Alumina ball and raschig ring
The process according to claim 5 wherein said iron-containing alumina ball are prepared by the process which comprises tumbling iron shot with powdered high refractory alumina with sufficient water to provide a heavy alumina coating on saidshot, and then heating said alumina coated iron shot to a temperature of about 2800 F. to 3400 F. for a time sufficient to result in said iron-containing ceramic ball.
pyrolyzing said preheated crushed oil shale with hot iron-containing alumina ball under conditions of temperature, pressure, and for a time sufficient to substantially convert said oil shale to produce a pyrolyzed admixture of shale oil,spent hot shale, and spent carbonaceous iron-containing alumina ball, wherein said iron-containing alumina ball contain about 10 to 90 weight percent iron in a sufficient state as to permit magnetic separation from said spent shale,
As will have been noted, certain of the processes tend to result in a limited amount of iron substantially on the surface of the alumina ball and raschig ring. It is to be anticipated that such surface iron may tend to promote formation of carbon at the surfaceof the ball at the reducing conditions involved in retorting of the shale oil, which may tend to decrease somewhat the life of the balls. Of course, such carbon effectively will be substantially burned off at the time of air treatment of the ball. Processes of ball-making by which most of the iron is internal tend to minimize this effect. At the same time such surface iron is presently believed to be advantageous in promoting the shift of CO in the retort to CO2 and H2.