Stacking Conveyors

Stackers are notorious generators – and are also very difficult to treat – of fugitive dust. The action of the product in free fall from the head roller of the stacker generates dust as exposed surfaces interact and fines, which naturally filter down to the bottom of the belt with the action of running over conveyor idlers, are liberted as they fall off the belt. The impact point on the stockpile below also generates more dust as the product strikes the top of the pile then runs down and settles.

Where the head chute is covered or partially covered, dry fog can be applied to spray fog into the area of dust generation at the head roller. Nozzles are pointed downwards to allow agglomeration with liberated dust as the product drops, the fog also follows the product downward as it drops due to the vacuum effect of air displacement, this also helps the process. Limitations on the projection of fog from the nozzles and exposure to wind make this method less effective for longer drop heights. Curtains around the head chute can be used to protect the fog and improve performance.




Drop height is important, as the larger drop necessarily means a higher velocity at impact and more dust. Luffing stackers, extended chutes, rock boxes or cascade type chutes are all options to minimise the disturbance and drop height, and dry fog can be also be applied with these solutions to tackle fugitive dust. When used with a luffing stacker, nozzles can be projected downwards from the bottom of the stacker infrastructure to tackle impact dust at the stockpile, but this may be limited by local wind velocity. Where extended or cascade type chutes are used, a ring of fog nozzles can be mounted on a circular or hexagonal manifold to combat dust as it exits the chute and on impact with the stockpile.