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LIME AND CEMEKT INDUSTRIES 713 



Approximate 

 output a day 



MANUFACTORY KiLH No. Barrels 



Buckeve cement co Dietzscli continuons. . . .1 60 



Diamond cement co ^ continuous 



Yankton S. D Johnson intermittent. . 6 



Bonneville cement co 'Revolving continuous 3 150 



A new plant near Egypt (Pa.) and another near Sandusky (O.) 

 are both installing revolving continuous kilns, as is also one at 

 Catskill (K Y.) 



Grinding the clinker. American practice uses a combination 

 which has brought this step in the manufacture of Portland"^ ce- 

 ment to a high degree of perfection. The machinery used is in 

 part of American manufacture and partly of foreign origin. 



It has been found that the best results are obtained by using 

 a gradual reduction of the clinker instead of attempting to grind 

 it all fine at once, and, mth this object in view, it is common to 

 break the material up first into lumps by means of crushers of 

 the Gates or Blake type and then pulverize it in ball or tube mills 

 or mills of the Grifiin type. Ball mills are sometimes used for 

 the first grinding but in that case in conjunction with Danish 

 tube mills. 



The absence of separators is sometimes commented on, it be- 

 ing claimed that, if the sufficiently fine material were removed 

 after each grinding, the capacity of the machines would be in- 

 creased. Wind separators are occasionally used abroad, but find 

 very little application in American practice. The following table, 

 taken from the Mineral industry, v. 6, gives the fineness of dif- 

 ferent brands of native and foreign cements. 



Per cent passingr sieves 

 No. IQ No. 100 No 200 



Saylors 100 96.4 



Giant 99 94.9 



Atlas 99.5 92.7 



Alpha 99.7 94.8 



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Rebuildicg. 



