EQUIPMENT MODIFICATION FOR FINE GRINDING OF MINERAL RAW MATERIALS

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.

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Research of the properties of rocks during fragmenting and crushing in mechanical mills

News of the Ural State Mining University ◽

10.21440/2307-2091-2021-2-81-87 ◽

2021 ◽

pp. 81-87

Author(s):

GOLIK Vladimir Ivanovich ◽

Keyword(s):

Energy Consumption ◽

Raw Materials ◽

Experimental Studies ◽

Mining Industry ◽

Pulse Amplitude ◽

Resource Base ◽

Crushed Material ◽

Mineral Raw Materials ◽

Systemic Crisis ◽

The Impact

Relevance and purpose. The systemic crisis in the mining industry has weakened the provision of the industry with proven reserves of the main types of minerals, which has made the search for technological solutions in order to restore the lost potential of the mineral resource base. Methodology. Theoretical studies of the movement of the grinding charge in the grinding chambers of planetary mills are based on the postulate of the equivalence of the forms of movement of the charge in mills. Grinding equipment of a new technical level is being improved in the direction of increasing the intensity of the effect of grinding bodies on the crushed material. The aim of the study is to increase the intensity of the impact of grinding bodies on the crushed mineral raw materials while minimizing the energy consumption of processing processes. The goal is achieved by integrating analytical and experimental studies with elements of engineering forecasting and modeling of the results. Results and scope. The results of studying the properties of rocks and their changes as a result of crushing and grinding in mechanical mills are presented. Information about devices for measuring the parameters of shock pulses and the practice of their application is systematized on the example of geological differences of rocks. Bench studies have confirmed the theoretically substantiated phenomenon of shock pulse amplitude suppression. The role of the processes of crushing and grinding in mills in the technological chain of waste-free utilization of the tailings of the concentration of chemically exposed ores is detailed. Сonclusions. The phenomenon of increasing the intensity of the impact of grinding bodies on the crushed mineral raw materials with the same energy consumption of processing processes can be used in the modernization of technologies for the development of mineral deposits.

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Combined activation technologies mineral raw materials

Горная промышленность ◽

10.30686/1609-9192-2021-5-100-105 ◽

2021 ◽

pp. 100-105

Author(s):

V.I. Golik ◽

A.V. Titova

Keyword(s):

Raw Materials ◽

Mechanical Energy ◽

Mining Industry ◽

Resource Base ◽

Crushed Material ◽

Mineral Raw Materials ◽

Centrifugal Mill ◽

Ore Processing ◽

Technological Chain ◽

The Stability

Relevance. The efficiency of using the products of subsoil exploitation is a factor in strengthening the mineral resource base of the mining industry. The success of improving ore preparation technologies is associated with the activation of mineral raw materials in mills, including impact mills – disintegrators. A fundamentally new approach to ore processing technology includes a combination of grinding methods in mills and other activators. The issues of increasing the activity of substances on the basis of combination form an urgent scientific and industrial problem. The aim of the study of the phenomenon of combined activation is to search for the possibility of increasing the level of activation, to ensure the stability of the acquired activity and to establish patterns of relationships between the activation processes and the technological processes of using mineral raw materials. Objects: products of the development of deposits of solid mineral raw materials in various mining sectors of the national economy. Methods: Laboratory, semi-industrial and industrial experiment using improved equipment for the activation of mineral raw materials. Results. The concepts of “mechanical activation” in mills and “activation with large mechanical energy” in a disintegrator are detailed. An assessment is given to the directions of improving the mills. The results of mechanochemical activation of powders oxides in a planetary centrifugal mill “Aktivator-2s” are given. The practice of activating mineral raw materials with a combination of activators of various types is described. It has been established that the efficiency of combining mills depends on the initial size of the crushed material and equipment options are recommended depending on this. It is shown that the combination of drum and vibration mills reduced the energy consumption of the product. The results of the combination and the vibrating mill in the technological chain of the concrete complex are presented. The algorithm for the combined activation of mineral raw materials is illustrated by the example of the technology applied at the mine, which includes grinding, mixing binders, inert aggregates and grout, as well as transporting the concrete mixture to the place of use. As a quantitative indicator of activation, an equivalent of activity or a proportional ratio of the combined components is proposed. The efficiency of using solid mineral raw materials increases when it is prepared in activators.

