CRUSHING AND PULVERIZING MACHINERY. 



439 



mill for the cement industry are controlled by the Atlas Portland 

 Cement Company. The mill has in consequence been used only in 

 the plants of that company, where it seems to have given good 

 satisfaction. 



In the Huntingdon mill three heavy rollers are suspended from 

 a circular horizontal head, the attachment being such as to allow free 

 radial swing to the rollers. The rapid revolution of the head causes 

 the rollers to diverge, swinging outward, and being pressed by centrif- 



FIG. 93. Huntingdon mills at Atlas plant. (Atlas Portland Cement Co.) 



ugal force against a horizontal annular die ring of steel. The material 

 fed in is pulverized between this fixed ring and steel-head rings attached 

 to the bottom end of each roller. The mill, therefore, differs from the 

 Griffin mill, chiefly in the fact that the single roller of the latter mill 

 is revolved positively by power applied directly to its upper end, 

 while in the Huntingdon mill the individual rollers are not positively 

 rotated. 



A Huntingdon mill requires about 40 H.P. If fed with material 

 varying from ^ to 1 inch in size, its output on clinker will be about 8 

 barrels per hour, ground so as to pass 92 per cent through a 100-mesh 

 sieve. On raw material its output will vary from 15 to 25 barrels per 



