Автор: Bukina Anastasiya
Источник: Матеріали науково-технічної конференції молодих вчених «Young scientists’ researches and achievements in science». Донецьк, 18 квітня 2013 р.
Thin crushing of materials finds wide use in construction, mining, metallurgical, food, chemical and other industries. A variety of types and standard sizes of mills for thin crushing speaks variety of processed materials, distinctions of requirements to products of crushing and scales of the corresponding productions. Now all new and higher demands are made to products an izmelcheniiya, have development energosberegashchy technologies of processing of minerals and other materials, volumes of productions with crushing operations considerably increase, interest to a mekhanoaktivation of various firm minerals and receiving materials with pains high technological properties increases. These purposes demands development and introduction of more perfect grinders. For thin crushing the greatest distribution grinders of abrasive-crushing action (millstone grinders, runners, ball-ring mills, beaded mills), shock action (mine mills, dezintegrator and dismembrator, centrifugal mills, jet mills) and shock using-up action (vibrating mills, planetary mills, gyroscopic mills, colloidal mills, etc.) [1, page 7-11].
It should be noted that specific energy consumption on superthin crushing is very high and on different sources makes from 50 kWh/t [2, page 12] to 1000 kWh/t [3, page 12].
The principle of the rational organization of crushing and crushing (properly to destroy a material with the smallest efforts and energy expenses) provides destruction of a multicomponent material mainly on interfaces of phases. Practice of work in the industry of vibrating inertial cars of small standard sizes showed that at their control for a mode of selective disintegration high completeness of disclosure of diverse phases without material recrushing is provided. Besides, application of a vibrating inertial way allowed to carry out mechanical crushing and crushing of especially strong materials, such, as amorphous steel, an elbor, fused electrocorundum, finstein, shaving of fast-cutting steel [2, page 221].
The principle of the rational organization of crushing and crushing (properly to destroy a material with the smallest efforts and energy expenses) provides destruction of a multicomponent material mainly on interfaces of phases. Practice of work in the industry of vibrating inertial cars of small standard sizes showed that at their control for a mode of selective disintegration high completeness of disclosure of diverse phases without material recrushing is provided. Besides, application of a vibrating inertial way allowed to carry out mechanical crushing and crushing of especially strong materials, such, as amorphous steel, an elbor, fused electrocorundum, finstein, shaving of fast-cutting steel [2, page 221].
Thus, the nomerous researches on thin crushing allow to draw a conclusion that the most effective remedy for receiving a product with granulometric structure - 50 microns at an initial food by a size 2 … 10 mm and rather small productivity on the final product (to 10 t/h) are a vibrating mill.
The first vibrating mills were created in the mid-thirties the last century and now received wide application in various industries, as the most effective devices for thin crushing of materials. Application of vibrating mills, in comparison with other types of mills, allows to reduce an electric power expense, to increase productivity, to reduce wear of pomolny bodies and a pomolny pipe, to use pomolny bodies from various materials, to reach high grinding tannins, to receive purer final product, to carry out crushing process in vacuum, the inert environment, at the different temperatures [4].
Vibrating mills are supplied more often the centrifugal (unbalance) vibrator Depending on an arrangement of the pomolny chamber in space all vibrating mills divide on horizontal, vertical and inclined. In horizontal mills crushing of a material results blowfoot and using-up influence grinding bodies. Therefore when crushing strong and abrasive materials the product of crushing can contain a significant amount of impurity from abrasion crushing and protaction bodies. In vertical mills shock character of a contact of grinding bodies, and using-up influence minimum [prevails3]. In turn to organize continuous process of crushing in horizontal vibrating mill it is simpler, than in vertical. Besides, on rotation possibility of working body all vibrating mills I cant to be divided into two groups: mills from the motionless mills chamber and mills with the rotating chamber. Despite obvious advantages of vibrating mills with the rotating chamber technical realization separate elements and design mills as a whole faces with about the considerable difficulties [4].
The simplest inertial horizontal vibrating mill at rotation of a power shaft a grinding pipe of a vibrating mill with grinding bodies (spheres) and a crushed material is given in a harmonious oscillating motion on a trajectory close to circular. A field of trajectories of all points of a grinding pipe - homogeneous as the specified trajectories have an identical form and identical parameters. Movement of spheres in a vibrating mill occurs aside, a vibrator opposite to rotation. The crushed material moves along the case on a difficult spiral. Thus spheres crush a material as a result of blows and an abrasion.
The circular circulation of grinding bodies arising at the expense of a homogeneous circular or elliptic field of trajectories of movement of the case of a pomolny pipe, does not create rather intensive hashing of pomolny bodies and a crushed material. Thereof stagnant zones are formed, there is a segregation of grinding bodies and a crushed material that is an essential lack of vibrating mills of the specified type. The segregation is that large pomolny bodies collect in the top part of the pomolny chamber, and small and a crushed material fall down. It sharply reduces effect of vibrating action of grinding bodies on a crushed material and efficiency of vibrating crushing.
The intensification of process of thin crushing can go on a number of the directions one of which is realization in designs of vibrating mill of horizontal type of the two-dimensional and three dimensional difficult fluctuations raising variable speed of movement of grinding bodies [5], use of mills with a nonconventional form of the working chamber. These innovations allow «turbolization» loading movement, to involve in process a so-called inactive kernel, and, finally, considerably to lower energy consumption of process of crushing [6, page 12].
So, for example, in Germany the design of a vibrating horizontal mill with a non-uniform field of fluctuations of working body at the expense of initiation of harmonious fluctuations eccentrically the established unbalance vibrator is developed [7]. Thanks to essential technological advantages, in comparison with the aligned systems [8, page 307-309], this vibrating mill was widely adopted when crushing various materials and formed a basis for production of almost similar cars in many countries of the world.
It should be noted that in recent years by pilot studies it is established and with industrial practice it is confirmed that the polyharmonious structure of working influence on a processed technological product essentially is more effective, than harmonic. Than the spectral structure of the used vibrating is richer cartreliability of formation in structures of the processed environment of movings highly effective resonant and close to resonant modes and deformations is higher than actions, subjects, and the grasp of active volume is wider than subjects [9, page 1, 10].
However as a result of complexity of formations of polyfriquency modes of fluctuations at this stage of development of vibrating equipment as rather simple, but the effective decision, can be successfully used biharmonic operation modes.
Thus, researches promoting creation of new designs of the vibrating mill intensifying thin crushing of various materials, have actual character.