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DETERMINATION OF THE MECHANISM FOR OPENING QUARTZ PARTICLES WHEN GRINDING QUARTZ-CONTAINING PRODUCTS IN A CENTRIFUGAL MILL

Sustainable Development of Mountain Territories ◽

10.21177/1998-4502-2020-12-3-454-460 ◽

2020 ◽

Vol 12 (3) ◽

pp. 454-460

Author(s):

Yuri KLYKOV ◽

◽

Marina KHUDOYAN ◽

Georgy KIBIZOV ◽

◽

...

Keyword(s):

Mechanical Properties ◽

High Efficiency ◽

Test Procedure ◽

Physical And Mechanical Properties ◽

High Energy ◽

Specific Productivity ◽

Crushed Material ◽

Centrifugal Mill ◽

Maximum Productivity

Introduction. Currently used grinding machines, among which drum mills are the most widely used, have a low efficiency, are bulky, are characterized by low specific productivity, significant consumption of steel for grinding bodies and lining, high noise level, and high energy consumption of the grinding process. The most promising devices of a new type that can effectively perform grinding operations at high technological rates are centrifugal mills. The centrifugal mill developed at SKGMI operates on the principle of self-grinding of pieces and particles of crushed mineral raw materials, when they collide and RUB in a mobile toroidal flow formed when the material moves between a rotating Cup-shaped rotor, a fixed body and the overlying layers of the crushed material. Grinding occurs due to the appearance of a gradient of particle velocities over the working body, due to their impact and, to a greater extent, abrasion. The tests of these mills for grinding various materials have shown high efficiency in operation, but until now, the issues of determining the physical and mechanical properties of the crushed material based on the establishment of the particle opening mechanism remain unresolved. The purpose of the tests. Determination of the physical and mechanical properties of the crushed material in a centrifugal mill based on the establishment of the particle opening mechanism. Test procedure. To solve this problem, a vertical centrifugal mill MC-600 with a rotor diameter of 600 mm was used. Tests of the centrifugal mill were carried out according to the following method. The speed of rotation of the rotor was 4.8 and 8.4 s-1, the height of the material column above the rotor was at the level of 250 and 350 mm; 6 radial ribs were installed in the rotor cavity of the mill. The time of each test was 4 hours. The tests were repeated 3–5 times for each mode of operation of the mill. Quartz was used as a reference material for determining the relative pulverizability coefficient. The research was carried out in the production conditions of the Izhevsk machinebuilding plant during the regeneration of spent molding quartz mixtures. Pieces of a liquid-glass mixture based on quartz sand with strength of 1.3 MPa and 4.25 MPa were used as the crushed material. The crushed material was dispersed according to the standard method for each hour of operation of the mill. Samples were taken in the size class -0.200 + 0.074 mm for their fractional analysis by size. Test result. 1. It was Found that the maximum productivity of a centrifugal mill when grinding pieces of material with a strength of 1.3 MPa was achieved with a loading weight of 90–100 kg, and with a strength of 4.25 MPa – 100–110 kg, which indicates the need to create an increased normal pressure of the layers of crushed material located above the mill rotor. It was found that the maximum productivity of a centrifugal mill when grinding pieces of material with a strength of 1.3 MPa and a rotor rotation frequency of 8.4 s-1 was 13.16 t/h, and when grinding pieces of material with a strength of 4.25 MPa – 10.0 t/h. 2. The Dependence of power consumption on the weight of the mill load and the rotor speed increases when the load weight is more than 100 kg. 3. The Highest fraction content of class -0.4 +0.16 mm is 72.14 %, and the content of class -0.074 mm is 3.9 %, i.e. there is no re-grinding of the source material. 4. The specific productivity of the centrifugal mill for the newly formed calculated size classes -0.074 mm and -0.200 mm was 1.28 t/h and 13.0 t/h, respectively. 5. Microscopic study of anshlifov showed that quartz grains in the crushed material mostly have a rounded shape, on average 90–95 % of the grains. In the initial material, about 90% of quartz joints with a binder, and in the crushed material, the number of joints does not exceed 3–5%. Thus, the degree of expansion of quartz reaches to 0.87. Conclusions. The paper presents the results of studies of a centrifugal mill in the conditions of the Izhevsk machinebuilding plant when grinding quartz-containing products. The physical and mechanical properties of the crushed material that significantly affect the efficiency of grinding are determined. The mechanism of the disclosure particles of quartz, which is primarily the mineral content of many ores and defined particle size obtained by grinding. At the same time, it was found that a large yield of thin classes significantly reduces the efficiency of further technology.

