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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. 

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. 

Metallurgical Coal Railcar Load-Out

Metallurgical Coal Railcar Load-Out

This is an example of a met coal railcar loadout bin that is suffering from chronic bridging and rat-holing. It is a good example of poor bin geometry combined with uneven discharge that is resulting in inconsistent discharge.

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

The existing bin consists of of twin funnel flow (first-in, last-out) pyramid hoppers leading to small square discharge openings. One discharge opening is metered with a screw feeder and the other is metered using a clamshell gate.

 

The combination of the small openings and multiple shallow walls as well as the behavior of the feeders results in a hopper that cannot reliably discharged with only gravity. Because the discharge openings are small one would expect a tendency for stable rat-holes to form over the openings, and for the bins to suffer from erratic discharge. Finally, a consequence of having a first-in, last-out discharge is that stagnant material is left along the silo walls. Stagnant material will gain strength over time, further creating the conditions for plugging and erratic discharge.

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Kamengo’s Solution

The solution to fixing this problem storage and feed system has two parts. The first half of the solution is to reconfigure the hopper to include steep sloped walls, and move away from pyramid style hoppers to more conservative plane flow hoppers with a wide and long discharge opening. The wide and long discharge opening is required to overcome the bridging dimension of met coal. Overcoming the bridging dimension is necessary to ensure that the material cannot bridge over the feeder.

 

Changing the bin geometry will promote a mass flow discharge. 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 each plane flow 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 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.

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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. 

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. 

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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.