Banana Screen Research Articles

Spatially permeable screening distribution characteristics of banana-type vibrating screen material groups and industrial application

ABSTRACT Screening is a critical technology to achieve clean and effective use of coal. Due to their ability to achieve equal-thickness screening and excellent working efficiency characteristics, banana screens are widely utilized for material classification. The current work employs a vibration test and analysis system to investigate the laboratory-scale and industrial banana screens’ kinematic features. The screen surface’s amplitude gradients at the inlet and outlet ends of the laboratory and industrial scale banana screens were 0.5 mm and 7.5 mm, respectively, verifying the “strong-in, weak-out” transfer law of the vibration energy. The results of the 6 mm screening experiment in the laboratory indicated that the coal samples were concentrated in the middle of the screen surface with the highest screening efficiency of 95.05% and the lowest total mismatch content of 2.68%. A Birtley’s four-stage banana screen was utilized to classify the 6 mm raw coal during the on-site heavy media separation at the Tunbao coal processing plant. Besides, a better screening performance was obtained with an efficiency of 89.92% and total mismatch content of 5.31%. The differences in accuracy of the distribution rate curves were all less than 5%, indicating that the laboratory banana screen is a prominent guide for industrial applications.

Design calculations and simulation dynamics of banana screen

The banana screen is a device used to classify materials widely used in screenings factories at home and abroad. It's working ability depends on many factors (kinematic parameters, technological parameters, particle size, and material moisture,...). If using the traditional method to determine suitable parameters to reach high efficiency, it is very difficult. Because the calculated results are not accurate, it takes a designer much time and makes the manufacturing cost increase. In this study, the author uses the computer software CREO, ADAMS, ANSYS to design and simulate the dynamics of the screen. The results of study are the dynamic parameters of the screen during the working time and are shown in different graphs (Elastic pillow deformation of spring; the force exerted on the elastic pillow; the center velocity of vibration box; center acceleration of vibration box; static energy of vibrates box; translational momentum of vibration box; moment momentum of vibration box). These results also can be applied to design banana screens, which have a high capacity and efficiency as well as a long lifetime.

Kinematic characteristics of banana screen surface and operational parameter optimization for coal classification

ABSTRACT Screening is an indispensable unit operation that is used extensively in many industries to separate particulate materials into different size fractions. A banana screen has high screening efficiency and is widely used for coal classification. In this study, the kinematic characteristics and velocity distribution of the banana screen surface during equal-thickness screening were investigated. High-speed dynamic test system results showed that the migration velocity and distance of different screen surface stages increase with running time from point 1 to point 5. Based on the experimental data and Box–Behnken response surface methodology results, the best screening effect occurred when the angle of eccentric blockψ was 100°, the excitation frequency f was 34 Hz and the feed rate Q was 3 kg/s. Furthermore, the sequence of influencing degree of various factors on screening efficiency η followed the order: f > ψ > Q. The actual screening efficiency was 92.993% when the operating conditions wereψ = 103°, f = 32 Hz, and Q = 3.5 kg/s, indicating a satisfactory screening performance of coal using a banana screen.

Performance optimization of banana vibrating screens based on PSO-SVR under DEM simulations

This paper carried out the numerical simulation about the movement of non-spherical particles on banana vibrating screen using direct element method (DEM) considering the complexity of particle collision and avoiding obtaining motion information with difficulty. Experimental prototype of banana vibrating screen under variable parameters was manufactured to verify the feasibility of simulations. Because the complex non-linear mathematical model is the basis of optimization. Based on the simulation data this paper applied the least squares support vector machines (LS-SVM) to establish relationships between vibrating parameters of banana screen and screening performance. LS-SVM based on statistical theory can effectively solve the mapping problem of small sample. At same time, in order to improving the quality of modeling, the kernel parameters of SVM were optimized by particle swarm optimization (PSO). Considering multi-extremum, large-scale, and non-differentiable of this computational model, the artificial fish-swarm algorithm (AFSA) with strong robustness and global convergence was applied to vibration parameters optimization. Finally, the optimal vibration parameters were: vibration amplitude 2.4 mm, vibration frequency 21 Hz, vibration direction angle 40 degrees.

Vibration Parameter Optimization of a Linear Vibrating Banana Screen Using DEM 3D Simulation

In this paper, the effects of vibration parameters of a banana screen, i.e. frequency, amplitude and vibration direction angle, on the screening efficiency per unit time were studied using the discrete element method (DEM). The simulations were validated according to data collected from an experimental prototype screen. Functional relationships between vibration parameters and screening efficiency per unit time are presented. The results showed that the screening efficiency per unit time first displays an increase and later a decrease when the frequency, amplitude or vibration direction angle increased respectively. Vibration parameter optimization was also investigated, using an orthogonal experiment. Based on the banana screen model, it can be concluded that when the frequency is 22 Hz, the amplitude is 2.2 mm and the vibration direction angle is 39°, the screening efficiency of a banana screen is optimal.

