FIBC Unloading:
A complete guide for disposable bulk bags
What's in the guide
1. Introduction
Flexible Intermediate Bulk Containers (FIBCs), commonly known as bulk bags, big bags, bulker bags, or bulka bags, revolutionised material handling operations across industries. These versatile containers, particularly disposable (single-trip) FIBCs, offer an efficient method for transporting and discharging bulk materials in manufacturing and processing facilities.
Disposable FIBC bags are single-use containers designed for one-time transport and discharge of bulk materials. These large, flat-bottomed bags provide a cost-effective solution for applications where cleaning and bulk bag recycling aren’t practical or economical. They’re particularly valuable in industries where cross-contamination must be prevented or where the costs of cleaning and returning bags outweigh the benefits of reuse.
The success of any bulk material handling operation heavily depends on selecting the right bulk bag unloading system and understanding its capabilities and limitations. This guide is part two of a 3-part series which covers intermediate bulk containers (IBCs), disposable FIBCs and reusable FIBCs. Each guide explores the various methods, components, and considerations essential for engineers and system integrators working with IBCs and/or FIBCs.
2. Getting bulk material out: key methods and considerations
There are two main methods for emptying materials from FIBC bulk bags: vacuum unloading and bag splitting. We’ll discuss each one in detail.
Vacuum unloading
Vacuum systems are one of the most controlled methods for extracting material from FIBCs, offering particular advantages for fine powders and materials that require careful handling. These systems use negative pressure to transfer materials through enclosed pipework, minimising dust emission and product loss.
System components include:
- Vacuum pump or blower sized to material characteristics
- Filter system to prevent product loss
- Collection hopper
- Discharge valve for controlled material release
- Pipeline system with appropriate diameter for material flow.
Key advantages for vacuum unloading of bulk bags
Vacuum unloading provides fully enclosed material transfer with minimal dust generation.
- Flexible routing options are available
- Good for remote discharge locations
- Compatible with automated systems
Challenges with vacuum unloading
Vacuum unloading of bulk bags tends to be a slow and inefficient option for FIBC unloading. Using a vacuum to empty bulk bags is extremely time-consuming, very loud, and fairly costly in terms of energy consumption and filtration. The following must be considered when selecting a vacuum unloading method:
- Significant power required for operation, typically 5-15 kW depending on capacity
- System sizing critical for efficient material flow
- Not suitable for cohesive or very dense materials
- Susceptible to lumping and clumping leading to blockages
- Regular maintenance of filters and seals required
- Require compressed air for filter cleaning.
Design considerations for vacuum unloading
- Piping radius should be at least 3x the particle size of the materials being handled
- Vacuum pressure typically ranges from -0.3 to -0.5 bar
- Filter area should be sized for material characteristics
- Consider material moisture content and temperature
- Account for system pressure losses.
Split bag methods of FIBC unloading
Split bag unloading involves creating an opening in the FIBC to allow material discharge into a bulk bag chute. This method is particularly common with disposable bags where bag preservation isn’t necessary, and it offers a straightforward approach to material handling. There are two primary approaches to splitting bags: manual cutting and engineered splitter frames.
Manual knife/blade method for FIBC
The most basic approach involves operators manually cutting bags using handheld tools like sickles (also called a reaper knife) or utility knives. While this manual unloading method has the lowest equipment cost, it presents challenges and risks that may not be manageable in a modern bulk material handling process. Manually cutting bulka bags then lifting them to empty into a bulka bag chute does not lend itself to precision bulk bag handling. Bulk bag disposal may also be a challenge, depending on the volume of bulker bags used in a process.
Challenges with manual FIBC splitting
- High risk of operator injury
- Inconsistent bag opening and material flow
- Limited control over material discharge
- Significant dust generation and limited options for dust control
- Potential for bag material contamination
- Difficulty maintaining clean operation
- Poor repeatability between operators
- Risk of uncontrolled material spillage
- Higher labour costs and slower operation.
Safety concerns for manual bulk bag splitting
- Direct operator exposure to cutting hazards
- Awkward cutting positions
- Potential for repetitive strain injuries
- Exposure to dust and material
- Risk of falling material during cutting
- Limited emergency stop options.
Splitter frame systems for FIBC
Splitter frames represent an engineered solution for bag opening, offering greatly improved safety and operational benefits. These systems are available in two main configurations: X-blade and U-blade arrangements.
An image of an X-blade cutter arrangement.
An image of a U-blade cutter arrangement.
X-blade arrangement
- Used for flat bottom bags (no spout)
- Bottom of bag is cut into four triangles, opening bag from corner to corner
- Provides largest opening for minimal bag residue
- Easily accommodates a grid underneath the splitter without needing additional height
- Ideal for high-throughput operations.
U-blade arrangement
- Designed for bags with a bottom spout
- Three-bladed cutting arrangement cuts around the FIBC spout
- A U-shaped flap is created for product to flow through
- More likely to need discharge aids due to smaller bag opening
- May need additional height on the frame to accommodate spout chamber.
