The conveyor, 471-DB-01, had been sprayed with used oil on 08/07/2020. On 08/08/2020 the kiln/cooler system became upset and caused unusually hot material to reach the conveyor. Once the hot material reached the conveyor, the oil that had been sprayed on the conveyor ignited. The fire was extinguished in approximately 35 minutes. There were no injuries associated with this event.