Effect of Operating Pressure on the Application of Multiple Cyclones in Dense Medium Separation (DMS) Plant

Abstract

In order to meet the market demands for minerals, it is necessary that large volumes of ores be treated at a rapid rate, and this has led to the use of multiple cyclones (in parallel) in the dense medium separation (DMS) plant since the single largest efficiently used cyclone (710 mm in diameter) can only process approximately 400 m3/h of material. However, the use of multiple cyclones came with a few problems that are all centered on the split of the ore feed and transport medium amongst the number of cyclones used. Poor splits often lead to poor separations, especially when treating ores with a high quantity of near-gravity material. This study therefore, focuses on the effects of operating pressure on the stability and efficiency of the cyclones. The effects of pressure on the stability and distribution of the ore in the cyclones were also investigated in this study. The analyses of the results obtained indicate that the circulating medium was stable with percentage stability in the range of 3 to 12%, with average medium stability of 8.3%. The results also show that changes in the circulating medium density and mixing box operating level had little effect on the cyclone pressure. The simulated results indicate that changes larger than 5% may adversely affect cyclone pressures. Tracer analysis was used to determine the efficiency, and its results show that the cyclones were cutting at a very high density cut point, which was due to the high operating head of the cyclones at 16D. It was discovered that operating the cyclone at maximum head of 12D to bring down the cut point reduce the wear rate on the cyclones. The tromp curves obtained from operating the cyclones at a lower pressure gave an average mean probable error of 0.048 (0.05 approximately) and an average cut point of 3.13. This indicates that the cyclones operate fairly similarly with very good separation efficiencies.