8 BULLETIN 572, U. S. DEPARTMENT OF AGRICULTURE. 



Iii a communication received, from the manager of one of the large 

 cement plants in the Lehigh Valley district the statement was 

 made that the raw cement material used in this district contains less 

 than 0.3 per cent. The samples analyzed in these experiments, 

 however, indicate that in no case does the raw mix used in the plants 

 of this district run as low as 0.3 per cent, but that some of these 

 plants make use of cement material almost as rich in potash as may 

 be found in any cement plant in the country. In general it may be 

 stated, however, that high potash-bearing raw material is not char- 

 acteristic of any particular part of the country. 



The values given in Table I for the potash contained in the daily 

 production of cement were obtained by multiplying the output in 

 barrels by the weight of one barrel (380 pounds) and by the per- 

 centage of potash in the cement as found by analysis. To obtain 

 the corresponding values for the potash in the daily run of raw mix, 

 the output of cement expressed in barrels was multiplied by the 

 weight of raw mix required per barrel of cement and then by the 

 percentage of potash in the raw mix. The difference between the 

 two values as thus determined represents the potash that escapes 

 daily from the kilns. As shown in the table, this varies in different 

 plants from 0.35 to 5.14 pounds of K 2 per barrel of cement pro- 

 duced. The average for all the plants listed in the table when 

 consideration is taken of the variation in output of cement of the 

 different- plants amounts to 1.93 pounds 1 per barrel of cement. 



Omitting the plants of the Universal Portland Cement Co., the 

 corresponding average for the remainder of the 99 plants of this 

 country from which samples were received amounts to 2.09 pounds. 

 The average for the nine Canadian plants is 1.95 pounds. The 

 total number of plants in this country from which samples were 

 received is only four less than the total number which operated in 

 1915 2 and nine less than the total number said to be in operation 

 in 1916. 



The average daily output of cement from the individual plants in 

 many cases is considered confidential information. In Table I, 

 therefore, it was necessary to give values for the output of the indi- 

 vidual plants which represent capacities rather than actual produc- 

 tion. The total annual production as obtained from these values 

 is consequently much in excess of that which is known to have been 

 produced in any one year. The values given for the potash lost 

 per barrel of cement are, however, independent of the output. If, 

 therefore, the average annual production of Portland cement in 



i In n> a Mng this calculation no account was taken of the potash in the coal, which at most would not 

 amount to more than a few tenths of a pound per barrel of cement. Any potash present, however, would 

 tend to increase the value given for the amount of potash volatilized. Cf . R. K. Meade, Portland Cement, 

 2ded., p. 179. 



2 Burchard, E. F., Cement in 1915. Mineral resources of the U. S., 1915, Part II, p. 195. 