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Simulation of aeromechanics of the grinding process in a centrifugal mill

Computer modeling analysis control optimization ◽

10.32434/2521-6406-2020-8-2-59-66 ◽

2020 ◽

Vol 8 (2) ◽

pp. 59-66

Author(s):

I.A. Ostashko ◽

◽

A.P. Naumenko ◽

Keyword(s):

Gas Dynamics ◽

Heterogeneous Medium ◽

Stokes Equations ◽

Flow Path ◽

Navier Stokes ◽

Maximum Diameter ◽

Navier Stokes Equation ◽

Crushed Material ◽

Centrifugal Mill

The article discusses aeromechanical processes in a centrifugal mill at different speeds of rotation in order to establish the regularities of the kinematics of the flow of a heterogeneous medium in the grinding chamber of the mill, its interaction with the working body and the classification of the crushed material when removed from the grinding chamber. The study of gas dynamics of processes in the flow path of a centrifugal mill has been carried out. The trajectories of streams, velocity and pressure fields were investigated. The influence of various factors on the efficiency of the classification and the maximum diameter of particles removed from the grinding chamber was revealed. The regularities of the movement of a heterogeneous medium, its interaction with the working body and the classification of the crushed material when removed from the grinding chamber were established, the gas dynamics of processes in the flow path of a centrifugal mill was studied. The main way to increase the speed of air flows is to increase the flow of transport air, which in turn affects the aerodynamics of the processes in the grinding chamber of the mill, productivity and grinding time of the material. Processes of gas dynamics in a compressed medium of the flow path of a centrifugal mill were described by a system of non-stationary Navier-Stokes equations of continuity, energy and equation of state in approximation of the turbulence model. Analysis of the results of mathematical modeling of processes in the working chamber showed that the air flow carries out a complex rotational movement in the transverse and longitudinal sections with the formation of local zones of increased turbulence. As a result of numerical modeling and analysis of the results, factors have been identified that make it possible to intensify the process of material grinding. The flows have a pronounced ballistic trajectory. They start their movement from the center of the bottom of the grinding chamber and move along the walls of the chamber while rotating in a spiral and moving down the wall of the hollow shaft. It is observed that the point of separation of the flows rotating in the lower part of the grinding chamber and the flows moving in the upper part is on 60% of the height of the chamber. Keywords: modeling, centrifugal mill, finite element method, Navier-Stokes equation.

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COMPARISON OF THE CRUSHED MATERIAL MOVEMENT MODEL IN THE BODY OF A VERTICAL CENTRIFUGAL MILL

Sustainable Development of Mountain Territories ◽

10.21177/1998-4502-2021-13-1-119-124 ◽

2021 ◽

Vol 13 (1) ◽

pp. 119-124

Author(s):

David MINASYAN ◽

◽

Alana ELOEVA ◽

Sergey NAZAROV ◽

Pavel SKVORTSOV ◽

...

Keyword(s):

Discrete Element Method ◽

Hydrodynamic Model ◽

Initial Velocity ◽

Bulk Material ◽

Discrete Element ◽

The Body ◽

Crushed Material ◽

Centrifugal Mill ◽

Bulk Medium ◽

Element Method

Introduction. Improving the performance, increasing productivity, reducing the metal consumption of grinding equipment and other mining machines is usually a very expensive process. It requires a large amount of development work, the production of prototype machines, and a large amount of experimental research. In this regard, one of the most important tasks is to simulate the movement of bulk material in operations for processing minerals in various equipment. In such modeling, the discrete element method (DEM) is widely used. The purpose of the research is to compare the models of the movement of the crushed material in the body of a vertical centrifugal mill. Research methodology The motion of the bulk medium in a vertical centrifugal mill was modeled using two models. In the first model, the cylindrical body of the centrifugal mill was assumed to be stationary, and on its surface and on the entire surface of the rotor, conditions were set for the absence of a relative speed of movement of the crushed material. In the second model, a hydrodynamic model was used to describe the motion of a granular material as a viscous incompressible liquid with a compression ratio that depends on the pres-sure. In this model, the viscosity coefficient is represented as consisting of two terms: a constant (analogous to dynamic viscosity) and an excess pressure over hydrostatic pressure. Research results It is established that both models give the same character of the movement of the material in the mill body. It is determined that the absolute velocity of the material movement near the walls and near the mill rotor is approximately the same for both models, but in the data obtained using the hydrodynamic model, as the material moves away from the walls and the rotor, it slows down more than for the model using the discrete element method. It is revealed that the absolute velocity of the material movement near the walls and at the axis of the mill rotor is approximately the same for both models, but in the data obtained using the hydrodynamic model, as it moves away from the walls and the rotor, the material slows down significantly more than for the model using the discrete element method. Based on the simulation results, it can be concluded that for a more accurate simulation of the processes occurring during the rapid movement of bulk material in the grinding equipment, it is preferable to use a model using the discrete element method. It is advisable to use the hydrodynamic model for conducting a large number of search dawns or as a predicate model that will allow you to quickly set the initial velocity values for particles in a model using the discrete element method. Conclusions 1. A hydrodynamic model of the motion of a bulk medium in a vertical centrifugal mill, represented as a viscous incompressible liquid with a compression coefficient depending on the pressure has been developed. 2. It is established that for a more correct simulation of the processes occurring during the rapid movement of bulk material in the grinding equipment, it is preferable to use a model using the discrete element method. At the same time, it is advisable to use the hydrodynamic model for conducting a large number of search calculations or as a predicate model that will allow you to quickly set the initial velocity values for particles in a model using the discrete element method.

