LIME AND CEMENT INDUSTRIES 711 



i 



Rotary "kiln. This consists of an inclined revolving iron cylin- 

 der lined with fire brick (pi. 17). The slurry or dried mix- 

 ture is charged at the upper end, and oil or gas fuel blown in at 

 the lower, the gases of combustion passing through the chamber 

 and out at the upper end, while the cement mixture slowly passes 

 down through it, the burned clinker being discharged at the 

 lower end. 



At the present time the rotary kiln is gaining favor in the 

 United States. It is claimed by Lewis 1 that the cost of oil fuel 

 in this type of kiln is 28 to 40c a barrel, depending on the price 

 of oil, but, using powdered coal, the fuel cost is greatly reduced. 



There has also been a great improvement in the mechanical 

 features of the kiln. 



In this country the rotary kiln was first experimented with in 

 1889, when the Atlas cement co. of New York began to experi- 

 ment at Coplay (Pa.) with revolving continuous kilns, employing 

 crude petroleum for fuel. The oil was blown in by jets at one 

 end and the products of combustion passed into a stack at the 

 upper end of the inclined revolving cylinder. This kiln has 

 been patented in England by Frederick Ransome, who also se- 

 cured an American patent for it. Since 1889 its success has 

 increased in America, and, though this type of kiln is said to 

 have been unsuccessful in England, in this country there are no 

 less than 40 of them in operation, both on the hard raw material 

 of the Lehigh valley and on the soft, wet marls of Ohio and 

 Michigan, and also limestones of - ISTew York. The revolving 

 continuous kiln is perhaps therefore an American device, since 

 its only successful development has been in this country. Orig- 

 inally employed with producer-gas, it was subsequently modified 

 so as to use jets of crude petroleum, while latterly experiments 

 have been made with a view to utilizing pulverized coal as fuel, 

 and several plants are working kilns employing this fuel. 



Certain improvements in the way of auxiliary cylinders for 

 regenerating the heat in hot clinker have been perfected, and 

 the Atlas cement co. has also worked out a scheme for sprinkling 

 and cooling the clinker in a third cylinder, so that, when dis- 

 charged from this, it will be ready for immediate grinding in 



the mill (pi. 18). 



■* 

 IMin. ind. 7: 113. 



