Volume of raw material handling operations is increased remarkably in last few decades in wide range of industries. Dry bulk solids are transferred and delivered with different ways. FIBC (Flexible Intermediate Bulk Container) also know as big bags are one of the most preferred way of handling bulk materials in granular and powder form. Well designed big bag handling systems are needed to be able to fully benefit from big bags.
Modular design of big bag unloading systems make them easy to be configured for each application need. While standard models have simple frame and discharge hoppers, high level models have complete solution in single main frame. Big bag unloading, product storage, dust collection, dosing and conveying can all be done in single unit.
Big bag unloading stations are also known as big bag discharging stations, bulk bag emptying units, FIBC dischargers, FIBC unloaders, FIBC emptiers, super sack dischargers, container bag unloaders, container bag dischargers, super sack unloaders and super sack emptiers.
Silo loading systems connected to big bag unloading stations are used for unloading raw materials from FIBC bags and fill them to storage silos. Silo loading can be done by mechanical conveyors or pneumatic conveying systems.
Pneumatic conveying systems installed after bulk bag unloading units transfer the bulk material through conveying pipelines to fill silos. This configuration is useful in applications where high transfer rates and long conveying distances are needed. In production lines where raw materials are stored in warehouses far from storage silos, big bag unloading stations can be installed closed to warehouses and pneumatic conveying systems are used to fill silos from long distances. This design prevents extreme use of forklifts and cranes for bulk material transfer in production site and increases overall efficiency.
Pneumatic transfer systems used for silo loading utilize blower pumps or compressors. Motor power, pipeline diameter, equipment selection depends on type of bulk material, transfer distance, silo height and transfer capacity. Level sensors, jet filters and other equipment are installed on storage silos to properly run silo filling system.
Mechanical conveyors can be used for silo loading from big bag unloading stations. Screw feeders, bucket elevators, rotary valves or chain conveyors are connected to big bag unloading stations to fill silos. Conveying equipment selection directly depends on conveying distance, height, transferred material and capacity. Bucket elevators are preferred for high silos. Screw feeders are preferred for shorter silos and short distances. Big bag unloading system can be installed on top of silo for faster filling. In this case rotary valve or butterfly valve are better choices which provide simple flow control. Dust collection systems may be needed depending on dust content of bulk solid. During silo loading, air content in the silo escapes to the atmosphere and carries some amount of dust together. Having vacuum fan and jet filter, dust collectors prevent any dust emission to the environment. Collected dust is sent back to the silo and product loss is prevented.
Bulk material stored in big bags can be filled into small bags automatically. Big bag unloading systems have optional built in bag filling units. For low filling capacities, these units are installed below the big bag discharge hopper and provide practical and cost effective solution. Big bag unloading and bag filling operations can be handled on single compact system. For higher bag filling needs, bag filling machines are installed near bulk bag unloading stations. Pneumatic conveying systems or mechanical conveyors are used to transfer bulk material from FIBC bag unloading station to bag or sack filling system.
Mixer automation systems are used to mix dry bulk solids with respect to certain recipes. Raw materials that are delivered within FIBC bags can be transferred to mixing units by combination of conveying equipment and bulk bag unloading system. Depending on type of application, pneumatic conveying or mechanical feeding systems can be used to fill mixers. Big bag unloading stations can be manufactured with built in dosing system. Amount of raw material to be loaded into the mixer is controlled automatically by the help of weighing and dosing system. Dust collectors can be used to prevent dust emission during mixer filling.
Dry bulk packaging systems are used to fill powdered or granular materials into bags, drums, jars, sacks etc. Bulk materials that are delivered within big bags are to be transferred to packaging machines without interruption. Loading hopper of packaging system should be kept full during filling and packaging. Big bag unloading systems can monitor the product level in loading hopper and maintain constant level automatically. Depending on packaging speed, mechanical conveying systems or pneumatic loading systems can be selected. Dust collectors can be used to prevent dust emission during hopper loading for materials with high dust content.
Big bag unloading systems can deliver dry bulk solids in powder and granular form to weighing and batching systems. Loading hopper of weighing system should be kept full during dosing and batching. Big bag unloading systems can monitor the product level in loading hopper and maintain constant level automatically. Depending on dosing speed and conveying distance, mechanical conveying systems or pneumatic loading systems may be used. Dust collectors can be used to prevent dust emission during hopper loading for materials with high dust content.
Bulk tanker trucks or open trucks are sometimes filled with powdered materials delivered within FIBC bags. These systems are generally composed of bulk bag unloading station, mechanical or pneumatic conveyor and loading bellow. Big bag unloading station transfers the bulk solid from big bag to conveying system. Conveying system transfers it to truck loading area. And loading bellow is used to fill tanker truck without any dust emission. Since truck loading operations are done within limited time, high capacity big bag discharge systems and bulk material conveying systems are used. For short distances, screw conveyors are preferred to transfer material from big bag unloading station to truck loading chute. For long conveying distances, pneumatic conveying systems provide better service. There may exist a storage hopper or silo above bulk truck loading bellow to compensate material flow between inlet and outlet. Bulk bag discharge and truck filling systems have automatic control system that monitors product level in truck and operates all equipment accordingly. Optional weighing system can be added to measure the amount of material that is filled to truck.
Big bag unloading systems can be supplied with wide variety of equipment for further conveying of the unloaded product depending on type of application.
Rotary valves provide controlled product flow from bulk bag unloading station to the down stream system. Dry bulk materials can be fed into mixers, tanks or other mechanical conveyors through rotary airlocks. Blowing seals are used to feed pneumatic conveying systems and ensure sealing of pressurized air in the pipeline.
Bulk solids in the big bags can be transferred to other handling systems with the help of screw conveyors installed below the big bag unloading unit. Screw conveyors can be used to transfer products to packaging machines, production lines, mixers or other similar equipment.
Slidegate valves can be installed below the discharge hopper of bulk bag unloading station. Product flow speed can be controlled by adjustable valve blade. Manual handwheel or pneumatic piston can be used on slidegate valves depending on type of application.
Butterfly valves placed on the big bag unloading system are simple valves used to open and close product flow in short time. Butterfly valves can be controlled by manual handle or pneumatic actuator.
Dosing systems feed processes with controlled amount of bulk materials. Depending application requirements, volumetric or gravimetric dosing systems can be installed on bulk bag unloaders. PLC or computer controlled dosing systems are available.
Instead of mechanical conveyors, pneumatic conveying systems are preferred in processes where the bulk bag unloading stations are far from feeding points. Pneumatic conveying equipment and pipeline are connected to bulk bag unloading systems. Powdered or granular bulk materials are transferred from bigbags to pneumatic conveying system and then conveyed to the required points. Depending on type of application, pressure conveying system or vacuum conveying system can be installed.
Big bag unloading stations with built in dense phase pneumatic conveying systems are used in applications where high conveying capacities and long distances are needed. Big bag unloading hopper is installed above a pressurized tank also known as pressure vessel. Several big bags are unloaded in one time to the pressurized tank. High pressure air is used to pressurize the tank and send the product through the conveying pipeline. Dense phase pneumatic conveying systems are generally preferred for materials like cement, calcium carbonate, PVC, soda and fly ash where high transfer capacities are needed.
Outlet of big bag unloading station is kept free of any equipment. Unloaded bulk solids move freely to down stream system.
Wide range of big bag unloading stations are available with respect to different applications. Big bag unloaders can be configured according to bulk solid types (powdered, granular, abrasive, food etc.) application types (silo filling, mechanical conveying, pneumatic transfer, mixer feeding etc.)
Big bag unloading systems can be provided with wide range of optional components and accessories for different application needs.
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