How can we distinguish between the visually similar spiral sand washers and spiral classifiers

Today, manufactured sand is widely used in infrastructure construction. Sand washing serves as the final step in the sand production line. The primary function of sand washers is to clean sand and gravel, remove impurities and silt, and achieve a high level of cleanliness, thereby enhancing the quality of manufactured sand. Sand washers generally come in two types: spiral sand washers and bucket wheel sand washers. There is also a device called a spiral classifier, which is a mineral processing equipment that can also be used for sand washing. Visually, the spiral classifier closely resembles the spiral sand and gravel washer, and both possess sand washing capabilities. So, how should we differentiate them?

1. Equipment Appearance

Since many people perceive significant visual similarities between spiral sand washers and spiral classifiers, let's first examine their external differences. The most noticeable distinction lies in their blades. The spiral sand washer features solid blade-type blades, while the spiral classifier employs suspended hollow blades.

2. Working Principle

The spiral sand washer requires an inclined installation. The lower section of the water trough is enclosed by three-sided weir plates to form a sedimentation tank. The spiral head is submerged within this tank. Driven by an electric motor via a reducer, the spiral rotates continuously. Cleaning water is supplied through a perforated plate at the bottom of the sedimentation tank, enabling three functions: washing, dewatering, and classification.

The spiral classifier operates on the principle that particles of different sizes and specific gravities exhibit varying sedimentation rates in liquid. Fine particles float in the water and overflow, while coarse particles settle at the tank bottom. The spiral conveys these settled particles upward for discharge, enabling mechanical classification. It filters the powder ground within the mill, returns coarse material via the spiral blades to the mill feed inlet, and discharges the filtered fine material through the overflow pipe.

3. Equipment Application

The spiral sand washer is primarily used for cleaning sand and gravel, with the wheel-type sand washer also being commonly employed. The output capacity of a spiral sand washer is determined by its length and width. Spiral classifiers are widely applicable in mineral processing plants for forming closed-circuit circulation systems with ball mills to divert mineral sands, or in gravity separation plants for classifying mineral sands and fine slimes. They are also used in metal ore processing flowsheets for particle size classification of mineral slurries, as well as for desliming and dewatering operations in ore washing processes.

4. Equipment Production Capacity

For sand washing operations, the larger blade surface area of spiral sand washers enables greater aggregate throughput within the same timeframe. Their processing capacity is approximately 2-3 times that of similarly sized classifiers.

5. Washing Effectiveness

For equipment of equivalent size, sand washers feature larger hoppers than classifiers, allowing extended sedimentation time for sand particles. Consequently, the washed sand achieves higher purity.

6. Model Classification

Spiral sand washers come in single-spiral and double-spiral configurations. Processing capacity can be increased by extending the washer length or installing dual spirals in parallel. Spiral classifiers primarily include high-weir single/double spiral, low-weir single/double spiral, and submerged single/double spiral types. Low-weir models are rarely used today, with high-weir and submerged types being the mainstream.

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