What is carbon black and what is it used for?
Carbon black is made by the incomplete combustion of petroleum and is used as a pigment or coloring agent in ink, paint and many other substances. Due to its ability to increase resistance to wear and abrasion, carbon black is also commonly used as a reinforcing agent for tires, protective coatings and in resistors for electric circuits.
Carbon black is considered a Group 2B carcinogen, “possibly carcinogenic to humans”, therefore choosing the right conveyor that will effectively move the material whilst minimizing any possibility of potentially harmful dust emissions is essential. As with all potentially hazardous materials, wearing appropriate PPE when working in the presence of carbon black is essential for the protection of operators, even with suitable dust control solutions in place.
Carbon Black vs. Activated Carbon
Carbon black can come in a variety of forms, each with several different names, and it is often confused with the activated carbon or activated charcoal family of products.
While both carbon black and activated carbon are used as absorbing agents and both have a high surface area compared to their volume (which is what makes them both good absorbing agents), their material properties, and thus material handling difficulty, differ. So first and foremost, we will try to clarify the key differences between the key product types.
|Carbon Black||Activated Carbon (a.k.a. Activated Charcoal)|
|Source||Formed from the incomplete combustion of petroleum||Derived from charcoal|
|Applications||Reinforcing agent (ie. tires, protective coatings, resistors for electric circuit)||Filtration & purification (ie. water, air, gasses)|
|Surface Area||High surface-area-to-volume ratio (but lower than that of activated carbon)||Very high surface-area-to-volume ratio|
|Particle Size||Fine in powdered form (though can be pelletized to increase particle size)||Large, granular|
Powdered carbon black is a very fine fluid-like powder with an extremely low bulk density (typically <15 lbs/cu. ft.). These fine powders, often referred to as “fluff”, can be challenging to handle and convey. Care must be taken to avoid the powder caking and clogging the conveyor, resulting in downtime and increased safety hazards during maintenance and cleaning. Additionally, finely powdered carbon black can easily become airborne, making controlling dust emissions of utmost importance.
Pelletized carbon black (often referred to as “prills” or “beaded” carbon black) are larger particles and have typical bulk densities in the 15-20 lb/cu.ft. range. The larger particle size and higher bulk density makes this form of carbon black easier to convey. While pellets have better flow characteristics and can reduce the potentially harmful dust emissions, they can still be easily crushed during transportation or prone to breakage when being conveyed, which can eliminate many of the benefits of their use. Thus, careful consideration of conveyor type needs to be made to avoid degradation and the loss of some of the beneficial qualities of this pelletized form.
Activated carbon (also known as activated charcoal), often confused with carbon black, has significantly different material properties and is typically much easier to handle. With larger particle sizes and a more granular make up, activated carbons normally have bulk densities above 20 lbs/cu.ft and exhibit better flow characteristics compared to their petroleum- derived cousins. As a result, these products can often be successfully conveyed in a variety of conveyors such as flexible screws or tubular drags.
Carbon Black Conveyor Considerations
When designing a conveyor system for true carbon black, the first thing to consider is the format of the material that will be conveyed (powdered vs. pelletized).
If you must convey carbon black in its powdered form (“fluff”), then a fully enclosed conveyor design that can effectively move this very low density, fine powder with maximum dust mitigation will be the most important requirement. Pneumatic conveying, or the use of specialist “diaphragm” pumps, can be good options for long distances and high rates but require highly efficient air/material separators. Additionally, the resulting systems can use large amounts of energy and require regular and expensive maintenance.
If your process will allow it, using carbon black in pelletized form (prills or beads) is strongly recommended. Pellets are easier to convey and bring less safety risks associated with fugitive dust. Selecting a gentle form of conveyor will be key to prevent the friable pellets from rubbing against one another and creating carbon black dust in order to maintain the beneficial characteristics of the pelletized product. Dense phase pneumatic conveying can be a good option, but once again can have very high energy requirements.
An extremely efficient clean and reliable alternative is the aeromechanical conveyor.
Aero Mechanical Conveyor
An aeromechanical conveyor is a great choice for conveying challenging materials, like pelletized carbon black, because of its unique and gentle conveying method (see below).
