How to Choose the Right Spiral Classifier

A spiral classifier is a device that classifies solid particles based on their different sedimentation speeds in the slurry. Spiral classifiers are generally categorized into high-weir types and submerged types. How should users make the right choice for production? Let’s explore this together.

1. Selection Based on the Number of Blades

A higher number of blades increases the classification area, facilitating better performance under demanding operational conditions. However, it also adds complexity to the equipment design. Therefore, unless specific requirements or constraints related to the mineral pulp dictate otherwise, it is advisable to use fewer blades whenever possible.

2. Selection Based on Grinding Fineness

The height of the overflow weir in a spiral classifier directly influences the effective sedimentation area for ore particles. In practice, the selection should be aligned with the required grinding fineness specifications.

The height H of the overflow weir on a high-weir spiral classifier is 1/4–3/8 of the spiral diameter D. This configuration is primarily used for ore classification with an overflow particle size of 0.83–0.15 mm. For submerged spiral classifiers, the height H is 3/4–1 of D, making them suitable for ore classification with an overflow particle size of 0.15–0.07 mm.

3. Select Based on Processing Capacity

The width of the spiral classifier tank significantly impacts the overflow discharge rate. A wider tank results in a faster overflow discharge rate, increasing the likelihood that coarse particles will be carried out with the overflow. Conversely, a wider trough provides a larger settling area for the ore, facilitating easier sedimentation.

Therefore, the classifier’s trough width must be compatible with the grinding mill’s processing capacity. When purchasing, carefully consider both the spiral classifier’s trough width and the grinding mill’s capacity to select the most appropriate equipment.

4. Select Based on Production Process

To achieve a coarser overflow and process materials with high specific gravity that settle rapidly, the spiral rotation speed can be moderately increased. However, it should not be excessive, as this may compromise classification efficiency.

Therefore, for two-stage grinding or closed-circuit grinding processes, the spiral speed of the classifier should be kept as low as possible. The optimal spiral speed should be determined according to the specific production requirements, enabling the selection of the most suitable spiral classifier.