AdvancedTopic 79 of 100Materials & Chemical
Crystallisation and drying
Form solids from solution and remove moisture.
In depth
Crystallisation forms solid crystals from solution via supersaturation, nucleation and growth, controlling size and purity (cooling, evaporative, anti-solvent). Drying removes moisture by heat and mass transfer (tray, spray, fluid bed, freeze). Psychrometry and drying curves (constant and falling rate) guide design.
Key points
- Metastable zone width
- Crystal size distribution
- Moisture content
ExampleSpray drying produces milk powder.
What is Crystallisation and drying?
Form solids from solution and remove moisture.
Why is it important to understand crystallisation and drying?
Crystallisation and drying turn solutions into solid products and remove moisture, which controls product purity and shelf life.
What drives crystallisation?
Supersaturation, which can be created by cooling, evaporation or adding an antisolvent, and it sets how crystals nucleate and grow.
What controls crystal size?
Cooling rate, agitation and seeding, which together set the balance between nucleation and growth.
How is Crystallisation and drying used in practice?
Typical applications include producing sugar crystals from a concentrated syrup, drying a food powder to a safe moisture level and crystallising a pharmaceutical to control its form and purity.
What should I learn before Crystallisation and drying?
Study "Filtration and sedimentation" first (topic 78 of 100 in Materials & Chemical). It covers the groundwork this topic builds on.
What are the key points of Crystallisation and drying?
Metastable zone width. Crystal size distribution. Moisture content.
Can you give an example of Crystallisation and drying?
Spray drying produces milk powder.
What comes after Crystallisation and drying?
The next topic is "Reaction kinetics", which builds directly on this one.
How difficult is Crystallisation and drying?
It is classed as Advanced in Materials & Chemical (topic 79 of 100). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Materials & Chemical.