ABSTRACT
Online X-ray Fluorescence (XRF) setup was constructed and optimized for analysing the P2O5 content in phosphate slurry (PS). Serval samples were analysed using two configurations of the setup, one with low and vertical flow and another with high and horizontal flow. The mean absolute error achieved through the first configuration was 0.87% and 0.38% using the second configuration. Reference samples were analyzed using the two configurations to construct the calibration curves. The curves cover a concentration range of P2O5 from 13.50 to 18.50% when considering the horizontal flow configuration, and a range of 14.00-15.60% when considering the vertical flow setup. An experimental study was conducted in order to optimize the measurement parameters for the online measurement of P2O5 in the phosphate slurry using the horizontal flow setup. A good signal-to-noise ratio (SNR) of [Formula: see text] was attained using an excitation energy of 20 kV or 25 kV, an excitation current of 600 µA, a distance of 18 mm between the sample and the detector, a measurement time of 60 s per spectrum and the use of an Aluminum filter between the X-ray tube and the measurement window. Online X-ray fluorescence analysis of P entails some challenges due to the low characteristic energy of P, the phosphate slurry matrix and the online analysis mode. However, the outcomes of this study indicate that XRF is a promising technology to meet the requirement for digitalization of chemical analysis of phosphate products.
ABSTRACT
Phosphate slurries are studied using the XRF technique and the effect of the particle sizes and the water content parameters are analyzed and reported for the first time. Samples of the phosphate slurry with different particle sizes (425 µm, 300 µm, 250 µm, 200 µm, 160 µm and 106 µm) and different water contents (30%, 40%, 50%, 60%) were analyzed using an energy-dispersive X-ray spectrometer (EDXRF). The results show that the relative error of measurement varies with the particle size of the analyzed sample, the water content and the element measured. The relative error increases with the increase of the particle size for the compounds P2O5, Al2O3, K2O, Cr2O3, Fe2O3 and Sr. The ratio between the relative errors related to the maximum and minimum grain sizes was 1.50 for P2O5, 4.01 for Al2O3, 15.58 for K2O, 1.22 for Cr2O3, 1.51 for Fe2O3 and 1.11 for Sr. Alternatively, an opposite evolution has been observed in the case of compounds CaO and SiO2. The relative error increases with increasing water content for all compounds existing in the slurry. Depending on the measured compound, the relative error increases by a factor that varies between 1.39 and 2.39. In the case of P2O5, the results do not show a clear correlation between the measurement error and the water content. A study will be conducted to investigate the effect of particle size and water content on XRF measurements in the case of phosphate slurry, aiming to develop an online XRF analyzer system for phosphate slurry.
