MANUFACTURE OF SALT 45 



2 DIRECT FIRE EVAPORATION 



There are two processes in use for the manufacture of salt 

 by direct heat, namely : 



A. The Pan Process 



B. The Onondaga Kettle Process 



A. Pan Process 

 Usually several pans are placed under one roof. They 

 are constructed of large wrought iron plates riveted together. 

 The thickness of the plates is from \ to |- inch. The 

 usual dimensions are: width 20 to 24 feet, length 100 feet 

 in two sections and depth 12 inches. The front section is 

 70 feet and the back one 30 feet long, separated by a loose- 

 fitting, wooden or iron partition, to allow the brine from the 

 back section gradually to enter the front one. Adjoining 

 the front pan is a back pan 30 feet long by 20 to 24 feet 

 wide and 12 inches deep. The walls under this pan are from 

 12 to 16 inches higher to enable the easy transfer of the 

 brine by syphon from the back to the front pan. The ends 

 of these pans are at right angles to the bottom while the 

 sides are oblique. The front pan is usually supported by 

 two central and two outside walls (though there are some 

 pans differently supported and constructed) which are 3 

 feet wide at their base and grates, tapering to one foot in 

 width under the pan bottom. The distance from the top of 

 the grate to the bottom of the pan is between 6 to 8 feet. 

 The grates are 3 to 4 feet wide by 5 to 6 feet long. The 

 walls are built in the most substantial manner and lined on 

 the inside with fire brick in the front portion and with ordi- 

 nary bricks farther back, where the heat is less intense. To 

 protect the pan bottom against a too intense heat directly 

 over the fires, a fire brick arch is built, the crown of which 

 is between 2 and 3 feet below the pan bottom. This arch 

 is solid from the front wall to about 2 feet beyond the grates, 

 where an open space of 6 to 8 inches wide is followed by a 

 second arch from 12 to 16 inches wide, and this again after an 



