558 



CEMENTS, LIMES, AND PLASTERS. 



power is used with electric transmission; in at least one plant natural 

 gas is used, partly in gas-engines and partly under boilers, and in a 

 few plants part of the power is derived from the waste gases of the kilns. 



Cost of coal for kilns and power. The total amount of coal used 

 per barrel of cement, both under the boilers, in driers, and in the kilns, 

 may vary from 170 Ibs. in a Lehigh-district plant using long kilns to 300 

 or 350 Ibs. in a wet-process plant. Even this latter figure is exceeded at 

 times, for one wet-process plant recently reported a total coal consump- 

 tion of over 400 Ibs. per barrel. 



Cost of gypsum used. The amount of gypsum or plaster used in 

 a large plant is quite an item, as 8 to 14 Ibs. may be used per 

 barrel of cement. Crude gypsum in small lumps may be bought as 

 low as 80 cents or so per ton when the cement-plant is located in a gyp- 

 sum-producing district. On the other hand, burned plaster plus freight 

 may cost as high as $6 to $10 per ton for a plant not so near the 

 source of supply. Assuming that on the average 10 Ibs. of gypsum or 

 plaster are used in each barrel of cement, these prices would make the 

 cost per barrel of cement range from cent to 5 cents. At, most of the 

 plants in this country the gypsum cost will probably range between 

 1 and 2 cents per barrel of cement. 



Distribution and cost of labor. The following statement* of the 

 distribution and amount of labor in a six-kiln Lehigh-district plant has 

 recently been published. The number of men given are those actually 

 employed in one twenty-four-hour day (two shifts), and the cost per 

 barrel has been based on an output of 1200 barrels per day. 



TABLE 210. 

 LABOR COSTS IN CEMENT-PLANT. 



* Eoilleau and Lyon. Cost of building and operating a Portland-cement plant. 

 Municipal Engineering, vol. 26, pp. 391-395. June, 1904. 

 t Contract work (estimated). 



