Verses 30–31 create a sustained figurative system: the initial mill is followed by its base, the substance it grinds, and the portion of grain supplied to it. This can be studied as an extended metaphor.
ImageLiteral objectSuggested sense
رَحَانَاOur millMilitary power
طَحِينَاFlourDefeated opponents
ثِفَالُهَاPad beneath a millBroad setting of warfare
لَهْوَتُهَاPortion of grainEnemies incorporated into the image
“Great destruction” paraphrases the message, but loses the designed unity of mill, base, grain and flour. The force of the poetry lies in that integrated image.