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Dewatered Nickel Laterite Tailings Truck Load-Out Bins

Dewatered Nickel Laterite Tailings Truck Load-Out Bins 

When a large nickel mine located in the South Pacific purchased two side-by-side truck load bins to handle a sticky, high-moisture content dewatered tailings, the mine chose Kamengo to design and deliver both the storage bins and Feeders because of our expertise, special equipment and long history of designing storage and feed arrangements handling very sticky and cohesive bulk solids.

 

The formula for designing a reliable truck load out system handling a cohesive material is to pair a correctly designed storage bin with a feeder that withdraws material evenly from its entire opening. The storage bin geometry, including bin shape and angle of sloping walls, must be chosen such that the stored material will discharge in a mass flow or a first-in, first-out discharge pattern. Further, the storage bin should discharge via a sufficiently wide and long opening, such that the material cannot bridge over the feeder. Finally, the feeder must withdraw material evenly from the full length and width of the bin discharge opening otherwise the whole bin/feeder arrangement will be susceptible to chronic rat holing.

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Kamengo’s Approach and Solution

Prior to starting equipment design, Kamengo conducted material flow testing using a sample of the dewatered nickel laterite. The testing includes a series of bench-scale tests that are used to derive the minimum geometry (angle of sloping walls, sloping wall material, discharge opening) required to reliably discharge a bulk solid. The standard that Kamengo uses, is that if the feeder were removed from the storage bin, it should completely self-empty with only the aid of gravity. If it cannot self-empty, then there is something wrong with the geometry of the storage bin.

 

To confirm both the geometry and suitability of the Kamengo Feeder, Kamengo conducted at-scale pilot testing. The testing included increasing the moisture content of the bulk solid until it was saturated to test the Feeder’s ability to discharge out-of-spec material.

 

In total Kamengo delivered two truck load out storage bins. Each storage bin is paired with a Kamengo Feeder. The strength of the Kamengo Feeder is that it withdraws material evenly from the entire width and length of the bin discharge opening. This is necessary when handling a difficult flowing material. A second advantage of the Kamengo Feeder is that it discharges over the length of the truck bed, allowing the truck to be filled without having to index it forward.

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. 

Platinum Group Metals (PGM) Concentrate Filter Cake Truck Load-Out Bin

Platinum Group Metals (PGM) Concentrate Filter Cake Truck Load-Out Bin  (A)

 

This case study is an example of a Kamengo truck load out bin discharging cohesive PGM filter cake into trucks. What makes this application challenging is that the filter cake will be stored in the storage bin for up to 72 hours and the material gains significant strength at rest. To overcome the shear strength of the bulk solid, the Feeder is discharging from a 10-foot (3m) wide bin opening. This installation went into service in 2020.

The Challenge and Kamengo’s Solution

Kamengo was chosen to deliver two truck load-out storage bins with feeders handling platinum group metals (PGM) concentrate filter cake. Each installation serves a different mine site. Each truck load-out arrangement includes a mass flow storage bin and Kamengo Feeder fitted with an integrated dust control system. Each storage bin is handling a PGM concentrate filter cake, and receives material directly from the filter press. Filter cake is expected to be stored in the storage bin up to 72 hours. To ensure material will not bridge over the Feeder, Kamengo delivered a 10-foot (3m) wide Kamengo Feeder. An advantage of choosing a Kamengo solution, is that the Kamengo Feeder handles loads very efficiently. As a result, a wide Kamengo Feeder is close to a tenth of the cost of an equally wide apron Feeder.

 

Both storage bins are located in a building. To minimize dusting, prior to discharging material into a truck, a Kamengo loading deck with a shroud lowers from the Kamengo Feeder over the truck bed. A dust control system holds the area within the shroud at a slight negative pressure. Air in the truck bed that is displaced by the falling filter cake is circulated first through self-cleaning filters, then through HEPA filters before being expelled into the building. Once the Feeder has completed a set number of strokes, equating the target discharge volume, the loading deck automatically raises.

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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. 

Recycled Shredded Aluminum Tall Metering Bin

Recycled Shredded Aluminum Tall Metering Bin

 

This case study is an example of a Kamengo tall bin metering recycled shredded aluminum into a kiln. What makes this installation challenging is that the material is quite light and has a propensity to intertwine, and thus gain significant strength when compacted. This installation went into service in 2018.

