Unbreakable laws physically direct differently sized particles when they’re screened. Gravity plays a part here, as does the oscillating stroke of the vibrating deck, all so that the different masses separate. But does the equipment need to deal with such paltry issues? Absolutely, for incorrectly sized mineral particles cause oversize and undersize problems, plus all kinds of end-process errors.
The goal isn’t always to get the fine mineral to a sizing aperture. In screening stratification work, the different grain sizes separate into sharply graduated layers on the screen deck. Naturally enough, the volume and flow rate used here isn’t brisk, but that sharpness-in-separation feature does have a role to play in many mining facilities. Alternatively, a fast, free-falling particle movement system comes into play when an adjustable screen alters its angle of attack. The greater deck inclination encourages particles to fall through the deck media. However, even though the flow rate is fast, the particles aren’t sized as efficiently. Clearly, an engineer must select one particle sizing approach or another, or perhaps he strives for a balanced screening effect.
Nothing is left to chance in a mining complex. In light of this level of processing diligence, the problem has gone back to the drawing board. Computer models study the assorted masses of the mining aggregate. In order to push this model to its limits, the screening equipment and media types are entered into the simulation. They include horizontally gyrating screening decks, the type that aid mineral stratification. For free-fall media, deck inclination angles are varied while the flow rate is increased then decreased. As these models resolve, the results trickle down the engineering ladder until they reach the equipment designers once more. We’ve come full circle.
The mechanical systems alter slightly to accommodate the computer models. Longer strokes are tied into the horizontally gyrating equipment when stratification layers are called for in one particular mineral processing line. In the meantime, a free-fall screening deck has swapped out its media for a new set of screens, perhaps ones that are fitted with wires or plastic panels filled with rectangular cutouts. Oversize issues fade away, undersize problems stop occurring, and the screening equipment encounters fewer feed blocking incidents.
Already, thanks to this post, we begin to understand the complex variables that surround screening decks. Gravity is the one true constant. Beyond screen inclination, though, there’s the media type, the stratification and free fall factor, and the gyrating stroke length that directs the particles until they’re sharply sized. To put it another way, it takes more than the correctly sized openings on a screen deck to control the particle sizing process in vibratory equipment.