Outline of classifying Principle and Application

Classifying is a production process that works according to the principle of the difference of sedimentation velocity of the materials in the moving media and classifies the particle groups in to two or more granularity grades, and this process is often used for classifying fine materials. In the classifying equipment, the movement methods of the media are different and various, including vertical rising flow, approximate horizontal flow and rotation movement. In addition, the media can be water or the air. The classifying process using the air as the medium is also called air classification.

If the materials are scaled in the rising water, the particles whose sedimentation velocity is higher than the speed of the water flow will sink to the bottom of the machine and become dust sand product; however, these particles whose sedimentation velocity is lower than the speed of the water flow will be discharged from the upper part of the classifying machine under the effect of the rising water flow an become the over flow product; the particles whole sedimentation velocity is equal to the speed of the rising water flow will be called separation granularity. In the ideal condition, the distribution proportion of the dust sand and over flow product respectively accounts for fifty percent.

The dimension density of the particles in the machine will determine its sedimentation form inside the grading equipment. The grading with high dimension density is called hindered settling grading. Because the hindered settling velocity of the particles is lower than the free settling speed, this grading process will save a lot water and is able to gain dust sand with higher density and the production capacity of the grading equipment will be improved. However, because the equal-settling ratio of hindered settling is higher than the equal-settling ratio of free settling and what is more, when the hindered settling is used for separation, the fine but heavy particles in the dust sand will account for a large proportion which will produce some influences on the precision of the scaling, for this reason, the hindered settling classification is not suitable for the process that the classification precision has higher requirement. The precision of particle classification is also influenced by the particle density and the shape other than the granularity of the particle itself.

The main application the scaling process in the ore beneficiation process is as follows:

(1) The preparation work when it is used for reselection is to scale the raw material in order to reduce the influences of the material granularity to the beneficiation process.

(2) Working together with the grinding mill, control and examine the granularity of the milling product, timely get the qualified products and reduce over crushing and make sure the qualification rate of the final products.

(3) It can also used for desliming and dehydration of raw material and products.

(4) Scale the products into different granularity grade in order to coordinate the different application of the materials.

The above analysis is provided by Hongxing Machinery experts and Hongxing Machinery is a professional mining machinery manufacturer in dryer machine design, research and development.