10 Things to Consider When Buying Spiral Chute

When designing and purchasing a spiral gravity chute, several interacting factors goes into the design of them. These design factors include flow rate, pitch, diameter, material, intended use, and environment. How do you choose the correct spiral gravity let down chute for your product? You test it. And, you test it again. Testing on spiral gravity chutes is very important because all products flow down differently. So come to Astro and experiment on our three samples, here at Astro in Hanover, MN. We would love to assist you in the right design because we care!

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• 18' outside diameter

• 30' outside diameter

• 54' outside diameter

Testing the Flow Rate, Pitch and Diameter

It is important to know what flow rate you are trying to achieve. This is in order to design a spiral that can achieve it. Therefore, how your product behaves sliding down the chute is the biggest influence to take into account. The whole system is designed around this key element. The required pitch must be finessed to achieve the desired amount of flow that is needed, given the diameter of the chute.  The flow rate is the function of the width, and the pitch you can get on it.

The right pitch is needed for your product to flow faster, but at a safe speed for minimal breakage of the items. This pitch has much to do with how a flight is stretched. The more you stretch it, the more you get a larger pitch.  However, there is a limit to how much a given size flight can stretch.

Spiral Gravity Chute Material

Our spiral chutes are made with either stainless steel or mild steel. It depends on the intended use and environmental factors, of course.  Do you require food grade vs non-food grade material? Plus, consider temperature and atmosphere when choosing the material and finish.

Common Products to Test on Spiral Gravity Chutes

• Raw and roasted coffee beans
• Peanuts, cashews, nuts & seeds
• Fertilizer
• Packages
• Snacks & candy
• Crackers & cookies
• Dry pasta
• Cereals
• Grains
• Frozen prepared foods, i.e. frozen burgers
• Pet food & animal treats
• Airport baggage handling
• Parcel handling

Collaborative Design on Chutes

Designing spirals is not an exact science. That's why we're here to assist you. All our spiral chutes are customized and fitted precisely to each unique environment and specification. Our team collaborates with our customers on design, fabrication, and implementation. Plus, there are virtually no limitations on the length of our spirals.  However, maximum length of a spiral chute in 'one piece' is 40'.

About Astro

It is important to work with experienced designers and fabricators, indeed. We have been manufacturing food processing equipment for over 30 years. Therefore, we have in-house capabilities for development, design, testing, and full fabrication. So call today to make an appointment to test your products!

If you want to learn more, please visit our website Keefam.

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Gravity separation is widely used in the beneficiation of metallic and non-metallic minerals due to its low environmental pollution and low cost. Gravity separation equipment is generally suitable for processing coarse-grained materials with a certain specific gravity difference. We have introduced some gravity equipment: jig machine, shaking table and centrifugal separator before. This article will introduce a gravity equipment in detail: spiral chute.

01

Definition of spiral chute

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The spiral chute is a gravity separation equipment that uses the inertial centrifugal force generated by the ore pulp in the spiral rotation motion to realize the separation of light and heavy minerals.

02

Separation range of spiral chute

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The spiral chute is widely used to separate non-ferrous metals, ferrous metals, non-metallic minerals, rare metal minerals and heavy minerals in tailings with a particle size range of 0.3-0.02 mm, such as iron, tin, tungsten, tantalum, niobium, gold mine, coal, monazite, rutile, zircon, etc.

03

Principle of spiral chute beneficiation

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The chute beneficiation is inclined flow separation. The operation process is mainly affected by the impact of the water current, the gravity of the mineral particles, the inertial centrifugal force and the friction force of the chute surface. The slurry is fed to a chute with a certain slope. Driven by the water flow, the ore particles are loosened and stratified. The upper light minerals are quickly discharged out of the chute, and the lower heavy minerals are retained in the chute or discharged from the lower part at a low speed. After receiving them separately, concentrates and tailings are obtained.

04

Composition of spiral chute 

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The spiral chute is mainly composed of these six parts:

(1) The ore divider is used for distribute slurry, located at the uppermost part.

