Improving the Efficiency of Rotary Dryer of the Sarcheshmeh Copper Complex

At the Sarcheshmeh copper complex, two rotary dryers are used to decrease the moisture content of the final concentrate. One of the most challenging problems was the blockage of hot gas chamber by the wet concentrate. This reduced the operational time and significantly increased the repair and maintenance costs. It was found that the main causes of blockage of hot gas outlet chamber was an excessive moisture content of the feed and the splashing of material into the chamber. The latter was due to the contact of the material with the body of the dryer and the underlying materials. In order to prevent the blocking of the hot air, the angle of the lifter plates was reduced from 90 to 75˚, the elbow angle of the hammer body increased from 135 to 155˚, and the ceiling of the hot air chamber was extended 70 cm into the dryer rotating section. After these modifications, in order to monitor the blockage process of the hot air chamber, the images of blockage level of the hot air chamber were captured and analyzed daily. Furthermore, the temperatures of the beginning and end of the combustion chamber was recorded and compared with the profiles before modifications. On account of these modifications, the operational period increased from 7 to18 days. In addition, the temperature of the dryer end point, which is an important indicator in determining the drying performance and moisture content of the product, was kept constant at about 90 °C. The temperature at this point before modifications was 50 °C which showed a significant increase in the drying performance.