The Spiders (24-7, 13-3 Atlantic 10) won their fourth straight game and have already clinched a first-round bye heading into next week's conference tournament. Cedrick Lindsay pitched in with 11 points.
Richmond went into halftime with a 37-30 lead, then dominated the second half, leading by as many as 17 points. Lindsay gave the Spiders their largest margin when he made a free throw after being fouled on a steal.
The Dukes (18-11, 10-6), who have lost four of their last five games, never got closer than 12 points the rest of the way.
Mike Brey is looking at former Notre Dame players to fill two assistant jobs that have opened up with the departures of Martin Ingelsby and Anthony Solomon.
Purdue's 2016-17 prospects got a jolt Wednesday when forward Caleb Swanigan announced he will return for his sophomore season.
Clemson's Jaron Blossomgame says he is withdrawing from the NBA draft and returning to school for a final season.