the staging discs 3 and or 4 the first refining ring 5 and the various staging discs 3 and or 4 make up the first refining disc within the area defined by the inner most edge of the first refining ring 5 is attached a first backing disc 6 the first backing disc 6 may be attached to staging discs 3 and or 4 by the use of screws bolts or other conventional fastening devices in a particular preferred embodiment the first backing disc 6 includes a recess 7 which is specifically adapted to receive retain and position a first deflecting ring 8 the recess 7 is preferably placed at the periphery of the first backing disc 6 such that the first deflecting ring 8 can be so placed of course it is possible that the first deflecting ring 8 and the first backing disc 6 may be manufactured as a single piece the first deflecting ring 8 includes an inner angled surface 9 which slopes away relative to the plane of the first backing disc 6 and or the imaginary center of the first deflecting ring 8 the first deflecting ring 8 further includes a first major surface 10 which may be parallel to the plane of the first backing disc 6 or may be angled such that the junction of the inner angled surface 9 and the first major surface 10 forms the highest point of either surface the slope of the inner angled surface 9 may range from between about 30 degrees to about 60 degrees but is preferably.