The Challenge

This installation was for a second recycling line feeding a kiln that the plant was installing. On the first recycling line, the metering bin to the kiln, which consisted of a carbon steel plane flow hopper fed by a belt feeder, suffered from inconsistent discharge and chronic hang-ups. To make the line work, the plant needs to keep a low-level of material in the storage bin.

 

When it came to designing the second line, the plant not only desired a metering bin that is reliable, but also wanted to increase the available storage before the kiln. The plant chose a Kamengo Feeder and tall bin.

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

The prior metering bin, including belt feeder, on the first line was suffering from chronic plugging for two reasons:

 

  1. The conveying action of the belt feeder, which is shearing material from the storage bin, was compacting the stored shredded aluminum against the front of the bin wall. As shredded aluminum compacts, it gains significant shear strength. With enough compaction, the shredded aluminum gains sufficient shear strength to bridge over the Feeder.
  2. The belt feeder had a tendency to withdraw material from the rear of the bin. This selective withdrawal of material induced a funnel flow, or first-in, last-out discharge pattern in the bin. In principle, there is nothing wrong with funnel flow as long as the effective opening of the bin exceeds the bulk solid’s piping dimension (or distance over which the bulk solid can form a stable rat-hole). Unfortunately, the piping dimension for shredded aluminum is quite large – in fact, it is larger than the metering bin. To handle shredded aluminum reliably without hang-ups it must be discharged in mass flow, or a first-in, first-out discharge pattern. To do so, the Feeder must withdraw material evenly from the hopper’s full discharge outlet. Further, the discharge outlet for the hopper must be wide and long.

Kamengo’s Solution

The solution to designing a reliable storage bin capable of metering shredded aluminum as two parts:

 

The first half of the solution is to choose a correct bin geometry for handling the shredded aluminum. In this case, Kamengo chose a plane flow hopper shape with steep sloping walls and 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 wide and long 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. To determine the minimum geometry, Kamengo conducted material flow characterization testing, which includes a series of bench scale tests, which are used to determine the minimum wall angle and the minimum bin discharge outlet width and length.

 

The second half of the solution is to pair the plane flow hopper with a fully-effective Feeder – in this case a Kamengo Feeder. A fully-effective feeder is one that withdraws material evenly from its entire opening, which by definition is necessary to actually achieve a mass flow discharge pattern in the hopper. Again, discharging in mass flow is often necessary when handling a difficult flowing bulk solid. What makes the Kamengo Feeder unique is that it can be made as wide as needed and as long as desired. The minimum bin discharge outlet width and length to reliably handle shredded aluminum is approximately 6-feet by 12-feet. To achieve mass flow, the Feeder inlet must match this outlet. This is very difficult to do with conventional technologies, but very easy to achieve with a Kamengo Feeder.

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.

Hog Fuel (Wood Waste) Tall Day Bin Retrofit

Hog Fuel (Wood Waste) Tall Day Bin Retrofit

 

This case study is an example of a retrofit of a tall 18-foot diameter, 4,000 cu-ft silo used to store and feed hog fuel (wood waste) into a power boiler. This retrofit was completed in 2010.

The Existing System Prior to the Retrofit

Prior to the retrofit, the storage silo converged with a 60-deg cone down to a vibrating hat. The mill could not put more than 3-feet of material in the storage bin before it would plug. This was problematic, because this storage silo was providing critical storage between the hog fuel pile and the power boiler’s metering bins.

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Why the Existing System Suffered From Chronic Plugging

The existing silo was suffering from chronic plugging for two reasons:

 

  1. Poor bin geometry. The sloping walls and discharge opening of the cone were insufficient to produce a reliable mass flow or first-in, first-out discharge pattern. First, the sloping walls were too shallow. As a result, material could not slide along the hopper walls, but would instead try to slip within itself in a funnel flow, or first-in, last-out discharge pattern. Second, the discharge opening was too small. The smaller the opening, the less strength a material requires to form a stable arch over the bin outlet that gravity cannot reliably break.
  2. Uneven discharge. The vibrating feeder withdrew material unevenly from the storage bin – pulling material primarily from around the silo walls, leaving behind a relative stagnant core of fuel. This selective withdrawal of material, in addition to the shallow sloping walls, induced a funnel flow, or first-in, last-out discharge pattern in the bin. In principle, there is nothing wrong with funnel flow as long as the effective opening of the bin exceeds the bulk solid’s piping dimension (or distance over which the bulk solid can form a stable rat-hole). Unfortunately, the piping dimension for wood waste is quite large – in fact, it is larger than the silo diameter. To handle hog fuel (wood waste) reliably without hang-ups, it must be discharged in a mass flow, or a first-in, first-out discharge pattern – where all the material in the storage bin descends as a single body and where all the material in the storage bin is in motion. To do achieve a mass flow discharge pattern, the Feeder must withdraw material evenly from the storage bin’s full discharge outlet.