Fig 2 – Particles are entrained in pockets of air between pairs of discs and gently flow through the system)
The cable assembly travels through the conveyor tubes at significantly lower speeds than dilute phase pneumatic conveying systems but is fast enough to create pockets of air which entrain the carbon black pellets in a cushion of air. This airstream with suspended particles results in significantly less shear forces than would be created in a screw or drag conveyor and minimizes breakage of the pellets and prevents caking and packing inside the tube.
The aeromechanical conveyor is also a fully enclosed dust-tight conveyor that does not require an additional dust collection system for containment since no air is being added to the conveyor to provide the motive force for the material.
Need to Convey Carbon Black?
If you are looking to move carbon black in any form or having trouble with an existing carbon black system, then ask the experts at Spiroflow! Submit our contact us form today and someone will get back to you to discuss your process in detail.
FIBC Bulk Bag Selection & Filling Guide: Principles of Design & Handling
What are FIBC bulk bags, what are they used for and why are they important?
FIBCS, also known as bulk bags or big bags or super sacks, are made of tightly woven strands of polypropylene, a flexible fabric designed for storage and transportation. These woven, flexible bags hold dry, flowable materials, ingredients and powders across industries including but not limited to: food and beverage, plastics, pigments, chemicals, pharmaceuticals, grains, construction materials, salt, peanuts, seeds and minerals.
Unlike smaller, dusty 50 lb.bags that are now dwindling in popularity, most FIBC bulk bags are built to hold at least 2,000 and up to 4,000 lbs. of product and protect operators with dust control solutions in both the filling and unloading processes. With the reduction in the number of bags needed for filling, storage and emptying (due to each bag holding more product) and the introduction of a flexible solution (vs. traditional rigid containers) comes a laundry list of benefits.
It’s no surprise that the global flexible intermediate bulk container (FIBC) market size is expected to reach $6.4 billion by 2026. As more and more products are supplied in FIBCs, all aspects of the bulk bagging system, including bulk bag filling, discharging, and conditioning become increasingly important.
“The global flexible intermediate bulk container (FIBC) market size is expected to reach $6.4 billion by 2026”
Benefits of FIBC Bulk Bags
FIBC bulk bags are growing in popularity as a bulk transportation and storage solution (vs. using traditional smaller bags and rigid boxes or drums) due to the benefits of bulk bags including:
- Safe and easy handling – Bulk bags are filled at the top and emptied at the bottom vs. tipped over, improving operator safety. Further improving safety are integrated dust collection systems available for bulk bag fillers and workers. Additionally, bulk bags are not moved manually by workers, but instead are moved by forklift or pallet jacks, minimizing risk for the operator due to there being no direct contact.
- Reduced storage, shipping and labor costs – Fewer bags means fewer trucks to ship, fewer bags to move and stable bags mean operators can stack bags 2 high on the plant floor saving on storage room. Additionally, the bulk bags themselves, once emptied, can be folded and stored at the facility using minimal space vs. a rigid container like a box or drum.
- Minimum risk of product damage or loss. The polypropylene flexible material is more tear and puncture resistant vs. rigid containers, which protects the contents from damage or loss from material leaking out of the bag. Additionally, the filling and unloading process for bulk bags reduces the risk of spillage vs. the tipping motion needed to unload rigid containers that must be both filled and unloaded from the top.
Who uses FIBC bulk bags?
FIBC bulk bags are used as a packaging unit for bulk bag filling by many different companies and organizations. Each is interested in safe and easy handling, reduced costs and minimum risk of damage or loss, as described in the benefits section above.
Examples of Companies That Use FIBC Bulk Bags:
- Suppliers and manufacturers of products to be discharged into FIBCs
- End Users and Buyers of products supplied in FIBCs
- Companies using FIBCs as a handling unit within their own plant
- Custom packers receiving products in bulk for packing into FIBCs
- Transportation/Shipping/Storage companies handling FIBCs
FIBC Bulk Bag Design & Filling System Guide
“The Choice Of FIBC Is Critical, Both With Regards To Design & Size As The Most Expensive Part Of An FIBC Packaging System Is The FIBC Itself.”
This informative Spiroflow guide will support you in your next FIBC purchase and bulk bag filling system design. Below we cover considerations for FIBC bulk bag selection (size, shape, loop system, spout, outlets and liners), bulk bag handling and bulk bag filling. Proper bulk bag design and the engineering of the bulk bag filling system are the difference between lumpy, uneven, unsafe bags and densified, flat-top, safe bags.
