Assessment of Phosphate Ore Digestion Kinetics and Mixing Behavior: A First Step in Unravelling NP-Fertilizer Production
2021
Poissonnier, Jeroen | Verberckmoes, An | Toch, Kenneth | Van der Borght, Kristof | Thybaut, Joris W.
The digestion with nitric acid of two phosphate ores with high P₂O₅ content, and their mixtures, has been investigated experimentally and via modeling. Experiments were performed in a 100 mL batch reactor at high dilution to avoid mass transfer limitations. The digestion rate exhibited a mild increase with the temperature in the range from 30 to 60 °C and a more pronounced one with the nitric acid concentration in the range of 0.005 to 1.0 M. The digestion rate of the phosphate ore with a high P₂O₅ content was significantly higher than that of the ore with a very high P₂O₅ content. Mixing experiments excluded the possibility of impurities in the former one being responsible for the enhanced digestion rate, its porosity being a more likely cause. A kinetic model explicitly accounting for the shrinking particle was constructed and yielded an activation energy of 32 kJ mol–¹ for the digestion reaction.
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