MANUFACTURE OF NATURAL CEMENTS. 



245 



ing hammers accomplish the reduction, is described in detail on 

 page 466, with illustrations. It is in use in at least three natural-cement 

 plants to the writer's knowledge. In two of these, at Fort Scott, Kan., 

 it is employed as a final reducer, taking a medium soft clinker from 

 pot crushers and reducing it to pass 50-mesh. In this work it is finishing 

 50 to 75 barrels (265 Ibs. each) of cement per hour. At the Pembina 



Separating Tailings from 

 Einishing Stone Products 



Conveyor for Cracker 

 Stone Product. 



Conveyor for Finishing/ 

 Stone Product 



FIG. 49. Installation of Berthelet separating system. 



plant in North Dakota the Williams mill is used as a preliminary reducer, 

 to prepare the material for the tube mill. In this work, which is on 

 very hard clinker, it is handling about 20 barrels per hour. 



Separating systems. The use of separators in the grinding depart- 

 ment of a natural-cement plant greatly decreases the power consump- 

 tion per ton of cement. 



The objections to the use of separators in Portland-cement plants do 



