In general, with thousands of organic compounds to chose from, melt
crystallization is especially interesting for the separation of isomers,
azeotropes and other close boiling compounds, temperature sensitive substances,
and all applications where high purity products are required.
Suspension melt crystallization is a well-known purification technique. A
single crystallization step is all that is necessary to produce 100% pure
crystals in eutectic systems.
- Product is crystallized only once
· pure crystals in a single
crystallization step
· no sweating required to remove impurities
·
low energy consumption
- Continuous operation
· minimum hold-up upstream and downstream products
· consistent product quality
Ultra-pure product can only be achieved by completely removing the pure
crystal from the impure melt. Conventional mechanical separations require
intensive washing of the filter cake with melted product to achieve even
moderate purity product. The Niro Purifier embodies patented wash column
separation technology and has been developed through 30 years of research with
over 100 units in commercial operations.
- Provides complete separation
· pure crystals + complete separation =
ultra purity
- Efficient separation
· no product recycled as wash liquid
The NIRO process has been successfully applied in the purification of a
range of organic chemicals including:
- p-xylene - alliance with UOP LLC and Stone & Webster
- m-xylene
- isocyanates including TDI 2.4/2.6 isomers and MDI 4.4
- p-dichlorobenzene
- acrylic acid
- caprolactam
- enantiomers and other compounds covered under secrecy agreement
Typical configuration for a suspension melt crystallation system.
Crude product is cooled in a scraped surface crystallizer. This produces
pure product crystals and a liquid concentrated in the impurities. This
slurry is pumped into a wash column where the solid crystals are separated and
washed to remove any remaining impurities. The pure product
crystals are melted and discharged from the system.
