1. Which of the following was the first alkaline process to be developed?
a) Soda process
b) Sulphate process
c) Sulphite process
d) Kraft process
Discussion
Explanation: Soda process was the first alkaline process to be developed. It was invented by Englishmen Hugh Burgess and Charles Watt in 1851 and was patented in 1854. The first successful soda mill commenced operation in 1866.
2. The soda process consisted of boiling wood _____ in sodium hydroxide liquor.
a) 1%–2%
b) 3%–5%
c) 2%–3%
d) 4%–6%
Discussion
Explanation: The soda process consisted of boiling wood in 4%–6% sodium hydroxide liquor at a high temperature (170°C). This process is now obsolete. Less than 2% of the pulp produced today uses this process which is very similar to the sulfate process, except that only sodium hydroxide is used. Essentially all former soda mills have converted to the sulfate process.
3. Kraft Process was developed in the year _____
a) 1750
b) 1850
c) 1879
d) 1995
Discussion
Explanation: In 1879, German chemist Carl F. Dahl developed the Kraft (sulfate) method of pulping wood. The process was essentially a modification of the soda process, but instead of sodium hydroxide, sodium sulfate was the major chemical used as the cooking liquor.
4. ‘Dissolving pulp” is obtained by which of the following methods?
a) Semichemical process
b) Sulphite process
c) Kraft process
d) Soda process
Discussion
Explanation: ‘Dissolving pulp” is obtained by sulphite process. It is a special grade of bleached sulfite pulp and is used for a variety of cellulose derivatives including RCF and cellulose acetate.
5. Which of the following methods is mostly used for making glassine?
a) Soda process
b) Kraft process
c) Semichemical process
d) Sulphite process
Discussion
Explanation: Sulphite process is mostly used for making glassine. It is also used as a source of cellulose for non-paper applications. It is because sulfite pulps have higher brightness, higher yields at a given kappa, lower odor and lower investment costs as compared to kraft pulps.
6. Several pulping processes are based on the use of sulfur dioxide as the essential component of the pulping liquor.
a) True
b) False
Discussion
Explanation: The given statement is true. Several pulping processes are based on the use of sulfur dioxide as the essential component of the pulping liquor. Sulfur dioxide dissolves in water to form sulfurous acid, and a part of the acid is neutralized by a base during preparation of the pulping liquor. The various sulfite processes differ in the kind of base used and in the amount of base added. These differences govern the resulting acidity or pH of the liquor. These processes depend on the ability of sulfite solutions to render lignin partially soluble.
7. Semichemical method of pulping involves mechanical pulping followed by chemical pulping.
a) True
b) False
Discussion
Explanation: The given statement is false. Semichemical pulping combines chemical and mechanical methods in which wood chips are partially softened or digested with conventional chemicals, such as sodium hydroxide, sodium carbonate or sodium sulfate, after which the remainder of the pulping action is supplied mechanically, most often in disk refiners.
8. The _______ uses sodium sulfite and a small amount of sodium hydroxide or sodium carbonate to give slightly alkaline liquor.
a) Basic-sulfite semichemical (NSSC) process
b) Acidic-sulfite semichemical (NSSC) process
c) Neutral-sulfite semichemical (NSSC) process
d) Alkaline-sulfite semichemical (NSSC) process
Discussion
Explanation: The neutral-sulfite semichemical (NSSC) process (applied mainly to hardwood chips) uses sodium sulfite and a small amount of sodium hydroxide or sodium carbonate to give slightly alkaline liquor. The NSSC pulp is obtained in higher yield but with higher lignin content than in the other sulfite processes. It is used mainly for the manufacture of corrugating medium.
9. ______ is the process after pulping.
a) Rolling
b) Bleaching
c) Digestion
d) Sheeting
Discussion
Explanation: Digestion is the process after pulping. The digestion process essentially consists of treating wood in chip form in a pressurized vessel under controlled conditions of time, liquor concentration and pressure/temperature.
10. Which of the following is the primary function of digestion?
a) To separate the fibers
b) To produce a well cooked pulp
c) To bleach the pulp
d) To increase the strength of the pulp
Discussion
Explanation: The primary function of digestion is to produce a well cooked pulp, free from the non-cellulosic portions of the wood (i.e., lignin and to a certain extent hemicelluloses). It’s other functions are- to achieve a maximum yield of raw material (i.e., pulp from wood) commensurate with pulp quality and to ensure a constant supply of pulp of the correct quality.