The spiral classifier is an essential piece of equipment in mineral processing, sand washing, and grinding circuits. It is often used in closed-loop systems with ball mills for pre-classification, check-classification, desliming, and dewatering. Based on the principle that solid particles of different sizes and densities settle at different speeds in liquid, fine particles overflow as slurry while coarse particles are pushed upward by the spiral blade. According to the spiral’s position relative to the slurry surface, there are three types: low weir, high weir, and submerged. The low weir type is rarely used today due to its small settling area. The high weir type, with adjustable weir height, is the most common in grinding circuits. The submerged type features a deep settling zone and a stable classification surface, making it ideal for fine or secondary grinding. This article provides a detailed comparison of their structures, applications, and selection guidelines to help users optimize classification efficiency and equipment investment.