Common benefits of splitter frames for a big bag
- Controlled and consistent bag opening
- Reduced operator intervention
- Integrated dust control options
- Improved safety compliance
- Predictable material flow
- Lower labour requirements
- Better process control
- Reduced material waste
- Enhanced plant cleanliness
- Lower risk of product contamination.
Splitter frame design considerations
- Load capacity (typically 1,000-2,000 kg)
- Frame material selection
- Corrosion resistance requirements
- Maintenance access
- Safety factor calculations
- Integration with dust control systems
- Compatibility with handling equipment
- Future expansion capability.
3. FIBC unloading: essential components and accessories
Dust control options
Effective dust management is crucial for operator safety, reducing material wastage, and environmental compliance. Three main approaches offer increasing levels of dust control.
Rubber skirts/skirting
The most basic dust control option, suitable for non-critical applications.
Features of rubber skirts
- Flexible rubber construction
- Simple attachment methods
- Basic dust containment
- Easy replacement
- Cost-effective solution.
Ideal applications for rubber skirting in FIBC unloading
- Non-hazardous materials
- Limited dust generation
- Basic containment needs
- Budget-conscious operations
- Temporary installations.
Limitations for rubber skirts as a dust containment method
- Limited effectiveness
- Wear and tear concerns
- Basic sealing only
- May require frequent replacement
- Not suitable for fine powders.
Dust extraction manifold
A dust extraction manifold is the most comprehensive dust control solution, suitable for critical applications when unloading powders from bulk bags. This is the preferred method for high-performance powder handling operations.
System components
- Extraction hood
- Airflow management
- Filter systems
- Monitoring equipment
- Control integration.
Performance features
- Maximum dust control
- Process monitoring capability
- Integration with facility systems
- Regulatory compliance
- Data collection options.
Design considerations for dust extraction manifolds
- Airflow calculations
- Filter selection
- Pressure drop analysis
- Maintenance access
- Energy efficiency.
Material conditioning and flow aids
Material conditioning and flow aids are crucial components in FIBC unloading systems, ensuring consistent and reliable material discharge. The choice between different systems depends on whether the material needs to be conveyed immediately or stored for controlled dosing. A number of flow aids exist, including lump breakers, shut-off valves, weather covers, load cells for accurate dosing and/or batching, and vibrators. We’ll discuss two main components here: Disposable FIBC Unloader (DFU) and the Dosing Screw Feeder (DSF).
Disposable FIBC unloader (DFU)
The DFU is specifically designed to discharge material directly into conveying systems, making it ideal for continuous processing operations. DFUs come in single or dual stations. A dual station optimises capital costs as both bulk bag unloaders can feed into a single conveyor. In addition, consolidated conveying results in reduced operating costs.
A DFU is also ideal for incorporating loss-in-weight dosing or batching into the process. The DFU is mounted on load cells and, when paired with a dosing screw feeder, it can metre out whatever amount of material is needed into the process. This is commonly used with flocculant and other treatment systems.
System features
- Direct conveyor integration
- Integrated storage hopper
- Level monitoring
- Controlled discharge rate
- Dust containment systems
- Safety interlocks
- Quick bag change capability
- Suitable for forklift loading.
Best suited to
- Continuous production lines
- Direct process feeding
- Offset unloading from reusable FIBC unloaders
- Offset unloading from disposable FIBC unloaders
- Automated operations
- High-throughput requirements
- Space-constrained installations.
Benefits of disposable FIBC unloaders
- Minimal material storage required
- Continuous material flow
- Buffer storage capacity
- Reduced handling steps
- Efficient space utilisation
- Lower risk of contamination.
Not recommended for:
- High throughput applications requiring a surge/buffer hopper
- Raw materials requiring bridge breaking and conditioning aids to discharge from the FIBC.
Dosing screw feeder (DSF)
A DSF system incorporates storage capability with controlled feeding through a screw feeder, providing precise material dosing for downstream processes.
Design elements
- Precision screw feeder
- Variable speed control
- Controlled discharge rate.
Best suited to:
- Accurate metering/dosing
- Gravimetric batching (loss-in-weight)
- Formulation systems (with load cells)
Benefits
- Accurate material dosing
- Controlled feed rates
- Process rate matching
- Batch processing capability
- Conveys hazardous material safely and without contamination
- Discharges directly to a Floveyor aero-mechanical conveyor (AMC) or tubular drag conveyor (TDC) via circular dropouts.
Not suitable for:
- High accuracy precision dosing (<1 kg accuracy)
- Friable or fragile materials (material testing recommended before purchase)
- Material blends sensitive to segregation (material testing recommended before purchase)
- Conveying distances exceeding 2 metres (6 ft 7 in).
4. Bulk material conveying options
Floveyor disposable FIBC unloaders have a modular design so each piece fits together seamlessly. This makes for a highly efficient, contamination-free conveying operation that’s devoid of dust.
Aero-mechanical conveyors (AMC)
AMCs offer efficient material transport with minimal product degradation. A high-efficiency motor drives an internally circulating rope assembly at high speed within the conveying tubes. Bulk material is fed into the feed housing and accelerated into the conveying tubes by the rope assembly. Conveying discs and low-pressure air pockets combine to suspend bulk material and draw it rapidly but gently to the discharge point.
