Analysis of technical solutions for dehydration and classification by size of mineral raw at thin and ultrafine vibration screening
Authors:   Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine, Lapshin E. S. , Shevchenko O. I. ,   Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine
Published: May 2023

The article is aimed at studying new technical solutions for dehydration and size classification in the case of fine and ultrafine vibratory screening of mineral raw materials. It is shown that the moisture content in many products is limited by GOST or temporary regulations. Water is the ballast in their transportation. An excessive amount of water contributes to the freezing of raw materials in winter conditions and causes great difficulties in unloading them from wagons. Traditional methods make it possible to effectively separate only materials with a particle size of more than 1 mm, and reduce the moisture content of the finished product to 18-22%, depending on the size, which does not meet the required standards. It is necessary to reduce moisture to 8-10% or less. In addition, the processing of various raw materials in most cases requires, simultaneously with dehydration, the separation of products of a wide range of sizes. To overcome the adhesion forces between wet particles, different excitations are used, one of which is a combined excitation that provides intensive movement of the liquid and particles relative to each other. Combined means excitation with various combinations of polyfrequency, impulse dynamic effects, and additional effects of various physical fields are also possible. The use of polyfrequency and impulse dynamic (“single impacts”) impacts on the MVG2.0 vibrating polyfrequency screen makes it possible to effectively separate the solid phase from the liquid when treating recycled water with a particle size of 20 microns. At the same time, the residual moisture in the oversize product is no more than 17%. The method of complex dehydration of wet mineral raw materials, combining three dehydration mechanisms (vibration, electrokinetic and vacuum), concentrated in one device, allows, at different initial moisture content of the raw material, to reduce the moisture content from 30 to 16%, from 20 to 14% and from 10 to 6%, t .e. reduce the humidity from 30 to 6% in several stages. These results were obtained for narrow size classes of 0.25÷0.63 mm. The use of modes with "double impacts" and disintegrating elements in the new vibro-impact screen made it possible to reduce the humidity from 30% to 8-10%. The separation efficiency of the +0–0.1 mm class was up to 65–70%. When using an activator, the moisture content of the material is reduced from 30% to 7-9%, and the separation efficiency of the +0-0.1 mm class is increased to 70-75%. Due to the use of a disintegrator over the activator, the moisture content of the oversize product was reduced to 6–8%, while the separation efficiency of the +0–0.1 mm class increased to 75–80%. Experimental method on the model of a vibro-impact screen for different fineness classes determined the conditions under which the maximum extraction of the class +0–0.1 mm and the decrease in humidity are determined. Currently, work is underway aimed at creating a vibro-impact screen, which will implement: expanding the range of impact on the processed material, increasing the life of the screen, the possibility of operational automatic control, increasing the stability of work and, at the same time, simplicity of design.