The filter aid bulk bags are supplied with lift loops in all four corners. These loops are attached to the bag lifting frame hooks and by electric hoist are raised to clear the hopper. The hoist is mounted on a trolley. Therefore, the bag can easily be pushed into place over the center of the hopper. The discharge chute of the bulk bag is placed through an iris valve into the discharge box. The iris valve is then closed, the discharge chute untied, and the discharge box door closed. After opening the iris valve, the bulk bag is now ready to dispense the filter aid into the hopper as needed. The hopper, in turn, feeds the lower end of the conveyor that discharges the filter aid to the mixing tank. When the desired amount is delivered, the iris valve is closed and the conveyor is stopped.

The bulk bag unloading system is equipped with bag activators which raise and lower opposite bottom sides of the bag. This promotes filter aid flow into the discharge chute. As the bag empties, the raising action increases until the activators cause a steep "V" shape in the bag. This ensures that the bag will be completely emptied.

The hopper design includes a vibrator which ensures easy flow to the inlet of the conveyor. There is also a sensor which will automatically stop the conveyor once the hopper is empty.