Skip to main content
Category

Solutions To Common Problems

Limestone Surge Bin Retrofit

Limestone Surge Bin Retrofit 

This is an example of a limestone bin that is suffering from chronic bridging. It is a good example of an instance where the behavior of the Feeder is inducing rat-holing and bridging despite the fact that the bin is constructed with correct geometry.

The Existing Storage and Feed Arrangement and Why it is Suffering from Chronic Plugging and Inconsistent Discharge

The existing bin consists of several stacked chisel hoppers, and is discharged using a slide gate that opens from the middle outwards. To control the discharge onto the conveyor below, the slide gate opening is incrementally adjusted. Unfortunately, the system suffers from chronic rat-holing and bridging.

 

In summary, the bin is suffering from chronic plugging because when the slide gate is only partially open it induces a funnel flow discharge pattern despite the fact that the geometry of the storage bin is correct, where if the slide gate were removed, the bin would self-empty in a mass flow or first-in, first-out discharge pattern. Funnel flow (which is a first-in, last-out discharge pattern) can be made to work with a large discharge outlet. However, when the discharge outlet is small, gravity is insufficient to overcome the strength of the bulk solid at the discharge outlet, and hence chronic bridging and rat-holing is expected.

 

As noted, the storage bin is designed to discharge in a mass flow, or first-in, first-out discharge pattern. The definition of mass flow is that during discharge, the entire mass of stored material comes down as a single body (single mass). To achieve this, material must discharge evenly from the entire discharge outlet of the storage bin. The tell-tale sign that you have mass flow is that material is sliding down the bin walls. In contrast, with funnel flow, material is stagnant along the hopper walls. When the slide gate is only partially open, then material is not permitted to withdraw evenly from the entire discharge outlet of the storage bin because the slide gate has limited the “live” opening. The result is stagnant material along the bin walls and a funnel flow discharge pattern.

Kamengo_Banner
Kamengo_Banner
previous arrow
next arrow

Kamengo’s Solution

The solution to fixing this problem bin is simple. Given that the bin geometry is correct, such that if the Feeder were removed, the entire bin would self-empty with gravity in a mass flow or first-in, first-out discharge pattern, only the behavior of the Feeder needs to be fixed. In this case, the feeder must be fully effective, which means that it must withdraw material evenly from its entire opening. The attached solution pairs the bin with a Kamengo Feeder. The reason for doing so is that the Kamengo Feeder withdraws material evenly from its entire opening, which by definition is necessary to actually achieve a mass flow discharge pattern in the bin.

Learn More

To learn more about the physics of storage bin and feeder design as well as the root causes of bin plugging, please visit KamengoU.

Fine Ore Pile Reclaim (Copper Mine)

Fine Ore Pile Reclaim (Copper Mine)

This is an example of a large fine ore storage reclaim that is suffering from chronic bridging.

Why the Existing Reclaim System is Suffering From Chronic Bridging and Inconsistent Discharge

The existing storage and feed arrangement consists of a storage building that has a flat floor and is being reclaimed from below through a series of long slots. Material is metered by a belt feeder below each slot. This case study is an example of making funnel flow work when handling a fine material.

 

In summary, because the storage facility has no sloping walls, but is instead reclaiming the pile through a series of long slots in the floor, the pile is expected to empty in a funnel flow or first-in, last-out discharge pattern. Funnel flow can certainly be made to work when the “effective” discharge outlet is wide and long. However, when the discharge outlet is small, gravity is insufficient to overcome the strength of the bulk solid at the discharge outlet, and hence chronic bridging and rat-holing is expected.

 

In the case of this facility, below each slot is a tapered chute and a belt feeder. The purpose the tapered chute is to try to even out the discharge by the belt feeder, because it has a propensity to withdraw material selectively from the rear of the slot. However, tapered chutes are only effective over short distances, and the slot is over 44-ft long. In summary, the tapered chute is having little effect, as a result the belt feeder is primarily pulling material from only a short section of the slot. As a result, despite the fact that the slot in the floor is long, effective opening through which material is being discharged (from the perspective of gravity) is small. And when the opening is small, rat-holing can be expected.

Kamengo_Banner
Kamengo_Banner
previous arrow
next arrow

Kamengo’s Solution

The solution to fixing this problem is to replace the chute and belt feeder with a fully-effective feeder. A fully-effective feeder is one where the feeder withdraws material evenly from its entire infeed opening. With a fully effective feeder, the full length and width of the slot is “live”, and with a large effective discharge area, the pile can reliably be discharged in a funnel flow discharge pattern.

