to receiver 26 a mud slurry containing lime which is to be recovered is fed from a tank not illustrated through line 36 and may be diluted by injected water from line 38 slurry from line 36 feeds into vat 40 to form a volume of mud slurry 42 in the bottom of the vat or tank during operation vacuum from the interior of drum 12 results in a depositing of a layer of mud 18 on the outer surface of the rotating drum with knives 14 and 16 scraping off the mud mud layer 18 may be sprinkled with water to assist washing by means of sprinklers indicated at 46 mud 48 scraped off of the drum falls onto conveyer 50 and into the input to a lime kiln 52 for further treatment fig2 illustrates the basic action of the doctor blades and their relation to the drum referring now to fig3 and 4 of the drawings 60 denotes generally that portion of the apparatus for holding the travelling doctor blade and for moving it back and forth along the horizontal axis substantially parallel to the axis of rotation of drum 12 the numeral 62 denotes a generally rectangular frame whose lower legs hold travelling blade 16 the upper portion of frame 62 is provided with a pair of ears 64 which receive an internally threaded.