FIBC Bulk Bag Design: Determining FIBC Size & Shape
When determining the bulk bag size, the following criteria must be considered for the bulk bag filling system:
- Product weight in the FIBC bag
- Product tamped bulk density
- Internal dimensions of the shipping container or vehicle on which the FIBC will be transported
- The net filled height of the FIBC (after filling)
When determining the bag shape remember:
- Rectangular base FIBCs will round out during filling in their mid-section
- Square or panel bags do not round out as much
To determine the correct base size and shape, the internal dimensions of the shipping container or trailer should be evaluated to ensure a “push fit.” ISO containers are usually 7 ‘ 6” wide internally.
“Push fit” means that when placed side by side in a container/trailer the exterior side of the bags touch the container wall and the interior sides touch each other. This prevents the bags from shifting during transport.
To place two FIBCs side by side across the container/trailer, use the following formula:
Maximum FIBC Base width = (3.14 X Internal Width of Container or Trailer)/(8 x (1 + Stretch Factor))
FIBC Rounded Out Diameter = (2x (Base length + Base width) x (1 + stretch factor)) / 3.14
The stretch factor can vary depending on the tightness of the weave of the FIBC fabric being used, the structural design of the bag and the density of the filled product. Generally, a figure of 3% – 5% should be used.
FIBC Manufacturer Relationship
To arrive at the base size that will fit the selected method of transportation, a close liaison with the FIBC manufacturer is required to ensure that they can supply the right size. The height of the bag depends on the filled density, the weight required and any height restrictions placed on the FIBC by the user.
Storage & Transportation Considerations
Where storage of filled bulk bags plays an important cost factor for both the filler and the discharger, the following should be considered:
- Safe Stacking Height – For safe stacking of FIBCs it is not advisable to stack bags two high if the bags are over 5’ high and three high if they are over 4’ high – regardless of whether they are on pallets or not. FIBCs should not be higher than twice the base plus width. Additionally, leveraging a bulk bag filler that results in higher densification should be considered to produce a flatter bag top, which is more stable for stacking.
- Test Filled Height – The filled height of the product in the FIBC after filling can vary considerably depending on the type of filling machine used and the characteristics of the product. It is important to get the product tested on the selected filling machine before ordering FlBCs. Bulk bag filling machines that have the capability of densifying the product during filling save on FIBC height and make a safer and more stable FIBC for stacking and handling.
FIBC Bulk Bag Design: Selecting & Sizing Lifting Loops, Spouts & Outlets
Lifting Loop Options
Lifting loops are usually located at the top four corners of the FIBC and are used to lift up and move the bag. They may also be of the ‘Cross Corner‘ type. ‘Pop Up’ loops help to enable a fork lift truck to engage the loops without additional labor, but they do incur additional costs. The length of the loop is generally 10” but may increase to 12” if the FlBC is to be picked up and moved by fork lift truck tines.
Bulk bag fill spouts are tailored to fit the filling machine head. When liners are used, some machines clamp only the liner, in which case the diameter of the filling spout can be increased to 20 – 24” to allow the product to reach the ‘shoulders of the FIBC’ and not bridge in its neck. This is most important with powders. A 15” diameter is the most com-mon filling spout diameter.\
The diameter of the outlet spout should be enough to insure the easy discharge of filled product from the bulk bag. Diameters tend to vary between 10” and 24”. Outlet spout length should be enough to ensure that it can be tied off and in most cases goose-necked. The length can vary from 16-36” dependent on the diameter.
Ease of discharge is also assisted by the correct design of the discharge machine. Most modern-day bulk bag discharge units can handle poor flowing products, depending on their design and choice of product flow promotion device.
Other FIBC Outlet Systems
These are many and various, but all are designed to accommodate a product or discharger type that cannot be overcome by a standard outlet spout.
