How Many Layers of Banana Screen Can Be Configured
Introduction
Banana Screen, as an efficient vibrating screening equipment, plays a crucial role in the material classification process in multiple industries such as mining, metallurgy, coal, and building materials. The number of Screen layers, as one of the core configuration parameters of Banana Screen, directly determines the separation efficiency of the equipment, the number of product particle sizes, and the subsequent operation and maintenance costs. A reasonable selection of the number of screen layers not only precisely matches the production requirements for material classification but also effectively enhances the economic efficiency of the overall production process.
Single-layer and double-layer Banana screens
Single-Deck Banana Screen
Main features
The core structure is a single inclined screen surface. The inclination Angle of the screen surface gradually decreases from the feeding end to the discharging end. This design enables the material to slide down rapidly at the feeding end with the help of a larger inclination Angle, reducing material accumulation. At the discharging end, as the inclination Angle decreases, the material movement speed slows down, providing sufficient time for fine screening. The vibration system of the single-layer Banana Screen acts directly on the single-layer screen surface, with small vibration energy transmission loss and stable screening efficiency.
Applicable scenarios
In the coal industry, Banana Screen is often used for the pre-screening of raw coal to remove large gangue and avoid overloading of subsequent crushing equipment. In the production of construction aggregates, the crushed materials can be preliminarily classified to separate the large pieces that do not meet the particle size requirements and return them to the crushing process.
Advantage
From a structural perspective, the single-layer configuration reduces components such as the screen surface support structure and material distribution device, resulting in a lower overall failure rate of the equipment. During the maintenance process, only a single screen surface needs to be inspected, cleaned and replaced. The operation process is simple, and the required maintenance time and labor costs are significantly reduced. Meanwhile, the energy of the vibration system can be concentratedly transferred to the single-layer screen surface, avoiding the loss of energy transfer between layers in multi-layer configuration.
Double-Deck Banana Screen
Main features
Two layers of parallel Screen surfaces (upper layer and lower layer) are set in a screen machine frame. Both layers of screen surfaces adopt the gradually shrinking inclination Angle design consistent with the single-layer Banana Screen. The upper screen surface usually selects a screen with a larger aperture for the initial screening to remove large pieces of material, while the lower screen uses a screen with a smaller aperture to conduct a secondary fine screening of the material under the upper screen.
Applicable scenarios
In the beneficiation process of metal mines, double-layer Banana screens are often used for the classification of ores after crushing, dividing the ores into three particle grades: large block return ore, medium block intermediate products, and fine feed ore materials, to achieve differentiated treatment of materials of different particle grades. In the production of sand and gravel aggregates, three types of products – coarse aggregates, medium aggregates and fine aggregates – can be produced at one time, meeting the demands for aggregates of different particle sizes in scenarios such as concrete mixing.
Design challenge
The two layers of screen surfaces and the materials on them will form a greater eccentric load. If the vibration system is not designed reasonably, it is very likely to cause severe shaking during equipment operation, affecting the screening accuracy and even damaging the equipment structure. Therefore, it is necessary to precisely design and optimize the parameters of the exciter, the installation position, and the rigidity of the screen body. The material under the upper screen needs to evenly cover the lower screen surface. If the flow-guiding device is improperly designed, it may cause local overload or insufficient screening of the lower screen surface. Therefore, it is necessary to precisely design it based on the particle size, moisture content, fluidity and other characteristics of the material.
The key factors determining the configuration of the number of layers
Required Screen Fractions
If only two products need to be separated, such as the material on the sieve and the material under the sieve, a single-layer Banana Screen can be selected. The single-layer sieve surface can achieve two-stage separation through one screening. If three products need to be separated, a double-layer Banana Screen is selected. The upper screen surface completes the first stage of screening to separate the material on the screen with the largest particle size. The material under the upper screen enters the lower screen surface for the second stage of screening. Eventually, two products of medium particle size and fine particle size are obtained. The three-stage separation is achieved through the synergistic effect of the two screen surfaces.
Material and Capacity
From the perspective of material characteristics, for materials with high viscosity and high mud content, if a double-layer configuration is adopted, the lower screen surface is very likely to be clogged due to material adhesion, resulting in a sharp decline in screening efficiency. At this time, a single-layer configuration is more suitable. For materials with uniform particle size distribution and good fluidity, the advantages of the double-layer configuration are more easily brought into play, and efficient multi-particle size separation can be achieved within a single machine. From the perspective of processing capacity requirements, in scenarios with extremely high processing capacity demands, single-layer or multiple single-layer machines are usually used in parallel to maximize efficiency. Because the effective screening area of the single-layer screen surface is relatively larger, the material passing capacity is stronger, and the processing volume per unit time is higher. In the double-layer configuration, the processing capacity of the lower screen surface is limited by the amount of material under the upper screen, and the overall processing capacity is relatively low.
The impact of layer number configuration on maintenance
Maintain channels and accessibility
Problem
The distance between the two Screen surfaces of the double-layer Banana Screen is usually small, generally only meeting the requirements for the normal passage of materials. Maintenance personnel find it difficult to directly enter between the layers for operation. When replacing the bottom screen plate, the relevant components of the upper screen surface need to be removed first or the upper screen surface needs to be moved temporarily through a special hoisting device. The operation process is cumbersome and time-consuming. When conducting daily inspections of supporting rubber, springs and other components, due to space limitations, it is difficult to comprehensively observe the wear and deformation of the components, which may easily lead to the omission of potential fault hazards.
Suggestion
During the equipment selection stage, it is required to design an interlayer maintenance passage of sufficient width to ensure that maintenance personnel can enter smoothly for operation. At the same time, a maintenance door of appropriate size should be set on the side of the screen machine. The position of the maintenance door should cover the key maintenance areas of the bottom screen surface and the inspection points of the supporting components, facilitating maintenance personnel to directly inspect and maintain the bottom components through the maintenance door.
Consideration of the lifespan of bearings and exciters
Load analysis
The total load of the double-layer Banana Screen is higher than that of the single-layer one, and it has higher requirements for the bearings and lubrication system inside the exciter. The load of a single-layer Banana Screen mainly consists of the Screen frame, the single-layer screen surface and the materials on the screen surface. A double-layer Banana Screen, on the other hand, needs to bear the weight of the second layer of the screen surface and the materials on that layer. The total load is usually higher than that of a single-layer screen machine of the same specification.
Impact on lifespan
If the double-layer Banana Screen is equipped with an exciter of the same specification as the single-layer one, the output power and carrying capacity of the exciter cannot match the high load demand of the double-layer screen machine, which will cause the exciter to be in an overloaded operating state for a long time. The wear rate of the bearing will increase significantly, and the overloaded operation will also cause the temperature of the exciter to rise.
Conclusion
The single-layer Banana Screen has a simple structure, low maintenance cost and high vibration transmission efficiency. It is suitable for scenarios that only require two-stage separation or high processing volume. The double-layer Banana Screen can achieve three-level separation through a single machine, meeting the requirements of fine classification. In the actual selection process, the number of particle sizes to be separated directly determines the basic choice of single-layer or double-layer. The material characteristics and processing capacity are important adjustment bases. Materials with high viscosity and high processing capacity are more suitable for single-layer or multiple single-layer parallel schemes. Materials with good fluidity can fully leverage the space advantages of the double-layer configuration.
