710 NEW YOEK STATE MUSEUM 



no available waste heat for this purpose. Tlie working part of 

 the kiln is divisible into three sections, viz, a heating, a burning, 

 and a cooling chamber. 



Butler describes it as folloAvs:-^ (see pi. 15) 



Suppoeiug the kiln to be in operation, the cooling chamber H 

 would be filled with calcined clinker, which is being cooled by 

 the cold air passing through it on its way to the burning chamber 

 F. The cooling chamber thus serves the double purpose of 

 cooling the clinker and giving its heat to the entering air. 



The burning chamber is filled with slurry. 



The heating chamber B is filled with slurry, which is introduced 

 at A. At fixed intervals, generally about every half hour, a 

 certain portion of the clinker is drawn out at the bottom, which 

 causes a general do^vnward movement of the mass throughout 

 the kiln, while a fresh portion of the slurry heated by the escap- 

 ing gases is raked forward into the calcining chamber, the neces- 

 sary fuel being added through the eyes EE. 



It sometimes happens that, owing to the clinker being slightly 

 overburned and vitrifying too much, the mass hangs up, and will 

 not drop properly when a portion is drawn from the bottom; 

 to overcome this difiiculty, eyes are placed at convenient levels 

 at the lower end of the calcining chamber, so that, with the aid 

 of iron bars, the mass may be detached and again set in motion. 



This kiln is said to be very economical in fuel consumption. 

 It however requires constant attention and charging. The labor 

 is great compared with that compelled by the common inter- 

 mittent kiln, and it has to be watched carefully, so that much 

 of the success in burning depends on the skill of the burner. 

 Butler claims that it yields a large percentage of unburned slurry. 



ISTewberry^ claims gi^eat economy of fuel for the Schofer type 

 of kiln, specially its modified form, the Aalborg. Only about 

 two tons of soft coal a day are required for each kiln, "with a daily 

 production of 75-80 barrels of cement clinker. This is only 

 about 12 fo of the weight of the clinker produced, and with coal 

 at $2 a ton corresponds to a cost for fuel of only 5c for each 

 barrel of cement produced. 



1 Butler, D. B. Portland cement. 



• 18th an. rep't U.S. geol. sur. pt 5, p. 1176. 



