Spiral classifier It is one of the machines used in ore-dressing plants. The spiral classifier is a mechanical device that performs particle classification based on the fundamental principle that solid particles of different densities accumulate at different rates in a liquid medium. It can separate the ground material from the ball mill into various particle sizes and, using spiral blades, tightly screw the coarse feed back into the ball mill’s discharge port, while discharging the coarser particles that have been filtered out through an overflow pipe. The spiral classifier is commonly referred to as a classifying machine. There are four main types of classifiers: the high-weir single-spiral and double-spiral designs, as well as the submerged single-spiral and double-spiral designs. The classifier mainly consists of a drive system, a rotating drum, a drying chamber, a lifting mechanism, a lower rubber support (piston pin), and a discharge valve. Spiral classifiers are widely used in mining operations to separate mineral sands in closed-circuit grinding systems paired with cement ball mills, or in ore-processing plants for classifying sand and fine mud. They are also employed in metal ore processing to perform particle-size classification of coal slurries, as well as in slurry washing processes for sludge dewatering and dehydration.

Overall indicates

The classifier mainly consists of a transmission system, balls, a drying chamber, a lifting system, lower rubber supports (piston pins), and an ore-discharge valve.

The water tank of this equipment is assembled with a tilted configuration. The specific tilt angle is determined based on the equipment selection criteria in the production process. A transmission system drives a screw conveyor that rotates inside the tank. The coal slurry, after being ground, enters the tank through a side feed inlet located below the discharge port, thereby forming a sedimentation zone for the coal slurry at the bottom of the tank. The area and capacity of this sedimentation zone depend on the magnitude of the tank’s tilt angle as well as the relative height of the overflow weir. The low-speed rotating screw conveyor provides a certain degree of mixing action. After mixing, lighter and finer particles float to the top, forming an overflow stream that overflows through the overflow weir at the end of the tank and is then fed into the next stage of the mineral processing procedure. Heavier particles settle to the bottom of the tank, forming tailings, which are transported by the screw conveyor to the discharge outlet and removed from the system.

In ore dressing plants, minerals need to be ground and crushed into tiny particles to facilitate the separation of valuable minerals from associated pyrite. However, excessive grinding can negatively affect cement production. Therefore, grading equipment is required to identify and remove mineral particles that do not meet the specified size requirements for further grinding, while those that meet the standards proceed to subsequent processing stages.

        Spiral classifier It’s one of the most important grading machines—how much do you actually know about it?

I. Principle of the Spiral Classifier

A spiral classifier is a machine that separates mineral particles based on the principle that solid particles of different sizes and proportions have different sedimentation coefficients in a solution. As the spiral auger blades propel the minerals forward, coarse-grained minerals adhere to the bottom of the tank, while fine-grained minerals float on the surface and are lifted upward by the blades, eventually being discharged through the overflow outlet.

In that way, minerals with different particle size distributions are separated: fine sand minerals proceed to the next stage of processing, while sand-like minerals are sent to a grinding and polishing machine for further cement grinding.

II. Spiral classifier Categorize

A spiral classifier is a general term for a class of equipment, and different types of spiral classifiers may have slight differences.

Based on the relative height of their overflow weirs, spiral classifiers can be classified into high-weir spiral classifiers, low-weir spiral classifiers, and submerged spiral classifiers. The varying heights of the overflow weirs result in differences in the size ranges of mineral particles that each type is best suited to classify.

The high-weir type is particularly effective at separating mineral particles with particle sizes greater than 0.15 mm and should be used in the first-stage grinding process. The submerged type, on the other hand, is more suitable for separating mineral particles with particle sizes of 0.15 mm or less; thus, it is often combined with a ball mill in the second-stage grinding process to form a synergistic grinding unit.