Pharmaceutical Technology Pt 606: Size Reduction Lecture Quiz

What is the recommended moisture content for materials to be ground dry?

 50%
 20%
 10%
 5% (correct)

Why are enclosed mills necessary for certain substances?

To reduce dust and protect operators (correct)
To reduce machine maintenance
To increase grinding efficiency
To increase product size

What is the primary reason for carrying out size reduction in multiple stages?

To achieve a fine product size (correct)
To reduce machine maintenance
To reduce dust formation
To increase grinding efficiency

Which method of size reduction involves the application of pressure?

Compression (D) Signup and view all the answers

What is the primary mechanism of the attrition method of size reduction?

Shear forces (B) Signup and view all the answers

What is the primary characteristic of materials that require enclosed mills?

High potency (B) Signup and view all the answers

What is the main purpose of incorporating a classifier in the system of a mill?

To retain particles until they are sufficiently fine (D) Signup and view all the answers

What is the benefit of using inert gases in certain cases of milling?

To protect sensitive materials from contamination (B) Signup and view all the answers

What is the result of the high degree of turbulence in the milling process?

Reduction of particle size through inter-particulate attrition (D) Signup and view all the answers

What is the typical particle size of the product produced by this method of milling?

5 um or less (C) Signup and view all the answers

What is the purpose of the motor-driven rollers in a ball mill?

To rotate the shell on its horizontal longitudinal axis (A) Signup and view all the answers

What is a key advantage of this method of milling compared to others?

The ability to produce particles with a smaller size than other methods (A) Signup and view all the answers

What occurs when the ball mill is operated at low speeds?

The mass of balls will slide or roll over each other (D) Signup and view all the answers

What is the purpose of pre-treating the feed to the mill?

To reduce the particle size to the order of 100 mesh (D) Signup and view all the answers

What is a characteristic of the ball mill that makes it suitable for use with toxic materials?

Its enclosed form (A) Signup and view all the answers

What is the primary mechanism of size reduction in a ball mill?

Impact of the particles between the balls (B) Signup and view all the answers

At what speed is the maximum size reduction achieved in a ball mill?

At about two-thirds of the speed at which centrifugation just occurs (B) Signup and view all the answers

What is a feature of the ball mill designed for batch milling?

A removable end plate or side entrance hatch cover (A) Signup and view all the answers

What is a major advantage of conical screening mills over oscillating granulators?

Reduced chance of screen breakage and metal contamination (A) Signup and view all the answers

What determines the size of the output in a conical screening mill?

The space between the rolls (C) Signup and view all the answers

Why is the conical screening mill effective for milling heat-sensitive materials?

It generates low heat (D) Signup and view all the answers

What is a disadvantage of oscillating granulators?

Wear on the screens (A) Signup and view all the answers

What is a characteristic of conical screening mills that makes them more desirable?

Their dual action of size reduction and mixing (C) Signup and view all the answers

What is the main purpose of size reduction in pharmaceutical technology?

To reduce larger size solid unit masses to smaller sizes (D) Signup and view all the answers

What is the general trend of the cost of size reduction as particle size decreases?

It increases (D) Signup and view all the answers

Which process requires the material to be crushed to expose cells for extraction?

None of the above (D) Signup and view all the answers

What does the Moh’s scale of hardness range between?

5 and 10 (A) Signup and view all the answers

Why might a soft but tough material present more problems in size reduction than a hard but brittle substance?

Because it has a higher moisture content (C) Signup and view all the answers

Which material cannot be marked with a good penknife blade according to the text?

Rubber (C) Signup and view all the answers

Which comparison does the text make to illustrate the difference between tough and brittle materials?

Blackboard chalk and rubber (D) Signup and view all the answers