Martin Engineering business development specialist – vibration – Susie O. Bartoli provides an outline on higher efficiency meshing processes for mining.
Quarrying and mining operations rely on screen vibration for various purposes, but they often encounter similar problems.
If the screening rack is properly engineered to accommodate the weight, volume, and type of motion, then the support structure will rarely require maintenance.
However, vibration is commonly created by a vibratory motor with moving parts that continually combat resisting forces, as well as the harsh industrial environment of bulk handling, which inevitably reduces equipment life.
Volumes and vibratory screening
As demand for mineral resources has steadily grown, bulk handlers and material recyclers have continually increased production volumes. When it comes to screening, this can impact the quality and accuracy of the separation process.
Simply increasing the volume or speed of throughput might require the material to undergo several passes to achieve proper separation.
Factors operators need to consider in vibratory screening applications:
- Efficiency – The volume of the material stream determines the amount on the screen, which can influence how well it is separated.
- Material – The speed, volume, and desired output of screening are dependent on the properties and angle of repose of the application.
- Angle of repose – The angle of repose is how the material spreads naturally across the surface. The loading method and type of vibratory motion assist in even distribution across the screen.
- Screen design – First, the screen must be able to withstand the additional weight. Then, whether dewatering or separating, the grid pattern, permeability, and type of vibratory motion need to promote the application’s separation.
- Effective Slope – The angle of applied vibration determines the speed at which the material moves down the screen. Gravity, amplitude, and frequency are factors in the screen’s effectiveness.
- Vibratory amplitude and frequency – Increasing either the amplitude or the frequency will increase the volume of material moving through the system.
- Vibratory motion – There are two general vibratory motions, linear (back-and-forth or up-and-down), and elliptical (rotational).
Electric and hydraulic screen vibrators
The weight and volume of the bulk handling environment require a powerful vibrator to do the job effectively.
While electric screen vibrators are common, hydraulic vibrators are more applicable for portable screen applications where no electricity is available.
The movement of a hydraulic screen vibrator is driven by a hydraulic pump that delivers pressurised fluid to the motor.
The motor then converts the fluid power into rotational motion, which is transferred to eccentric weights. Eccentric weight is a rotating mass that is offset from the centre of rotation, creating an unbalanced force.
Industrial electric vibrators for material screening should use inverter-duty rated and Class H insulated windings to prevent overheating in continuous-duty environments.
Martin Engineering’s Screen Vibrators produce up to 16,500 lbs (7483 kg) of centrifugal force. The adjustable eccentric weights tailor performance for 3- or 4-panel screens, featuring low-maintenance, greaseable, long-lasting cylindrical roller bearings.
The high-strength cast aluminium cases are IP66 rated for dust and water protection with available explosion-proof models that bear the cETL, ATEX, and IECEx marks for use in hazardous locations.
An example of a hydraulic screen vibrator is the Martin Hydraulic Screen Vibrator, which provides up to 8,300 lbs (3855 kg) of centrifugal force for efficient material separation. The IP66 enclosure ensures a dry and grit-free internal environment and uses the same mounting bolt patterns as electric vibrators.
Conclusion
Proper vibration is essential, but it is also a wear part, so high-quality, durable equipment is vital to prevent excessive downtime. A well-constructed system, along with proper calibration and placement of vibrators for the application, is essential for efficient and optimised screen separation.
To further extend the equipment’s life, these systems should be easy to maintain and accessible, ensuring both workplace safety and lower operational costs.