Table 8-1

Table 8-1. Summary of Major Pulping Processes

		Treatment					Relative Strength*
				Pulp		Form of
Process	Acronym	Chemical	Mechanical	Yield (%)	Wood Used	Wood	Softwood	Hardwood

Mechanical
Stone groundwood	SGW	None	Grinder	93-95	Softwood (mostly)	bolts	5	3
Pressure groundwood	PGW	None	Grinder	93-95
Refiner mechanical	RMP	None	Disk refiner	93-95	Softwood (mostly)	chips	5-6	3
			(pressure)
Thermomechanical	TMP	Steam	Disk refiner	80-90	Softwood	chips	6-7	-
			(pressure)
Chemithermomechanical	CTMP	Sodium sulfite or	Disk refiner	80-90	Hardwood	chips	-	5-6
		sodium hydroxide^a	(pressure)
Chemimechanical^b	CMP	Sodium sulfite or	Disk refiner	80-90	Hardwood	chips	-	5-6
		sodium hydroxide

Semichemical
Neutral sulfite	NSSC	Sodium sulfite +	Disk refiner	70-85	Hardwood	chips	-	6
		sodium carbonate
Green liquor	GLSC	Sodium hydroxide +	Disk refiner	70-85
		sodium carbonate
Nonsulfur	—	Sodium carbonate +	Disk refiner	70-85
		sodium hydroxide
Chemical
Kraft	—	Sodium hydroxide +	None	45-55	Both	chips	10	7-8
		sodium sulfide
Sulfite	—	Calcium bisulfite	None	40-50	Both	chips	9	7
		in sulfurous acid^c,d
Magnefite	—	Magnesium bisulfite	None	45-55
		in sulfurous acid^e
Soda	—	Sodium hydroxide	None	40-50	Hardwood	chips	—	7-8
Soda-oxygen	—	Sodium hydroxide +	None	45-55	Hardwood	chips	—
		oxygen
Soda-anthraquinone	SAq	Sodium hydroxide +	None	45-55
		anthraquinone
Dissolving
Prehydrolysis kraft	—	Steaming and kraft	None	35
		(two-step process)
Acid sulfite	—	Acid sulfite (Ca, Na)	None	35

^{Source: Smook (1986), Young et al. (1989)

*}Very "rough" ranking based on full range of pulp strengths