56 
CEMENT MATERIALS AND INDUSTRY. 
fBULL. 243. 
When the heav}^ Western oils are used for kiln fuel, it may be 
estimated that 1 gallon of oil is equivalent in the kiln to about 10 
pounds of coal. The fuel consumption, using dry materials, will 
range between 11 and 14 gallons of oil per barrel of cement; but the 
daily output is always somewhat less with oil fuel than where coal 
is used. 
Natural gas in the kiln ma}^ be compared with good Pennsylvania 
coal by allowing about 20,000 to 30,000 cubic feet of gas as equivalent 
to a ton of coal. This estimate is, however, based upon too little data 
to be as close as those above given for oil or coal. 
EFFECT OF COMPOSITION ON BURNING. 
The differences in composition between Portland-cement mixture 8 
are very slight if compared, for example, to the differences between 
various natural cement rocks. But even such slight differences as do 
exist exercise a very appreciable effect on the burning of the mixture. 
Other things being equal, any increase in the percentage of lime in 
the mixture will necessitate a higher temperature in order to get am 
equally sound cement. A mixture which will give a cement carrying 
59 per cent of lime, for example, will require much less thorough 
burning than would a mixture designed to give a cement with 64 per 
cent of lime. 
With equal lime percentages, the cement carrying high silica and 
low alumina and iron will require a higher temperature than if it were! 
lower in silica and higher in alumina and iron. But, on the other 
hand, if the alumina and iron are carried too high, the clinker will] 
ball up in the kiln, forming sticky and unmanageable masses. 
CHARACTER OF KILN FUEL. 
The fuel most commonly used in modern rotary kiln practice is 
bituminous coal, pulverized very finely. Coal for this purpose should 
be high in volatile matter and as low in ash and sulphur as possible.] 
Russell gives the following analyses of West Virginia and Pennsyl- 
vania coals used at present at various cement plants in Michigan: 
Analyses of kiln coals. 
Fixed carbon . 
Volatile matter 
Ash 
Moisture 
Sulphur 
56. 15 
35.41 
6.36 
2.08 
1.30 
56. 33 
35.26 
7.06 
1.35 
1.34 
55. 82 
39.37 
3.81 
1.00 
.42 
51.69' 
39. 52 
6.13 
1.40 
1.46 
