Mineral powder classifier

The classifier is a device that uses the principle of different sedimentation speeds of solid particles in liquid or gas to classify the particle size, desludging, dehydration and other operations of the granular material. The following is a detailed introduction to the classifier:
Working principle

Gravity sedimentation principle: Classification is carried out based on the principle that solid particles of different sizes, different specific gravities, and different sedimentation speeds in liquids. Fine ore particles float in the water and overflow, and coarse ore particles sink to the bottom of the tank and are pushed to the upper part by devices such as spirals and discharged. For example, the spiral classifier works based on this principle1.
Centrifugal force principle: The centrifugal force field is used to make the particles subject to centrifugal force. Particles of different sizes have different movement trajectories under the action of centrifugal force, thereby achieving classification. For example, in a cyclone classifier, after the dust-laden airflow enters the cyclone separator, under the action of centrifugal force, the coarse particles are thrown to the wall of the device and fall along the wall, and the fine particles are discharged from the central tube with the airflow.
Airflow classification principle: The airflow is used to act on the particles, so that the particles are affected by drag, gravity, etc. in the airflow, and the movement states of particles of different sizes in the airflow are different, thereby achieving classification. For example, the AF series airflow classifier can classify spherical, flake, and needle-shaped particles. The product particle size is steplessly adjustable and the classification efficiency is high.
Structural composition

Spiral classifier: It is mainly composed of a transmission device, a spiral body, a trough body, a lifting mechanism, a lower support (bearing) and a discharge valve. The transmission device is used to drive the spiral body to rotate; the spiral body is a component that pushes the coarse ore particles to rise; the trough body is a container for slurry; the lifting mechanism can adjust the height of the spiral body; the lower support supports the spiral shaft; the discharge valve is used to control the discharge of slurry1.
Hydraulic classifier: The basic structure is circular, and the main body is composed of an upper cylinder and a lower cone. The middle is a coarse particle classification chamber, and the annular fine particle classification chamber surrounds it. The slurry is vertically fed to the distribution plate from the middle of the coarse particle classification chamber through a special pipeline. The rising water flows into the coarse particle classification chamber through the gap to achieve coarse particle classification, and fine-grained minerals enter the fine particle classification chamber, and are classified using fluidized bed technology3.
Types and features

Spiral classifier

High weir type: The overflow weir is higher than the rotating axis of the spiral, but lower than the upper edge of the spiral at the overflow end. The sedimentation area is low and the weir type is large. The weir height can be adjusted within a certain range, which can adjust the particle size of the classification. It is a commonly used equipment in the grinding cycle.

Submerged type: There are 4-5 spiral blades at the overflow weir end that are all submerged in the slurry. The sedimentation area is large, the classification pool is deep, the agitation of the spiral has little effect on the surface of the slurry, the classification surface is stable, the overflow is large and fine, and it is often used as a classification equipment for fine grinding or secondary grinding.

Low weir type: The overflow weir is lower than the rotating axis of the spiral. The sedimentation area is small. In actual production, it is only used to wash sand ore with little mud and dewater coarse particles. It is rarely used in grinding cycles.

Airflow classifier

Turbine classifier: The structure is mostly vertical, using frequency conversion control technology, simple operation, can be used for fine classification in battery materials, medicine, chemical industry, food and other fields, can effectively control the product particle size, and has a high classification efficiency2.

Cyclone classifier: It uses centrifugal force to achieve classification. It has the characteristics of simple structure, large processing capacity, and low resistance. It is often used for coarse particle classification in mining, building materials and other industries.

Hydraulic classifier: It has the advantages of high efficiency, low energy consumption, and no noise. It can adjust the particle size of the classified product by changing the height of the fluidized bed and the amount of rising water according to the parameters such as the feed particle size, mineral specific gravity and slurry concentration. It is suitable for the classification of various minerals3.

Application field

Mineral processing industry: In the mineral processing plant, it is equipped with a ball mill to form a closed loop, and the minerals that meet the particle size requirements are discharged from the overflow end to the next process as finished products, and the coarse sand is sent back to the ball mill for re-grinding. It is also used for classifying ore sand and fine mud in gravity mineral processing operations, and desludging in mineral washing operations1.
Building materials industry: used for grading machine-made sand in gravel yards, which can effectively control the stone powder content in machine-made sand, improve the quality of machine-made sand, and meet the particle size requirements of concrete mixing stations, dry mortar, etc. for sand and gravel aggregates.
Chemical industry: Grading chemical raw materials such as plastic particles, rubber particles, pigments, fillers, etc. to meet the particle size requirements of raw materials for the production of different chemical products.
Food industry: used for grading fruits, vegetables, etc., such as the roller-type grader drives the rollers to move forward in parallel through the double-helix rotation, and gradually increases the gap between the rollers, so that the fruits and vegetables fall from the gap between the rollers to the fruit conveyor belt, completing the purpose of fruit selection.