CYANAMID — MANUFACTURE, CHEMISTRY AND USES 7 



cannot be absorbed by liquid carbides as the latter leaves the 

 furnace, since calcium cyanamide cannot exist at the tempera- 

 ture of liquid carbide. As the carbide cools it becomes practi- 

 cally impermeable to gases and absorption takes place only on 

 the surface to a slight depth. 



Processes for the nitrifying of a heated mass of lime and 

 coke have not been commercially successful. 



The energy consumption for the fixation of one ton of nitro- 

 gen as calcium cyanamide is about three horse power years, 

 including the manufacture of the carbide and all subsequent 

 factory operations. 



PREPARATION FOR USE AS FERTILIZER. 



Cyanamid finds its principal use in agriculture, as a source 

 of nitrogenous plant food, and for this reason practically all 

 the crude calcium cyanamide is converted into a form more 

 suitable for its incorporation in complete fertilizers. To this 

 end, water is added to the crude material in a rotating cylinder ; 

 the one or two per cent, of calcium carbide is decomposed and 

 the lime slaked. This powdered Cyanamid is converted to 

 granulated Cyanamid as follows: A small amount of water 

 is mixed with it, and the damp material is run through brick 

 presses. The resulting bricks harden rapidly, and are stored 

 until the material is to be shipped, when they are run through 

 a series of crushing rolls and screens. The coarse material, 

 which passes through a 15-mesh standard screen and over a 

 60-mesh standard screen, is practically free from dust, and 

 is known commercially as Granulated Cyanamid. The fine 

 material, mostly smaller than 60-mesh, is either incorporated 

 with fresh powdered Cyanamid and again run through the 

 brick presses, or it is mixed with several per cent of an odor- 

 less oil to reduce the dustiness, and is sold without further 

 treatment. Both grades of Cyanamid are packed in ordinary 

 fertilizer bags, and are distributed in carload lots to manu- 

 facturers of mixed fertilizers. Material so prepared contains 

 nitrogen equivalent to 18 to 20 per cent, of ammonia, and is 

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