CRUSHING AND PULVERIZING MACHINERY. 467 



produced by this mill. At the plant in question the materials used 

 are hard limestone and shale. The raw materials are run through 

 a Gates crusher, which gives a product averaging 1^ inches in size. 



FIG. 106. Section of Williams mill. 



Three Williams mills, using about 18 H.P. each, take the product 

 from this crusher and reduce it to give the following residues: 



Mesh of sieve ............. 20 50 100 200 



Per cent residue ........... 25 45.1 60.9 69.5 



Per cent passing ........... 75 54.9 39.1 30.5 



The three Williams mills in use handle sufficient raw mix to give 

 a production of about 1000 barrels per day. From these mills the 

 material is fed to three tube mills, which take up 60 to 70 H.P. each, and 

 complete the reduction so that 92 to 93 per cent passes a 100-mesh 

 sieve. 



Another test, for the record of which I am indebted to the manu- 

 facturers of the Williams mill, was carried on in a plant also using lime- 

 stone and shale, crushed to about H mcn 



Mesh of sieve ........... 20 50 100 200 



Per cent residue ......... 26.8 51.3 68.7 76.0 



Per cent passing ......... 73.2 48.7 31.3 24.0 



