Archive: Jul 2023

How to Prevent Bridging in Material Hoppers (aka The Ketchup Effect)

Have you ever struggled to get ketchup or any thick sauce out of a bottle? That’s the same issue that production facilities face when they try to move solids or powders through material hoppers. The material gets stuck, and production stops.

Unlike liquids, bulk solids and powders will not flow readily without intervention. Even some thick liquids like ketchup are notoriously difficult to handle. The material clings to the vessel walls, or becomes more compact – also known as bridging.

What is bridging?

Bridging in material hoppers refers to the phenomenon where bulk materials, such as powders, granules, or pellets form an arch-like structure over the outlet. It stops material from flowing freely, which leads to several production problems:

• Need for manual intervention to loosen the material
• Lower productivity and machine downtime
• Inconsistent product formulas
• Stagnant material that can spoil or contaminate the next batch
• Material waste from throwing away spoiled material or out-of-spec batches

What causes bridging in material hoppers?

• Know your material’s flow properties. Choose non-cohesive materials whenever possible. If cohesive materials are necessary, consider additives or treatments to reduce their cohesive properties.
• Control moisture. Implement proper moisture control measures to ensure the material remains within the acceptable range for smooth flow. This might include using desiccants, heaters, or dehumidifiers.
• Select the right design of material hoppers. Select an appropriate hopper design based on the material’s characteristics. Conical material hoppers with an angle between 50 to 60 degrees, and the right outlet size, can help promote steady flow.
• Consider hopper liners. Using hopper liners made of low-friction materials like Teflon can help reduce material adhesion and bridging.
• Use the right flow aid. Many manufacturers use industrial flow aids to break up material blocks and encourage regular, reliable flow. Aside from speeding up production, it prevents stagnant or spoiled material and the safety risks from manual intervention and cleaning.

Solve bridging in material hoppers with AirSweep

Preventing bridging in material hoppers is essential to ensure the continuous and efficient flow in industrial processes.

Both global brands and SMEs use AirSweep to get smooth, on-demand flow. AirSweep is a pneumatic flow aid that releases powerful, high-pressure air pulses that break up bridging and sweep the vessel walls clean. It is energy-efficient, requires very little maintenance, and has proven effective for even the toughest flow problems.

AirSweep can be installed on material hoppers as well as other process equipment like silos, chutes, conveyor belts, or any place where material tends to hang up.

Since AirSweep uses aeration rather than vibration, it does not cause metal fatigue and damage small or thin material hoppers. AirSweep is also certified safe to use in hazardous and flammable environments, and there are models that are specifically designed for sanitary applications.

Contact us to find out more about AirSweep and how it can reduce bridging in your material hoppers.

5 Questions to Ask Before You Buy a Flow Aid

Poor material flow slows down production, compromises product quality and consistency, and can even create workplace safety hazards. That’s why many industries turn to flow aids to move material consistently and reliably.

Flow aids are bulk solid handling equipment that stimulate or improve the movement of material. They prevent bridging, ratholing, clogging, or material residue on vessel or pipe walls. Some flow aids like AirSweep can even be used to flush vessels clean between batch runs.

How do I choose the right flow aid for my process?

Before choosing a flow aid (or any bulk solids handling equipment for that matter) understand the characteristics of your bulk material – such as particle size, shape, density, moisture content, and flowability.

For example, fluidizers work for very light powders like flour but lack the volume and pressure to activate moist and heavy materials. Vibrators can also make some materials more compact.

A commercial bakery tried both types of flow aids to resolve the issue of flax bridging on the discharge and caking on vessel walls.

“The vibrators that came installed on the bottom of the hopper above the mixture practically turned the flax into concrete,” said the maintenance manager. “Then we installed fluidizers, which were terrible. We still had to use hammers and sticks, and spent an hour a day to clean and keep things flowing.”

Flax is a very moist, sticky material. Since vibration or agitation can make it settle, it needs a powerful pneumatic flow aid that releases enough pressure to move it through the vessel and even sweep the walls clean.

AirSweep was the only flow aid that fits the bill. It solved 90% of their material retention problems, reduced material waste, and saved time and manpower costs.

How much energy and plant air will it consume?

A flow aid may seem “cheaper” but actually cost more to run. For example, fluidizers run continuously, but AirSweep releases short pulses in sequence – which means it uses plant air and electricity more cost-efficiently.

Can it reduce worker intervention?

