The Mikro-ACM® air-classifier mill is a high-speed impact mill that offers grinding and classifying in a single machine. The Mikro-ACM® air-classifier mill combines the features of ultrafine grinding and internal classifying and is available in a range of sizes from 3 / 450 kW. Soft to medium hard products up to a hardness of 4 Mohs,e.g. powder coatings, resins, chemicals, food, pharmaceuticals, wax, coal, lime, etc. can be grinded to D97 = 10 /m and steep particle size distributions can be achieved. Induced airflow through the grinding chamber in conjunction with an internal dynamic classifier wheel provides superior particle size control. The closed circuit grinding principal with distinct grinding and classifying zones offers unsurpassed stability even under full load conditions. The co-axial arrangement of the classifier and rotor disc drive shafts produces a compact mill profile. The grinding chamber and the drive motors are mounted on a rigid steel baseframe while the pulleys and drive belts are concealed within the baseframe. The Mikro-ACM® air-classifier mill is ideal for use with powder coatings, resins, food and pharmaceutical operations. The Mikro-ACM® air-classifier mill incorporates explosion protection up to 11 bar, low noise and an outstanding accessibility. The Mikro-ACM® air-classifier mill is suitable for a wide range of high performance milling operations where an ultrafine material with steep particle size distribution is required.

Design Features:

• Grinding and classifying in a single machine

• Cool and smooth grinding

• Steep particle size distribution

• Sharp classifier cut point that is instantly adjustable

• Easy cleaning and maintenance

• Low specific energy requirements

• Compact design

The Mikro-ACM 150 air-classifier mill, pictured above, can achieve <75m with a throughput of 4.5 t/h when grinding cacao. The Mikro-ACM 150 air-classifier mill is ideal for use in powder coating, chemical and food operations.

The Mikro-ACM® SB Air Classifying Mill offers many advantages including a split body design that allows for the mill housing to swing open giving total unhindered access to all internals.  This reduces the downtime when thorough cleaning is required between products.  The addition of an air purge on the high efficiency classifier enables the Mikro-ACM® SB Air Classifying Mill to produce ultra fine product with steep particle size distributions.  This is especially important where top size control is critical.  Air purging is utilized on the heavy duty bearing assembly to prevent infiltration of ground product that ensures low maintenance and high reliability.  The liners are made of wear-resistant Ni-Hard and are reversible to provide maximum life.  Replacement is accomplished without the need for tools. 

A standard feature of the Mikro-ACM® SB Air Classifying Mill is its design for pressure shock resistance to 11 bar.  This provides additional safety when handling materials which are classified as being potentially explosive.  This construction also ensures low noise levels.  The Mikro-ACM® SB Air Classifying Mill is available in a variety of sizes from 10-75 HP.

The Mikro-ACM® air classifying mill carbon black design was developed for the reduction of grit in products such as carbon black, clays, and various mineral fillers.  Mills for this application must be designed so that there is positive engagement of the process material to the grinding zone for effective size reduction.  In addition, the conventional impact grinding elements are not particularly suited to have much of an effect on low-density intrinsically fine materials.   

A special "fan blade" rotor assembly that creates a high vortex grinding zone was developed.  Particles are reduced in size by means of particle to particle attrition (autogenous grinding).  In the final effort to achieve the best particle presentation, the feed is introduced below the rotor insuring that 100% of the feed is introduced to the grinding mechanism.  The end result is a significant reduction in grit below 45 microns, compared to existing technologies used for the same application.

The Mikro-ACM® Model 2 System successfully integrates the unit operations of size reduction, air classification, and air conveying to achieve a synergistic use of process energy.  Size reduction is accomplished by mechanical impact of material particles against rotating machine components, fixed liners, and other particles.  Classifying into coarse and fine fractions is accomplished by exposing particles to the differential action of the air flow and centrifugal force in a dynamic air classifier at the top of the milling chamber.  Fineness can be adjusted by changing the classifier speed.

Product flows through the system as follows; feed material enters through an airlock and is entrained in air.  The feed mixture then flows into the mill.  Oversized particles are rejected for further grinding action, while fine particles pass into the integral air classifier.  The fine fraction passes into a cyclone or fine filter for collection.

The Mikro-ACM® air classifying mill with its co-axial drive arrangement features a very compact profile.  As a standard, all mill sizes from 10 to 75 hp are supplied with cast iron bodies and wear resistant components.  Both drive motors are mounted on a common structure; drives are concealed underneath the structure with noise abatement.  In combination with closed circuit pneumatic feeding, noise levels are reduced to below 85 dba*.  For applications which require stainless steel construction, the internal material contact surfaces can be supplied in 304 or 316 stainless steel. 

All mills supplied in cast iron construction are rated for pressure shock resistance to 150 psi.  The Mikro-ACM® air classifying mill 100-600 series features fabricated construction, which is also available in high-pressure design.