BULLETIN OF THE 



No. 144 



Contribution from the Bureau of Soils, Milton Whitney 3 Chief. 

 December 24, 1914. 



THE MANUFACTURE OF ACID PHOSPHATE. 



By Wm. H. Waggaman, Scientist in Fertilizer Investigations. 

 INTRODUCTION. 



The acid-phosphate industry in the United States has grown to 

 enormous proportions. In spite of the fact that numerous other 

 forms of phosphatic fertilizer have been proposed or patented from 

 time to time, and the application of raw ground-rock phosphates 

 directly to the field has been recommended by some agronomists 

 and agricultural chemists, the annual production of superphosphate 

 continues to increase There is little doubt, therefore, that this 

 material will continue to be the basis of most of our commercial 

 fertilizers. 



While the general procedure followed in making acid phosphate 

 is a familiar one, many of those engaged in the production of this 

 material have but little knowledge of the chemistry involved and are 

 unfamiliar with numerous details of its manufacture, which are of 

 great economic importance. 1 Competition has become so keen in 

 the fertilizer industry during the last few years that in order to make 

 a reasonable profit the manufacturer can no longer afford to carry on 

 his business in the loose way formerly so prevalent, but must practice 

 the most modern scientific methods and exercise the closest supervi- 

 sion over every detail of his factory processes. It is believed that 

 the preparation of this bulletin is justified by the information it will 

 furnish the fertilizer manufacturers; but it is intended primarily to 

 give the progressive farmer a clearer knowledge of that compound 

 which is the basis of f ertilizers, in order that he may more intelligently 

 buy and handle his fertilizer and determine for himself its true 

 value. Such knowledge, it is believed, should tend greatly to clarify 

 prevailing ideas concerning the value of factory and of home-mixed 

 fertilizers, and to throw light on the attendant question of inordinate 

 profits alleged to be made by manufacturers. This paper describes 



1 Brogdon, J. S., Manufacture of Acid Phosphate. Amer. Fertilizer, 39 (5), pp. 25-29 (1913). 



Note. — Describes the manufacture of acid phosphate from phosphate rock, detailing the chemical and 

 mechanical changes involved. Of interest to fertilizer manufacturers generally. 



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