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Attack of Tunisian Phosphate Ore by a Mixture of Sulfuric and Phosphoric Acid: Thermochemical Study by Means of Differential Reaction Calorimetry

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DOI: 10.4236/ampc.2018.810028    291 Downloads   527 Views

ABSTRACT

A calorimetric, Differential Reaction Calorimetry (DRC), study of the thermochemical of the attack of a phosphate ore from Gafsa region (Tunisia) by a mixture of sulfuric and phosphoric acid is undertaken at different solid-liquid ratio and different temperature. The plot of the quantity of heat measured by integrating the raw signal as a function of the dissolved mass in the same volume solution at 25 presents three straight segments attributed at the formation of the hemihydrate (CaSO4·1/2H2O:HH), the dihydrate (CaSO4·2H2O:DH) or a mixture of these two products checked by X-ray diffraction, infrared spectroscopy and thermal analysis (Differential Scanning Calorimeter: DSC). The attack by the acid mixture was performed at higher temperature and showed in addition the formation of another form of calcium sulfate:anhydrous (CaSO4:AH). Moreover, the variation of mass enthalpy versus temperature presents a break at the T = 45. According to our results, it seems that the effect of the temperature on the sulfo-phosphoric attack reaction on the natural phosphate (NP) generates a change of mechanism at around 45.

Cite this paper

Lachkar-Zamouri, O. , Brahim, K. , Bennour-Mrad, F. and Khattech, I. (2018) Attack of Tunisian Phosphate Ore by a Mixture of Sulfuric and Phosphoric Acid: Thermochemical Study by Means of Differential Reaction Calorimetry. Advances in Materials Physics and Chemistry, 8, 411-427. doi: 10.4236/ampc.2018.810028.

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