THE ROTARY KILN. 



481 



The history of the gradual evolution of the rotary is of great interest, 

 but as the subject cannot well be taken up here, reference should be 

 made to the papers cited below,* which contain the details of this his- 

 tory, accompanied in many cases by illustrations of early forms of rotary 

 kilns. 



Summary of burning process. As at present used, the rotary kiln 

 is a steel cylinder, about 5 to 7 feet in diameter; its length for dry 

 materials is 60 to 150 feet, while for wet mixtures an 80-foot or even 

 longer kiln is commonly employed. 



This cylinder is set in a slightly inclined position, the inclination 



FIG. 116. Plan and elevation of 60-foot rotary kiln. (Engineering News ) 



being approximately one half inch to the foot. The kiln is lined, ex- 

 cept near the upper end, with very resistant fire-brick, to withstand 

 both the high temperature to which its inner surface is subjected and 

 also the destructive action of the molten clinker. 



* Duryee, E. The first manufacture of Portland cement by the direct rotary kiln 



process. Engineering News, July 26, 1900. 

 Eckel, E. C. Early history of the Portland-cement industry in New York State. 



Bulletin 44, New York State Museum, pp. 849-859. 1901. 

 Lesley, R. W. History of the Portland-cement industry in the United States. 



8vo, 146 pp. Philadelphia, 1900. 

 Lewis, F. H. The American rotary kiln process for Portland cement. Cement 



Industry, pp. 188-199. New York, 1900. 

 Matthey, H. The invention of the new cement-burning method. Engineering 



and Mining Journal, vol. 67, p. 555, 705. 1899. 

 Smith, W. A. Manufacture of cement, 1892. Mineral Industry, vol. 1, pp. 49-56. 



1893. 

 Stanger, W. H., and Blount, B. The rotatory process of cement-manufacture. 



Proc. Institution Civil Engineers, vol. 145, pp. 44-136. 1901. 

 Editorial. The influence of the rotary kiln on the development of Portland-cement 



manufacture in America. Engineering News, May 3, 1900 





