Within the metallurgical and hydrometallurgical industries, GEA Messo AG
evaporation and crystallization systems are a decisive process unit in solution
mining production, by-product recovery and internal process water management.
GEA Messo AG offers complete solutions for recovery of products and /
or by-products for example in alumina refinery, nickel sulphate production,
processing of aluminium salt slags.
GEA Messo AG has supplied worldwide
more than 30 plants for various industries with application of the following
evaporation and crystallization technologies:
- Multiple effect
- Multiple stage flash
- Thermal and mechanical vapour recompression
- Evaporative crystallization
- Vacuum cooling crystallization
Typical application of metallurgical and hydrometallurgical industries as
example.
Evaporation Process in Alumina
Refinery
In an alumina refinery the spent liquor
from the precipitation stage has to be pre-concentrated before it can be
recycled to the bauxite digestion. Different evaporative techniques are
utilized for this concentration, whereby each system has its own advantages as
well as limitations.
Today the choice is mainly between multiple stage
flash or falling film evaporator systems. Rising film evaporators, which found
acceptance in the past, have been essentially discontinued due to lack of their
operating flexibility, whilst forced circulation evaporators are only used when
salts precipitate during the concentration process.
The choice between
multiple stage flash multiple effect falling film or forced circulation
evaporation system depends basically upon the concentration factor and
solubility behaviour of the liquor in addition to the overall refinery process
and the specific requirements of each site.