Abstract: In a rotary concentrator for continuous separation of a vehicle fluid and a concentrate of solids from an abrasive solids-containing fluid, a plurality of solids-detaining baffles and pockets are provided within the concentrator to collect deposits of the abrasive materials. This depositing of materials upon interior surfaces of the concentrator provides an autogenous, relatively stationary protective layer of abrasive material which protects those surfaces from the abrasive action of solids-containing material flowing past them during operation of the concentrator.