Roller Screen for Open-pit Coal Mines in Producing and Processing

The heavy-duty roller screen currently under production and processing is used in the open-pit coal mine project in Mongolia. Our Mongolian client is a company specializing in the coal mining industry. It has the second largest open-pit coal mine in the local area, with a huge annual coal output. Therefore, the client has extremely high requirements for the quality and performance of the equipment. This Roller Screen takes into account the harsh working environment of open-pit coal mines and the screening requirements of customers in its design. It adopts 10 screen shafts, each of which is driven by a separate motor and reducer. The feed particle size is less than or equal to 350mm. Materials smaller than 250mm will pass directly through the screen surface. Materials larger than 250mm will be rolled and sieved on the screen surface.

The working principle of Roller screen

Power transmission

The motor serves as the driving device to provide power, which is transmitted to each roller through transmission mechanisms such as chain drive or gear drive.

Roller rotation

The rollers rotate at a certain speed under the drive of power. The rotation directions of adjacent rollers can be the same or opposite. When the rotation directions are opposite, it is more conducive to the loosening and screening of materials.

Material screening

After the materials enter the roller screen, they move forward driven by the rollers. There is a gap between the rollers to form the screen surface. Materials smaller than the gap of the screen plate fall from the gap to the collection device below under the force of their own weight and the rotation of the rollers, and are conveyed out of the equipment by the collection belt, etc. Materials larger than the gap of the screen tray continue to be conveyed forward from above the screen tray and enter the next process.

The structural composition and design key points of Roller screen

Screening system

Screen shaft

The setting of the number of Roller screen shafts is determined based on the finished particle size of the material and the fineness requirements of the screening. The number of screen shafts is usually 6 to 20. The more screen shafts there are, the longer the material rolls on the screen surface, and the finer the screening.

Screen shaft spacing

The screening principle of Roller screen is to control the passage of materials by the distance between the screen shafts.

Screen surface layout

If the inclination Angle is too small, the material will stay on the screen surface for too long. Although this can improve the screening accuracy, it will reduce the overall screening efficiency.

Drive system

Driving mode

The drive methods are divided into independent drive and linked drive. In independent drive, each screen shaft is driven by a separate motor and reducer. Interlocking drive involves multiple screen shafts being driven by the same set of drive devices. Its structure is relatively simple and the cost is lower. However, when dealing with complex material screening, the flexibility of adjustment is not as good as that of independent drive.

Drive unit

The motor drives each part of the roller screen to operate. During the working process, the motor drives the reducer and the transmission device, making the screen shaft rotate, thereby pushing the materials forward and conducting screening.

Auxiliary system

Self-cleaning device

The comb plate is installed on the rotating roller. As the roller rotates, the comb plate will exert a pulling force on the material, pushing it forward to complete the material conveying process on the screen surface. The rotation of the comb plate can play a certain role in stirring and loosening the material, preventing the material from accumulating and caking on the screen surface, avoiding the clogging of the screen holes, and ensuring the smooth progress of the screening process.

Bottom plate of the feeding port

The base of the feeding port provides a stable foundation for the roller screen, ensuring that the equipment remains stable during operation and will not shake or tilt due to the entry of materials, thus guaranteeing the smooth progress of the screening work. The wear-resistant material can withstand the long-term impact and friction of materials, extending the service life of the equipment.

Daily inspection and maintenance

Lubrication condition

Regularly check the lubrication status of each lubrication point. Add lubricating oil as required by the equipment user manual on a regular basis and replenish or replace the grease on a regular basis.

Fastening bolts

Check if all fastening bolts are loose, including those at the bearing housing, motor reducer, gearbox and other parts, and tighten them in a timely manner.

Clear accumulated materials and entangled objects

Regularly or when necessary, clean the roller screen plates and sweep the accumulated materials and entangled objects on the scraper in a timely manner to prevent excessive accumulation of debris from causing wear to the screen plates.

Sealing inspection

When the compression bolts can no longer be screwed in, the shaft end sealing packing needs to be replaced to ensure the sealing effect.

Wear condition inspection

Check the wear condition of the roller screen plates and the scrapers in the cleaning device. When the wear reaches a certain degree, they should be replaced.