Standardization of tertiary crusher circuit operation at the Sarcheshmeh copper complex by process audit

The most effective way of maximizing the throughput is to maintain the highest possible crusher power draw which has been practised in various plants. A process audit at the Sarcheshmeh copper complex tertiary crushing circuit indicated that the crushing efficiency at this stage was lower than the target value. To initiate the standradzation process, the power data were transferred to the control room and the ultrasound level sensor was used to monitor the level of the material in the crushing chamber. The high variation in the power draw and some basic problems justified the use of process standardization through process inspections. The first problem was non-uniform feeding of crushers which was alleviated by changing the feed chute design. The uniform distribution of the feed increased the life time of the fixed bowl by twofold and reduced the standard deviation of the power draw measurements from 8.5 to 3.2 kW. The lower feed tonnage compared to the design value (531 t/h) was the second challenge which was resolved by increasing the height of the feeder adjustment plate, removing the blocked part of the feeder and increasing the feeders speed. The resulting increase in the feed rate from 350 to 540 t/h reduced the operating time of the crushing circuit by 18%. Another difficulty was not taking full advantage of the control loops which was made operational by a series of corrective actions which decreased the number of crusher shutdowns from 10 times to 1. The coarse particle entrance to the under screen product was the fourth problem. In order to minimize this problem, the large gap between the screen frames and the screen cloth was eliminated and screen ear rings were installed. By implementing these modifications, the amount of product (percentage of passing 12.7 mm) increased from 65% to 80%.