176 passes through valve 180 and is introduced into refiner 10 at inlet 27 whereas the material in line 178 passes through 184 and is introduced into refiner 10 at inlet 26 in refiner 10 the material at inlet 27 and 26 is further refined in respective distinct refining zones and discharged from the refiner along respective discharge lines 58 56 the discharged material passes respectively through valves 518 and 520 to the refined storage chest 179 fig7 also shows a simplified adaptation of the control system of fig3 centered about the control station 502 signals commensurate with the gap widths in refiner 100 are delivered over lines 504 to controller station 502 along with any other data that may be used in conventional control techniques in addition the respective flow rates in lines 176 and 178 are delivered along signal paths 506 to the controller station 502 in like fashion signals commensurate with the refining gap widths and other relevant data from the refiner 100 are delivered along signal paths 508 to the control station 502 and the discharge flow rates in lines 58 56 are similarly delivered along data paths 510 to station 502 a level signal or the like is also transmitted from the storage chest 179 along data path 512.