UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1226 
Washington, D. C. ▼ March, 1924 
THE RECOVERY OF POTASH AS A BY-PRODUCT IN THE 
BLAST-FURNACE INDUSTRY. 
By Albert R. Merz and William H. Ross, 1 Scientists in Soil Laboratory Investiga- 
tions, Bureau of Soils. 
CONTENTS. 
Page. 
Introduction 1 
Recovery of potash in the cement industry 2 
Method of investigating loss of potash in the blast-furnace industry 2 
Reactions within the blast furnace 3 
Classification and sources of iron ores 4 
Blast-furnace fluxes 5 
Blast-furnace fuels 5 
Factors governing volatilization of potash in blast furnaces 6 
Potash in blast-furnace raw materials and slags 8 
Estimated loss of potash in the blast-furnace industry 15 
Possibility of potash recovery 16 
Summary 18 
Bibliography 19 
INTRODUCTION. 
When a potash silicate is mixed with lime and ignited at a tempera- 
ture above 1, 000° C. more or less of the potash is set free, depending 
on the temperature and the proportion of lime used. It was observed 
by Ross 2 that when one part of feldspar was ignited with three parts 
of calcium carbonate complete volatilization of the potash occurred at 
a temperature of 1, 300 to 1, 400° C. This suggested a possible 
procedure for the commercial production of potash from silicate rocks, 
and attempts have been made on a commercial scale for the direct 
recovery of potash in this way. It unfortunately happens, however, 
that the percentage of potash in all commercial grades of insoluble 
silicates is comparatively low, and no process for recovering potash 
from such materials can offer much promise of profitable application 
unless there is also produced some product of value in addition to the 
potash. 
1 Acknowledgment is made to B. M. Jones, William Hazen, T. R. LeCompte, W. B. Pope, and G. J. 
Hough, of the Bureau of Soils, for assistance in the analytical work. 
2 Ross, William H. The extraction of Potash from Silicate Rocks. Circular No. 71, Bureau of Soils, pp. 
1-10. Original Communications, Eighth International Congress of Applied Chemistry, v. 15, pp. 217-229. 
1912. 
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