Sizing a Settling Tank for Washed Clay: The Residence Time That Drops Sand While Keeping Fine Clay in Suspension

This paper addresses washed clay that still contains gritty sand, or that loses its finest and most plastic fraction to the overflow. It presents a settling-tank sizing rule based on particle settling velocity and residence time, derived entirely from stated assumptions and a computation whose code and full output accompany the paper. The sweep covers settling residence time from 0.5 to 8 hours. The headline outcome is: best x 2; sand remaining at best 0.0045; sand remaining at 0p5h 0.2592; clay lost at 8h 0.086; combined at best 0.026. These figures identify a specific operating point or bound that a workshop can apply directly, and they also show how quickly performance deteriorates away from it. No kiln was built, no ware was fired, and nothing was measured for this study. SIMULATED, NOT MEASURED.