System components
- Rope and disc assembly
- Fully enclosed tubes
- Drive system
- Discharge housing
- Feed housing
- Rope tensioner mechanism
- Control system
Performance characteristics
- High throughput capability (up to 100 m³/hr)
- Gentle material handling
- Low power consumption
- Minimal maintenance
- Flexible routing options
- Clean-in-place (CIP), Clean-out-of-place (COP), dry cleaning with inert air or gas
- Minimal material-on-material contact
- Minimal material-on-equipment contact.
Applications
- Dry powders and granules up to 12 mm (0.5 in) in size
- Friable materials
- Mixed material sizes
- Variable feed rates
- Complex routing requirements
- Clean environments, including hygienic food processing
- Straight-line installations
- 24-hour-per-day operations
- Process temperatures from -5°C (20°F) to 120°C (250°F)
- Batching operations where total batch transfers are desirable.
Advantages of modular design for AMC and FIBC unloaders
A Floveyor AMC paired with a Floveyor FIBC unloader is one of the most effective and reliable solutions for getting your bulk materials into your plant, a storage vessel or a road vehicle. This is a proven solution for decanting materials from flat-bottomed bags. It opens the bag completely on the first attempt. Contamination from strings and torn plastic are minimised, ensuring workplace and environmental safety by containing dust and spillage.
Tubular drag conveyors (TDC)
TDCs convey across multiple planes at slow speed to handle multiple outlets. The fully enclosed system and rope assembly are designed for industries requiring a more stringent level of cleanliness and safety in bulk material handling.
TDC design features
- Enclosed tube construction
- Rope and disc assembly
- No contamination risks from chain-on-chain wear
- Multiple inlet and discharge points
- Modular design
- High reliability
- Complies with food-safe standards
- Flexible layouts
- Available in straight-line and horizontal configurations
- Conveys materials around bends and corners, and vertical elevations
- Operates in two directions using bi-directional rope assembly
- Starts and stops under load.
Operational benefits
- Dust-tight operation
- Low maintenance requirements
- Energy efficient
- Quiet operation
- Minimal product degradation
- Conveys over long distances
- Conveys across multiple planes
- Low breakage and material wastage
- Maintains batch and blend integrity
- Lower maintenance costs
- Excellent for materials that may suffer from cohesiveness and agglomeration.
Typical applications
- Abrasive and explosive materials
- Dusty products
- Multiple discharge points
- Temperature-sensitive materials
- Clean-in-place requirements.
FIBC screw feeder for disposable FIBCs
A large surge hopper on a screw feeder accommodates the complete volume of an emptied disposable FIBC. The integrated screw feeder provides accurate modulation of material flow using a variable speed drive.
FIBC screw feeder design features
- Integrated FIBC cutting blades
- Dust sealing membrane
- Bump railing
- Bridge to protect screw flighting
- Removable safety grid
- Connection for dust extraction
- Manoeuvrable using a forklift.
FIBC screw feeder with dual stations
For those plants requiring high throughputs or continual operation, a dual station screw feeder for disposable FIBCs is available. All the design features of a single FIBC screw feeder are in place with the addition of redundant surge hoppers for continuous forklift operation.
Case study: Successful disposable bulk bag unloader implementation
Hydrated lime example
Floveyor provided a global lime supplier with a relocatable truck loading system for safely handling hydrated lime across multiple sites in Australia and New Zealand. Hydrated lime is highly caustic and generates hazardous dust, requiring robust containment. Floveyor’s Endura Truck Loader F5 features an integrated dust extraction system, 54 TPH unloading rates, and an 1800 L storage hopper. Designed for mobility, it can be detached and transported easily. Since 2015, these systems have enabled efficient, high-volume transfer while maintaining safety and environmental compliance, reinforcing a strong partnership between Floveyor and the client.
Read the full case study: Relocatable truck loading system for global supply of hydrated lime
Conclusion
Selecting the right disposable FIBC unloading system requires careful consideration of material properties, operational needs, and facility constraints. Success depends on matching the unloading method and accessories to specific application requirements while maintaining focus on safety, efficiency, and cost-effectiveness.
Consider these key takeaways:
- Evaluate material characteristics thoroughly before system selection
- Match system capabilities to operational requirements
- Consider total cost of ownership, not just initial investment
- Plan for future capacity needs and system flexibility
- Prioritise safety and maintenance accessibility
- Work with experienced suppliers for optimal system integration
- Look for manufacturers offering modular design to maximise operational performance.
Remember that while initial costs might favour simpler solutions, the total cost of ownership should include considerations for maintenance, operational efficiency, and potential material losses. Working with experienced suppliers who can provide modular, integrated solutions often leads to better long-term outcomes, lower total cost of ownership and more successful installations.
Get in touch with Floveyor
Gain efficiency with Floveyor disposable FIBC bulk bag unloading solutions. Optimise your bulk material handling, improve operator safety and reduce downtime. Contact us for more information, or get a quote.
