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ANNUAL REPOET SMITHSONIAN INSTITUTION, 1923 



The ovens are separated b> flues in which part of the gas generated 

 by the distillation is burned to provide the heat necessary for the 

 coking. 



It is from the volatile matter in the coal given off that the by- 

 products are obtained. The ammonia is thus the result of the union 

 of nitrogen and hydrogen, according to some reaction which is 

 not fully known. 



The coal contains from 1 to iy 2 per cent nitrogen, and of this only 

 about 15 per cent is recovered in the form of ammonia. This means 

 that we only get about 7 pounds of ammonia per ton of coke. 

 The hot gases from the ovens containing the ammonia are cooled 

 and scrubbed with water to remove the tar. They then go to 

 saturators filled with sulphuric acid, and when the gas bubbles 

 through this acid an intimate contact is established between the two 

 and ammonium sulphate is precipitated as a solid salt according to 

 the reaction 2 NH 3 +H 2 S0 4 =(NH 4 ),S0 4 . 



The ammonium sulphate thus formed in the saturators is then 

 drained and dried in centrifugal driers, after which it is ready for 

 sale. It then contains 24 per cent of ammonia equivalent to about 

 20 per cent of nitrogen. 



The remainder of the gas, now freed from ammonia, after leav- 

 ing the saturators may then be further scrubbed with absorbent oils 

 for recovery of other by-products, and if the gas is to be used for 

 municipal purposes it must be further purified by removing any 

 sulphur that it may contain. 



PRODUCTION CAPACITY 



The annual productive capacity of the country's existing by- 



product coke oven plants is said to be about 35,000,000 tons of coke, 

 which would correspond to a maximum ammonium sulphate output 

 of about 550,000 tons, equivalent to 110,000 tons of combined 

 nitrogen. 



