Pulp & Paper Questions and Answers – Retention, Formation and Drainage

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This set of Pulp and Paper Multiple Choice Questions and Answers (MCQs) focuses on “Retention, Formation and Drainage”.

1. _________ occurs by direct mechanical trapping of relatively large particles or by colloidal interactions that result in the flocculation of fines with large.
a) Formation
b) Drainage
c) Retention
d) Flocculation
View Answer

Answer: c
Explanation: It is added to bind fillers to the paper. Fillers, such as CaCO3, usually have a weak surface charge. The agent to retain is a polymer with high cationic, positively charged groups.
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2. Overall retention should be _________ to keep the process economical. As long as excess white H2O is minimal and excess white H2O is treated to remove solid materials.
a) 10-20%
b) 90-95%
c) 25-35%
d) 45-50%
View Answer

Answer: b
Explanation: An additional feature of a retention agent is to acc. the de-watering in the wire section of the paper machine. Polyethyleneimine and polyacrylamide are examples of chemicals utilized in this process.

3. First—pass (or one pass) retention is often separated into various sub-categories of total solids including fibre retention, fines retention, and ash (i.e., filler) retention.
a) True
b) False
View Answer

Answer: a
Explanation: It’s the natural or artificial removal of surface and sub-surface H2O from an area. The internal drainage of most agricultural soils is utilized to prevent severe H2O logging.

4. What is the hidden part?

_________% = (cHB – cWW) / cHB X 100%

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a) First pass measurement
b) First pass retention measurement
c) Colloidal retention
d) Synthetic polymer retention aids
View Answer

Answer: b
Explanation: First—pass retention (Ret. F.P.) can be approximated by the relative change in solids content from the headbox (H.B.) stock to the white water (W.W.) tray divided by the initial solids content of the headbox. This is done by measuring the consistencies (c) at the headbox and in the white H2O. This could be done for total solids or fractionated samples.

5. _________ of the fines fraction is of central importance, the Britt jar is a useful tool because it measures retention through a screen with 76 film holes without formation of a mat.
a) Formation
b) Drainage
c) Retention
d) Flocculation
View Answer

Answer: c
Explanation: The Britt jar or dynamic drainage retention jar is a useful tool because it measures retention through a screen; it measures colloidal interactions without interference from filtration mechanisms.

6. _________ will withstand a moderately high level of shear and remain intact during the sheet forming process.
a) Hard floes
b) Soft floes
c) Drainage
d) Formation
View Answer

Answer: a
Explanation: A strain in the structure of a substance produced by pressure, when its layers are laterally shifted in relation with each other. There is a continuum of floe strengths.

7. Soft floes may decrease opacity and the quality of formation in the final sheet.
a) True
b) False
View Answer

Answer: b
Explanation: Hard floes may decrease opacity and the quality of formation in the final sheet. Opacity is decrease by aggregation of mineral fines in large clumps, meaning that light travels through fewer interfaces and is not scattered as much.
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8. _________ is a function of fiber length, retention aids employed, and turbulence and is controlled by the size of the floes.
a) Formation
b) Drainage
c) Retention
d) Flocculation
View Answer

Answer: a
Explanation: Microflocs are floes with a size on the order of 100 µm; macroflocs are floes that are visible to the naked eye. Formation is a function of fiber length, retention aids employed, and turbulence and is controlled by the size of the floes.

9. What’s the name of the equation?

U= (1) / (ŋR) (dp) / (dw)

a) Kozeny-Carman eq
b) D’Arcy eq
c) CSF eq
d) Sizing eq
View Answer

Answer: b
Explanation: H2O removal by filtration results in the layered nature of paper. The D’Arcy eq. models flow through a porous media.
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10. What is the name of the equation?
R = kS2 ((1 – E)V) / (E3)
a) Kozeny-Carman eq
b) D’Arcy eq
c) CSF eq
d) Sizing eq
View Answer

Answer: a
Explanation: Filtration of paper webs has been developed by Campbell in 1947 and Ingmanson in 1954, 1959, 1963 and are based on treatment of the Kozeny—Carman in 1937 equation, which gives R as follows where A: is a constant based on the mat composition, S is the specific surface area of the solids / unit volume, E is the mat porosity, and V is the volume fraction of the web occupied by solids.

Sanfoundry Global Education & Learning Series – Pulp and Paper.
To practice all areas of Pulp and Paper, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn