PHILIPPINE RAW CEMENT MATERIALS. 



223 



In ordinary practice this material would probably be combined with not more 

 than 3 parts of limestone number 7 as follows: 



Table XI. 





Total. 



Individual constituents. 



Silica 

 (SiO.). 



Alu- 

 mina 

 (AI.O3) 



Iron 



oxide 



(Fe.Os). 



Cal- 

 cium 

 oxide 

 (CaO). 



Magne- 

 sia 

 (MgO). 



Volatile 



(C0o4- 



H0O+, 



etc.) 



Clay (No. 1) 



Schist (No. 9) 



Limestone (No. 7!___ 



Unburned 



82.25 

 17.75 

 300. 



49.50 



14.23 



1.14 



18.62 

 2.23 

 0.54 



3.84 

 0.20 



0.26 



0.02 



166.86 



1.52 

 0.09 



5.23 

 0.38 

 131. 



400. 

 136.6 



64.87 



21.39 



4.04 



167.16 



1.61 



136.6 



Volatile 



Burned 



263.4 



24.62 



8.12 



1.53 



63.46 



0.61 









In like manner the materials numbered 2 to 6 inclusive could be mixed with 

 schist number 9 and limestone number 7. The following proportions would give 

 a correction of the silica-alumina ratio to 3 to 1. 



Sample number. 



Parts sample. 



Parts schist 



2 



66.3 



33.7 



3 



71.3 



28.7 



4 



73.5 



26.5 



5 



74.4 



25.6 



6 



92.1 



7.9 



The comjjosition of the ash of the coal has not been considered in 

 preparing the above figures, but the relative proportions of the raw con- 

 stitutents may be varied to include this factor, which is not a large one. 



It is not only the existence in this region of a superabundance of 

 limestone and of shales that could readily be recomposed to be suitable 

 for the manufacture of cement which attracts attention, but the coal is 

 at hand; the city of Cebu is an open port making transportation easy 

 and the cost of labor and supplies should be as low as they would be 

 at any other point in the Islands. 



FUEL FOE BURNING CEMENT. 



The item of fuel used in the burning of Portland cement is an im- 

 portant one. In 1885 Mr. P. Eansome ^'^ patented a rotary kiln for 

 calcining cement in which the firing was effected by means of producer- 

 gas. The powdered raw material was fed in by means of a hopper at 

 the upper end of the kiln and traveled slowly down the furnace in con- 

 sequence of an angle of inclination and a constant revolution of the 

 kiln, while the producer gas in a large volume of flame entered the 

 kiln at the opposite end. The interior of the cylinder contained a series 

 of projecting longitudinal steps by which the raw material was caught 



^Redgrave, G. R. and Spackman, C, Calcareous Cements London (1905), 167. 



