UNITED STATES DEPARTMENT OF AGRICULTURE 



J^T^ju 



BULLETIN No. 572 



Contribution from .the Bureau of Soils 

 MILTON WHITNEY, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



October 5, 1917 



THE RECOVERY OF 

 THE 



SH AS A BY-PRODUCT IN 

 INDUSTRY. 



By William H. Ross, Albert R. Merz, and C. R. Wagner, 

 Scientists in Soil Laboratory Investigations. 



CONTENTS. 



Page. 



Introduction 1 



Potash in raw materials and loss through 



volatilization in cement manufacture 3 



Percentage of volatilization of potash in 



cement plants 11 



Reliability of the results obtained 14 



Estimated percentage of potash in the flue 



dust from different plants 15 



Ratio of potash to soda in cement dust 17 



Potash-producing plants in the United States. 18 



Acknowledgment 22 



Summary 22 



INTRODUCTION. 



The present work is a continuation of an investigation that has 

 been in progress in this laboratory for several years on the practica- 

 bility of recovering potash from silicate rocks. Early in the investi- 

 gation the conclusion was reached that owing to the small percentage of 

 potash in commercial grades of any insoluble potash silicate, no process 

 for recovering potash from such material can offer much promise of 

 profitable application unless at the same time some product of value 

 is recovered in addition to the potash. This principle now seems to 

 be more or less generally recognized, and in the numerous patents 

 that have appeared during the last two or three years on the subject 

 of decomposing feldspar and other potash silicates specifications are 

 given in most cases for the recovery, in addition to potash, of one 

 or more of such various products as compounds of aluminum and of 

 silicon, cement, raw material for the manufacture of glass or pottery, 

 structural material, and pigment. 



In a publication * prepared about five years ago, it was shown that 

 when 1 part of feldspar and 3 parts of calcium carbonate were ignited 

 about an hour at a temperature of 1,300-1,400°, the potash in the 



1 Ross, "William H., Circular No. 71, Bureau of Soils; Eighth Intern. Congress of Applied Chemistry, 

 15, 217 (1912). 



103837°— 17— Bull. 572 1 



