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Low cost retrofit of bag dump station to bulk bag unloader upgrades safety, productivity at specialty chemical company

MULBERRY, FL — ArrMaz Custom Chemicals produces specialty chemicals for the mining, water treatment, fertilizer, asphalt, and construction industries at its 200,000 sq ft (18,580 sq m) manufacturing facility here. Since its beginning as a phosphate producer in 1967, the company has introduced numerous products and expanded its markets into 70 countries.

In addition to extensive quality control and customer service programs, the company has implemented a "Total Safety Culture" procedure to protect both its employees and the subtropical ecosystem of central Florida. In a number of ways, ArrMaz goes beyond OSHA and environmental regulations, to the extent of operating the majority of its open air manufacturing facility under a roof to provide safe working conditions while minimizing storm water runoff.


Adding bulk resin to an agitated tank

One ArrMaz product is a resin soap called Arr-Muls that is used as an emulsifier in slow-setting asphalt and as an air-entrainment agent in masonry cements. The process uses heat and agitation to dissolve a solid resin into sodium hydroxide or potassium hydroxide to produce an aqueous soap solution.

To move the solid resin, which was purchased in 50 lb (22.7 kg) sacks, the company originally installed a Flexicon manual bag dump system consisting of a hopper with a dust collector and 22 ft (6.7 m) flexible screw conveyor that discharges into a 6000 gal (22,713 l) tank. Each batch requires 20,000 lbs (9090 kg) of the resin, which required operators to lift, slit and dump 400 of the sacks.

In late 2008, ArrMaz considered a low cost retrofit of its bag dump station to add bulk bag unloading capability. Plant Engineer Hernan Cortes liked the idea of preventing potential injury from repetitive lifting and slitting, and of eliminating the wasted product and handling associated with disposing of 400 empty sacks per batch.

The Flexicon flexible screw conveyor was retained since it is not only well suited for use with a bulk bag discharging station, but also has handled the resin effectively despite the material's tendency to interlock and degrade. The existing dust collection exhaust system was also maintained, but moved from above to beside the hopper to allow positioning of bulk bag spouts directly above the hopper.

The new hardware consists of a four-post unloading frame, at the top of which is a cradle with wide receiving cups that support a removable bulk bag lifting frame that is raised and lowered using a forklift, allowing operators to connect full bags and disconnect empty ones at floor level.

A conventional iris valve located atop the existing manual dumping hood prevents material flow from the bulk bag while the bulk bag is being untied and once the bag has been opened, allows controlled discharge of the bulk resin into the hopper which feeds the flexible screw conveyor.

The frame is also equipped with spring-loaded POP-TOP™ bag extension devices that raise the bag-lifting frame and elongate the bag as it loses weight, promoting the flow of material from the corners of the bag through the bag spout.

Simultaneously, pneumatically actuated FLOW-FLEXER® plates raise and lower opposite bottom sides of the bag into a "V" shape at timed intervals, loosening agglomerated material and directing it through the bag spout.

With the new system in place, the company began purchasing 99+% of its resin in 2,205 lb (1,000 kg) bulk bags, which are discharged in their entirety and supplemented with manually dumped 50 lb (22.7 kg) sacks to achieve target batch weights of 20,000 lbs (9090 kg). "The retrofit added bulk bag unloading capability which practically eliminates manual lifting, slitting and disposing of paper sacks, which pleased the operators and cut resin loading time from about 60 minutes down to 15," Cortes said, adding, "At the same time the retrofit retained the operation of our original bag dump station with dust collection, which enables us to achieve accurate batch weights without investing in an automated weigh batching system."

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Low Cost Retrofit of Bag Dump Station to Bulk Bag Unloader Upgrades Safety, Productivity at Specialty Chemical CompanyClick to enlarge
Forklift operator positions bag lifting frame on top of the bulk bag unloader. The 22 ft (6.7 m) long flexible screw conveyor transports resin from the bag dump hopper into a 6000 gal (22,713 l) tank.
Low Cost Retrofit of Bag Dump Station to Bulk Bag Unloader Upgrades Safety, Productivity at Specialty Chemical CompanyClick to enlarge
Low Cost Retrofit of Bag Dump Station to Bulk Bag Unloader Upgrades Safety, Productivity at Specialty Chemical CompanyClick to enlarge
Cradle at top of the bulk bag unloader supports the removable bulk bag lifting frame. An iris valve between the bag spout and manual dumping hood controls the rate at which the bulk resin enters the hopper.
Low Cost Retrofit of Bag Dump Station to Bulk Bag Unloader Upgrades Safety, Productivity at Specialty Chemical CompanyClick to enlarge
At top of the unloading frame, POP-TOP™ bag extension devices raise and elongate the bulk bag, promoting flow through the bag spout. At bottom, pneumatically actuated FLOW-FLEXER® plates raise and lower opposite bottom sides of the bag, loosening material and directing it through the bag spout.
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