14 BULLETIN 415, U. S. DEPARTMENT OF AGRICULTURE. 
SUMMARY. 
Considerable interest is being evinced in processes for the recovery 
of potash and other products from alunite. This mineral is a hy- 
drous sulphate of potash and alumina. It occurs in important 
deposits both north and southwest of Marysvale, Utah. 
Difficulty in effecting a complete separation of the potash after 
the ignition of the mineral has been experienced both in the labora- 
tory and in factory practice; and since the material must be regarded 
as a relatively low-grade potash carrier, cheapness and efficiency in 
the extraction of the potash are essential to its successful commer- 
cial development. 
Eleven samples of light-colored alunite from the undeveloped, but 
readily accessible, area north of Marysvale were ignited at different 
temperatures and the residues subsequently leached with water. A 
temperature between 750° and 800° C. was found to be best for the 
complete extraction of the potash with the minimum amount of 
water. Temperatures above 800° C. caused a fixation of the potash, 
particularly where the samples contained much silica. 
An experiment to test the influence of fineness of grinding on the 
subsequent extraction of potash from alunite showed that nothing 
is to be gained by grinding the material finer than 60 mesh. 
Since practically all of the constituents of high-grade alunite have 
their market in the East, it is suggested that it would prove more 
economical to ship the mineral East, taking advantage of the lower 
freight rate on raw material, than to manufacture the finished prod- 
ucts near the mines. The freight charges, even then, however, are 
so great as to leave a very narrow margin of profit on the products 
in normal times. 
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