- Flat Bottom
- Conical Bottom
- Hygiene Flaps and Hygiene System
- Fully Bottom Opening Bags
FIBC Bulk Bag Design: Liners
Lined FIBCs/bulk bags are usually used for fine powders, food and pharmaceutical products. Liners are only rated as moisture proof and not waterproof. Polythene will allow the ingress of moisture over a period and require careful attention to properly tie the bag off after filling. Standard design liners are normally extruded in a tube. The circumference of the extruded tube should be equal to the base perimeter of the FIBC plus 2% to eliminate over stretching. Liners are normally manufactured from linear blend polythene as it is stronger than low density polythene and reduces the risk of shredding or crumbing when it is cut. Liners are between 5/16“ thick dependent on the product and the protection required. These liners are only suitable for products being filled with a temperature not greater than 176°F as they will start to plasticize above this temperature. For temperatures above 176°F, special liners should be used.
FIBC Bulk Bag Design: Bag Construction & Quality
FIBCs are designed to be lifted by their loops when filled and strength is built into the FlBC to give a safety factor of 5:1 for single trip bags and 6:1 for multi-trip (used more than once) bags. UN Chapter 16 FIBCs are tested to a safety factor of 8:1. FIBCs designed to hold food or pharmaceutical products should be manufactured in such a fashion to ensure loose cotton ends or frayed material from hand cut areas do not occur. Outlet spouts should be hemmed, and tie cords should have ‘flames’ ends.
FIBC Bulk Bag Handling
Pallets are by far the easiest method of moving filled FIBCs. The following considerations are important for safe and efficient movement by pallet:
- The correct size of pallet should allow the rounded section of the FIBC to overlap the edges of the pallet so that when two palletized bags are placed side by side, the bags touch and not the pallets. This increases stability of the bags when packed in containers/trailers.
- The FIBC should be positioned as close to a central position on the pallet as possible, especially after filling. A wide range of mechanical devices to assist the fork lift truck driver to achieve this are available as well as side shift on the truck itself.
- If the FIBCs are to be stacked, close slatted pallets, both top and bottom should be used to stop ‘pinching’ of the bag by allowing the top and the bottom of the FIBCs to protrude through the slats. These tend to be expensive and may only be financially justified for ‘in plant’ use unless return of them can be guaranteed.
Particle shape as well as size plays an important part in the time it takes to remove entrained air. Plate shaped particles, of clays for instance, take three to four times the amount of vibration to remove entrained air than a similar sized round particle. Granular particles will lose their entrained air quickly under their own weight. The larger the granule, the shorter the time it takes to get to a tamped bulk density. Even then, vibration will ensure added stability is achieved. Vibration will only act on the weight of the material above the weight of the vibration platform. Therefore, vibration should not be commenced until a minimum weight of 450 lbs. is in the FIBC.
Principles Of Bulk Bag Filling
During the development of FIBC bulk bag filling machines, certain basics have been identified that must not be overlooked when filling FIBCs.
- Correct position of empty FIBC bulk bag in relation to machine base – All woven polypropylene bags will stretch to some extent during filling when hung by their loops. The FIBC should be positioned so that the seams of the FIBC can stretch down during the filling cycle, with the actual comers of the bag only touching the base when the fill cycle is complete.
- Base Vibration for Densification – The bulk density of the product in the filled bag should be as near as possible to its tamped bulk density. This should be achieved while the FlBC is awaiting removal from the filling machine.
- Fill Rate Control and Displaced Air Exhaust – Complete control of the product passing through the filling head must be maintained to facilitate a steady filling rate. The filling head must also allow for the exhaust of displaced air to prevent dust and pressurization of the FIBC during filling.
- Liner Inflation & Attachment to the Filling Head (Slip Seal) – For FIBCs with liners, inflation is particularly necessary prior to filling. The liner needs to be sealed to the filling head to insure there is no dust release. However, during inflation and filling the liner must also be free to move inside the FIBC and take up the shape of the bag without stretching. To extend product storage life, consider purging the bag of oxygen using nitrogen purging prior to filling. Oxygen feeds on bacteria. Thus, a nitrogen purge and heat-sealing process can significantly extend stored product life.
- Robust construction – Robust construction will ensure long life and protection from potential damage from fork lift trucks.
- Operator Access – Ensure operator ease of access to:
- Attach the loops to the FIBC Support Arms
- Connect the filling spout/liner to the filling head
- Disengage the filling spout/liner from the filling head.
