VERFAHREN ZUR HERSTELLUNG KUGELFOERMIGEN PHENACETINGRANULATES UND VORRICHTUNG ZUR DURCHFUEHRUNG DES VERFAHRENS

1480189 Mixing screws BAYER AG 4 April 1975 [6 April 1974] 53147/75 Divided out of 1480187 Heading B1C [Also in Division B5] A melt-spraying device for the production of granules of phenacetin comprises intermeshing self-cleaning screws 3, 4 mounted for rotation in the same direction in a heated housing, the clearance between adjacent parts of the screws and of the housing being 4-30 x 10-3 times the screw diameter, a spray nozzle, and a heated pump for feeding melt from the heated housing to the spray nozzle. Water or steam are passed through a heating jacket 9 and cooling fluid through a jacket 8 at the inlet 5 to prevent premature melting. The screws 3, 4 may be heated. The heated surfaces may be much hotter than the temperature to which the phenacetin is heated due to the short residence time e.g. at from 150‹ to 303‹C. The molten phenacetin at 140‹C is passed through a line 10 (Fig. 1 not shown) and pumped by a piston pump (11) through a vortex nozzle 12 to be atomised and acidified in air or water at 20‹C.