What type of milling operation can be performed in a ball mill?
Anonymous Quiz
10%
a) Wet milling only
7%
b) Dry milling only
80%
c) Both wet and dry milling
4%
d) Neither wet nor dry milling
What is an advantage of using ball mills for unstable or explosive materials?
Anonymous Quiz
62%
a) They can be sealed within an inert atmosphere
17%
b) They can be sterilized and sealed for sterile milling
13%
c) They have low installation, operation, and labor costs
8%
d) They are efficient for fine grinding of hard and abrasive materials
In a fluid-energy mill, what is the primary force responsible for particle size reduction?
Anonymous Quiz
7%
a) Impact
14%
b) Compression
77%
c) Attrition
2%
d) Cutting
Why is air commonly used as the fluid in fluid-energy mills for pharmaceuticals?
Anonymous Quiz
3%
a) It is less expensive than other fluids
4%
b) It has a lower viscosity than other fluids
90%
c) Most pharmaceuticals have a low melting point or are thermolabile
2%
d) It is more efficient for size reduction than other fluids
What is a crucial factor to consider when selecting fluid-energy mills for production?
Anonymous Quiz
5%
a) The speed of rotation
42%
b) The number and angle of the nozzles
46%
c) The cost of a fluid-energy source and dust collection equipment
7%
d) The grinding chamber geometry
What is a primary advantage of fluid-energy mills?
Anonymous Quiz
13%
a) Low capital and running costs
71%
b) Quick production of powders with all particles below a few micrometers
10%
c) Low potential for build-up of compressed product in the mil
5%
d) No need for dust collection equipment
What is a disadvantage of fluid-energy mills in terms of cost?
Anonymous Quiz
10%
a) Low capital and running costs
58%
b) High capital and running costs
25%
c) High installation costs but low running costs
7%
d) Low installation costs but high running costs
What is a drawback of fluid-energy mills related to milled particle size?
Anonymous Quiz
73%
a) The potential for build-up of compressed product in the mill
15%
b) The inability to produce particles smaller than a few micrometers
4%
c) The inefficiency in grinding hard and abrasive materials
7%
d) The high cost of dust collection equipmen
Which type of material cannot be crushed by pressure or impact and must be cut instead?
Anonymous Quiz
86%
a) Fibrous materials
7%
b) Friable materials
7%
c) Moist materials
0%
d) Solid materials
At what percentage of water content does comminution become hindered during milling?
Anonymous Quiz
78%
a) 5%
6%
b) 10%
2%
c) 25%
13%
d) 50%
What effect does an increase in moisture content have on the rate of milling to a specified
product size?
product size?
Anonymous Quiz
11%
a) Increases the rate
78%
b) Decreases the rate
1%
c) No effect on the rate
9%
d) Rate varies depending on the material
Which type of mill is better suited for producing free-flowing spheroidal particles?
Anonymous Quiz
4%
a) Impact mil
63%
b) Attrition mill
7%
c) Compression mill
26%
d) Ball mill
In which type of milling can a metastable form of material be produced?
Anonymous Quiz
63%
a) Wet milling
17%
b) Dry milling
12%
c) Attrition milling
8%
d) Impact milling
What type of atmosphere should be used for milling thermolabile, easily oxidizable, and
combustible materials?
combustible materials?
Anonymous Quiz
3%
a) Normal air
15%
b) Dehumidified air
79%
c) Inert atmosphere of carbon dioxide or nitrogen
3%
d) High-pressure atmosphere
Why might a cooling jacket or heat exchanger be necessary during milling?
Anonymous Quiz
3%
a) To reduce energy consumption
93%
b) To prevent heat-related changes in the material and avoid stalling of the mill
3%
c) To increase milling efficiency
1%
d) To maintain a specific particle size
What factor is crucial for a mill to operate satisfactorily?
Anonymous Quiz
72%
a) The feed should be of the proper size and enter at a fairly uniform rate
6%
b) The mill should have a high-energy output
9%
c) The mill should have a wide range of speed settings
13%
d) The mill should be able to change between wet and dry milling
When is wet grinding recommended?
Anonymous Quiz
28%
a) If the product undergoes physical or chemical change in water
54%
b) If the product requires further size reduction and flocculation is not an issue
11%
c) If the product is sensitive to heat
6%
d) If the product is required to have a specific particle shape
What is a key factor to consider when selecting a mill for pharmaceutical applications?
Anonymous Quiz
17%
a) The product's resistance to size reduction
17%
b) The mill's versatility of operation
58%
c) Dust control to prevent loss of costly drugs and contamination
8%
d) The mill's ability to process a wide range of materials