If the apex capacity is exceeded a condition known as roping may occur. Normally, the underflow sprays out of the apex. When roping occurs, the air core inside the apex collapses and the spiraling motion is almost lost. The discharge looks like a rope.
In extreme cases, roping can lead to blockage. Cyclone blockage is rare, but it can occur if large particles, small grinding media, or some other foreign object blocks a small apex.