Exp 2 Flashcards
What is the aim of the screen effectiveness study?
To find the effectiveness of given screen
What apparatus is used in the screen effectiveness study?
Sieve shaker, sieve set, balance
What are the two classes of separations in chemical industries?
- Diffusional operations
- Mechanical separations
What do diffusional operations involve?
Transfer of materials between phases
What do mechanical separations involve?
Separation of solid particles from gases or liquids or separation of one type of solids from a mixture of particles
What are the methods used for separations?
- Use of screens / porous membrane
- Differences in sedimentation rates
- Electrical / magnetic properties of substances
What is screening?
A method of separating particles according to size alone
What happens to materials passed through series of screens of different sizes?
They are separated into sized fractions
How are solids processed in industrial screening?
Dropped on or thrown against a screening surface
What do the undersize or fines do in screening?
Pass through the screen openings
What do the oversize or tails do in screening?
Do not pass through the screen openings
What is the outcome of a single screen separation?
Two fractions are produced
What are unseized fractions?
Fractions where the upper or lower limit of the particle sizes is known, but the other limit is unknown
What materials are industrial screens made of?
- Woven wire
- Silk
- Plastic cloth
- Metal bars
What is the range of mesh sizes for standard screens?
4 in to 400 mesh
