The Mikro Bantam® Hammer and Screen Mill is part of the original Mikro Pulverizer® Hammer & Screen Mill product line that was introduced in 1923. Today, with over 4,000 installations, these mills are the standard throughout the world for processing powder coatings, propellants, foods, pharmaceuticals, chemicals, pigments, industrial minerals and plastics.
With Alpine High Pressure Roller Mill products are produced with a precipitous granule distribution. The high pressure roller crusher is also called roller crusher or roller press.
The significant difference of high pressure roller grinding compared with compaction is that the press forces between the rollers are lower because no new adhesive forces need to be created.
The mill feed is transported to the most narrow gap by the counter rotating rollers through friction effects. Both rollers are pressed against each other using hydraulics. This milling force is transferred to the mill feed. Through selective contact of the individual granules are created at extremely high inner tensions which lead to fractures.
The use of the optimal milling force leads to compact mills with extremely low energy requirements. Because only the outer particles of the material bed have contact with the surface of the rollers, milling that is almost contamination-free is possible.
High Pressure Roller Mills are used in the cases of medium-fine crushing of hard materials such as ceramics, minerals from 5 up to 9 on the Moh's hardness scale, metals and metal alloys. High Pressure Roller Mills are used in continuous operation or in a closed circuit with screening machines or classifiers.
The grinding air is injected tangentially via Laval nozzles in the nozzle ring into the machine. This causes a spiral jet of air to form in the grinding zone, from which the mill derives its name. A high pressure forms in the mill as a result of the spiral flow of air that can rise to 1 bar overpressure in operation without product. The integrated injector is charged with compressed air which ensures that the product is conveyed into the machine against the overpressure present in the machine. This, however, is associated with a considerable compressed air consumption, which can be as much as 30% of the total grinding air requirement.
The feed product circulates close to the nozzle ring and is thus intercepted repeatedly by the air jets exiting the nozzles. Comminution is the result of inter-particle collision caused by the particles flowing at different speeds in the nozzle jet. Comminuted material is conveyed along with the air to the discharge, the spiral flow subjects the particles to a classification: only fine particles are discharged, coarse particles remain in the mill.
Alpine® AS Spiral Jet Mills are characterized by a special geometry of the mill housing in the area of the discharge, which contributes towards a finer classification effect and a sharp top cut.
The product also has an effect on the air flow within the machine: the more product there is in the machine, the more the spiral flow is braked and the lower is the centrifugal force and the coarser the end product. The relationship of the product to the classifying air flow rate is therefore the most significant parameter for setting the fineness of the spiral jet mill. In principle, different nozzle angles can also be used to achieve the required fineness values, whereby the complete nozzle ring must be exchanged in this case.
As requirements in the pharmaceutical industry continue to ask for tighter particle distributions, additional steps such as on-line classification may be required. The Mikro® Acucut Air Classifier utilizes dual stage operating controls to ensure sharp cuts and narrow band particle size distributions typically below the 10 micron range. This permits control of maximum and minimum particle size diameters with unparalleled accuracy. With precise control of the air flow and rotor speeds this unit will produce the same sharp cuts each time, every time. The high energy dispersion also ensures that the maximum percentage of fines is reclaimed. Easily operated, cleaned and maintained, the Mikro® Acucut Air Classifierr keeps downtime to a minimum.
Options are available for effective control of product contamination, protection against corrosion, handling abrasive materials and classifying adhesive powders. The Mikro® Acucut Air Classifier is ideal for chromatography materials, alumina, silica, toner and metal powders. Extremely high dispersive energy applied to the process material ensures unparalleled yields even with sticky and difficult to disperse products.
The Mikro® Acucut Air Classifier is a forced vortex unit designed to disperse, then classify fine particles into coarse and fine fractions. High energy dispersing air enters the rotor radially around the entire outer edge. Feed material enters this dispersion air zone through an inlet in the rotor ring. Particles are acted upon by centrifugal and drag forces. Air carries the dispersed fines inward to the central fractions outlet, coarse move outward to the rotor periphery. Cut points are adjusted by airflow, rotor speed or both.
The wet material is fed through customized feeding systems into the grinding and drying section of the dryer's main body. The grinding rotor disperses the wet material into very fine particles and the fine particles are fluidized in the grinding chamber by temperature-controlled, hot gas coming in from the air heater.
The hot air (or inert gas) can be heated up to 650 °C and as the wet product is dispersed, it is reduced in size in the bottom section of the dryer. The system is kept under a negative pressure by the exhaust fan and the surface area of the product is increased enormously so that water (or other solvents) is evaporated instantaneously.
The dry and fine particles are conveyed with the gas stream to the top section of the dryer where a separator classifies the particles by size. Then the particles pass the classifier at the set cut point and are conveyed with the exhaust air to a powder air separating system like the cyclone, cyclone filter or cyclone scrubbers.
The Micron Dryer flash dryer retains a fluidized bed of product in the drying chamber to ensure a low level of adhesion of wet material on the inside wall of the drying chamber. Moreover, process parameters like classifier speed and outlet temperature can be adapted to control moisture content and particle size of the end product.
Ultra fine regular end product - Due to its specially designed dispersion rotor, our flash dryers are able to produce ultra-fine powders in one step from suspensions, slurries, pastes and dough, filter cakes or wet powders.
High evaporation capacity - Due to the combination of high ?T with a good dispersion of the wet product in the air, our flash dryers can evaporate large quantities of liquids.
Compact design - Compared to other direct drying technologies, the flash dryer requires up to 50% less space.
Multi-purpose - Filter cake or slurry, in the same machine. Therefore with the Drymeister-H unlimited mechanical dewatering is possible previous to the final drying stage.
Easy access - Either for cleaning, inspection or maintenance inside the dryer, our flash dryers offers the best accessibility from the market, regardless which size.
Various systems available - Open, closed- and recycle system concepts.