Rotary Screener Machine

Rotary Screener Machine

Rotary screens (also known as drum screens or rotary sieves) are key screening equipment in fertilizer production processes, used for separating finished products from recycled materials and achieving product grading. This equipment is widely used in the production of organic fertilizers, bio-organic fertilizers, and compound fertilizers. It can classify and screen dried and cooled granular materials according to particle size. Qualified finished products proceed to the packaging process, while unqualified large particles and powder are returned for re-granulation. Rotary screens are a new generation of self-cleaning screening equipment following electric vibrating screens, featuring high screening efficiency, low noise, low dust generation, long service life, low maintenance, and convenient inspection.

In the production of organic and compound fertilizers, the granular materials after granulation, drying, and cooling are often uneven in size and contain impurities such as powder, debris, oversized lumps, and stones. Rotary screens, through the synergistic effect of mechanical rotation and the force of gravity, accurately grade the materials according to particle size, ensuring uniform particle size in the finished product. This is a core post-processing equipment for ensuring the quality of fertilizer products. The equipment has a screening capacity of 60 tons/hour to 1000 tons/hour, and the finest part can be ≤3mm.

Equipment Structure

The rotary screen mainly consists of the following core components:

(I) Drum Assembly: This is the core working component of the equipment, composed of a drum frame and screen mesh. The drum is typically cylindrical or hexagonal in design. One to three layers of grading screens can be installed inside the drum as needed to achieve multi-stage screening. The drum is installed on the frame at a 3°-5° inclination.

(II) Frame Section: This is the supporting structure of the entire equipment, constructed entirely of high-quality carbon steel plates and channel steel, and has passed strict product qualification certification and specific process requirements.

(III) Transmission Section: This consists of a motor, reducer, coupling, etc. The motor is connected to the drum assembly via the reducer and coupling, driving the drum assembly to rotate around its axis. The transmission section has a simple structure and is easy to assemble and maintain.

(IV) Screen Mesh System: This uses a modular screen, and different aperture sizes of metal mesh (manganese steel, stainless steel) or polymer material mesh can be selected according to production needs. The screen mesh is installed and welded onto the drum cage of the main shaft. Some models use screens composed of circular flat steel rings, which are highly wear-resistant and have a long service life.

(V) Feeding, Discharging, and Sealing Devices: These include the feed inlet, discharge outlet, sealing cover, and funnel. The entire screening mechanism is designed within a sealed dustproof cover. A chute is provided in the coarse material section to directly deliver coarse material to the transport machinery.

Application range of equipment

Rotary screening machines have a wide range of applications. In fertilizer production, they are commonly used for screening organic fertilizers, compound fertilizers, and bio-organic fertilizers, primarily separating finished products from recycled materials. They can also be used for product grading, resulting in uniformly classified finished products. In the chemical industry, they are suitable for grading and screening chemical raw materials. In the mining and building materials industry, they can be used for grading and screening ores, sand, gravel, and ceramsite. In the power industry, they can be used for screening fuel for circulating fluidized bed boilers. In environmental protection and solid waste treatment, they can be used in waste treatment and composting processes. In the grain and food industry, they can be used for screening and grading grains and feed.

Types of available raw materials

Rotary screening machines can process a wide variety of materials. Fertilizers: organic fertilizer granules, compound fertilizer granules, blended fertilizer granules, bio-organic fertilizer granules, etc. Minerals: ores, sand, gravel, ceramsite, coal, coal slime, etc. Environmental materials: compost products, waste treatment materials, etc. Grains: grains, feed, etc. The equipment can process various solid materials with a particle size of less than 300mm.

How the device works

The working principle of a rotary screen is based on the synergistic effect of mechanical rotation and the gravity of the material. Its workflow is as follows: Granulated, dried, and cooled granular material enters the equipment evenly from the feed inlet at the high end of the drum. The drum is installed at a 3°-5° angle and rotates at a constant speed of 10-15 r/min driven by a transmission device. Under the combined action of gravity and friction from the inner wall of the drum, the material moves slowly from the high end to the low end along the drum's axis. During this process, the lifting plates on the inner wall of the drum continuously lift and drop the material. Qualified particles with a diameter smaller than the screen mesh size pass through the screen holes and fall into the collection tank below; large particles or impurities with a diameter larger than the screen mesh size continue to move with the drum towards the low end and are discharged from the slag discharge port at the end of the drum. Through multiple layers of screens with different mesh sizes, the material is separated into several grades, including finished product, return material, and coarse material.

Equipment operation method

(I) Pre-start Preparation: Operators should carefully read the equipment instruction manual, familiarize themselves with the machine's performance, and understand its structure and operating procedures. Check that all bolts are secure. Inspect the screen for damage; replace any damaged parts immediately. Check the spring components for looseness. Check the lubrication of the transmission device.

(II) No-load Start-up: The rotary screen should be started under no-load. Feeding can only begin after the machine is running normally. After starting, observe whether the drum rotation direction is correct.

(III) Operation Monitoring: Ensure uniform feeding during operation and avoid overloading. Observe the screening effect and adjust the feed rate promptly. Listen for any abnormal noises from the equipment. Regularly check for screen blockage.

(IV) Shutdown Operation: First, stop feeding. Disconnect the power supply only after all material has been discharged from the drum. Maintain accurate equipment usage and maintenance records and complete shift handover procedures.

Equipment maintenance methods

(I) Daily Maintenance: Clean residual materials and dust from the equipment after each shift. Check the screen surface for damage; replace it immediately if damaged. Check for loose spring components. Check all fastening bolts for looseness. Add an appropriate amount of lithium-based grease to the transmission box grease fitting each shift.

(II) Periodic Maintenance: Regularly check the screen for wear; replace it promptly if severely worn. Regularly check the lubrication of all bearings. Regularly check the sealing devices for integrity to prevent dust leakage. Regularly check the tension of the drive belt.

(III) Calibration Management: During the initial operation of the equipment, check the anchor bolts at least once a day to prevent loosening. Regularly check whether the tilt angle of the rollers is within the set range.

Equipment troubleshooting

Screen clogging: Clean the clogged screen after shutdown. Control the moisture content of the feed material within a suitable range. Adjust the feed rate to the rated value. Select equipment with a screen cleaning mechanism.

Screen damage: Replace damaged screens promptly. Install a debris removal device at the feed inlet to prevent hard objects from entering.

Excessive equipment vibration: Check and tighten the foundation bolts. Check the roller balance and correct it if necessary. Check the bearings for damage and replace them promptly.

Poor discharge: Clear blockages from the discharge port. Check and adjust the roller tilt angle to 3°-5°.

Abnormal noise: Check the bearings for damage and replace them. Check gear wear. Tighten any loose transmission components.

Application of equipment in production line

Rotary screens are a core screening component in the post-processing stage of organic fertilizer and compound fertilizer production lines. The upstream process is a drum cooler—cooled granules are fed into the screen via a belt conveyor. The downstream process is an automatic packaging scale—qualified finished granules enter the packaging process. Unqualified large granules and powder are returned for re-granulation.

The complete post-processing flow is: granulation → drying → cooling → screening → packaging. Rotary screens can also be deployed in the post-fermentation stage for initial screening of raw materials, removing large, incompletely decomposed pieces.