Applications of the discrete element method and Fibonacci sequence on a banana screen

PurposeThe purpose of this paper is to design the geometrical structure of banana screen, and this study aims to improve the screen efficiency.Design/methodology/approachThe discrete element method was used to simulate the sieving process of banana screen with the inclinations of decks improved by Fibonacci sequence. The effect of each deck along screen length on the screening efficiency of particles was studied in this paper.FindingsThe comparisons among three groups of industrial banana screens with five different consecutive Fibonacci numbers have been made, and the variations of fine particle ratio were also investigated. The results show that the banana screening improved by the 5 Fibonacci sequence, 3, 5, 8, 13 and 21, has the good screening performance in the simulation. It is found that the inclination degree of the first deck at the feed end is the key factor to determine screening efficiency of banana screens.Practical implicationsIt is not possible to consider all real physical factors exactly in a virtual model. The experiment prototype of banana screen was used to simply verify the feasibility of the methodology.Originality/valueThis work is helpful for designing the geometric parameters of the curved screen and gives a broad perspective to improve the efficiency of banana screens.

Model of banana screen for robust performance

Screens are an important production unit in crushing plants. The performance of the screen is essential to the performance of the crushing plant. In this paper a mechanistic model of a banana screen is described and a novel model for screen deck configuration is presented. The developed model can be used for optimization of a screen so that it has the best possible performance with respect to different feeding conditions, in order to obtain a desired separation. The simulation results were compared to full scale test data and the conclusions from this comparison is that the screen model needs further parameters to handle the necessary screen deck configuration. An initial static model was derived to explain how the screen deck configuration will affect the screen efficiency. The modification of the screen deck parameters resulted in a better correlation both regarding size distribution and predicted capacity.

Investigation of screening performance of banana screens using LIGGGHTS DEM solver

Deeper understanding of screening performance of banana screens helps mineral processing engineers to control and optimize them. In this article, screening performance of banana screens using a DEM (Discrete Element Method) solver ‘LIGGGHTS’ is investigated. An industrial double-deck banana screen with five panels and two laboratory single-deck banana screens with three and five panels are simulated. Effects of design parameters including incline angle of each panel, vibration amplitude and vibration frequency on screening performance of both the industrial screen and laboratory screens are studied. Also, the effects of operational parameters including simulation time and feed particle size distribution on screening performance of the industrial screen are examined. Simulation results are expressed in terms of recognized and comprehensible quantities for engineers, i.e., screen efficiency and screening recovery. To validate simulation results, a parameter named partition number is defined. Comparison of the partition numbers of simulations related to the laboratory screens with those available in the literature demonstrates a good agreement which validates the DEM simulations and the used software. Also, the results indicate that the industrial and laboratory screens show a totally different behavior with respect to changes in design parameters.

DEM simulation of particle flow on a single deck banana screen

A mathematical study of particle flow on a banana screen deck using the discrete element method (DEM) was presented in this paper. The motion characteristics and penetrating mechanisms of particles on the screen deck were studied. Effects of geometric parameters of screen deck on banana screening process were also investigated. The results show that when the values of inclination of discharge and increment of screen deck inclination are 10° and 5° respectively, the banana screening process get a good screening performance in the simulation. The relationship between screen deck length and screening efficiency was further confirmed. The conclusion that the screening efficiency will not significantly increase when the deck length L⩾430mm (L/B⩾3.5) was obtained, which can provide theoretical basis for the optimization of banana screen.

Banana Screening Method and Simulation of Banana Screening Process Using Discrete Element Method

This paper presented the fundamentals of banana screening method and the structural features of the banana screen. Based on soft-dry ball contact model, banana screening process was simulated by using 3D discrete element method. The results show that the material bed on banana screen possesses a characteristic of thin and constant thickness along the screen plate. The particles velocity on the screen deck shows a decreasing distribution along the screen deck length and the decrease of velocity changes from steep at the feed end to flat at the discharge end. The instantaneous efficiency of banana screen can reach to above 0.95 and the efficiency of steady state is about 0.83. Numerical simulation results can provide references for insight understanding of the banana screening mechanism and optimization of banana screen.

