Selecting the right spiral classifier depends on several technical and operational considerations. The main criteria include the type of material to be classified, desired particle size, processing capacity, and the specific application within your mineral processing circuit.
Based on the height of the overflow weir and the degree of spiral submergence within the tank, spiral classifiers are broadly categorized into three types: high weir, low weir, and submerged.
In the high weir type, the overflow weir is typically positioned higher than the spiral shaft’s lower bearing but below the upper edge of the overflow end spiral. This design provides a larger sedimentation area compared to low weir types. Its weir height is adjustable within a certain range, allowing for fine-tuning of the sedimentation zone area to meet specific classification particle size requirements.
The low weir type features an overflow weir positioned lower than the overflow end bearing. This results in a smaller settling area, reduced overflow capacity, and significant slurry surface agitation by the spiral. Consequently, it is primarily used in actual production for washing sand ore with low mud content and for dewatering coarse particles, seldom for precise grading processes.
For the submerged type, typically 4 to 5 turns of the spiral blades at the overflow end are fully submerged below the liquid level in the settling area. This creates a large and deep settling pool.
These structural differences dictate their optimal functions. The high weir spiral classifier is better suited for separating particles coarser than 0.15mm, making it ideal for the first stage of grinding circuits. In contrast, the submerged spiral classifier offers a stable classification surface, high overflow output, and produces finer particle sizes. Therefore, it is more suitable for separating overflow products with a particle size of less than 0.15mm and is often integrated into the second stage of grinding circuits(Spiral Classifier for Mining – Baichy Machinery, n.d.).
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Reference:
Spiral classifier for mining—Baichy Machinery. (n.d.). Retrieved June 10, 2025, from https://www.baichy.com/Beneficiation/Spiral_Classifier.html
