Ore sieving forces fall in line as soon as they reach a screen. At least that’s the theory. In reality, a few processing factors can adversely affect screening decks. Flow wetness is one of those factors. Bear in mind, this is a mining environment, which means there are uncontrollable geological elements in play. To deal with the moisture, a smart equipment designer knows what damage this watery spoilage can elicit.
Mining Equipment Flow Facilitation
Mechanically dynamic, a pair of electric motors generate the necessary vibrational energy. The ore oscillates on the screen media until it’s sieved, sorted and sent on its way. Screen inclination comes next. As the deck oscillations reach their operational stride, at approximately 3500 RPMs, the tilted screen media calls upon the aid of gravity. Typical inclination angles occupy the 15 to 35 degrees range. Then there’s the speed of the ore to add to the mix. Moving fast, the multi-tonnage loads are held in check, this time by a series of rubberized bumpers, plus the equipment’s alloy-reinforced frame. Last in the assembly of flow-controlling parts, the sized screening media filters the ore.
Dealing with Screen Moisture
With almost everything under control, the ore wetness problem throws a spanner in the screening works. It’s joined by a second, even harsher nuisance factor. There’s dust in the air. It’s flowing as a cloud around the wet ore. That gritty material mixes with the deck moisture to clog the screen apertures. It doesn’t look like much at first, but as the fines mix with deck moisture, the mucky coating thickens. The clogs are a processing obstacle, sure, but there’s a second problem, and it’s growing worse at a worrying rate. Simply put, as the airborne fines and ore wetness join together to form that screen defeating mush, the deck oscillating motors start to overload. Heat is generated as the twin motors attempt to handle the extra weight, then they begin fluctuating wildly. Stressed as the oscillating assembly hits its upstroke, the moving parts suddenly accelerate as the machinery enters its downstroke.
There’s a big price to pay when this muck is left to accumulate. Granted, system clogs will lower a mining facilities productivity figures. More significant if harder to detect faults are to come, though. The oscillating parts are bending and warping because of the extra load. Screen sheet wear is inevitable, too. One solution is to push the issue away from this ambiguous configuration. Left like this, it’s neither wet or dry, just moist and doughy. Mining engineers accomplish this feat by either adding clog-dissipating water sprays or by reducing the number of fines present in the ore stream.