(2) The ore feed chute is located between the ore divider and the chute.

(3) The chute is the main part, which is connected by a number of spiral pieces with bolts. Spiral pieces are made of glass steel.

(4) The cutting chute is connected to the discharge end at the lower part of the spiral chute.

(5) The ore receiving bucket is a concentric annular cylinder, which can collect the different grade streams intercepted by 4 ore cutting chutes and send slurry to the next operation.

(6) The chute bracket refers to the pillars around the spiral chute and the upper cross frame.

05

Classification of spiral chute

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According to the particle size of the ore that can be processed by the spiral chute, it can be divided into three categories:

(1) For coarse-grained chute, the feed size is above 2-3mm, and the maximum can reach 100-200mm.

(2) For ore sand chute, the feeding grain size is 2-3 mm.

(3) For sludge chute, the feed size is less than 0.074 mm.

If you want to learn more, please visit our website Spiral Chute.

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06

Structure parameters of spiral chute

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(1)The diameter of the chute. The processing capacity of the chute is proportional to the square of the diameter. When conditions permit, large-diameter spiral chute should be used to handle coarse materials.

(2)The cross-sectional shape of the spiral chute is related to the particle size of the materials. For the particle smaller than 2mm, the ratio of long and short axis is 2:1. The long axis is horizontal. It is appropriate that half of the long axis is equal to one third of the diameter of the spiral.

(3)The size of the pitch is usually defined by the ratio of the pitch to the diameter of the spiral, which is called the pitch-diameter ratio. When the ratio is about 0.73, the sorting effect is better.

(4)The length of the spiral chute and the number of turns. They determine the running distance of the material. It takes 3-4 laps for easy beneficiation ore, and 5-6 laps for difficult-to-select ore. 

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Advantages of spiral chute

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(1) Energy efficient. The spiral chute has no moving parts and consumes no power.

(2) Less space occupation. The equipment occupies a small area and has a large processing capacity per unit area.

(3) Water saving. There no need to add flushing water during the separation process.

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(4) Stable separation index. When the ore volume, ore concentration, particle size and grade change, the impact on the separating index is small.

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Disadvantages of spiral chute

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(1) Large height difference. It need a pump to lift the slurry for feeding.

(2) Low concentrate grade. It is suitable for use as roughing equipment.

(3) Poor separation effect for conjoined or flake ore.

(4) The parameters of the spiral chute are not easy to adjust to adapt to changes of ore properties.

09

Operation points of spiral chute

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(1)Suitable ore concentration:

Generally, the ore concentration for roughing separation is 30%-40%, and the concentration is 40%-60% for beneficiation. During the separation, the ore particle size and ore concentration are required to fluctuate within 5% of the error range. 

(2)Suitable ore volume:

The size of the feed ore volume directly affects the thickness and speed of the ore flow. The ore volume should be large when separating coarse-grained materials, and small when separating fine-grained materials. When roughing, the ore volume should be large, and when concentration, the ore volume should be small.

10

Development trend of spiral chute

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(1) Large-scale, large processing capacity, based on scale effect to create benefits.

(2) Improve the separation of fine particles and fine particles, especially for particle size of -0.047 mm.

(3) Enhance the enrichment of useful minerals, and improve the separation efficiency of the spiral chute and the recovery rate of minerals.

(4) Energy saving and environmental protection, small floor space.

(5) Convenient operation, stable separation process, simple structure, easy maintenance and management.

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To Wrap Up

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With the increasing awareness of energy saving and environmental protection, the use of gravity separation method for ore pre-selection, recovery of monomer heavy minerals in the grinding circuit, and addition of gravity separation equipment in the magnetic separation or flotation process to recover coarse useful minerals or abandoning the final tailings will be an inevitable development trend. If you want to know more about spiral chute, please feel free to consult our online customer service.

For more Durable fiberglass spiral chuteinformation, please contact us. We will provide professional answers.