Published on 14 August 2021
Introduction. The huge energy costs of fine and ultrafine grinding operations have led to numerous studies aimed at developing new devices and methods for producing powdered materials. The first way leads to an increase in specific productivity while maintaining energy consumption at approximately the same level. The second way allows not only to increase the specific productivity, but also to reduce the specific energy consumption, since with a decrease in the exposure time, the body is more easily deformed and destroyed. The grinders in which the intensification of the destruction process is carried out in the first way can include planetary and vibrating mills. The second method of intensification is used in jet and various types of centrifugal mills. It is determined that vertical centrifugal mills are the equipment of a new type that can effectively perform grinding operations at high technological indicators and low energy consumption. The purpose of the research. Development of measures for obtaining a finely dispersed product by destroying mineral raw materials in vertical centrifugal mills by mechanical means. Research methodology. The paper uses a comprehensive research method: analysis of the state of grinding equipment according to literary and patent sources; development of mathematical models of the movement of bulk material in the working space of a vertical centrifugal mill based on the Navie-Stokes equations; computer modeling of the movement of the crushed material using the OpenFOAM package for solving hydrodynamic equations; a solver program was created to perform calculations, implementing the SIMPLER algorithm and using the MRF model; laboratory experiments; granulometric method for the analysis of grinding products; fractional analysis of crushed material with a grain size of 0.08 mm using an X-ray analytical centrifuge ВrооkhаvеnBI-ХDС. The development of measures for the effective evacuation of the crushed product from the working space of a centrifugal mill was evaluated by comparative tests of mills using various design solutions. Research results and discussion 1. It is established that vertical centrifugal mills are the devices of a new type capable of effectively performing grinding operations at high technological indicators and low energy consumption. 2. A mathematical model of the movement of bulk material in the working space of a vertical centrifugal mill has been developed based on the Navier-Stokes equations, which allows determining the speed and direction of movement of material layers at any point in the working space, the energy costs for their movement, the influence of the height of the material column on the nature of its movement in the space above the rotor. 3. The directions of increasing the efficiency of grinding mineral raw materials in a vertical centrifugal mill are determined by reducing the number of radial ribs installed in the cavity of the mill rotor; making cutouts in the radial ribs of the rotor, in the area near the rotor hub; installing coaxial rings in the working space of the mill above the rotor. 4. A method of effective evacuation of the crushed product from the mill body by installing additional screening surfaces in the peripheral part of the working space of the mill has been developed. 5. For the first time, the distribution of the granulometric composition of fine and medium - dispersed crushed product obtained as a result of processing lump dolomite in a centrifugal mill was obtained. It was found that particles with a size class of -0.08 + 0.03 mm are absent in the output of the crushed product from the mill. Conclusions. A mass-produced vertical centrifugal mill will find its effective application at enterprises of the Russian Federation for the preparation of powdered materials and will allow to obtain a significant effect by reducing the price of the final product, simplicity of design and maintenance of equipment, as well as small occupied production areas.
Tags: центробежная мельница вертикального типа, математическое моделирование, экспериментальные исследования, уравнения Навье- Стокса, пакет Open Foam, режимы измельчения, тонкодисперсное измельчение, интегральное распределение.
ISSN 1998-4502 (Print) ISSN 2499-975Х (Online)