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What angle should the trommel screen feed chute be to prevent material backflow?
release time:
2026-11-13
Material backflow at the feed inlet during trommel screen operation is a problem many customers encounter. Sand backs up out of the feed inlet and falls to the ground, requiring manual cleanup—wasting material and adding
Material backflow at the feed inlet during trommel screen operation is a problem many customers encounter. Sand spills back out of the feed inlet and falls onto the ground, requiring manual cleanup—wasting material and adding workload. In severe cases, material piles up like a small hill on the outside of the drum at the feed end, forcing screening operations to stop. The problem usually lies in the match between the feed chute angle, drum rotation speed, and feed rate.
An excessively shallow feed chute angle is the primary cause of backflow. When the chute angle is below 45°, quartz sand flows poorly inside the chute, and when the material falls to the feed end of the drum, its speed is insufficient to slide smoothly into the drum—some sand bounces back and overflows from the feed inlet. Check the actual inclination angle of the chute, increase it to 50–60° if necessary, and install wear-resistant liners on the inner wall of the chute to reduce friction resistance. The alignment between the chute outlet and the drum feed inlet is also critical; if the offset is too large, material hits the drum end plate and bounces back, also causing backflow.
If the drum rotation speed is too low, material accumulates at the feed end and backs up. A trommel screen relies on drum rotation to move material forward; when the speed is insufficient, material stays too long at the feed end and cannot advance toward the discharge end—the more it accumulates, the more it backs out through the feed inlet. Normal speed is generally controlled at 12–18 r/min, with the higher end of the range used for materials with high fine powder content. Adjust the speed via the frequency converter, making each adjustment 2 r/min, and observe the backflow situation before deciding the next step.
When the feed rate exceeds the trommel screen's processing capacity, backflow is inevitable. When the feed volume exceeds the material advance rate inside the drum, the feed end quickly fills up, and new sand has nowhere to go but to overflow from the feed inlet. Check whether the feeder frequency is set too high and lower the feed speed appropriately. If overall line capacity needs to be increased, prioritize widening the screening surface or switching to a larger trommel screen—do not rely on overloading the feed to make up production.
During daily inspections, check each shift for material accumulation at the feed inlet. When backflow is found, troubleshoot in this order: first check the chute angle, then adjust the drum rotation speed, and finally check the feed rate. If you encounter equipment operation problems, you are welcome to contact the Shanlu Heavy Industry technical team: Manager Zhang 13583776655 (same on WeChat).
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