- ‘Tie off’ the filling spout (The operator should be able to carry out all of these functions at shoulder height without the need to climb on the machine)
- Electrical controls (Preferably microprocessor based (compact) and easily accessible by the operator. All bag filling functions should be able to be performed manually (as required by the operator) and automatically (once the filling cycle is initiated).
Bulk Bag Filling Automation
The above basic bulk bag filling principles have been augmented by options designed to automate the filling operation and reduce operator involvement. These developments have enabled an increasing number of products to be handled in FIBCs, leaving the future open for more companies to benefit from the advantages offered by this form of packaging.
- Pallet Magazine/Stacker – Several pallets can be placed ready for the filling operation to commence. This equipment then selects a lone pallet from the stack to be sent to the filling machine.
- Slip Sheet Dispenser – A slip sheet is then placed on the pallet automatically prior to filling.
- Automatic Bag Loop Release – Once the bag is filled it is automatically released from the filling machine ready for automatic removal. Take Off/Accumulation Conveyor – The filled bag is then conveyed away, allowing a new bag to be placed ready for filling.
- Spinning Head – This is an attachment to the filling head suitable for use with ‘baffle’ bags and granules where vibration alone is not capable of both de-aerating and dispersing the product. The Spinning Head disperses the product stream as it enters the bag to achieve an even fill.
The choice of FIBC bulk bagging system is critical, both with regards to design and size, as the most expensive part of an FIBC packaging system is the FIBC itself. The wrong choice is not only expensive in terms of product waste and high labor costs but could also lead to a loss of customer confidence in FlBC bulk bagging solutions. To choose a standard size at a reduced price that does not suit the exact needs and those of a customer can lead to a system that will not meet your application or needs. Trials should always be conducted on the chosen filling equipment, taking into account shipping, storage, fill weight requirements, bagging rate requirements and any special considerations for the specific flowable material or application.
Filling – Why Choose Bulk Bags?
No matter what the product – whether it is food or chemical, pharmaceutical or agricultural, it will need to be transported either to or from your facilities. The best option for transporting bulk solids and powders is in bulk bags or FIBCs. In this article, we will look at the positives of using bulk bags and how a bulk bag filler and bulk bag unloader can help you save money.
Benefits of Bulk Bags
Bulk bags are made from woven polypropylene and can hold up between 2,000 and 4,000lbs. They are filled from the top and emptied out of the bottom which is a more ergonomic design when compared with a drum or box and there is no need for transporting on pallets which can help reduce shipping costs. When compared with small sacks, bulk bags require much less manual handling and with the help of lifting aides can be much safer. Bulk bags can also be collapsed down once they are emptied which will save space in your facilities, unlike a box or drum which will continue to take up space once they are emptied.
Bulk Bag Filling Equipment
At Spiroflow we have three types of bulk bag fillers; the CTE, the C Series & the Base model. Whether you have low or high volume needs we have you covered. Spiroflow bulk bag fillers can fill up to 40 bags per hour & densify highly aerated material with consistent weighing accuracy.
Save Money and Space with the CTE Filler
Our Cone Table Elite (CTE) Bulk Bag Filler is one of the most versatile and capable bulk bag fillers in the industry. Unlike other fillers, the CTE bulk bag filler features our patented cone table densification system which vibrates the bag to densify the material in the bag. This means you will get more product in your bulk bag and reduce storage costs.
Watch our video to see how the CTE filler works: Click Here
If you’re looking to save money and reduce storage space get in touch with us today to ask about bulk bag filling equipment.
Gently does it with Spiroflow’s CableFlow Tubular Cable Drag Conveyors
Spiroflow’s Cableflow Tubular Cable Drag Conveyors are a further development of the best in class Aeroflow aeromechanical conveyors operating with reduced clearances and at reduced running speeds.
Being highly energy efficient, especially when compared to pneumatic conveying systems, Cableflow conveyors are designed for gentle material handling and for conveying in multiple planes – perfect for confectionery and snack foods, plus many other food types. Conveying in a totally sealed tubular system to ensure the dust-free transfer of material, they can provide complete material batch transfer of bulk products from single or multiple in-feed points to single or multiple discharge points with little or no damage. And with the option to include Spiroflow’s patented DART (Dynamic Automatic Rope Tensioner) rope tensioning system, users can be assured of extended cable life and minimum maintenance.
