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Chapter 25 



BLOW- BACK 

 VALVE 



PLUG SCREW FEEDER 



REFINER FEED 

 SCREW 



Figure 25-21. — Pressure refining system for TMP. (Drawing courtesy of Sprout Waldron 

 Div., Koppers Co., Inc.) 



CHEMI-THERMOMECHANICAL PULP (CTMP) 



Nyblom and Levlin (1981) found that a good quality mechanical pulp can be 

 produced from birch if chips are pretreated with alkaline sulfite liquor and then 

 disk-refined; they observed that such pulp, for use as a substitute for ground- 

 wood pulp in printing papers, is often bleached with peroxide in the refiner, and 

 finally acidified. The birch chemi-thermomechanical (CTMP) pulp, prepared 

 on a pilot scale was intended for use as a magazine paper, and was favorably 

 compared with a spruce (Picea sp.) TMP of the same freeness produced in the 

 same refiner as the birch. 



An acceptable newsprint can be manufactured from a pulp furnish containing 

 85 percent aspen (Populus tremuloides Michx.) chemi-thermomechanical pulp 

 and 15 percent sulfite pulp (Keays and Leask 1973). McCarty (1973) succeeded 

 in making a 100-percent aspen newsprint from CTMP. In Japan, one of the 

 largest manufacturers of newsprint of the world incorporates a significant pro- 

 portion of CTMP made from local hardwoods (Namiki 1973). 