 

A great example of a fully-effective feeder is the Kamengo Feeder. In addition to being fully-effective, the Feeder offers consistent metering, and can be made as wide as needed and as long as wanted. As a result, the Kamengo Feeder offers valuable advantages when designing for a difficult flowing material.

Learn More

To learn more about the physics of storage bin and feeder design as well as the root causes of bin plugging, please download our white paper entitled: The Design of Reliable Storage Bins and Feeders for the Mining Industry. 

Dry-Stacked Tailings Filter Cake Truck Load-Out Bin

Dry-Stacked Tailings Filter Cake Truck Load-Out Bin

This is an example of a tall truck load-out bin designed specifically to handle difficult flowing cohesive, high-moisture content dry-stacked tailings filter cake.

Why Conventional Clam Shell Bins Suffer from Chronic Bridging and Inconsistent Discharge

Standard truck load-out bins use a clamshell or slide gates to meter discharge. Unfortunately, many of these systems suffer from chronic bridging and rat-holing.

 

In summary, these bins suffer from chronic plugging because when the clam shell or slide gate is only partially open it induces a funnel flow discharge pattern despite the fact that the geometry of the storage bin may be correct, where if the slide gate or clam shell were removed, the bin would self-empty in a mass flow or first-in, first-out discharge pattern. Funnel flow (which is a first-in, last-out discharge pattern) can be made to work with a very large discharge outlet. However, when the discharge outlet is constricted, gravity is insufficient to overcome the strength of the bulk solid at the discharge outlet, and hence chronic bridging and rat-holing is expected.

 

Ideally, a cohesive bulk solid such as a high-moisture content filter cake should be discharged in mass flow, or a first-in, first-out discharge pattern. The definition of mass flow is that during discharge, the entire mass of stored material comes down as a single body (single mass). To achieve this, material must discharge evenly from the entire discharge outlet of the storage bin. The tell-tale sign that you have mass flow is that material is sliding down the bin walls. In contrast, with funnel flow, material is stagnant along the hopper walls. When the clam shell or slide gate is only partially open, then material is not permitted to withdraw evenly from the entire discharge outlet of the storage bin because the slide gate has limited the “live” opening, causing some sections of material in the storage bin to be stagnant during discharge. The result is a funnel flow discharge pattern.

Kamengo_Banner
Kamengo_Banner
previous arrow
next arrow

Kamengo’s Solution

The solution to a reliable truck load-out storage bin for handling cohesive materials such as high-moisture content filter cake is simple. First, ensure the geometry of the storage bin is correct, such that if the Feeder were removed, the entire bin would self-empty with gravity in a mass flow or first-in, first-out discharge pattern. Typically, Kamengo would recommend a plane flow hopper with a long and wide discharge opening, as this is among the most conservative bin shapes. Second, pair the storage bin with a fully-effective feeder – that is a feeder that withdraws material evenly from its entire infeed opening. By definition, to achieve mass flow, where the stored material comes down as a single body, the feeder must withdraw material evenly from its entire opening. If the Feeder withdraws material selectively from the bin discharge outlet, sections of material in the bin will be stagnant and funnel flow will ensue.

 

A great example of a fully-effective feeder is the Kamengo Feeder. In addition to being fully-effective, the Feeder offers consistent metering, and can be made as wide as needed and as long as wanted. As a result, the Kamengo Feeder offers valuable advantages when designing for a difficult flowing material.

Learn More

To learn more about the physics of storage bin and feeder design as well as the root causes of bin plugging, please download our white paper entitled: The Design of Reliable Storage Bins and Feeders for the Mining Industry. 

Crushed Glass Metering Bin

Crushed Glass Metering Bin

This is an example of a small metering hopper designed to handle crushed glass.

Why Conventional Equipment Often Suffer from Chronic Plugging and Inconsistent Discharge

Typical metering hoppers handling crushed glass use a pyramid hopper that converge to a small opening that is discharged using a screw feeder.

 

In summary, a pyramid hopper with a small opening is typically a poor choice of bin shape for handling difficult flowing materials. The bin shape promotes a funnel flow discharge pattern. Funnel flow (which is a first-in, last-out discharge pattern) can be made to work with large bins with large discharge outlets. However, when the discharge outlet is small, gravity is insufficient to overcome the strength of the bulk solid at the discharge outlet, and hence chronic bridging and rat-holing is expected.

 

In addition, the pyramid hopper is discharged by a feeder that preferentially withdraws material from the hopper outlet, which again, promotes a funnel flow discharge pattern.

Kamengo_Banner
Kamengo_Banner
previous arrow
next arrow

Kamengo’s Solution

The solution to a reliable crushed glass metering hopper has two parts.

