IX, A, 1 



West and Cox: Philippine Cement Raw Materials 87 



rotary kiln made of an iron pipe, 8 inches in diameter and 32 

 inches long. The lining material consisted of hard-burned mag- 

 nesite. The furnace was rotated by means of a 0.5-horsepower 

 motor with a speed of 1 revolution per one minute and twenty- 

 five seconds and was heated by means of a Hoskins gasoline 

 burner to which gasoline was supplied at about 50 pounds' pres- 

 sure. Temperature measurements were made by a Le Chatelier 

 thermocouple connected with a reflecting galvanometer. In one 

 series of experiments the following temperatures were recorded : 

 Temperature of hottest section, 1,630° ; temperature at six inches 

 from hot end, 1,500° ; temperature at feed end, 1,200°. 



We constructed a kiln like that of Campbell except that it 

 was 1.11 meters in length. The apparatus failed to produce 

 satisfactory results, and we were unable to obtain a uniformly 

 well-sintered clinker, principally on account of the difficulty in 

 hindering the escape of heat. 

 A large amount of heat was 

 continually reflected toward the 

 burner, and escaped at the open- 

 ing where the clinker emerged. 

 Cement obtained from our rotary 

 contained considerable free lime, 

 and although a few assorted 

 specimens of clinker came with- r- , .^ 



Pig. 1. Cement furnace, exterior. 



in the specifications of initial 



and final-set and boiling tests, yet the tensile strengths of neat 

 and sand-mortar-briquettes were too low to pass specifications. 

 The bricks of unplastic volcanic tuff in the course of the rough 

 journey through a rotary were ground to a powder, some of 

 which was blown out of the feed end.'- 



The usual type of stationary kiln used for experimental cement 

 burning consists essentially of an updraft kiln.'^ A temperature 

 of 1,370° (Seger cone No. 12) is obtained without difficulty. In 

 a stationary upright kiln the cement mixture and fuel are fed 

 usually in alternate layers. However, this method of burning 

 produces clinker contaminated with the fuel ash which changes 

 the calculated composition, and in such a furnace it is almost 

 impossible to heat a raw cement mixture uniformly for a given 

 length of time. 



" We were able to overcome this to a large extent by molding our cubes 

 with an agar-agar solution instead of water, which increased the plasticity 

 of the tuff and rendered the dried blocks considerably more durable. 



"Bull. Ohio State Geol. Surv. (1904), IV, 3, 244. 



