GYPSUM DEPOSITS OF NEW YORK 



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use at Mannheim, Germany. The calciner consists of a fire box 

 and automatic stoker opening into the chamber that contains the 

 rotating cylinder. Above the cylinder and connected to it by a pipe 

 is a chamber through which a spiral conveyor passes. The gypsum 

 ground to a size not larger than a hickory nut is charged into the 

 forewarmer, is conveyed by the spiral to the other end and dis- 



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Fig. 9 Arrangement of installation for Cummer process 



charged into the rotary cylinder. A fan forces the hot air and 

 gases from the fire ]>ox into the cylinder and this calcines the gyp- 

 sum and forces it toward the discharge end of the cylinder. The 

 material is agitated by a continual lifting and dropping brought 

 about by a series of shelves or buckets on the sides of the revolv- 

 ing cyhnder. The larger lumps which would require a longer period 

 of heating for calcination, owing to their weight, are moved most 

 slowly toward the discharge point, and thus receive the most heat, 



