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Journal of Thermal Analysis and Calorimetry

, Volume 80, Issue 3, pp 701–708 | Cite as

Thermochemical investigations of natural phosphate with ammonium sulfate additive

  • Vilma Petkova
  • Y. Pelovski
  • I. Dombalov
  • Kaia Tánsuaadu
Article

Summary

The free energy of the acidic ammonium sulfate is a good precondition it’s use as an additive or reagent for decomposition of natural phosphates on the way to obtain NPS or NPKS complex fertilizers. During our previous studies it was confirmed that as a result of thermo-mechanical treatment new solid phases are formed as a result of the phosphates decomposition. The aim of this study is to find out appropriate conditions for thermal treatment of Tunisia phosphorite with ammonium sulfate where the content of P2O5 soluble forms has its maximum. The process was investigated under dynamic thermal conditions. Structure and phase transformations of the mixtures to intermediate and final solid products are confirmed by different techniques. X-ray powder diffraction, infrared spectroscopy and electron microscopy have been applied successfully and relationship found between phase structure and thermal treatment applied. As a result of the complex studies optimal temperatures are determined. The solid products under optimal conditions contain phosphorous in soluble forms available for plants in the soil. As a final it is concluded that the final products could be used as complex mineral fertilizers.

thermal decomposition ammonium sulfate calcium ammonium polyphosphates released gases solid phases Tunisian phosphate 

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Copyright information

© Springer-Verlag/Akadémiai Kiadó 2005

Authors and Affiliations

  • Vilma Petkova
    • 1
  • Y. Pelovski
    • 2
  • I. Dombalov
    • 3
  • Kaia Tánsuaadu
    • 4
  1. 1.Central Laboratory of Mineralogy and Crystallography, Bulgarian Academy of Sciences
  2. 2.University of Chemical Technology and Metallurgy
  3. 3.University of Chemical Technology and Metallurgy
  4. 4.University of Tallinn

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