Crystallization tank from GEA Niro
Crystallization tank from GEA Niro

What is a crystallization tank?
A crystallization tank is a double-jacketed tank where ice-water is circulated in the jacket. Thereby, the concentrate is gradually cooled in order to maintain a super-saturated solution to get as rich a crystallization as possible.

What does GEA Niro offer?
In the Food & Dairy industry, crystallization tanks are used for the production of whey, permeate powders, and lactose. Crystallization of lactose takes place in super-saturated solutions in crystallization tanks.

The crystallization process

The crystallization tank is equipped with a powerful agitator designed to keep all the content in the tank in suspension to avoid lactose crystals from settling at the bottom of the tank. The crystallization time of whey and permeate concentrate for powder production depends on the solids content of the concentrate - the higher solids content the shorter time. When the concentrate leaves the evaporator at approx. 60 % solids it is flash-cooled to 30 °C before pumped to the crystallization tank where further cooling is done.

Typically, 80 % of the lactose is crystallized after 14-16 hours. For practical purposes, the necessary tank volume is calculated as follows (based on 3 tanks – one being filled up, one crystallizing and one being emptied.

Volume of each tank= L raw whey permeate per day x %TS 
                                            %TS in the concentrate x 3

Whey products
Whey products
As CIP time and maintenance has to be foreseen, an extra tank is installed. 

For the production of lactose powder, it is important that the crystals are big, therefore the crystallization starts at 50-60 °C in the crystallization tank where the concentrate is cooled slowly to 15-20 °C. Tank volume for 48 hours' production is recommended.