The effect of particle size and water content on XRF measurements of phosphate slurry

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 P₂O_5, 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.