 

The first half of the solution is to choose a conservative hopper shape. Kamengo prefers using a plane flow hopper with a wide and long discharge opening. A plane flow hopper only converges in one plane at a time, and is vertical in the opposite plane. The purpose of using a conservative bin shape with a long and wide discharge outlet is to employ a geometry where if the Feeder were removed, the entire bin would self-empty with gravity in a mass flow or first-in, first-out discharge pattern.

 

The second half of the solution is to pair the plane flow hopper with a fully-effective feeder – that is a feeder that withdraws material evenly from its entire infeed opening. By definition, to achieve mass flow, where the stored material comes down as a single body, the feeder must withdraw material evenly from its entire opening. If the Feeder withdraws material selectively from the bin discharge outlet, sections of material in the bin will be stagnant and funnel flow will ensue.

 

A great example of a fully-effective feeder is the Kamengo Feeder. In addition to being fully-effective, the Feeder offers consistent metering, and can be made as wide as needed and as long as wanted. As a result, the Kamengo Feeder offers valuable advantages when designing for a difficult flowing material.

Learn More

To learn more about the physics of storage bin and feeder design as well as the root causes of bin plugging, please download our white paper entitled: The Design of Reliable Storage Bins and Feeders for the Recycling Industry. 

Corn Lignin Filter Cake Metering Bin

Corn Lignin Filter Cake Metering Bin

This is an example of a solution to fix a corn lignin filter cake metering bin that is suffering from chronic bridging.

Why the Current Storage and Feed Arrangement is Suffering from Chronic Plugging and Inconsistent Discharge

The existing storage and feed arrangement consists of a long pyramid hopper with shallow walls that is discharged by a long chain conveyor. Filter cake falls through breaker bars into the hoppers, from where it is sheared from the bin by the chain conveyor.

 

The chain conveyor has a tendency to pull material from a short portion of the rear of the bin while compacting material at the front of the bin. The compaction is particularly problematic as it is leading to high loads being transferred to conveyor causing the conveyor to trip. The stagnant material at the front of the bin is permitted to gain strength both as a result of compaction from the conveyor as well as compaction under gravity. The result is that the material at the front of the hopper is permitted to gain significant strength, making it at risk of bridging over the conveyor.

Kamengo_Banner
Kamengo_Banner
previous arrow
next arrow

Kamengo’s Solution

The solution involves replacing the existing lower hopper with a new plane flow hopper that is constructed with sufficiently steel sloping walls and lined with a low friction liner. Below the new hopper is a long and wide Kamengo Feeder that will feed onto the existing chain conveyor.

 

The advantage of the Kamengo Feeder is that, unlike the chain conveyor, it meters material evenly from the hopper’s full discharge outlet. In combination with correct hopper geometry, the Kamengo Feeder will produce a first-in, first-out discharge in the storage hopper. Of critical importance, the full weight of the stored lignin sits on the Kamengo Feeder with no vertical load placed on the chain conveyor, which will reduce wear on the conveyor as well as power needed to drive the conveyor. Further, the Kamengo Feeder will do all the metering and as such the chain conveyor will simply be used as a conveyor. A second advantage of the Kamengo Feeder is that it discharges evenly across its full discharge length and as such over the full length of the chain conveyor infeed, avoiding problematic surge loading, which could place a strain on the conveyor and cause it to trip.

Learn More

To learn more about the physics of storage bin and feeder design as well as the root causes of bin plugging, please download our white paper entitled: The Design of Reliable Storage Bins and Feeders for the Biomass Industry. 

Hog Fuel (Wood Waste) Tall Day Bin

Hog Fuel (Wood Waste) Tall Day Bin

This is an example of a storage bin designed specifically to handle difficult flowing biomass, including stringy woody biomass.

Why Conventional Live Bottom Bins Suffer from Chronic Plugging and Inconsistent Discharge

Standard storage bins used to handle biomass are typically negative taper, and use a live bottom reclaim system such as augers or a stoker.

In summary, live bottom negative taper bins struggle handling biomass because: 1) they allow the stored biomass to compact on itself and place a heavy load on the reclaim system, 2) promote material compaction by driving material against the bin front wall, and 3) withdraw material in a funnel flow discharge pattern, which induces rat-holing.

