A large U.S. plastics compounding manufacturer required a bulk bag unloading system capable of discharging and conveying calcium carbonate at flow rates up to 9,000 lb/hr. The material has a bulk density of 30-80 lb/cu ft. To meet the company’s challenge, Metso BEST Inc designed and manufactured a system that incorporates both standard and custom-made components.

The system’s basis is Metso BEST’s Model BBU heavy-duty, 4,000 lb capacity bulk bag unloader with 1,800 rpm, ¾ hp vibratory-motor agitation. Standard features include bag-transport frame, upper bag-support frame, and heavy-duty rubber hopper isolators. (Shown here, bulk bag unloader with screw conveyor is tested in Metso BEST's on-site facilities to ensure successful integration of the controls with the bulk handling equipment prior to shipment.)

System requirements include a 20 cu ft storage hopper and 12 ft long screw conveyor. To offset the difficulty of conveying calcium carbonate and ensure optimum system performance, Metso BEST engineers doubled the screw-conveyor motor’s normal horsepower and increased the conveyor’s standard shaft size. A 2 ton electric hoist, powered trolley, and monorail were added to allow safe, easy bag changes. Finally, an easy-to-use control panel was designed and built in Metso BEST’s UL-listed, in-house panel shop.