Question: Should we convert from manual dumping of sacks to discharging from bulk bags?
Answer: Dry, bulk chemicals have long been purchased in 50-lb (23-kg) paper and plastic sacks for several reasons. In volumes smaller than rail and truckloads, sacks were often the only packaging in which to purchase many such products. Sacks also enabled plant personnel to physically lift, slit and dump the material, and weigh batch ingredients by simply counting the number of bags dumped.
Disadvantages are significant, however, and include: the increased cost of material purchased in smaller packages, high labor cost and injury associated with manual lifting, material leakage and airborne dust contaminating workers and the plant environment, bag scraps entering the process, wasted material trapped in emptied bags, and disposal of excessive packaging waste. But the most significant problem can be weighing inaccuracy resulting from workers losing count of bags dumped, and/or poorly estimating weights for batches that are not multiples of 50 pounds.
The availability of many dry, bulk chemicals in bulk bags in the 1990s enabled processors to reduce material costs and alleviate personnel of heavy lifting, but not until the introduction of advanced bulk-bag handling equipment in the last five to ten years has the case for converting from manual dumping of sacks to discharging of bulk bags been so compelling. Processors can now choose between a myriad of bulk-bag discharger designs that fit every possible cost and performance requirement. These range from basic half frames that require a forklift to suspend the bag above a bag spout interface, to self-contained bulk-bag weigh batching systems that load the bag, condition it, discharge the contents by weight, convey it to downstream process equipment or storage vessels, and collapse empty bags — all under automated control and completely dust free.
Systems are also available that allow continuous loss-of-weight feeding directly from bulk bags, mixing into liquid streams, delumping of agglomerated material, and conveying of weighed batch ingredients mechanically or pneumatically to any interior or exterior plant location. High integrity connections of sealed bulk-bag discharging systems have virtually eliminated the very sight of bulk materials in many applications, improving plant hygiene and product quality while eliminating the cost and environmental impact of wasted product and bag scraps.
Advances in bulk-bag discharging technology, and the availability of machinery to fill specific requirements, have made converting from manual sack dumping advisable in all but the lowest-volume bulk handling applications.
David Boger is vice president sales and marketing for Flexicon Corp. (Bethlehem, Pa., www.flexicon.com)
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