There are several interesting upcoming crystallization conferences and meetings. Continue reading
This is the sixth blog post in a special series dedicated to crystallization. In case you missed the previous posts in the series, they are available here:
- Introduction to Crystallization and Precipitation
- Common Ways to Reduce Solubility and Drive Crystallization
- Supersaturation: Driving Force For Crystal Nucleation & Growth
- Importance of Crystal Size and Shape Distribution
- Impact of Process Parameters on Supersaturation and Crystal Size and Shape
Previously, we looked at a case study that neatly illustrated the concept that slow supersaturation generation often results in a growth dominated process that is typically repeatable. As a rule of thumb, slow cooling works great – but its main drawback is the extended cycle times that often result. To overcome this problem, a common technique often used is non-linear cooling.
If we dive a little bit deeper into the governing equations of crystal growth and nucleation.. Continue reading
This is the third blog post in a series dedicated to crystallization. In case you missed the first and second in the series, they are available here: Introduction to Crystallization and Precipitation and Common Ways to Reduce Solubility and Drive Crystallization.
Supersaturation is the driving force for all solution crystallization processes. Crystallization scientists gain control over crystallization process and product quality by carefully controlling the prevailing level of supersaturation during the process. Continue reading
A question was posted regarding crystallization monitoring and control:
“If you had to choose between supersaturation control or FBRM crystal size control on an industrial scale, which would you choose?”
Supersaturation monitoring and control only makes sense if you have a very reliable model of the system (i.e. where you can predict nucleation and growth as a function of supersaturation), stable reactor control, and a precise supersaturation measurement.
In R&D this is certainly achievable, and there are good examples of supersaturation control including this on-demand webinar, by Dr. Mark Barrett, describing calibration-free supersaturation control.
However, in an industrial crystallizer, your supersaturation-based control would likely be based on limiting the level of supersaturation to avoid conditions that would produce high levels of spontaneous or secondary nucleation.
And that’s not really control, just avoidance.