Concept:
Cleaning and grading of agricultural granular materials are done by separating particles according to size, shape, and other physical properties.
Step 1: Agricultural grains contain impurities such as dust, stones, broken grains, straw pieces, and other foreign materials.
Step 2: Screening is an important method used for separating grains according to size.
Step 3: A vibratory screen vibrates continuously and allows smaller particles to pass through the openings.
Step 4: Larger particles are retained on the screen surface and are separated.
Step 5: Hence, vibratory screen is used for cleaning, grading and separation of agricultural granular materials.
\[
\boxed{\text{Vibratory screen}}
\]