Your flow aid should be so effective that once you install it you can walk away and focus on other parts of the plant. If you still need to hammer vessels or do any other kind of manual cleaning, it’s time to look for a better alternative.

An asphalt plant in Mexico spent every Monday hammering silos, even if they had electric vibrators installed.

“Over the weekend, when the plant was unstaffed, the asphalt materials would settle completely. When workers returned on Monday, they had to climb seven meters down into the dark silo, and clear thick layers of compacted material,” said the sales manager.

But when they traded the vibrators for AirSweep, workers put away the hammers for good. “After four years, we finally have the right solution! We are very happy with the system.”

Is it easy to clean and maintain?

All bulk solids handling equipment must be periodically cleaned and checked for sanitation and safety purposes.

AirSweep is designed for fast and easy maintenance. It can be removed from the vessel with simple tools. And since the nozzle shuts tightly closed after each pulse, there is no material feedback that can contaminate the rest of the system.

Will AirSweep work with my material and process?

AirSweep can activate almost any bulk powder or solid—dry, wet, sticky, moist, and more. Tell us about your material and the kind of problems you encounter, and our engineers can recommend the best model and set-up for your needs.

Bridging, Ratholing, and Other Problems In Material Handling

All manufacturing processes need efficient material flow for smooth operations and cost-efficiency. Sluggish and inconsistent flow can cause production delays and compromise product quality and safety.

For example, in the food and pharmaceutical industry, stagnant material can cause cross-contamination between different materials or batches. This can lead to the presence of foreign substances, allergens, or contaminants in the final products, posing significant health risks to consumers.

Other industries that use precise or patented formulas – such as chemicals, cement, pharmaceuticals, electronics, and manufacturing – may also lose product integrity and performance if materials aren’t mixed in the correct proportions.

The two most common problems in material handling are “bridging” and “ratholing.” Let’s look at their definitions, causes, and what you can do to prevent these flow problems.

What is bridging?

Bridging, also known as arching, occurs when bulk materials form a stable, compacted bridge across a hopper or silo outlet. This restricts – and eventually stops – material flow.

Bridging is common in fine powders, fibrous substances, or materials with high moisture content. These have a tendency to bind together and become even more compact as more material is poured into the vessel.

Bridging can become even more challenging when materials stick to the hopper walls. This often happens with moist, sticky solids like cement mixes or food ingredients like whey protein.

What causes bridging?

Bridging and other problems in material handling are caused by two major factors: the material properties and the shape of the vessel.

Material properties include particle size and shape, tendency to attract moisture, and natural cohesion and adhesion. Cohesion is the tendency of particles to stick together, and adhesion is the tendency to stick to vessel walls and other surfaces.

The geometry of the hopper or silo outlet also impacts the potential for bridging. A funnel-shaped outlet with a steep angle and narrow opening can be more prone to blocks. External factors such as vibrations or uneven flow rates can also disturb the material flow.

What are some materials that are prone to bridging?

These materials are more likely to cause material handling problems.

• Fine powders like cement, fly ash, powdered sugar, cocoa powder, detergents and cleaning agents, or some additives and preservatives
• Fibrous materials like wood chips, tobacco, straw, and certain types of grain
• Hygroscopic materials like sugar, salt, fertilizers, and other powders that absorb moisture from the air
• Thin flakes or fluffy materials like certain cereals, animal feed, and plastic flakes
• Sticky or viscous materials like adhesives, resins, or certain chemicals
• High-fat or oily materials like nuts, seeds, and certain grains
• Resins and polymers with high cohesive properties
• Chemicals and salts with electrostatic properties

What is Ratholing?

Ratholing is also one of the most common problems in material handling. It occurs when material cakes on the vessel walls.

Ratholing causes two problems: it narrows the space for the material to flow out (also called funnel flow) and leaves stagnant material that can spoil or contaminate the formula.

Ratholing can also limit the bin’s total capacity.

What causes ratholing?

Like bridging, ratholing is caused by material properties like cohesion and particle size distribution, and vessel geometry. It tends to happen in cone-shaped hoppers with walls that aren’t steep enough to encourage flow. If the material is even a little cohesive, it sticks to the walls.

What materials are more prone to ratholing?

