UNITED STATES DEPARTMENT OF AGRICULTURE 
j BULLETIN No. 572 ¥ 
Contribution from the Bureau of Soils \ 
MILTON WHITNEY, Chief 
Washington, D. C. PROFESSIONAL PAPER October 5, 1917 
THE RECOVERY OF POTASH AS A BY-PRODUCT IN 
THE CEMENT INDUSTRY. 
By Witu1am H. Ross, ALBERT R. Merz, and C. R. WAGNER, 
Scientists in Soil Laboratory Investigations. 
CONTENTS. 
Page. Page, 
EG AG COC) 6E arte A ly Re i Ag 1 | Estimated percentage of potash in the flue 
Potash in raw materials and loss through dust from different plants................-- 15 
volatilization in cement manufacture....... 3 | Ratio of potash to soda in cement dust...... 17 
Percentage of volatilization of potash in Potash-producing plants in the United States. 18 
COME plAMESK eye wee nS LO ak At PACkm owledomentyces eae sue eee eateries 22 
Reliability of the results obtained..........- 145 SUMMALY os aicclcene cicicisais wa ceeecenoen eens 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—B ull. 572——1 
