What is a spiral classifier？

The spiral classifier is a device that utilizes the principle of different sedimentation speeds of solid particles in a liquid based on their specific gravity for mechanical classification. It is widely used in closed-circuit processes in conjunction with ball mills to separate and classify ore sand in mining plants. It can also be applied in gravity separation plants for classifying ore sand and fine mud, as well as in metal ore dressing processes for size classification of ore pulp. Additionally, it finds application in de-sliming and dewatering operations during ore washing.

Types: There are four classifiers: high weir single spiral and double spiral, submerged single spiral and double spiral.

• High weir spiral classifier is suitable for coarse particle classification, the maximum size of overflow is generally 0.4~0.15mm;
• Submerged spiral classifier is suitable for fine particle classification, the maximum size of overflow is generally below 0.2mm.

Applications of Spiral Classifier

• Mining Plants: Used in conjunction with ball mills to form a closed-circuit for ore sand separation and classification.
• Gravity Separation: Applied for classifying ore sand and fine mud to enhance mining efficiency.
• Metal Ore Dressing: Used in the ore dressing process for size classification of ore pulp to meet subsequent process requirements.
• Ore Washing Operations: Involved in de-sliming and dewatering processes during ore cleaning.

Advantages Of Spiral Classifier

• The energy consumption of spiral classifier is 50% lower than other classification equipment, and the output is also increased by 50%.
• The water tank has a large slope, which is convenient for forming a closed-circuit ring grinding operation with the ball mill, and forms a self-flow sand return.
• Simple operating process and stable working status, greatly reducing maintenance costs.
• Its spiral structure can ensure a large enough settling area to extend the material suspension time, which is more conducive to the even distribution of materials during the classification process.
• Users can adjust the parameters of the spiral classifier according to their needs, such as spiral speed, inclination and outlet size to achieve different classification requirements.

Principle of Spiral Classifier

The working principle of the spiral classifier is based on the different sedimentation speeds of solid particles in a liquid due to their varying specific gravities. When the ore pulp enters the tank from the side feed inlet, it forms a sedimentation zone at the bottom of the tank. The slowly rotating spiral provides a certain degree of agitation to the pulp. After agitation, the light and fine particles suspend on the surface, forming an overflow that flows over the weir at the end of the water tank into the next mineral processing step. The heavy and coarse particles settle at the bottom of the tank, forming a return sand that is transported by the spiral to the discharge port for removal, thus achieving the desired classification.

Structure of Spiral Classifier

The spiral classifier mainly consists of the following components:

• Transmission Device: Includes an electric motor, reducer, cylindrical gear pair, and bevel gear, responsible for driving the rotation of the spiral.
• Spiral Body: Composed of a hollow shaft, supports, spiral blades, and lining iron, which is the main working part of the classifier.
• Tank: Holds the entire slurry and bears the weight of the machine and all its loads. Constructed by welding steel plates and various steel sections.
• Lifting Mechanism: Used to raise or lower the spiral for maintenance or to adjust the processing level within the tank.
• Lower Bearing (Bushing): Supports the spiral and bears the load during operation.
• Discharge Valve: Located at the bottom of the tank, allowing the slurry to be drained when necessary.

General Specification