Ratholing is a flow issue that affects specific materials, often characterized by their cohesive and interlocking properties. Some common materials that are prone to ratholing include:

• Cohesive powders like flour, cement, coal, pharmaceuticals, or food ingredients like coffee
• Granular materials such as fertilizer granules or prilled chemicals
• Minerals, ores, and fine sands with high cohesive strengths and fine particle sizes
• Plastic pellets with strong cohesive properties
• Chemical powders with strong cohesive properties
• Flaky or elongated particles can form preferential flow paths
• Animal feeds with pellets or ground materials

Solve problems in material handling with AirSweep

Thousands of plants around the world use AirSweep flow aid systems to solve bridging, ratholing, and other material flow problems. The nozzle releases highly pressurized air pulses to promote on-demand, first in and first out flow.

AirSweep breaks up material blocks and sweeps the vessel walls clean. It is the only flow aid that can handle problematic powders and even sticky and moist solids without damaging the vessel or consuming a lot of energy.

AirSweep can even be used on thin or small vessels, or installed in hard-to-reach areas.

Tell us about your problems in material handling and get a customized proposal for your process.

Improve Mining Equipment Safety and Efficiency With DAZIC

The mining and materials processing industry uses various tools and equipment to extract, process, and handle mined materials. These machines can carry from a hundred to over a thousand tons of material in one load. It speeds up the process—but also has risks.

Any equipment malfunction or abnormal change in speed could cause a material spill. Workers could get injured, and the material pile-up would take days to clean up. That’s why it’s important for mining equipment to have alarms or sensors to detect a problem even before it breaks down.

In this article, we’ll look at the common mining tools and equipment, and what you can do to prevent malfunctions and material spills.

Types of mining equipment

• Excavators. These are used to extract minerals and ores from the earth. They are equipped with buckets or hydraulic attachments to remove overburden or dig into the ground.
• Bulldozers. These push large amounts of soil, rock, or other materials to prepare the site for mining operations.
• Conveyors. These transport bulk materials like minerals or ores within mining and processing facilities.
• Crushers. These break down large rocks or ores into smaller, more manageable sizes. It includes jaw crushers, cone crushers, and impact crushers.
• Grinding mills. These grind or pulverize mined materials to achieve the desired particle size or extract valuable minerals from ores.
• Agitators and mixers. These are used for blending and mixing substances in tanks or vessels.
• Vibrating screens. These are used to separate particles, or sort and classify materials according to size.
• Concentrators. These separate valuable minerals from the mined ore through processes like flotation, gravity separation, or magnetic separation.
• Pumps. These help with transporting slurries (mixtures of water and solid) during mineral extraction and processing, removing excess water from a site, transferring fuels or other chemicals from storage vessels to different parts of the mine, or transferring tailings and other waste material.
• Fans and blowers. These are used for ventilation, dust control, or material movement.

The role of speed switches in mining operations

DAZIC zero speed switches can be attached to mining equipment to improve efficiency and safety.

A speed switch monitors the speed of rotating machinery or equipment. When it detects that equipment is running outside of normal speed parameters, it sends an alarm so the operator can stop operations or adjust equipment settings.

This has numerous benefits and applications in the mining process:

• Prevent material spills and downtime
• Prevent equipment damage and repairs
• Protect worker safety
• Synchronize multiple machines used in complex processes
• Identify bottlenecks or issues caused by variations in speed to adjust and optimize the process
• Comply with safety regulations that may be mandated for certain types of mining equipment

Common mining equipment that uses zero speed switches

DAZIC zero speed switches can be attached to any equipment that has a rotating shaft. This includes:

• Conveyor systems. DAZIC can be installed on conveyor drives or tail pulleys to monitor the belt’s rotational speed. It helps detect belt slippage, jams, or unexpected stops.
• Crushers and Grinders. DAZIC quickly flags speed deviations that could indicate overloading or equipment failure.
• Agitators and Mixers. DAZIC can be installed on the shafts to monitor the rotational speed.
• Fans and Blowers. DAZIC can indicate issues such as motor failure, belt slippage, or obstructions in the airflow system.
• Pumps. DAZIC detects speed changes caused by impeller damage, cavitation, blockages, or motor failure.

Get the right speed switch for your equipment and process

DAZIC has a full range of zero speed switches for different process requirements such as shaft input speeds, mounting styles and housing material, and more. Tell us about your project and we can recommend the best DAZIC zero speed switch.

How to Improve Material Handling Efficiency in the Food Industry

The food industry follows strict industry and government regulations for quality control and product safety. If your business fails to comply, you could face stiff fines and penalties and suspension of license. In cases when authorities feel that there’s a risk to consumer health, you may be required to recall all your products at your own expense.

