Document Type : Research Paper
Due to the importance of material classification issue in grinding circuits, the performance of primary and secondary hydrocyclones in grinding circuit of Esfordi phosphate plant was investigated by sampling within 7 days from feed, overflow, and underflow of these hydrocyclones. At first, the d80 of above streams samples were calculated by the screening analysis. The results showed that the average values of d80 of feed, overflow and underflow of primary hydrocyclone were respectively 238.7, 236.5 and 100.9 microns, and 100.9 and 94.1 microns for the feed and underflow of secondary hydrocyclone. For the primary hydrocyclone, with plotting distribution curves, its cut-points, the actual and corrected cut-points were calculated which were 35 and 45 microns, respectively; whereas they were equal to 100 microns according to the design documents. However based on the undesirable performance of primary hydrocyclone, it was tried to investigate on its performance using simulation software. The results indicated 80 microns cut-point and 192.30 kpa of pressure drop in particle classification. In addition, the amount of circulating load obtained 931.84% (in primary mill design, this amount was equal to 150%), and high feed rate to hydrocyclone was one the major reasons for this high circulating load. To solve this problem, it was considered one more hydrocyclone could be added to this circuit in the form of parallel and series, and results were studied using BMCS software. The results of this criterion of adding a parallel hydrocyclone, showed 86 microns of cut-point with 62.91 kpa of pressure drop which were suitable for the circuit.