Kamengo_Banner
Kamengo_Banner
previous arrow
next arrow

Kamengo’s Solution

The solution to a reliable biomass storage bin starts with good bin design and moving away from the negative taper bin to a positive taper bin where the majority of the load in the bin is carried by the bin walls, and where the biomass will accelerate from the storage bin during discharge. However, for reliable discharge, the geometry of the positive taper storage bin must be correct. The most conservative bin shape for handling biomass is a plane flow hopper shape with a wide and long discharge opening. A plane flow hopper only converges in one plane at a time, and is vertical in the opposite plane. The plane flow hopper is the most conservative hopper shape. The purpose of using a conservative bin shape with a long and wide discharge outlet is to employ a geometry where if the Feeder were removed, the entire bin would self-empty with gravity in a mass flow or first-in, first-out discharge pattern.

 

The second half of the solution is to pair the plane flow hopper with a fully-effective feeder – that is a feeder that withdraws material evenly from its entire infeed opening. By definition, to achieve mass flow, where the stored material comes down as a single body, the feeder must withdraw material evenly from its entire opening. If the Feeder withdraws material selectively from the bin discharge outlet, sections of material in the bin will be stagnant and funnel flow will ensue.

 

A great example of a fully-effective feeder is the Kamengo Feeder. In addition to being fully-effective, the Feeder offers consistent metering, and can be made as wide as needed and as long as wanted. As a result, the Kamengo Feeder offers valuable advantages when designing for a difficult flowing fibrous material.

Learn More

To learn more about the physics of storage bin and feeder design as well as the root causes of bin plugging, please download our white paper entitled: The Design of Reliable Storage Bins and Feeders for the Biomass Industry. 

Hot Lime Silo Retrofit

Hot Lime Silo Retrofit

This is an example of a hot lime silo that is suffering from chronic bridging. It is a good example of poor bin geometry combined with uneven discharge that is resulting in chronic bridging.

Why the Existing Storage and Feed Arrangement is Suffering from Chronic Plugging and Inconsistent Discharge

The existing bin consists of a 25-foot diameter silo and 55-deg cone that converges to a 2-foot diameter opening that is fitted with a basket gate.

 

In summary, the silo is suffering from chronic plugging because the shallow cone and the behavior of the basket gate are inducing a funnel flow discharge pattern. Funnel flow (which is a first-in, last-out discharge pattern) can be made to work with a large discharge outlet. However, when the discharge outlet is small, gravity is insufficient to overcome the strength of the bulk solid at the discharge outlet, and hence chronic bridging and rat-holing is expected.

Kamengo_Banner
Kamengo_Banner
previous arrow
next arrow

Kamengo’s Solution

The solution to fixing this problem storage and feed system has two parts. The first half of the solution is to replace the bottom half of the cone with a mass flow chisel hopper with a wide and long opening. The result is an expanded flow bin, with the lower half of the storage silo emptying in mass flow and upper portion emptying in funnel flow. As long as the funnel flow portion is emptied completely on a regular basis the storage bin geometry will be reliable.

 

Mass flow is a first-in, first-out discharge pattern. The definition of mass flow is that during discharge, the entire mass of stored material comes down as a single body (single mass). The tell-tale sign that you have mass flow is that material is sliding down the bin walls. To achieve this, material must discharge evenly from the entire discharge outlet of the storage bin. This requirement leads to the second half of the solution.

 

The second half of the solution is to pair the plane flow chisel hopper with a fully-effective feeder – that is a feeder that withdraws material evenly from its entire infeed opening. Again, by definition, to achieve mass flow, where the stored material comes down as a single body, the feeder must withdraw material evenly from its entire opening. If the Feeder withdraws material selectively from the bin discharge outlet, sections of material in the bin will be stagnant and funnel flow will ensue.

 

A great example of a fully-effective feeder is the Kamengo Feeder. In addition to being fully-effective, the Feeder offers consistent metering, and can be made as wide as needed and as long as wanted. As a result, the Kamengo Feeder offers valuable advantages when designing for a difficult flowing material.

Learn More

To learn more about the physics of storage bin and feeder design as well as the root causes of bin plugging, please visit KamengoU.

Lime Silo Retrofit

Lime Silo Retrofit

This is an example of a solution to fix a lime bin that is suffering from chronic bridging.

Why the Existing Silo is Suffering From Chronic Plugging and Inconsistent Discharge

The existing bin is a silo with a steep cone that converges to a vibratory feeder. The vibratory feeder employs a shallow cone and a small outlet.

 

In summary, the silo is suffering from chronic plugging because the shallow cone of the vibratory feeder is inducing a funnel flow discharge pattern, while constricting the material discharge to too small an opening. Funnel flow (which is a first-in, last-out discharge pattern) can be made to work with a large discharge outlet. However, when the discharge outlet is small, gravity is insufficient to overcome the strength of the bulk solid at the discharge outlet, and hence chronic bridging and rat-holing is expected.

