Rotary dryer is a type of industrial dryer machine which is used to reduce the moisture content of the materials massively by bring the wet material into direct contact with a heated gas, or indirect contact with the heated cylinder.

Rotary dryer usually consist of a large, rotating cylindrical tube which is supported by concrete foundation or steel beams. The rotary dryer usually have a 4 degree slope so that the discharging end is lower than the feed inlet end. Thus, when the material goes into the rotary dryer from the feed inlet end which is higher than the discharging end, the material can go trough the rotary dryer by gravity.

On the inner wall of the cylinder tube of the rotary dryer, there are many lifting plates with a certain slope. After the material goes into the cylinder tube, as the rotary dryer is rotating, the material is lifted up and down bya series of lifting plates. When the material get high enough to leave away the lifting plates, it will falls down to the bottom of the rotary dryer. During this process, the material will contact with the hot flue gas completely, and the moisture of the material is evaporated. The hot gas flue can either move towardsthe discharging end from the feedinlet end, or moves towards the feedinlet end from the discharging end.

The hot flue gascan begenerated by one hot air furnace, and in this way, the rotary dryer is called direct heated dryer. This type dryer is suitable for the material which admit some contamination such as sands, ore, etc.

Or also we can make one furnace which is surround the cylinder tube, and the fire is outside the rotary dryer, and heat the outside of the cylinder tube directly, and then the heated cylinder tubedry the material which is inside the cylinder tube. This type rotary dryer is named as indirect heated dryer.Indirect heated dryers are used when product contamination is a concern.

For the rotary dryer, there is one high pressure induced draft fan which is used to make the hot flue gas go into the cylinder tube from the hot air furnace. At the end of the rotary dryer, there is one cyclone dust separator, Inside the cyclone dust separator, the dust falls down and gets out of the discharging hole, and the steam goes into the atmosphere directly.

In one word, the rotary dryer is simple to be operated, and it is very suitable to dry variety of materials such as metallic and nonmetallic mineral, clay in cement industrial,coal slime in coal mine, silica sand, wood shavings, wood chips, sawdust,chicken manure, cow dung,poultry manure, grass, grain, etc.

For more details of rotary dryer, you can also refer to http://www.dinglimachinery.com/products/drying/rotary-dryer-01.html.