Principles of Mineral Processing and How Inclined Screens and Screen Size Matter

December 4, 2018

On a large-scale mineral processing deck, moving parts orient themselves when aggregate loads drop free of vibratory feeders. Everything about the equipment feels kinetically charged, so there are motors buzzing and powered solenoids snapping shut. Still, among all the energized machine parts, inclined screens are performing their own role in the mineral processing sequence. Angularly adjusting to suit any demand, they perform their aggregate sorting magic.

Intelligently Oriented Inclined Screens

The goal here is to strike a balance. The correct screen angle is set, and that inclination is determined by the process engineer, who selects the screen media, aperture size, and aggregate velocity. Now, as the feed section discharges its mineral load, gravity takes over. The inclined screen also employs vibrational momentum, courtesy of a pair of mounted motors, but it’s gravity that sets the aggregate tumbling downwards. Using flight trajectory formulas, the behaviour of the loose matter is now brought under control of the mining equipment. The vibrating motors impart energy, the screen angle and gravity introduce forward and downward motion, and the steep relapse angle increases the chance of an aperture hit.

Inclination-Related Screen Sizing

What material and kinetic factors influence screen size selection? Why does the link between inclination angle settings and screen size impact flow efficiency? Well, undesirable aggregate channelling events occur when this angle-to-aperture size issue isn’t handled properly. Material build-up is a major problem when inclination settings aren’t optimally configured. Pegging and aggregate blinding are two of the more troubling screening hindrances. They present as clogs and pasty layers, which choke the sorting process. Stopping such mineral processing clogs, processing engineers size their screens and adjust inclination angles, but they don’t use some inefficient trial and error method to stumble upon the right screening configuration. No, they use mathematical formulas, which call upon known engineering constants, such as “gravity free fall.”

Plugging In the Equipment Variables

The aggregate type, its shape, size, and velocity, are added to the formula. Back at the equipment, there’s the number of decks and the motor stroke length to consider. Finally, with all relevant equipment and stream variables plugged into the formula, screen aperture size and deck inclination are adjusted so that the aggregate load can be processed efficiently and productively. As for a mining equipment designer’s job here, it’s to provide a screen inclination and stroke length adjustment mechanism, one that’s easy to use and one that can reliably be locked at the desired angle.

High-performance inclined screening decks switch out their differently sized sorting media panels in seconds. No tool is required to get the job done. Just as importantly, this equipment range must include an easy to use inclination adjuster that locks at any desired angle.

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