Research On Kinetics Of The Magnesium Removal From Phosphorite

With the depletion of the world’s phosphate resources, the exploitation of the low grade phosphate are becoming more and more important, for the most part of low grade phosphate rock minerals are associated with a certain amount of the mineral dolomite. Magnesium Contained in the dolomite has a variety of adverse effects on wet process phosphorous acid production. Researchers have proposed many methods to remove magnesium in phosphate, But most of them have poor data regularity, too much phosphorus loss and hard to apply in the industry. Magnesium removal process proposed by our laboratory overcomed these shortcomings, by using recycled magnesium hydrogen sulfate to wash the phosphorous, We achieve a low phosphorus loss and high magnesium removal rate, and the magnesium removal process has been applied to industrialization. This paper carried out a kinetic research on the technology, ground phosphate rock before and after magnesium removal are analysised and screened, phosphorus and sulfur content were also discussed. The effects of hydrogen ion initial concentration and reaction temperature were studied and the model parameters were fited. The experimental research results were as follows:(1) Average particle size of ground phosphate rock before and after magnesium removal decreases slightly, for the size difference is small, the size can be considered invariant. So using the same particle model unreacted shrinking core model to describe the reaction system was reasonable.(2) A considerable amount of tiny calcium sulfate crystals generated and a small amount of coarse particles crack in the reaction, which is the main cause of phosphate particle size decreases slightly.(3) Nonlinear fitting is better than the linear fitting by comparison,according to K and n obtained by nonlinear fitting, the data were fitted after linear transformation of Arrhenius formula, and K0 and E was determined, finally, relationship between XA* and CB0, T is determined by multiple linear fitting.Macroscopic kinetic model formula for the magnesium removal process is...