GROUND WOOD PULP MILLS AND CHEMICAL FIBER MILLS 



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diameter which turn slowly under constant influx of water. The bolts must be ground in the 

 direction of the fiber. Two, three, and four pocket grinders are found, weighing from 5 to 10 tons; 



(c) The fluid pulp is carried through screens, retaining the long splinters, which are transferred to 

 a pulp engine for further mechanical refining; 



(d) The fiber may be ground or lacerated a second time both in stampers and rotary mills; 



(e) The pulp is separated according to its fineness by rocking screens of different mesh which allow 

 the water to run-off. The screened product is taken up by endless belts of cloth (in the so-called 

 "wet machine") which carry it as a thin matting through a series of pressure rolls (pressure either 

 hydraulic or spring pressure); 



(f) The mattings are dried by super- 

 heated steam, by pressure or 

 in the air. Pulp is shipped in 

 rolls about 3 feet long and 

 IV2 feet in diameter. It is not 



paper but merely the leading 

 raw material for ordinary paper. 

 The actual price of mechanically 

 ground wood pulp depends entirely 

 on the amount of water retained in 

 it. When the product is shipped over 

 long distances, it becomes necessary 

 to use a large amount of heat for 

 the efficient expulsion of the water 

 adhering to the fibre. Aside of this 

 requirement, the pulp mill can get 

 along without any heat and without 

 any power other than that furnished 

 by a waterfall. 



The ground wood pulp is more 

 mealy and less interlaceable than 

 the chemically prepared fiber; it 

 contains lignin as well as cellulose; 

 exposed to the sun, it soon turns to 

 a brownish tint. 



Wet machine for ground wood pulp. Trevor Mfgf. C, 

 Lockport, N. Y. 



Pulp grinder. Trevor Manufacturing Company, Lockport, N. Y. 



