A factor analysis study of phosphate beneficiation by calcination

Mineralogical changes during beneficiation of phosphate ore by calcination and washing were studied by factor analysis with oblique rotation, and by using factors of factors (obtained with a factor-factor correlation matrix as input). Several minerals and reactions are indicated, including the possibility of distinguishing between different contributions to the CO₂ variance. From the point of view of using the results as a guide for multiregression analysis and building a linear model for the process, the most important results are as follows. The parameters of the product grade (P₂O₅ and chloride) are influenced by factors measured by x-ray fluorescence (Al₂O₃, SiO₂ SO₃ and MgO). Factors measured by thermogravimetry (water of hydration, portlandite and carbonate) have only a small influence. Most of the variance for halite is determined by elements derived from clay, whereas most of the variance for CO₂ is correlated with MgO. Magnesium replacing calcium in the francolite indicates the CO₂ level and thus the decrease in P₂O₅ content. The MgO content in the francolite can be used to indicate the maximum P₂O₅ content in the product.