Kamengo_Banner
Kamengo_Banner
previous arrow
next arrow

Kamengo’s Solution

The solution to fixing this problem bin has two parts. The first half of the solution is to rip out the funnel flow cones, and replace them with a steeper mass flow cone and mass flow chisel hopper. Doing so fixes the geometry of the silo such that if the Feeder were removed, the entire bin would self-empty with gravity in a mass flow or first-in, first-out discharge pattern. The second half of the solution is to pair the new cone and hopper with a Kamengo Feeder. The reason for doing so is that the Kamengo Feeder withdraws material evenly from its entire opening, which by definition is necessary to actually achieve a mass flow discharge pattern in the silo. If the Feeder instead withdrew material unevenly, a funnel flow discharge pattern would ensue (regardless of the bin geometry), and rat-holing would occur.

Learn More

To learn more about the physics of storage bin and feeder design as well as the root causes of bin plugging, please visit KamengoU.

Construction & Demolition Debris Truck Load-Out Bin

Construction & Demolition Debris Truck Load-Out Bin

This is an example of a tall 30,000 cu-ft (825 cu-m) truck load out storage bin designed to handle construction and demolition wood waste and other difficult flowing fibrous materials. 

Why the Material is Challenging

Processed construction and demolition wood waste gains strength very quickly when it is subject to compaction, including compaction under its own weight in a storage bin. When processed C&D wood waste compacts it gains shear strength very quickly. Compact C&D wood waste enough and you will form bricks that have the strength of a cement block. It is this strength that enables the material to bridge over wide openings. 

 

Processed construction and demolition wood waste is a relatively low-density material, and this means that the force supplied by gravity to keep the material moving is less relative to other bulk solids. With gravity being the primary force for emptying the storage bin, it is easy to design a storage and feed system where the strength that C&D wood waste gains under compaction exceeds what gravity can break. These storage bins suffer from erratic discharge and/or chronic plugging. 

 

Processed construction and demolition wood waste is a highly variable material. It can be stringy and have long sticks. A conservative design includes using a wide and long bin opening, steep and lined bin sloping walls, and using a feeder that pulls evenly from the entire opening of the storage bin. 

Kamengo_Banner
Kamengo_Banner
previous arrow
next arrow

Why Conventional Storage and Feed Solutions Often Suffer from Chronic Bridging and Inconsistent Discharge

Standard truck load out bins use clam shell gates to control discharge. The problem is that when the clam shell is partially open, a funnel flow discharge pattern is induced, which introduces a high risk of bridging and rat-holing. Further, there is little control in how the truck is filled and the loads that are transferred to the truck. 

Kamengo’s Solution

The solution to a reliable C&D waste truck load out bin that provides a controlled discharge of material has two parts. 

 The first half of the solution is to use a plane flow hopper shape with a wide and long discharge opening. A plane flow hopper only converges in one plane at a time, and is vertical in the opposite plane. The plane flow hopper is the most conservative hopper shape. The purpose of using a conservative bin shape with a long and wide discharge outlet is to employ a geometry where if the Feeder were removed, the entire bin would self-empty with gravity in a mass flow or first-in, first-out discharge pattern. 

 

The second half of the solution is to pair the plane flow hopper with a fully-effective feeder, which withdraws material evenly from its entire opening. A fully effective feeder is, by definition, necessary to actually achieve a mass flow discharge pattern in the hopper, which is necessary when handling a difficult flowing fibrous bulk solid. 

 

Kamengo’s proposal is to use a plane flow shaped truck load-out storage bin with a vertical section and roof to provide up to 30,000 cu-ft (825 cu-m) of live storage. The storage bin has steep sloping walls, and each sloping wall is lined with a single seamless sheet of UHMW. The storage bin has a wide and long 6-foot by 24-foot opening, which is necessary to overcome the bridging dimension of C&D waste. 

 

The storage bin is paired with a Kamengo Feeder. The Kamengo Feeder is capable of filling a range of truck beds. Of critical importance, the Kamengo Feeder withdraws material evenly across both its entire length and width. The result is that the stored material is withdrawn evenly from the full discharge outlet of the truck load out bin. An even withdrawal of material is absolutely required to achieve a first-in, first-out discharge. The Kamengo supplied PLC has a user interface where the truck driver selects their truck-type and is given instructions on starting the loading procedure. Based on the truck type, the Kamengo Feeder, which delivers a consistent, predictable volumetric discharge, will deliver the volume desired for the chosen trailer type. 

Learn More

To learn more about the physics of storage bin and feeder design as well as the root causes of bin plugging, please download our white paper entitled: The Design of Reliable Storage Bins and Feeders for the Biomass Industry.