Raymond mill operation criterion 2: large sand return refers to coarse-grained particles returned by the grading equipment to Raymond mill for regrinding during closed-circuit grinding.

Generally, the return ore volume is often several times more than the original feed ore volume. We call the ratio between the return sand volume and the raw ore volume as the return sand ratio.

The "large sand return" here requires us to maintain the "ideal sand return ratio" during Raymond mill operation. Practice has proved that the return sand ratio will directly affect the production efficiency of Raymond mill.

When the return sand is large, the increase of Raymond Mill total ore feeding accelerates the discharge speed of Raymond mill, shortens the residence time of ore in the cylinder and speeds up the circulation.