Kamengo’s Solution

The solution to the silo had two parts:

 

The first half of the solution is to modify the bin geometry of the silo such that it will promote a first-in, first-out discharge pattern. In this case, Kamengo placed insert plates lined with a low friction liner into the silo to construct two plane flow hoppers – one stacked on top of the other, and one 90-degrees to the other. A plane flow hopper 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 insert plates open up to a 6-foot wide by 12-foot long opening. This wide and long opening is required to ensure gravity will always be sufficient to break the strength of the arch that hog fuel would create above the Feeder. In summary, by replacing the cone with the insert plates, Kamengo fixed the geometry of the silo such that if the Feeder were removed, the silo would self-empty with only the aid of gravity. The minimum geometry required for gravity discharge, including minimum slope angle of the insert plates and minimum discharge opening were all selected based on the flow properties of hog fuel.

 

The second half of the solution was to pair the plane flow hoppers with a fully-effective Feeder – in this case a Kamengo Feeder. A fully-effective feeder is one that withdraws material evenly from its entire opening, which by definition is necessary to actually achieve a mass flow discharge pattern in the hopper. By definition, to achieve mass flow, the bulk solid must descend the storage bin as a single body with all the stored material in motion, and the only way to achieve this is for the feeder to 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.

 

Again, discharging in mass flow is often necessary when handling a difficult flowing bulk solid. What makes the Kamengo Feeder unique is that it can be made as wide as needed and as long as desired. This feature is particularly valuable given that the chosen minimum discharge opening of the silo is 6-foot by 12-foot. To achieve mass flow, the Feeder inlet must match this outlet. This is very difficult to do with conventional technologies, but very easy to achieve with a Kamengo Feeder.

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 Retrofit

Hog Fuel (Wood Waste) Tall Day Bin Retrofit

 

This case study is an example of a retrofit of a 37-foot tall, 6,000 cu-ft silo used to store and feed hog fuel (wood waste) into a power boiler. The hog fuel at the mill is particularly challenging because it contains hickory bark and can be very stringy.

When Kamengo first met the mill, the plant engineers were exploring options to replace the entire hog fuel feeding system. However, upon learning of a retrofit to a similar size tall bin that Kamengo had completed for a pulp mill in Washington State, USA, the mill found that it could solve its feed issues by retrofitting its existing bin

 

Kamengo replaced the lower half of the bin with a rectangular plane-flow mass flow hopper and Kamengo Feeder. The Kamengo Feeder is ahead of a live bottom bin with screw feeders feeding biomass fuel into the boiler. Since the screw feeders cannot maintain a significant head of material above them, the Kamengo Feeder is used to reliably meter just enough material that the screw feeders can handle to ensure good, steady material discharge into the boiler.

 

This retrofit was completed in 2004.

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Why the Existing Storage and Feed System is Suffering from Chronic Bridging and Inconsistent Discharge

Prior to the retrofit, the storage silo converged with a 60-deg cone down to a vibrating hat. The mill could not put more than 6-feet of material in the storage bin before it would plug. This was problematic, because this storage silo was providing critical storage between the hog fuel pile and the power boiler’s metering bins.

