Research of the polydispersed products terminal velocities to determine their separation ability in the pneumatic classifier

Classification (fractionation) is the process of granular products separation into two or more fractions according to the particles sizes, moreover given size limit and content of other products in the main product is very insignificant. For example, fractionation of granular products is intended for producing fertilizers, for removal of fine particles (dust removal) from filling of burning furnaces chambers; it is used for electrodes manufacturing, for cleaning and preparing of the seeds for planting, which is the most important technological process in agriculture. High separation degree by classification of the dispersed products affects not only the raw materials consumption and its quality but it also determines the efficiency of other machines and apparatus operation in the technological scheme, which ultimately affects the technical and economic indicators of the whole production. This work is devoted to the experimental research in order to determine the terminal velocities of different polydispersed products, such as buckwheat, carbamide, carrot seeds, millet, radish seeds. Knowledge of these values is important for the development of models and devices for pneumatic classification. The research methodology of the particles terminal velocities using developed using a laboratory stand is presented. Designed stand plays an important role in the study of the separation processes and classification, as pneumatic classification effectiveness depends on the knowledge of particles terminal velocities of the products for which this device is intended to. Based on the obtained experimental results one has made graphics of comparing the terminal velocities of different substances and the dependence of terminal velocity from the mass of the mounting. Since in the most cases one takes into consideration the average terminal velocity, it causes big difference between modeling the process and its implementation in the designed stand. It can be expected that the obtained data will greatly increase the operating efficiency of the pneumatic classifier.