A low cost retrofit of a bag dump station to a bulk bag unloader executed by Flexicon at a speciality chemical company has upgraded safety and productivity at the plant.
ArrMaz Custom Chemicals produces speciality chemicals for the mining, water treatment, fertiliser, asphalt and construction industries at its 18,580m² manufacturing facility.
One particular ArrMaz product is a resin soap called Arr-Muls 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.
Solid resin is purchased in 50lb sacks and moved using a Flexicon manual bag dump system consisting of a hopper with a dust collector and a 22-ft flexible screw conveyor that discharges into a 6000 gallon tank. Each batch needs 20,000lb of the resin, which requires operators to lift, slit and dump 400 sacks every time.
In late 2008, Flexicon representative Harry Orr suggested that ArrMaz consider a low cost retrofit of its bag dump station to add bulk bag unloading capability. Plant Engineer Hernan Cortes decided that the retrofit was a good solution to prevent potential injury to workers from repetitive lifting and slitting of the bags in addition to eliminating the handling issues associated with disposing off 400 empty sacks per batch.
The Flexicon flexible screw conveyor was retained for its suitability with the bulk bag discharging station as well as proven resin handling capability. The existing dust collection exhaust system was also retained, but moved to a new position beside the hopper to allow positioning of bulk bag spouts directly above the hopper.
The new hardware consists of a four-post unloading frame topped by a cradle with wide receiving cups that support a removable bulk bag lifting frame, which 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. Once the bag has been opened, it allows controlled discharge of the bulk resin into the hopper, which feeds the flexible screw conveyor.
Spring-loaded Pop-Top bag extension devices in the frame 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.
Pneumatically actuated Flow Flexer plates simultaneously raise and lower the opposite bottom sides of the bag into a V-shape at timed intervals, loosening the material and directing it through the bag spout.
Following the retrofit, ArrMaz has switched to purchasing most of its resin stock in 2,205lb bulk bags, which are discharged completely into the hopper and supplemented with manually dumped 50lb sacks to achieve target batch weights of 20,000lb.
Key benefits of the retrofit added bulk bag unloading capability include almost complete elimination of manual lifting, slitting and disposing of paper sacks, and reduction in resin loading time from about 60 minutes down to 15. The retrofit also retained the operation of ArrMaz’s original bag dump station with dust collection, allowing the company to achieve accurate batch weights without investing in an automated weigh batching system.
Flexicon’s flexible screw conveyors, bulk bag unloaders and bag dump stations are available in Australia from Flexicon Corporation (Australia)