Altenburger Maschinen Jäckering GmbH

Careful Grinding - Solutions for Complex Grinding Problems

Air turbulence mills such as the ULTRA-ROTOR have been operating in most branches of the size reduction industry for many years. Their principle of operation uses the extreme turbulence generated inside the mill to either simply mill the product or to simultaneously mill and dry it.

They are energy efficient, robust and low maintenance. Soft to medium hard materials can be processed by introducing them into the high velocity air stream between the stationary and rotating elements of the mill. The extreme turbulence which causes the particles to constantly change direction and impact against each other allows them to fracture along boundary lines and be micronised.

Any heat generated when the particles are so rapidly reduced is dissipated into the air stream. By introducing hot air into the system it is possible to simultaneously dry and grind which is an excellent method of handling heat sensitive or sticky materials. Explosive or very heat sensitive materials can be processed in cryogenic systems cooled with liquid nitrogen or operating within an inert atmosphere. Jäckering have many years of experience in manufacturing pressure shock resistant systems for these applications.

The operating principle of the mill is a rotor fitted with special tools and rotating at a high peripheral speed within a solid replaceable stator. The mechanical design is conservative allowing the mill to operate safely under
severe conditions and high peak loadings.

The tooling on the rotor and the design of the liner of the stator accelerate the particles to very high velocities within the air eddies ensuring high energy impact between the particles and excellent heat transfer between the air stream and the product.

Material enters the mill at the base of the rotor and on leaving the grinding zone it enters a sifting section where the oversized particles are returned to the bottom of the grinding zone.

As the micronising effect is achieved from particle to particle attrition the wear on the mill components is minimised. For very difficult products the rotor tooling and the stator liner can be supplied in special materials.

Mahltrocknung und gleichzeitiges Coatieren

Single Operation Drying and Grinding

Simultaneous drying and grinding can be achieved by simply using heated air in place of ambient air. This allows a wide
range of wet products to be dried and ground without agglomeration. Particle sizes down to 5 micron and moistures as
low as 0.5% have been achieved with products such as Filter cakes, Slurries, Vegetable Protein (soya, wheat, milk),
Modified Cellulose.

The thermal efficiency of these systems approaches 100 %. Approximately 1kWh of thermal energy per kilogram of water evaporated is required. Coating the powder with less than 1% additive can be done by simply spraying
it into the air stream. Residence times in the drier are a fraction of a second and this allows heat sensitive products
to be safely processed.

The Micronising Process

For micronising the material is fed into the lower section of the mill adjacent to the air intake. The finished product is collected in a hopper/cyclone, a fan on the exhaust provides the driving mechanism for the operation.

Selective grinding of compound or mixed materials is an interesting application for the ULTRA-ROTOR. For example
a high degree of separation can be achieved from a compound of aluminium and plastics.

ULTRA ROTOR

ULTRA-ROTORs are air turbulence mills that use the extreme turbulence generated inside the mill to either simply grind the product or simultaneously grind and dry it.

The product is fed in the mill at the base of the rotor which rotates at high peripheral speed within a solid replaceable stator. The material is accelerated to very high velocities and air eddies ensure high energy impact between the air stream and the product. As the micronizing effect is achieved from particle attrition the wear on the components of the mill is minimized. By introducing hot air into the system it is possible to simultaneously grind and dry which is an excellent method of handling heat sensitive or sticky materials. The mechanical design is conservative allowing the mills to operate safely under severe conditions and high peak loadings.

Every mill is purpose-built for the special requirements of our customers and more than 50 years of experience make us a reliable partner.