Test and calibration processes for the differential reaction calorimeter (DRC): Application: Dissolution of calcium fluorapatite in the hydrochloric acid

Soussi-Baatout, Amira; Hichri, Monia; Bechrifa, Ali; Khattech, Ismail

doi:10.1016/j.tca.2014.02.006

Cited by 9 publications

(3 citation statements)

References 14 publications

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“…Phosphates rocks were obtained from a mine located at Gafsa (Tunisia [40]. The experimental protocol followed to study the dissolution of the NP in the sulfo-phosphoric mixture can be described as follows: 100 g of the attacking solution, S, (20 g of concentrated sulfuric acid and 80 g of recycled phosphoric acid, 20% of P 2 O 5 ) and a mass "m" of the NP in a sealed sample holder which prevents its contact with the attacking solution were placed in the measuring reactor.…”

Section: Methodsmentioning

confidence: 99%

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

Lachkar-Zamouri¹,

Brahim²,

Bennour-Mrad³

et al. 2018

AMPC

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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˚C presents three straight segments attributed at the formation of the hemihydrate (CaSO 4 •1/2H 2 O:HH), the dihydrate (CaSO 4 •2H 2 O: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 (CaSO 4 :AH). Moreover, the variation of mass enthalpy versus temperature presents a break at the T = 45˚C. 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˚C.

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Section: Methodsmentioning

confidence: 99%

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

Lachkar-Zamouri¹,

Brahim²,

Bennour-Mrad³

et al. 2018

AMPC

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“…The DRC used is a SETARAM model which works based on the simple principle of differential thermal analysis which continuously measures a temperature difference, ΔT, between a measuring reactor and a reference one. The infallibility of this apparatus for kinetic and thermodynamic studies has been thoroughly researched by Amira et al [34]. The experimental protocol followed to study the dissolution of the PN in the mixture of sulfuric and phosphoric acid solution can be described as follows: 100 g of the attacking solution, S, (20 g of concentrated sulfuric acid and 80 g of recycled phosphoric acid, 20% of P 2 O 5 ) and a mass "m"…”

Section: Methodsmentioning

confidence: 99%

Effect of Different Kinetic Factors on the Thermochemistry of Sulfophosphoric Attack Reaction of Natural Phosphate Tunisian by DRC

Lachkar-Zamouri¹,

Brahim²,

Bennour³

et al. 2018

AMPC

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Mixture of phosphoric and sulfuric acid solutions has been used to investigate the dissolution of natural phosphates (PN) by DRC. The effect of concentration, particle size and stirring speed reaction is examined. Thermochimique properties of each kinetic parameters reaction are determined. It was found that these parameters have a considerable effect on the thermochemical aspect of the attack reaction. It is known that the process of PN sulphophosphoric acid attack leads to the formation of dihydrate (CaSO 4 •2H 2 O: DH). The present work shows the precipitation of other residues their formula depends on factors studied. The increase in concentration leads to the formation of hemihydrate (CaSO 4 v1/2H 2 O:HH) beside DH for the low values of% H 2 SO 4 due to the solubility of dihydrate on the etching solution and the precipitation of (Ca (H 2 PO 4) 2 •2H 2 O) next of DH for low agitation values because of the lack of turbulence between the liquid phase and the solid phase which favors the precipitation of this latter compound.

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“…The literature survey reveals the presence of other works including thermodynamic and kinetic studies of phosphate attack by acids. For example, Vaimakis et al [11] studied the reaction mechanism of selective dissolution of calcite found in phosphate ores by diluted acetic acid, and Soussi-Baatout et al [12] studied the thermodynamics of the phosphate attack by hydrochloric acid.…”

Section: Introductionmentioning

confidence: 99%

The aid of calorimetry for kinetic and thermal study

Belgacem

Leveneur

Chlendi

et al. 2018

J Therm Anal Calorim

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Phosphoric acid, non-renewable chemical, is used in different industries. Production of this chemical from natural phosphate can be done by two routes: wet-process and thermal-process. The nature of the natural phosphate, i.e., its chemical composition, plays an important role on the kinetics and thermodynamics of phosphoric acid production. Thus, the establishment of a kinetic model, based on reaction mechanism, for the dissolution of natural phosphate is cumbersome due to the presence of impurities. Besides, one should use an online analytical method because the dissolution reaction is fast.The dissolution of two natural phosphates with different percentage of phosphorus pentoxide (P2O5), phosphate samples (28 wt. % of P2O5) from Gafsa region (Tunisia) and phosphate samples (18 wt.% of P2O5) from Cheketma-Kasserine region (Tunisia), were studied from a kinetic and thermal aspects. Experiments were performed by using a Tian-Calvet calorimeter. Two acid solutions were used for the dissolution, one with phosphoric acid (S1) and the other a mixture of phosphoric and sulfuric acid (S2).For both natural phosphate, it was found that in case of using S1 solution the heat released due to the dissolution was lower than in case of using solution S2. This difference was explained by the precipitation of monohydrate sulfate calcium to its dihydrate form. By using a granulometry distribution lower than 500 μm, heat released during the dissolution of both phosphates by S1 was similar, i.e., -230 J g -1 , and the same observation was done by using S2 solution, i.e., between -300 and -350 J g -1 . We have demonstrated that granulometry distribution plays an important role, and by using a granulometry lower than 120 μm for Cheketma-Kasserine region phosphate, the heat released during the dissolution was higher, i.e., -400 J g -1 with solution S2. Avrami model was found to describe the precipitation of calcium sulfate, and three distinguished domains were obtained by using Gafsa region phosphate compared to two domains with Cheketma-Kasserine region phosphate.

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Test and calibration processes for the differential reaction calorimeter (DRC): Application: Dissolution of calcium fluorapatite in the hydrochloric acid

Cited by 9 publications

References 14 publications

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

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

Effect of Different Kinetic Factors on the Thermochemistry of Sulfophosphoric Attack Reaction of Natural Phosphate Tunisian by DRC

The aid of calorimetry for kinetic and thermal study

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