The Application Of Flip Flow Screen In Coal Preparation Plants
With the improvement of coal mining mechanization, the proportion of fine coal and fine coal powder in raw coal has reached 40%-50%. Different particle sizes of coal and gangue are mixed, and it is necessary to use screening equipment to separate the gangue to improve the quality of coal and meet the requirements of users. The high moisture content in the coal leads to the tendency for the fine particle size materials to stick together easily, be difficult to be loose and get clogged in the screen holes, resulting in a decrease in screening efficiency, non-loose and non-layered particle groups, and overall movement making the screening process difficult to complete.
The flip flow screen can effectively overcome the adhesion and clogging problems of damp fine particle size materials through the high-frequency oscillation movement of the screen surface, significantly improving the screening efficiency of fine coal.
Situation and problems of fine-grained material separation in coal preparation plants
Due to the influence of the moisture and viscosity of raw coal, vibrating screens are prone to clogging when screening fine particles, resulting in low screening efficiency and severely affecting the separation effect. Existing screening equipment such as probability screens, Flip flow screens, roller screens, trommel screens, banana screens, etc., among which the Flip flow screen is currently the most effective equipment in the coal washing industry for dry screening of wet, sticky, and fine materials while balancing processing capacity and screening efficiency.
The Flip flow screen is a device used for screening fine, wet, and sticky materials that are difficult to separate. Especially in cases where the screen mesh is prone to clogging, the elastic screen plate of the Flip flow screen can ensure efficient screening without clogging the screen. The Flip flow screen has the advantages of simple and reliable structure, low failure rate, and high screening efficiency, and can ensure the long-term reliable operation of the washing and selection process.
Advantages of Flip flow screen and problems of existing screening equipment
Compared with ordinary screening equipment, the replacement of the screen plates of Flip flow screen is simple, quick, time-saving and labor-saving. It can greatly save manpower and material resources and provide a reliable guarantee for the normal operation of the washing and selection process.
The application of Flip flow screen can improve the screening efficiency of fine particles, high moisture content and other difficult-to-screen coal types, reduce the amount of coal slime entering the washing process, effectively alleviate the pressure on the downstream coal slime water treatment system, save the investment and burden of subsequent coal slime treatment equipment, and improve the overall washing capacity of the coal washing plant. Currently, the main problems existing in the fine particle and high moisture content classification screening equipment are:
If the amplitude is increased and the vibration intensity is raised, it will affect the reliability and stability of the equipment (breakage of the screen frame and other structural parts, etc.), and at the same time, it will cause serious noise pollution；
When the moisture content of raw coal is high, the situation of clogging the screen mesh during screening is serious, and it has not been well solved yet;
The screening efficiency is low, about 30% – 60%;
Due to the working characteristics of the vibrating screen, the screen mesh, bearings and other components need to be replaced regularly. When replacing the components, it is complex, time-consuming and laborious, and the on-site maintenance work of the workers is very intense;
The equipment energy consumption is high.
Working principle of Flip flow screen
In order to enhance the coal processing capacity of the coal preparation plant for fine-grained and high-moisture raw coal, the Flip flow screen was introduced. This equipment operates by having the sieve plate perform periodic reciprocating oscillation, causing the sieve surface to undergo continuous expansion and contraction. This enables the damp and fine-grained materials adhering to the sieve surface to be constantly loosened and dispersed, preventing fine particles from getting stuck and blocking the sieve holes. At the same time, it accelerates the process of particle stratification and sieving.
Compared to traditional vibrating screens, it can significantly reduce the ineffective energy consumption during equipment operation. The efficient polyurethane sieve plate is installed on the fixed crossbeam (connected to the sieve body) and the floating crossbeam (connected to the floating balance beam). Due to the interlaced movement of the sieve body and the floating balance beam, which drives the sieve plate to tighten and relax, a reciprocating motion is formed.
Flip flow screen screen plate and vibration damping system
Features of the flip flow screen screen plate
Using high-elastic polyurethane, it has excellent wear resistance, excellent chemical properties and physical properties, making the screen plate have the characteristics of long service life and high screening efficiency；
Suitable for various material processing industries, with significant effects on handling viscous and flaky materials, such as coke, coal, clay, limestone, garbage, etc.;
The service life of the screen plate is 6000-8000 hours.
Vibration damping system of the flip flow screen
Vibration damping rubber springs, using the nonlinear stiffness characteristic of rubber, maintain stable vibration damping effect under load changes. It can minimize the dynamic load transmitted to the equipment foundation, low noise, no maintenance, and the designed vibration damping effect is over 97%；
Shear rubber springs, responsible for ensuring the horizontal vibration of the floating screen frame, have the function of adjusting the amplitude of the floating screen frame；
Guide plate springs, responsible for ensuring the vibration direction of the floating screen frame, and at the same time have the effect of extending the service life of the shear rubber springs.
The Application of Flip Flow Screen in Coal Preparation Plants
Process flow
The raw coal is transported by the conveying equipment to the raw coal grading Flip flow screen. After grading, the materials larger than 13mm enter the lump coal washing system for washing; the materials smaller than -13mm enter the bottom coal system for washing. The original screening chute, the chute for the material on the screen, the chute for the material below the screen, the lump coal washing equipment, and the bottom coal conveyor belt are fully utilized.
Easy installation
When installing the Flip flow screen, adjustments can be made based on the existing equipment foundation. Only the force on the foundation needs to be rechecked, and as long as the dynamic load requirements of the equipment are met, it is sufficient.
Conclusion
After introducing the Flip flow screen, the coal preparation plant was able to steadily enhance its processing capacity for difficult-to-sift raw coal, reduce equipment failure downtime, and provide reliable equipment support for the stable and efficient operation of the production process of the coal preparation plant.
