What is Spiral Chute and Why Do We Use Them?

Spiral let-down chutes, also called gravity chutes, are commonly used to quickly and easily move a product downward in a controlled manner to minimize or eliminate product breakage. Many of these chutes are installed in bins for the purpose of filling the bin “damage-free.” There are no moving parts, no motors, and these spirals last for years and years with virtually no maintenance.

For more information, please visit Keefam.

50′ Spiral Let-Down Chute s

In this case, the client already had some bins with spiral chutes installed. They were expanding and needed more storage and chutes. Astro was approached with hand drawn sketches, overall dimensions, and desired flow rate. Three 50 foot chutes were needed. In addition, each chute was to be built in the full 50 foot length.

4′ Wide Diameter Chutes

With an overall diameter just over four feet wide, these were among the largest chutes we have built. There are lips on both the inside and outside of the chute to keep product contained. All welding is continuous and accomplished with a very neat MIG weld by using Fronius welding machines. However, no grinding was required for this spiral let-down chute.

Special Delivery

This spiral chute has no center pipe, but instead features a heavy exterior frame supporting the whole structure. With nuts being very heavy, extra cross support was employed to hold the weight. All chutes were shipped on time, on one truck, and arrived at its destination in excellent condition. The contractors installed the chutes after the floor was in, and the rest of the containment was built after the chutes were installed.

Astro Metal Craft Chutes

We have been building spiral let-down chutes of various sizes, styles, and metals for over 15 years of its 30+ year old existence. Complementing the spirals, we also build screw conveyors, other processing equipment, and heavy gauge railings in stainless steel, mild steel, or aluminum.

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.

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.

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.

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.

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.

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.

The company is the world’s best Sortation Equipment supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

(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. 

(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.

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

(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.

(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.

(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.