A reactor for washing sand contaminated with hydrocarbons comprises a vessel having an aperture in a bottom portion thereof. A steam cleaning device is located near a top of the vessel for receiving contaminated sand and cleaning the contaminated sand as it is introduced into the vessel. A rinsing device is positioned below the steam cleaning device for rinsing the sand with water. A sand conveying device comprising an air injection device is positioned in the bottom portion of the vessel for urging sand out of the aperture using compressed air, such that the sand is partially dewatered as the sand is urged out of the aperture.