RECOVERY OF POTASH IN THE CEMENT INDUSTRY. 15 
The two sets of analyses shown in this table were made on different 
samples collected from four months to six months apart. The close 
agreement in each case affords evidence that at least for these plants 
the samples collected are representative, and that the potash content 
of the raw material used m cement manufacture is surprisingly 
uniform. : : 
Further evidence in support of this conclusion is available. Thus, 
R. K. Meade, consulting engineer for the Clinchfield Portland Cement 
Co., reports’ that he found 2.49 pounds of potash volatilized at 
this plant per barrel of cement, basing his calculations on the 
results of analyses of samples secured about a year prior to the 
time that our samples were obtained. This result differs but 0.03 
pound from that given in Table I. Again, of two samples of raw mix 
which were collected and forwarded to this laboratory nine months 
apart by the Tidewater Portland Cement Co., both were found to 
contain 0.71 per cent potash. 
It may be pointed out also that as a rule those plants which are 
situated near one another and apparently use material from the 
same geological formation show much the.same potash content in 
the raw material used. Thus, there may be compared in this con- 
nection the different plants at Bath, Pa.; Nazareth, Pa.; Fenton, 
Mich.; Mason City, lowa; Concrete, Wash.; and Hudson, N. Y. 
The values listed in Table I for the weights of dry raw mix 
required per barrel of cement show greater variation than might be 
expected, and it is possible that some of the values given may depart 
somewhat from values representing true working conditions. Where 
no values could be obtained it was assumed that 608 pounds of raw 
mix would be required per barrel of cement. It is recognized, also, 
that in individual cases the samples collected may not be representa- 
tive of normal working conditions, but from the observations made 
it is thought that in the majority of cases the results given are repre- 
sentative. | 
ESTIMATED PERCENTAGE OF POTASH IN THE FLUE DUST FROM 
DIFFERENT PLANTS. 
The percentage of potash occurring in the flue dust from any 
plant will vary (1) with the’percentage of potash in the raw mate- 
rial; (2) with the percentage of potash volatilized; and (8) with the 
amount of dust carried off from the kilns mechanically. 
As already pointed out, the quantity of dust collected daily in 
the flue stacks and treaters of the piant of the Security Cement 
and Lime Co. amounts to about 61,000 pounds. .If it be assumed 
that this represents a recovery of 95 per cent of the total dust, 
1 Written communication. 
