The use of the Atritor Dryer-Pulveriser and its more up to date equivalent, the Atritor Cell Mill-Dryer, for simultaneous drying and milling dates back over 80 years. The first Atritor unit designed and constructed for the drying and fine milling of coal in the 1920's, was used for direct injection into burner systems - for steam boilers, cement and lime kilns. The

original Atritors are also equipped with a basic classification system - rejecter arms - which acts as a coarse particle reject system at the outlet of the unit where particle size distribution of the product is important. The new Cell Mill-Dryer has an advanced dynamic classifier capable of cut-points down to 20 microns and the advantage of external coarse particle rejection, so that the coarse can be reintroduced into the wet feed at a considered stage.

Production of dry clay such as kaolinitic clay, bentonite and ball clay for instance is possible by the application of hot air up to 930°F (500°C), which is drawn into the high velocity impact mill to flash dry the wet material as it is pulverised. The Multirotor Cell Mill-Dryer represents Atritor's commitment to meeting the demands of customers  now  looking

for even more advanced solutions to processing powder products.

The high turbulence of the multi-stage rotor combined with split second residence times in the flash drying zone mean that the unit is also well suited for heat sensitive products such as Organo Clay and PVC. The same high turbulence and multi-stage path through the Mill-Dryer make the application of high accuracy, high homogenous coatings very successful. Coating materials can be applied as granules or liquids by direct injection into the base of the mill chamber.

Because  processors  have   been

traditionally slow to adopt new technologies, there is still a lot of work to be done to draw attention to the possible advantages of using simultaneous drying, milling and, more recently, classification, using the Multirotor Cell Mill-Dryer with integral classifier.

However, the pressure of energy saving is an increasing driving force for change. Many companies are beginning to realise that, where before they would maintain independent drying and milling processes, the combination of these unit operations in one process system can save considerable amounts of applied energy. E.g. kaolinitic clay dried on a separate band dryer and then milled has been typically using up to 20% more LPG and electrical energy than the equivalent material processed on an Atritor Dryer-Pulveriser system. The greater the attraction between the particles of the primary material on drying, the greater this proportional energy saving will be. Some customers have been surprised at the simplicity of the argument that the drying fine particulates is an agglomeration exercise, which then requires more energy to be applied down stream to break these attraction forces apart again.

Wet Milled Calcined Kaolin
Wet Milled Ground CaCO3 - GCC
Organo Clay (Bentonite)
Marble Cutting Waste
Kaolinitic Clays
Food ingredients - potatoes, starch
Ca(OH)2
Wet Milled Fluorspar
Titanium Dioxide
Zirconium Silicate
Talc

Precipitated Chemical Compounds
Precipitated CaCO3 - PCC
Di-Calcium Phosphate
Natural Ball Clay
Precipitated Pigments
Casein
Precipitated Stearates
Industrial Waste
PVC
Zeolites
Natural Bentonite