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Chemical Engineering - Mechanical Operations

Exercise : Mechanical Operations - Section 1
11.
Pebble mills are tumbling mills widely used for grinding in the manufacture of paints & pigments and cosmetic industries, where iron contamination in the product is highly objectionable. Pebbles used in pebble mill are made of
bronze
stainless steel
flint or porcelain
concrete
Answer: Option
Explanation:
No answer description is available. Let's discuss.
12.
Filter aids like asbestos, kieselguhr, diatomaceous earth etc. are used to increase the porosity of the final filter cake & reducing the cake resistance during filtration. Filter aid is
added to the feed slurry.
precoated on the filter medium prior to filtration.
separated from the cake by dissolving solids or by burning it off.
all 'a', 'b'&'c'.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
13.
Which of the following relationships between co-efficinet of friction (μ) between rock & roll and a (half of the angle of nip) of the particle to be crushed is correct ?
μ > tan α
μ ≥ tan α
μ > tan 2α
μ ≤ tan α
Answer: Option
Explanation:
No answer description is available. Let's discuss.
14.
Pick out the wrong statement pertaining to the roll crushers.
Maximum feed size determines the required roll diameter.
For hard material's crushing, the reduction ratio should not exceed 4.
Both the rolls run necessarily at the same speed.
Reduction ratio and differential roll speed affect production rate & energy consumed per unit of surface produced.
Answer: Option
Explanation:
No answer description is available. Let's discuss.
15.
Which of the following is not an ultrafine grinder (colloid mill)?
Micronizers
Agitated mills and fluid energy mills
Toothed roll crusher
Hammer mills with internal classification
Answer: Option
Explanation:
No answer description is available. Let's discuss.
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