphates. The Ca++ concentration, particularly in acidic pH, showed a great effect on the formation of aqueous CaHPO4. The aqueous CaHPO4 concentration sharply decreased by increasing Ca++ concentration where the depression becomes more challenging. Therefore, the main purpose of adding depressants is to reduce Ca++ ions by forming Ca-depressant complexes.


Phosphate Depressants Calcium ions Oxalate Sulfate Reverse flotation Acidic media 



The authors would like to dedicate this work with great respect to Prof. Elgillani, D. A., Professor of Mineral Processing, Mining Engineering Department, Cairo University, one of the pioneers in the flotation field in general and the flotation of semi-soluble minerals in specific.


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Copyright information

© Institute of Chemistry, Slovak Academy of Sciences 2018

Authors and Affiliations

  1. 1.Mining, Petroleum, and Metallurgy Department, Faculty of EngineeringCairo UniversityCairoEgypt

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