desirably have a bulk density of from 45 lbs ft 3 to 50 lbs ft 3 and a size ranging from 4 to 300 mesh the particles from dryer 56 may be used directly as a product or optionally mixed with wet filter cake particles at the dry wet particle mixing stage 60 the dry particles from dryer 56 are conveyed through 62 the wet particles are conveyed through 58 alternatively the dried particles from dryer 56 may be returned to the main conveyor 44 and mixed with the filter cake particles to produce a final product preferably the dry wet particle mixing whether in a separate mixing stage 60 or in the main conveyor 44 provides a product having a solids content of from 40 to 60 by weight preferably 45 to 50 by weight alternatively the wet particles from the belt press 40 may be used directly with little or no mixing of dry particles the particles used as a final product either with or without addition of dry particles from the dryer 56 have a bulk density of from 50 lbs ft 3 to 60 lbs ft 3 and a size ranging from 4 to 100 mesh the mixing ratio of dry particles from dryer 56 to wet particles from belt press 40 ranges from 0 to 50 by weight preferably 5 to 30 by weight the purpose of the heater 36 is to prevent the growth of bacteria in the material produced by this process if the filter cake or the granules from the pin.