The existing silo was suffering from chronic plugging for three reasons:

  1. Poor bin geometry. The sloping walls and discharge opening of the cone were insufficient to produce a reliable mass flow or first-in, first-out discharge pattern. First, the sloping walls were too shallow. As a result, material could not slide along the hopper walls, but would instead try to slip within itself in a funnel flow, or first-in, last-out discharge pattern. Second, the discharge opening was too small. The smaller the opening, the less strength a material requires to form a stable arch over the bin outlet that gravity cannot reliably break.
  2. The vibrating feeder withdrew material unevenly from the storage bin – pulling material primarily from around the silo walls, leaving behind a relative stagnant core of fuel. This selective withdrawal of material, in addition to the shallow sloping walls, induced a funnel flow, or first-in, last-out discharge pattern in the bin. In principle, there is nothing wrong with funnel flow as long as the effective opening of the bin exceeds the bulk solid’s piping dimension (or distance over which the bulk solid can form a stable rat-hole). Unfortunately, the piping dimension for wood waste is quite large – in fact, it is larger than the silo diameter. To handle hog fuel (wood waste) reliably without hang-ups, it must be discharged in a mass flow, or a first-in, first-out discharge pattern – where all the material in the storage bin descends as a single body and where all the material in the storage bin is in motion. To do achieve a mass flow discharge pattern, the Feeder must withdraw material evenly from the storage bin’s full discharge outlet.

Kamengo’s Solution

The solution to fixing the silo had two parts:

 

The first half of the solution is to modify the bin geometry of the silo such that it will promote a first-in, first-out discharge pattern. In this case, Kamengo cut off the bottom portion of the silo, including the cone and replaced it with a plane flow, mass flow hopper and Kamengo Feeder. A plane flow hopper is the most conservative hopper shape.

 

The new hopper converged to wide and long 6-foot wide by 18-foot long discharge opening. This wide and long opening is required to ensure gravity will always be sufficient to break the strength of the arch that hog fuel would create above the Feeder. In summary, by replacing the cone with the new plane flow hopper, Kamengo fixed the geometry of the silo such that if the Feeder were removed, the silo would self-empty with only the aid of gravity. The minimum geometry required for gravity discharge, including minimum slope angle of the plane flow hopper and minimum discharge opening were all selected based on the flow properties of hog fuel.

 

The second half of the solution was to pair the plane flow hopper with a fully-effective Feeder – in this case a Kamengo Feeder. A fully-effective feeder is one that withdraws material evenly from its entire opening, which by definition is necessary to actually achieve a mass flow discharge pattern in the hopper. By definition, to achieve mass flow, the bulk solid must descend the storage bin as a single body with all the stored material in motion, and the only way to achieve this is for the feeder to 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.

 

Again, discharging in mass flow is often necessary when handling a difficult flowing bulk solid. What makes the Kamengo Feeder unique is that it can be made as wide as needed and as long as desired. This feature is particularly valuable given that the chosen minimum discharge opening of the silo is 6-foot by 18-foot. To achieve mass flow, the Feeder inlet must match this outlet. This is very difficult to do with conventional technologies, but very easy to achieve with a Kamengo Feeder.

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. 

Soda Ash Tall Metering Bin

Soda Ash Tall Metering Bin 

 

This is an example of a tall 2,500 cu-ft (70 cu-m) storage bin designed specifically to handle soda ash.

Why Soda Ash is a Difficult Flowing Material and Why Conventional Conical Storage Bins are Inappropriate for the Material.

Soda ash’s granular nature gives it the look and feel of an easy flowing material. However, wall friction testing of the material by Kamengo reveals that a poor choice in bin shape, liner and sloping wall angles will result in: 1) inconsistent discharge; 2) flooding of conveyors; 3) hang-ups; and/or 4) chronic caking and lumping. This is because if any of the above are incorrect, a funnel flow discharge pattern in the storage bin would be induced.

 

Funnel flow is a first-in, last-out flow pattern where material sluffs from the top down through a core in the storage bin. The challenge with funnel flow is that the majority of material in the storage bin remains stagnant during discharge. The problem is that stagnant material is permitted the opportunity to gain strength as it compacts under its own weight, which promotes caking. Further, as the material gains strength, it is able to bridge over wider openings, eventually leading to stable rat-holes and bridging. The alternative to funnel flow is mass flow. In contrast to funnel flow, mass flow is a first-in, first-out discharge pattern where all of the material in the storage bin is in motion during discharge.

