Study on the Effect of Liberation Properties of Phosphate Ore with Different Particle Sizes on Flotation at Different Grinding Degrees

In this work, the medium-low grade calcium-magnesium phosphate ore in Zhijin, China, was investigated through systematic mineral processing studies using a scanning electron microscope, x-ray fluorescence spectrometer, and BGRIMM process mineralogy analyzer in combination with the ImageJ software and flotation experiment. The aim of this study was to suggest a process flow to optimize the flotation index of Zhijin phosphate ore. The effect of the liberation properties of fluorapatite on flotation behavior were analyzed with various particle sizes under different grinding fineness. Based on the characteristics of fluorapatite, we propose a double reverse flotation process with two routes for coarse- and fine-grained ore, respectively. The results showed that the flotation process can effectively improve the grade of phosphate ore and reduce the MgO content. As the degree of liberation increases, the flotation index increases first, and when the liberation degree reaches a certain value, the flotation index decreases. The maximum grade of fluorapatite was obtained for a grinding fineness of 82.86%, while the maximum grade of P₂O₅ was obtained for the − 53 + 38-μm particle size for flotation concentrate at various particle sizes.