For more information on the cable drag conveyor or our dynamic automatic rope tensioner fill in our contact us form and we will be in touch with more information.
Conveying Tea – Choose the Right Conveyor
Tea can come in many forms before it is packaged or processed such as loose leaf tea or instant powdered tea. The type of tea you are looking to convey could affect which type of conveyor will be most suitable for your application. At Spiroflow we have the broadest range of conveying equipment on the market and this means we can give you an objective opinion on which conveyor will work best for your tea application.
Conveying tea is not without it’s challenges from dusting and degradation to maintaining batch integrity. In this blog, we will discuss our mechanical conveying range and how each bulk material conveyor will be suitable for conveying tea.
Flexible Screw Conveyors:
Our flexible screw conveyor is made up of one moving part – the spiral inside a tube. Because of this, the flexible screw conveyor is a very versatile and low cost conveyor. It is ideal for conveying blends of tea or flavored teas as it is easily cleaned using the quick release flanges so you can have a fast turnaround between flavor batches. Furthermore the spiral continually mixes the blend as it conveys using the helical motion, this will allow you to maintain the batch integrity of the tea flavors as you convey.
The Aero-Mechanical conveyor creates an airstream which moves the product up the tubes along with high-speed discs and a rope. This conveyor is a great choice for conveying both instant tea and loose leafed tea as it offers total containment. So any dust created from the tea will be contained within the conveyor which reduces the risk of explosions caused by static build up on the combustible tea dust. This conveyor is airtight and runs quietly and with minimal energy, making it a superior choice for conveying tea.
Cable Drag Conveyors:
The cable drag conveyor operates in a similar way to the Aero-mechanical conveyor as it has evenly spaced discs connected by a rope, however, it drags the product along the tube rather than creating an air stream. If you are conveying tea in leaf form this is an excellent choice as it is extremely gentle at conveying friable products and will reduce degradation on your product. As this product does not use vacuums, air blasts, belts or buckets this would be the best choice if minimizing the degradation of your product is of top priority.
As leafed tea is somewhat abrasive it can lead to higher rates of wear and tear on your conveyor so choosing to stock relevant spare parts in case of breakdowns is always wise. To read more about why we recommend having a spare parts strategy read our blog: Why We Recommend Having a Spare Parts Strategy
Are you looking to convey tea?
If you are looking for a suitable conveyor to convey your tea then get in touch with us to discuss how we can help. At Spiroflow we have over 45 years in the solids and bulk handling industry and with the broadest range of products, we can help solve any conveying challenge.
Conveying Chocolate, Cocoa Powder & Cocoa Beans
Challenges in Conveying Chocolate
Chocolate is a delicate and often expensive product and must be conveyed gently to preserve the integrity of the product especially if the conveyor is to be used at the end of the process before packaging. Degradation can also occur at the beginning of the process as the cocoa beans are friable and this can cause the end flavour result to vary. Furthermore, the bulk material conveyor must be quickly and easily cleaned so that no cross-contamination occurs when the batches are being changed.
Which bulk material handling conveyor is best for conveying chocolate?
The right conveyor depends on the product and what you are trying to achieve. Whether you need a hygienic conveyor or an energy efficient conveyor we have something to suit every chocolate application:
Flexible Screw Conveyors
The flexible screw has only one moving part, the spiral and as it constantly remixes as it conveys so it is ideal for conveying cocoa powders especially flavoured cocoa powder blends. This conveyor can come with a reverse bung, drop out tray and quick release flanges which makes it an extremely hygienic conveyor and will help avoid cross-contamination when you switch batches. Watch our video about the hygienic FSC and how it could help you with your process.
Read our case study on how we installed a sack tip hopper and an FSC to convey cocoa powder: Case Study 1009
Cable Drag Conveyors
The cable drag conveyor operates as it sounds, the discs and cable are dragged along inside the tube and gently drags the product along. It is a very gentle conveyor as it is not running at high speeds so it is ideal for friable products such as cocoa beans.
Learn more about how a cable drag conveyor conveys coffee beans in our case study 1023.
Let us help
We have over 45 years experience in the solids and bulk handling industry and we have the widest range of mechanical conveyors in our industry. Get in touch with us today to discuss how we can help with your chocolate application.