 

For a Soda Ash silo, which typically has a relatively large storage volume for the given discharge rate, mass flow is preferred for several reasons. To reduce caking and prevent the stored soda ash from developing the strength needed to form a stable rat-hole, it is preferable for 100% of the stored material to move downwards over the course of a 24 hour period, and not just a small section of stored soda ash that lies within a core over the bin opening. Second, because it can take up to a month to empty a soda ash bin and it may never actually be permitted to fully empty. If the bin is emptying in a funnel flow discharge pattern, sections of soda ash will never leave the bin and simply be permitted to harden and become un-flowable. Third, soda ash is a relatively fine material, and if a stable rat-hole forms and collapses, the material would fluidize and mix with air, causing it to rush from the bin, which would introduce an engulfing hazard around the bin.

 

Standard soda ash bins are conical shape and discharge from a small opening. Typically, the angle of the cone is too shallow to produce a mass flow discharge pattern, and hence these bins discharge in funnel flow.

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Kamengo’s Solution

The solution to a reliable soda ash bin that provides a very controlled discharge has two parts.

 

The first half of the solution is to discard the standard cone and replace it with plane flow hoppers with lined and sufficiently steep hopper walls needed to produce a mass flow discharge pattern. 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 solution employs a Kamengo Feeder with a wide and long 3-foot by 10-foot opening. 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 soda ash bin. An even withdrawal of material is absolutely required to achieve a mass flow or first-in, first-out discharge. The Feeder delivers batches of soda ash to a screw conveyor below, which in turn, provides a final metering into the process.

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.

ROM Coal Ore Truck Load-Out Bin

ROM Coal Ore Truck Load-Out Bin

 

This is an example of a 53,000 ft3 (1,500 m3) ROM Coal Ore Truck Load-Out Bin.

Why Conventional Truck Load-Out Bins Suffer from Chronic Bridging and Uncontrolled Discharge

A standard ROM truck load out bin consists of a large conical hopper and silo that is discharged using a very large clamshell gate. Unfortunately, these systems suffer from chronic bridging and flooding from collapsing rat-holes.

 

In summary, a conical hopper is satisfactory bin shape as long as the discharge opening is large and that the hopper is discharged evenly from its entire opening. The challenge with a clamshell gate is that it operates partially open in order to control the flow of discharge. When the opening is not fully live, bridging and the formation of rat-holes should be expected.

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Kamengo’s Solution

The solution to a ROM truck load out bin has two parts.

 

The first part is to choose a bin shape that promotes reliable discharge. Kamengo’s preferred method for a tall, large storage bin handling a moderately difficult flowing material is to use “expanded flow”. Expanded flow uses a combination of mass flow and funnel flow, and is typically the most cost-effective bin shape for a tall and very large storage bin.

 

With expanded flow the bottom of the bin discharges in mass flow and the top of the bin discharges in funnel flow. The benefit of expanded flow is that one is able to benefit from the advantages of both flow patterns while minimizing their drawbacks. The expanded flow hopper shown combines a chisel hopper with a funnel flow cone and circular silo. A benefit of this arrangement is that bin wall loads are handled efficiently, reducing the overall cost of the bin.

 

The second half of the solution is to pair the expanded flow bin with a fully-effective feeder – that is a feeder that withdraws material evenly from its entire infeed opening. This is necessary to achieve mass flow in the lower portion of the bin, and to avoid the formation of rat-holes, which are particularly dangerous for large truck load-out bins. 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 rat-holes will form.

 

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. 

ROM Ore Metering Bin

ROM Ore Metering Bin

 

This is an example of a rock ore bin handling a mix of large particles and fines 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.

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

The existing bin consists of a narrow 6.5-foot diameter ore pass leading to a short hopper and an apron feeder.

 

In summary, the bin is suffering from chronic plugging because the apron feeder is withdrawing material preferentially from rear of the hopper, which is inducing a funnel flow discharge pattern that is extending up into the ore pass. 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.

 

The alternative to a funnel flow discharge pattern is mass flow. Mass flow is a first-in, first-out discharge pattern where 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 hopper walls. In contrast, with funnel flow, material is stagnant along the hopper walls. When the feeder withdraws material preferentially from one side of the hopper, then material is not permitted to withdraw evenly from the entire discharge outlet of the storage bin. The result is stagnant material along the bin walls and a funnel flow discharge pattern.

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Kamengo’s Solution

The solution to fixing this problem bin has two parts.

 

The first half of the solution is to discard the existing hopper and replace it with a plane flow hopper with sufficiently steep hopper walls needed to produce a mass flow discharge pattern. 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 rock ore that contains a mix of large particles and fines.

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. 

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.

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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.

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

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.

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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.