MANUFACTURE OF NATURAL CEMENTS. 249 



Fuel costs. It is probably sufficiently accurate to assume that in 

 the average natural-cement mill the consumption of fuel in the kilns may 

 range from 20 to 65 Ibs. coal per barrel of cement. An additional 8 to 

 20 Ibs. of coal will be required to furnish power for grinding and other 

 mill operations. The total coal consumption may therefore vary from 

 28 to 85 pounds per barrel of cement. In cost coal may easily vary 

 from $1 to $4 per ton, and these figures have been used as the limits 

 in the calculations below. 



Total costs per barrel. Using the above data as a basis, the fol- 

 lowing estimates of the total costs of manufacture have been prepared. 



TABLE 107. 



ESTIMATES OF COST OF NATURAL-CEMENT MANUFACTURE. 



Min. Max. 



Rock at mill SO. 05 $0.10 



Labor at mill 06 .17 



Coal for kilns 02 .12 



Coal for power 02 .05 



Interest, supplies, etc 03 .06 



Total $0.18 $0 . 50 



Though the minimum quoted may seem surprisingly small, it is 

 very close to the actual costs attained in a prominent district. The 

 above costs do not, of course, include the cost of packing materials, 

 though they do include the labor involved in packing. This distinction 

 has been made because barrels and sacks are usually charged for at a 

 sufficient price to give a small profit on their use. 



Through the courtesy of the manager, a typical daily cost report of a 

 large American natural-cement plant is presented in Table 108, below. 

 This mill averages 500 barrels of cement per day, employing 60 men in 

 the quarry, kilns, mill and packing-house. The output per day averaged, 

 therefore, about 8J barrels for each man employed. If quarry labor be 

 excluded, the output per day averaged 20 barrels per day for each man 

 employed in kilns, mill and packing-house. The rate of pay is, however, 

 higher than in most mills, so that the total labor costs are rather high. 



The total cost of cement-manufacture at this plant is therefore close to 

 34 cents per barrel. This includes packing labor, but not cost of sacks 

 or barrels, and makes no allowance for interest charges or for sales and 

 general superintendence. Labor costs, as above noted, are high; and 

 the cement is of low Cementation Index, and therefore requires a very 

 large amount of fuel, averaging about 65 Ibs. of coal per barrel. 



