How does the Single Drum Rotary Sand Dryer work?

River sand is a construction material primarily formed by the erosion and abrasion of river water, sourced from natural stones in riverbeds. It typically features a smooth surface with a considerable amount of impurities. The composition of river sand is intricate, comprising fine sand, medium-coarse sand, coarse sand, as well as sand and gravel. In the construction industry, river sand has extensive applications, commonly used in preparing concrete, cementitious materials, road-building materials, and artificial marble. Additionally, river sand can also serve as an additive in areas such as casting, metallurgy, and heat treatment to enhance material wear resistance and high-temperature durability.

However, despite the widespread applications of river sand in various fields, its often high moisture content necessitates processing with a river sand dryer. River sand drying reduces the moisture content effectively, enhancing its quality and usability, thus meeting the demands of the construction and industrial sectors for raw materials.

The Single Drum Rotary Dryer for river sand drying plant process is as follows:

1. River Sand Feeding

River sand is transported by a belt conveyor or a bucket elevator to the hopper and then fed into the higher end of the rotary dryer through the feeder and the feeding pipe. The inclination of the feeding pipe is greater than the natural angle of repose of the river sand, ensuring its smooth entry into the dryer.

2. River Heating and Heat Transfer

The heat carrier, which can be hot air, flue gas, or other heated gases, enters the lower end of the dryer. There are two main ways of heat transfer:

Convective heat transfer: The hot heat carrier comes into direct contact with the wet river sand. As the heat carrier flows through the drum, heat is transferred from the carrier to the river sand through convection, causing the moisture in the sand to evaporate rapidly.
Conductive heat transfer: In addition to convection, the drum wall also conducts heat to the river sand in contact with it, further enhancing the drying effect.

3. Rotation and River Sand Material Movement

The single drum rotates slowly around its axis. Inside the drum, there are evenly distributed lifting plates. As the drum rotates, these lifting plates continuously lift and scatter the river sand, ensuring that the sand is evenly distributed and dispersed within the drum. This allows the sand to have more uniform contact with the hot air or heat source, improving the drying efficiency.

Thanks to the inclination of the drum and the combined action of the lifting plates and the hot air flow, the river sand gradually moves from the feeding end to the discharging end of the drum during the drying process.

4. Discharge of Dried River Sand

At the other end of the drum, there is a discharging device such as a belt conveyor or a screw conveyor. The dried river sand is discharged through this device and collected for subsequent use.

5. Exhaust and Dust Removal

The moist air generated during the drying process, along with some fine particles and dust carried by the river sand, is exhausted from the drum by an induced draft fan. To reduce environmental pollution, most single drum rotary dryers for river sand are equipped with dust collection and exhaust gas treatment systems, such as cyclone dust collectors, bag filters, or wet scrubbers, to remove dust and other pollutants from the exhaust gas before it is discharged into the atmosphere