RECOVERY OF POTASH IN THE CEMENT INDUSTRY. 11 
approximately to 75,000 tons annually. If, however, the dust 
from all plants losing less than 1 pound of potash per barrel of 
cement be considered as too low grade for use as a source of fertilizer 
material and the figures from such plants be omitted in the calcula- 
tions, then the value for the available recoverable potash in the ce- 
ment industry of this country as normally operated becomes 71,000 
tons annually. 
PERCENTAGE OF VOLATILIZATION OF POTASH IN CEMENT PLANTS. 
As shown in Table I, the proportion of the total potash (K,O) that is 
volatilized varies in different plants from 24.5 to 95.9 per cent. The 
lowest values were obtained for plants widely separated from one 
another. In the Hudson River district the percentage volatilization 
varies from about 30 per cent to 45 per cent, and inthe Lehigh Valley 
district from about 40 per cent to 60 per cent. In plants situated in 
the northern Central States considerable variation was noted. The 
highest values were found for plants located in southern California, 
and in Colorado and Utah. - 
It may be pointed out that as much variation occurs in the per- 
centage of potash volatilized trom plants using oil as from those 
using coal. It is also to be noted that the average percentage 
volatilization (46 per cent) in plants using the wet process is almost 
as great as that (47 per cent) in plants using the dry process, and 
in fact the highest percentage volatilizations, 95.9 per cent and 
90.7 per cent, were found for plants using the wet process. This 
result is contrary to what seems to have been the general opinion 
.among cement manufacturers, as indicated by the following excerpts 
from communications received from two firms using the wet process: 
(a) “Our plant is a wet-process plant, and the amount of potash 
which goes up in the air we figure is infinitesimal as compared with 
plants using the dry process of manufacture.” (b) ‘In our manu- 
facture of Portland cement we use the wet method of grinding 
our raw materials and in a short time I believe the entire cement 
industry will depart from the present dry method and adopt the 
wet method so that there will be no more precipitation of volatilized 
potash in our smokestacks.”’ 
That a smaller proportion of dust should be carried over mechanic- 
ally in the wet-process plants is to be expected, and the loss of dust 
should be particularly reduced in those plants in which the kilns 
are provided with cross-partition plates which continuously raise the 
wet slurry and allow it to fall again as a spray. Judging from the 
observations that have been made in other industries, however, it is 
not so apparent that the wet process should retard very greatly the 
escape from the kilns of that portion of the potash which actually is 
volatilized. 
