How to Separate Cream From Milk?

Milk consists mainly of water, protein, fat, lactose and minerals (inorganic salts) and trace amounts of other substances (such as phospholipids, vitamins, enzymes, pigments, and gases, white blood cells, etc.).

Milk fat is one of the most important components of cow's milk. Fat is high in calories and is a carrier and transmitter of vitamins A, D, E and K. In the figure below we can see the general form of fat in milk.

If milk is left to stand for a while in a vessel, due to the density difference, the fat will rise and form a layer of cream on the surface.

However, it is impractical for industry to skim milk only by static sedimentation, which is both time consuming and prone to spoilage. The most common method of milk skimming nowadays is centrifugal separation, which is the use of strong mechanical force to accelerate the process of fat separation in milk.

The above diagram shows the internal diagram of the disc stack centrifuge. Milk enters from the bottom feed tube, during the rotation of the centrifuge, the heavier solid impurities will settle on the bowl wall and then be discharged through the slag discharge port, the lighter liquid phase will gather in the center of the centrifuge, surrounded by the heavier liquid phase to form two concentric circles finally discharged through different discharge ports at the top.

In a disc stack centrifuge, the gap between the discs is fixed so that each time the milk passes through the discs, the solids inside cannot reach the uppermost exit between the discs due to the centrifugal force of gravity. Each time the milk passes through the gap between a two discs, some of the solids are blocked, resulting in a very pure skim milk.

Separation is an indispensable part of processing skimmed milk and centrifuges are now the most economical means of making skimmed milk. Depending on the needs of the milk, different centrifuges can be selected to achieve sterilization, fat standardization and defatting respectively.

ZK disc stack centrifuges are mainly used for the separation of solid-liquid mixtures. And it can be used for materials with a solid-liquid weight difference greater than 0.05g/cm³ (solid weight greater than liquid weight).


  1. ZK SEPARATION zkcentrifuge.com