Proverbs 27:22 New English Translation

²²If you should pound^[a] the fool in the mortar
among the grain^[b] with the pestle,
his foolishness would not depart from him.^[c]

Proverbs 27:22 tn The verb means “to pound” in a mortar with a pestle (cf. NRSV “Crush”; NLT “grind”). The imperfect is in a conditional clause, an unreal, hypothetical condition to make the point.
Proverbs 27:22 tn The Hebrew term רִיפוֹת (rifot) refers to some kind of grain spread out to dry and then pounded. It may refer to barley groats (coarsely ground barley), but others have suggested the term means “cheeses” (BDB 937 s.v.). Most English versions have “grain” without being more specific; NAB “grits.”
Proverbs 27:22 tn The LXX contains this paraphrase: “If you scourge a fool in the assembly, dishonoring him, you would not remove his folly.” This removes the imagery of mortar and pestle from the verse. Using the analogy of pounding something in a mortar, the proverb is saying even if a fool was pounded or pulverized, meaning severe physical punishment, his folly would not leave him—it is too ingrained in his nature.

New English Translation (NET)