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Center of expertise - Cold grinding & recycling

Cold grinding & recycling at the highest level

Kaltmahlen: Feine Pulver - große Wirkung

Only as powder many materials really get in shape and can be used efficiently. Cold grinding and recycling with N2 and CO2 can solve many problems of the crushing process.

Messer operates a highly-specialised technical center for cold grinding in Willich, Germany. Its technology features a special counterrotating peg mill and a tumble screen which allow very fine grain sizes to be achieved when grinding with liquid nitrogen – something that is not possible with conventional procedures. The extremely low temperature of the nitrogen makes it much easier to crush, say, thermoplastic materials in the mill. This also prevents agglutination.

Kryogenes Kaltmahlen und Recycling - Oliver Dietrich
Technology manager Oliver Dietrich talking with a customer

The precisely measured and evaluated results from Willich can be transferred to industrial procedures. Plus the layout of the plant is the same as that of a production plant and can therefore be used as a reference. Fine grinding of synthetic materials or natural products, such as spices, is an art which the Messer Group has mastered. Messer therefore has a technical center for cryogenic grinding in Germany that is open to customers of all the subsidiaries for the purposes of carrying out tests.

Kaltmahlanlage in Ungarn
Cryogenic grinding plant in Hungary


Cold grinding and recycling with Messer
Many materials are easier to use and much more effective in a powder form.

However, it is often the case that they cannot easily be powdered due to their physical properties. These properties include the tendency to melt, sensitivity to changes in temperature and showing tough or elastic properties. This often occurs with plastics, natural rubbers, elastomers, pharmaceuticals and spices.

Cold grinding solves these problems
The cold grinding process involves cooling and embritteling of materials with extremely cold liquid nitrogen or carbon dioxide. The process results in production of fine particles with a high level of quality. In addition, process volumes increase significantly. During the grinding process heat sensitive materials are cooled with cryogenic gases in order to protect them from increases in temperature resulting from the heat generated by the process. This means that it is impossible for the powdered material to melt or become sticky.

The Messer Group’s cold grinding and recycling lab offer the customer tailor made solutions including production cost estimates and pilot trials
We offer a highly specialised materials trial process. We are able to carry out sample cold grindings. The final working parameters, including process volumes, power and nitrogen requirements and the resulting particle size distribution are then measured, evaluated and made available to the customer.


Cryogenic grinding technology enables the separation of composite materials into their pure components
The application of cryogenic grinding allows composite materials such as fibre-reinforced thermoplastics, tin cans with product remains such as paint and lacquer adherences, galvanised plastic parts (e.g. sanitary facilities) or old tyres to be separated into their pure components. The success of the process is due to the different linear extension coefficients and embritteling abilities of the materials.

Advantages at a glance

  • Higher process volumes
  • Higher volumes of a finer product
  • Lower energy consumption
  • No melting or sticking of temperature sensitive plastics
  • Set grinding temperatures prevent heat damage
  • No loss of aromatic materials during the grinding of spices
  • Greater protection against dust explosion

Messer Groups' cryogenic equipment

Paddle Screw Cooler
In the paddle screw cooler, granulates or powders are cooled up to  -196°C by liquid nitrogen. This cooler type is normally used for cold grinding processes. Here, tough, elastic or temperature sensitive materials such as thermoplastics, elastomers, spices, pharmaceutical products or waxes can be cooled.
Coolers are available with capacities from about 50 to 3000 kg per hour. Typical gas requirement is from 0.5 to 2.0 kg/kg product.

Wirbelschneckenkühler
Paddle screw cooler WSK150, 1.1 kW


Cryogen Control Valve Unit for Liquid Nitrogen
In a cryogen control valve unit, the dosage of liquid nitrogen is regulated in accordance with a 4-20 mA signal. A control valve is mounted on a stainless steel frame, together with safety valves, manometers, a dirt trap and an evaporator coil for captive medium supply. If required, it can also be supplied with a solenoid or membrane valve as an open/close valve. The unit is also available in a stainless steel cabinet with viewing windows. The unit is normally constructed in a DN15 and a DN25 version.

Regelventileinheit DN25 im Schrank
Control valve unit DN25 in cabinet


Vacuum Insulated Pipe
A flexible pipe for nitrogen (3 to 5 m) between control unit and paddle screw cooler is also available.

Equipment
Accessories for control valve unit: Super vacuum insulated pipe for nitrogen

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