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Cell Mill-Dryer-Classifier-Coating Units

Process Description

A Cell Mill-Dryer-Classifier system can process a range of fine wet-milled mineral products, presented to the process as 65/35 solids/water suspension and to particle size specifications generally less than 10µm with a high percentage below 2µm.

The system includes the patented Atritor steam or hot air injection for the aqueous suspension. To ensure that any residual coarse agglomerates are rejected from the dry product stream, the Mill-Dryer is fitted with a high integrity classifier unit; the classifier has an inverter controlled variable speed drive to allow adjustment of cut point, and the coarse particles are rejected and reintroduced at the base of the dryer.

Air is drawn through a packaged gas-fired heater designed to raise the air temperature from ambient to 400ºC. Control of the dryer outlet temperature at around 90ºC maintains product moisture level. Spray injection occurs on the Cell Mill body at a point adjacent to the bottom two rotors.

Process    "cells"    are     created
* An example of the Atritor CM1500 calcium carbonate drying and coating plant

between the serrated body liners and the high velocity rotors and the high turbulence within these cells gives perfect conditions for optimum particle de-agglomeration and for efficient flash drying with maximum exposure of product surface to hot air.

The accurately metered surfactant is inspirited by a compressed air driven venturi into a tangential port above the slurry entry point.

After final classification, ducting carries the air & dry product from the Cell Mill to a reverse-jet product collection filter. The duct has a sensor to monitor the temperature of the air/product mixture as part of the air heater control system, providing a consistently dry product.

The product is discharged from the filter through a rotary valve and the filtered air passes to the main process fan.



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