There is a close correlation between the airflow rate of a grain de-stoner and the moisture content of grain materials. In general:
Higher material moisture requires larger airflow
When the material moisture is high, the cohesive force between particles increases and agglomeration easily occurs, which reduces the permeability of the material layer. Meanwhile, high moisture also strengthens the adhesion between stones and grains, making stone-grain separation harder. At this time, a larger airflow is needed to enhance the aerodynamic effect on materials, disperse agglomerates, enable air to pass through the material layer uniformly, and effectively separate stones from grains.
For example, when processing high-moisture paddy, properly increasing airflow helps paddy jump and roll on the sieve surface. Stones can be exposed more easily and sink to the lower layer for separation from paddy grains.
Lower material moisture allows reduced airflow
For low-moisture materials, grain particles are loose with good permeability, and the adhesion between stones and grains is relatively weak, so separation becomes easier. If the airflow is too high, grains will bounce excessively and may even be blown out of the sieve surface. This not only causes grain loss but also impairs stone removal performance.
Therefore, lower airflow can be adopted for low-moisture materials to maintain proper material movement on the sieve. It ensures effective stone separation while avoiding excessive flying and loss of grains.
For instance, dried low-moisture corn can move steadily on the sieve surface under low airflow to achieve good destoning results.
Practical operation
In actual production, airflow of the destoner shall be flexibly adjusted according to the real moisture of materials to obtain optimal stone removal efficiency. Operators can judge whether airflow is appropriate and make adjustments by observing machine running status, material movement on sieve and final cleaning effect.