Many of these industry regulations – such as the Good Manufacturing Practices (GMP), Hazard Analysis and Critical Control Points (HACCP), and the Codex Alimentarius – set standards for material handling efficiency.

For example, they require proactive, preventative measures against material spoilage and contamination. The food industry uses many materials that quickly degrade or develop mold or microorganisms. In addition to prioritizing safety and following proper handling practices, it is crucial to prevent your material from becoming stagnant and adhere to the FIFO principle.

First-In, First-Out (FIFO) Flow

In a nutshell, FIFO ensures that the oldest material is used first. It maintains the freshness, integrity, and even nutritional value and consistency of the material and the final product.

FIFO starts in the warehouse. Clearly label products with their production or expiration dates and establish proper inventory rotation procedures. Regularly monitor stock levels and adjust replenishment orders accordingly to maintain optimal inventory turnover.

However, FIFO is also important during the production process: when material sits in silos and hoppers. Many bulk powders and solids have a tendency to segregate or stick to vessel walls. Others are prone to bridging and ratholing.

Bridging occurs when a solid bulk material forms an arch or bridge over an opening, obstructing the material flow, while ratholing happens when material funnels through a central flow channel.

In all these cases, stagnant material is left inside the vessel. This increases the risk of spoilage and contamination and compromises the quality and safety of the entire batch run.

Achieve material handling efficiency and safety with AirSweep

AirSweep is an innovative flow aid system that can help achieve a First-In, First-Out (FIFO) flow during material handling.

AirSweep releases bursts of compressed air to dislodge and activate material that may have become stagnant or formed bridges or ratholes in storage vessels.

By installing AirSweep units at key points within the storage vessel or hopper, the system effectively breaks up material bridges and ratholes. Material can flow freely and consistently.

AirSweep is effective for all materials, including damp and sticky powders and solids used in the food industry. Watch how it works on corn grits that have been soaked in water and left in the hopper for three days. The air pulses break up the hard, cakey mixture in minutes.

AirSweep promotes material handling efficiency and food safety by:

• Facilitating FIFO or the removal of older material first before accessing fresh or newer material
• Preventing material segregation and stagnant zones
• Resolving bridging and ratholing
• Ensuring that the material flows uniformly and maintains its proper distribution within the storage vessel or hopper

AirSweep in the food industry

AirSweep systems are widely used in the food industry to improve material handling and ensure efficient flow in various applications.

• Silos. AirSweep can dislodge grains, flours, powders, and granules that have settled and become compact during storage.
• Hoppers. AirSweep ensures consistent discharge, maintaining proper ingredient flow and preventing material stagnation.
• Conveyors and chutes. AirSweep prevents material build-up and blockages to facilitate the smooth transfer of food materials between processing stages.
• Mixing and blending equipment. AirSweep promotes uniform material flow and prevents ingredient segregation, ensuring thorough blending and consistent product quality.
• Packaging and filling equipment. AirSweep maintains a consistent flow of food products for fast and accurate packaging operations.

USDA-accepted AirSweep

The USDA-accepted model is specially designed for the food industry and other industries requiring sanitary equipment and frequent cleaning.

• Only the nozzle tip comes in direct contact with the material, preventing contamination
• The flanged connections allow quick removal and re-installation with simple hand tools
• The surfaces are also resistant to corrosive products and industrial-grade cleaning chemicals

Watch the video to see why AirSweep USDA-accepted model is the best choice for achieving material handling efficiency and safety in the food industry:

Trusted by food manufacturers worldwide

AirSweep is used by some of the world’s leading food manufacturers, local businesses, and SMEs. Read more about AirSweep in the food industry or contact us for a customized presentation and proposal.

The Role of Flow Aids in Bulk Material Processing

Bulk material processing is a critical aspect of many industries, including manufacturing, mining, agriculture, and construction.

However, many materials—powders, granules, and pellets—have challenging flow characteristics that can slow down processing operations. Flow aids can overcome these challenges to improve productivity and overall efficiency.

Common flow challenges in bulk material processing

A material’s physical properties can affect its flow patterns. These include particle size, shape, moisture content, and cohesive tendencies.

Particle size

Smaller particles tend to be more prone to cohesive forces and can easily clump together, leading to flow problems such as arching and bridging. That’s why fine powders like titanium dioxide and carbon black can be very challenging to work with, especially when they pass through feeders and hoppers.

Larger particles, on the other hand, have a tendency to interlock, impeding flow through hoppers or chutes. This is a common problem in the cement and mined materials industries.

