Beneficiation of Low-Grade Phosphate Deposits by a Combination of Calcination and Shaking Tables: Southwest Iran
Three quarters of the world’s phosphate deposits are of sedimentary origin and 75%–80% of those include carbonate gangue. In this study, carbonate sedimentary phosphate deposits of the Lar Mountains of southwest Iran are studied. These deposits consist mainly of calcite, fluorapatite, quartz, kaolinite and illite, with an average P2O5 grade of 9%–10% (low-grade). Various pre-processing and processing methods have been developed for concentrating low-grade phosphate up to marketable grade and this study aims to select the optimal method to produce an economically viable grade of phosphate concentrate from low-grade ore. Different concentration methods, including calcination and gravity separation, were applied on samples at both a laboratory and semi-industrial scale (pilot scale). Using an integrated method of calcination (performed in a rotary kiln) and shaking table for concentrating the low-grade phosphate ore, the results show promise at producing grades of 30.77% P2O5 with 60.7%–63.2% recovery.
A factor analysis study of phosphate beneficiation by calcination
Abstract 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.
Absorption of Sulfur Dioxide by Limestone in a High Temperature Fluidized Bed
The importance of the limestone desulphurization process for the control of sulfur dioxide pollu­ tion has been emphasized. Details of the experimental set-up for such a process along with the necessary analytical procedures have been described. Factors influencing the sulfation reaction have been critically discussed.