Analyses thermiques Le comportement thermique a été tudié par ATG et ATD afin de prévoir la température et les conditions de calcination nécessaire à l'obtention du rendement maximum. L‘étude a mis en évidence 3 pertes de masses successives en relation avec 3 domaines de températures, matières organiques, ainsi qu‘à la décomposition des carbonates, et ce pour les trois couches étudiées (figures 12 et 13). - La première perte de masse (1 ~ 2%), attribué au départ de l'eau d'adsorption (humidité) est observée de la température ambiante jusqu’à 100°C. 18 N. Bezzi et al.
2 ELECTRICAL CONDUCTIVITY (EC) EC is reciprocal of electrical resistance; it indicates presence of cations (K + ; Na +,Ca 2+…. ) and anions (Cl - ; HCO 3 - ; SO 4 2- …) Unit: μS/cm or mS/m (S=Siemens). Values in most natural waters: μS/cm Measure electrical current in the solution by using electrical circuit with two platinum plates. EC is often used as (fully automated) water quality check for TDS (total dissolved solids), e.g. for drinking water. In agriculture for quality of the irrigation/drainage water.
3 MEASUREMENT OF pH pH can be measured with the help of a glass electrode: Diffusion of H + ions across the glass membrane Difusion rate proportional to pH of solution redox reaction electrical current reading Calibration is essential: e.g. at pH = 4.0; 7.0; 10.0
Radiocrystallographic Analyses The use of X-ray diffraction permits determination of the structure of the samples. It allows, at first, to control the different phases of the studied material, and subsequently the determination of its crystal parameters. Figures 1 and 2 present the The diffraction pattern performed on powdered samples, obtained by grinding the raw samples (phosphate and cokeof a solid combustible) at 25°C. The diffraction pattern of the raw phosphate sample (Figure 1) shows various lines. Some can be attributed to the carbonate fluorapatite ((CaF)Ca4(PO4)3) contained in the ore and others correspond to the carbonate CaCO 3 phase.
Infrared Spectroscopy The presence of apatite and carbonate phases in bright phosphates are confirmedby infrared spectroscopy technique
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Pourcentage en (H 2 O)Acidité du phosphate Conductivité du phosphate (µS/cm) La Résistivité du phosphate Brut 0 % (H 2 O) % (H 2 O) % (H 2 O) % (H 2 O) % (H 2 O) % (H 2 O) % (H 2 O) % (H 2 O)