A system for purifying petroleum or oil shale is provided. The system includes a pressurized cracking tank configured to receive petroleum or crushed oil shale; and a rotary kiln configured to receive product from the pressurized cracking tank. A method of processing petroleum or oil shale is also provided. The method includes feeding the petroleum or the oil shale into a pressurized cracking tank; heating the petroleum or the oil shale to withdraw oil vapors containing hydrocarbons; and feeding the petroleum or the oil shale from the pressurized cracking tank into a rotating kiln.