Particle Shape

Irregularly shaped particles may interlock or form arches, hindering material flow. One mineral processing plant that worked with pebbles and crushed materials took over an hour to fill a supersack, with operators frequently stepping in to hammer the vessels.

Moisture Content

Moisture can increase particle cohesion and create adhesive forces between particles, leading to material agglomeration and blockages. On the other hand, excessively dry materials may become powdery and prone to dusting, which also causes flow issues.

This frequently occurs in the food industry. Many raw ingredients like butter or whey either have an inherently high fat and oil content. Others, like sugar or cocoa, have a tendency to attract and retain moisture.

The food industry also uses dry powders like preservatives, spices, and nutritional additives. These have to be added in very precise amounts, so even the slightest irregular flow can compromise an entire batch.

Cohesive Tendencies

Cohesive materials have a natural tendency to stick together due to intermolecular forces such as surface chemistry or electrostatic charges. This is common in the chemical, cement, and pharmaceutical industries which use binding agents, solvents, lubricants, and disintegrants.

These properties can cause common flow problems such as arching, bridging, ratholing, and segregation. These issues can lead to material blocks, uneven discharge, lower production, and increased downtime.

Flow Aids used in bulk material processing

Flow aids enhance material flow by breaking up cohesive masses, preventing material build-up, and promoting consistent discharge.

• Pneumatic flow aids. These use compressed air to break up cohesive friction and loosen material blocks. Examples include fluidizers, air cannons, and AirSweep.
• Vibrators. These use vibrations to loosen compacted materials, similar to shaking or hitting a ketchup bottle. Some plants still employ workers to hit vessels with a hammer; others use industrial vibrators or air knockers.
• Mechanical Agitators. These use gyratory forces rotating blades or paddles to break up material clumps and prevent bridging. Like vibrators, they use continuous agitation to dislodge stagnant material.
• Bin Activators. These combine vibratory or gyratory forces to dislodge compacted material.

Each flow aid has its pros and cons. Fluidizers, which use gentle aeration, are cheap and often pre-installed in vessels. However, gentle air pulses are usually only effective for light powders like flour.

Vibrators, mechanical agitators, and bin activators provide more power, but use a lot of electricity and can damage the vessel. Some powders or irregular particles can also become more compact when agitated.

AirSweep: best flow aid for bulk material processing

AirSweep is a unique flow aid that uses high-pressure air pulses that are more powerful and cost-efficient than vibrators, mechanical agitators, and bin activators. It can break up bridging, arching and ratholing, and promote first-in/first out flow.

AirSweep’s unique design and operation provide several advantages for bulk material processing:

• Versatility. AirSweep can be used in a wide range of industries and applications, including silos, hoppers, chutes, conveyors, and other material-handling equipment. It is proven effective for various materials, including powders, granules, pellets, and even sticky or cohesive substances.
• Reliability. AirSweep is made of high-quality materials and hand-assembled in the USA following strict quality control measures. It requires minimal maintenance and is designed to withstand the harsh conditions commonly encountered in industrial environments.
• Energy-efficiency. AirSweep’s controlled, sequenced pulses use less air and energy than other flow aids, which run continuously and have a limited activation radius. Thus, you need fewer units and resources to activate more material—and get more continuous material flow.

AirSweep improves overall plant efficiency

An AirSweep system can help you increase productivity and lower costs. Here are some key advantages that make it a worthwhile investment.

• Get on-demand flow. Preventing ratholing, bridging, and other material blocks that can affect material flow and operations. This leads to increased throughput, reduced downtime, and higher production rates.
• Lengthen machine lifespan. Unlike other flow aids, AirSweep prevents vessel and equipment wear and tear and extends the lifespan of machinery. This minimizes maintenance and repair expenses.
• Reduce waste. Material buildup and inconsistent discharge often lead to product waste. With AirSweep, all materials are properly discharged and utilized.
• Protect worker safety. AirSweep automates material flow. Workers don’t have to enter confined spaces, be exposed to potentially hazardous materials, or use manual methods that can lead to accidents or injuries.
• Comply with regulations. Consistent flow can help a process meet environmental regulations, health and safety standards, and quality control guidelines.

Optimize bulk material processing with AirSweep

AirSweep increases productivity, enhances equipment efficiency, and minimizes operational costs and material waste. Find out how AirSweep can help improve your process. Tell us about your material flow challenges, and get a free customized proposal.