Using SPH one-way coupled to DEM to model wet industrial banana screens

Large banana screens with multiple decks are used extensively in the process separation of many valuable export commodities. They are high capacity vibrating screens with a curved profile. Discrete Element Method (DEM) modelling using non-spherical particles has previously provided significant insight into the operation of these dry industrial screens. Here we introduce the use of Smoothed Particle Hydrodynamics (SPH) to model the flow of slurry (water and fine material) through a double deck banana screen. This paper firstly reports on the underlying DEM model of the coarse particulate flow on a full-scale banana screen. We then use Smoothed Particle Hydrodynamics (SPH) to model the transport of fine particle slurry over and through the double deck banana screen. Finally, we combine the DEM with SPH models using a one-way coupling to simulate the effects of adding a slurry flow to coarse particulates on the banana screen. The key outcomes from this study are that; SPH is ideally suited for the high speeds and the high fragmented and filamentary nature of the fluid flow through the screen deck openings; the fluid only (SPH) model of slurry behaves similarly to the DEM approach in that more fluid is screened as the velocity slows, except near the earlier panels on the top deck; and, use of a porous media derived from DEM in one-way coupled approach with SPH produces clear and reasonable changes in fluid structure, separation and wetting of the screens consistent with slurry behaviour. Specifically, the fluid layer was much thicker in the coupled case, with slurry being trapped inside a coarse particle bed and which is sensitive to the fluid viscosity.

Separation performance of double deck banana screens – Part 1: Flow and separation for different accelerations

Banana screens are often used for high capacity separation of iron ore, coal and aggregates into different size fractions. They consist of one or more curved decks that are fitted with screen panels with arrays of square or rectangular holes. The screen structure is vibrated at high frequency to generate peak accelerations of around 4–6 g which separates particles flowing over each screen according to their size. Screens are often used to close comminution circuits and return specific size fractions of rock to different destinations such as pebble mills, crushers and back into the mills. All multi-deck screens are difficult to sample for intermediate products which makes measurement and optimization very difficult. Banana screens are even more difficult because the screen cut size varies with the varying slope of the decks. In this paper, the discrete element method (DEM) is used to simulate a full industrial scale double deck banana screen for a range of accelerations. The nature of the particle flow through this complex machine is explored for a range of peak accelerations. Critical aspects of the flow are linked to the separation performance.

Separation performance of double deck banana screens – Part 2: Quantitative predictions

Banana screens are often used for high capacity separation of iron ore, coal and aggregates into different size fractions. They consist of one or more curved decks that are fitted with screen panels with arrays of square or rectangular holes. The screen structure is vibrated while a dense stream of particles flows over it and is separated according to size. The material discharging from the top of the deck is the oversize and may become a coarse product or be crushed and recycled to the screen feed. The material falling through the deck can be further separated by additional decks below. Each lower deck returns a product stream and the material passing out through the bottom deck is the undersize. In this paper, Discrete Element Method (DEM) is used to explore the separation performance of a full industrial scale double deck banana screen for a peak acceleration of 5 g. The separation efficiency of each deck is analysed and the individual contributions of each screen panel are assessed using outputs from the model. Residence time distributions for particles on each deck provide insight into both the transport characteristics along the deck and the separation performance through each deck. The top and bottom decks have very different flow behaviour with very different bed structure and motion. The stresses applied by the flowing particles to the screen cloths and the impact and abrasive wear on the screen surfaces are evaluated. Finally, the energy absorbed by particles provides insight into the extent of particle degradation produced by transiting the screen.

DEM simulation of particle flow on a multi-deck banana screen

Banana screen is an important innovation in screening process in the past decades to improve screen capacity. Although, it is increasingly employed in the mineral industry, the control and optimisation are still limited due to the lack of fundamental understandings of the process. This paper presents a numerical study of the particle flow on a banana screen at a particle scale by means of Discrete Element Method (DEM). Typical 3-deck and 5-deck banana screens are simulated. The effects of operational conditions and geometry on the screen performance are studied by a series of controlled numerical experiments. The results are analysed in terms of partition curves, distributions of percentage passing and other flow information, such as particle volume and velocities along the screen deck. They are useful to the development of a better understanding and the control of banana screening processes.

Particle methods for modelling in mineral processing

The Discrete Element Method (DEM) is a computational method that is well suited for modelling flows of particulate materials in mineral processing. Smoothed Particle Hydrodynamics is a particle-based method for modelling fluid flows and is highly compatible with DEM allowing relatively easy coupling of particulate and liquid phases. In this article, we will explore recent modelling of some important unit processes used in mineral applications using these particle-based methods. Specifically, models of a particle and slurry motion are presented for a full three-dimensional semi-autogenous mill at several different scales. These are used to explore particulate motion in the charge, slurry motion within the charge, discharge through the grate and pulp lifter system and the varied breakage processes occurring within these machines. The importance of rock shape and its evolution on the balance of breakage mechanisms within the mills are discussed. Finally, an example of application of DEM to predict particle behaviour in a twin deck vibrating banana screen is presented.