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.
Processing of an East Mediterranean phosphate ore sample by an integrated attrition scrubbing/classification scheme (part one)
ABSTRACT In this study, an Egyptian siliceous/calcareous sedimentary phosphorite was subjected to beneficiation by unsophisticated economic means. The mineralogical and chemical examination showed that the ore sample is a typical example for the East Mediterranean phosphorites with 21.80% P2O5, 10.93% acid insoluble and 16.61% loss on ignition. The primary crushed sample was classified into three size fractions without any milling and they were separately subjected to an integrated attrition scrubbing study. Screening and classification on the 2.30 mm and 0.071 mm sieves were sequentially introduced with the attrition process. The effect of solid%, attrition speed and time were studied and optimized for each size fraction. Results showed that three products were produced and could be categorized according to their P2O5 content into the coarse tailing (+2.30 mm), the attrition concentrate (−2.30 + 0.071 mm) and the phosphate fines (−0.071 mm). The P2O5 contents of these products reached 12.24%, 28.72% and 18.77%, with P2O5 distribution reached 6.74%, 51.75% and 41.51%, respectively. A global P2O5 of 28.72% was obtained with a recovery of about 52%. A tentative flow-sheet for the whole process was postulated.
Physical Structure and Chemical and Mineralogical Composition of the Mazidagı (Turkey) Phosphate Rock
The physical structure and chemical and mineralogical composition of Mazidagi (Turkey) phosphate rock have been investigated by using chemical analysis, X-ray powder diffraction, scanning electron microscopy (SEM), thermal analysis, mercury porosimetry, and BET surface area methods. The results of X-ray powder diffraction analysis showed that the major minerals of the rock are calcite, fluorapatite, and carbonate fluorapatite. It was also found that the phosphate rock consists of two different phases which are dispersed in the rock heterogeneously in the SEM photographs, namely, a dark gray calcite-rich phase and a light gray phosphorus-rich phase. Qualitative analysis based on the SEM photograph revealed that fluorapatite and carbonate fluorapatite were only concentrated in the phosphorus-rich phase. Calcite having particle sizes smaller than approximately 2 μm were agglomerated between compact phosphorus-rich phases having particle sizes between 100 and 300 μm. The rock has a large pore-size distributio...