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CONTROLLED VIBRATING MILL FOR GRINDING BULK MEDIUM

Vibrations in engineering and technology ◽

10.37128/2306-8744-2020-4-2 ◽

2020 ◽

pp. 11-20

Author(s):

Olena Solona

Keyword(s):

Energy Consumption ◽

Structural Model ◽

Resonant Mode ◽

Low Energy ◽

Specific Productivity ◽

Mechatronic Systems ◽

Crushed Material ◽

Low Energy Consumption ◽

Vibration Impact ◽

Bulk Medium

One of the advanced types of grinding equipment are vibrating mills, which provide high specific productivity at relatively low energy consumption, adjustable tone of grinding products. Vibration impact on the product significantly increases the shock-absorbing effect with the possibility of wide and separate variation of shock and abrasion factors. Significant speed of mechanical and heat and mass transfer processes, a high degree of homogeneity of the obtained products, the possibility of efficient fine grinding and dispersion of the product at relatively low energy consumption lead to the widespread use of vibratory grinding. The constructive scheme of the mill is developed, in which the flat vertical vibrating field provides lifting of a part of loading and by means of the transport-reloading device carries out its continuous adjustable movement from one grinding chamber to another, thereby circulating-spatial movement of the environment in which there is a grinding process. shock interaction of grinding bodies and material that is crushed. The priority direction of development of science and technologies at the modern level is the development, creation and implementation of new generation mechatronic systems. One of the most important rules for the construction of vibrating mills is the need to maximize the degree of their automation in order to increase productivity, improve the quality of grinding and reduce the cost of the process. Also in the article the structural model of the controlled vibromill with spatial-circulating loading movement which at change of weight of a working body in the course of separation and unloading of the crushed material from a grinding chamber constantly adapt to a resonant mode of work at the set technologically optimum parameters (productivity) and the minimum power consumption.

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SHS PROCESSING OF MINERAL RAW MATERIALS AND PRODUCTION WASTES IN ATMOSPHERIC ENVIRONMENT

СИНТЕЗ И КОНСОЛИДАЦИЯ ПОРОШКОВЫХ МАТЕРИАЛОВ. Сборник тезисов Международной конференции ◽

10.30826/scpm2018013 ◽

2018 ◽

Author(s):

V.E. LORYAN ◽

◽

A.R. KACHIN ◽

I.P. BOROVINSKAYA ◽

◽

...

Keyword(s):

Raw Materials ◽

Atmospheric Environment ◽

Mineral Raw Materials ◽

Production Wastes

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Crushed Bricks: Demolition Waste as a Sustainable Raw Material for Geopolymers

Sustainability ◽

10.3390/su13147572 ◽

2021 ◽

Vol 13 (14) ◽

pp. 7572

Author(s):

Gigliola D’Angelo ◽

Marina Fumo ◽

Mercedes del Rio Merino ◽

Ilaria Capasso ◽

Assunta Campanile ◽

...

Keyword(s):

Energy Consumption ◽

Building Materials ◽

Mechanical Performance ◽

Raw Materials ◽

Construction Material ◽

Raw Material ◽

The European Union ◽

Total Energy Consumption ◽

Demolition Waste ◽

Crushed Brick

Demolition activity plays an important role in the total energy consumption of the construction industry in the European Union. The indiscriminate use of non-renewable raw materials, energy consumption, and unsustainable design has led to a redefinition of the criteria to ensure environmental protection. This article introduces an experimental plan that determines the viability of a new type of construction material, obtained from crushed brick waste, to be introduced into the construction market. The potential of crushed brick waste as a raw material in the production of building precast products, obtained by curing a geopolymeric blend at 60 °C for 3 days, has been exploited. Geopolymers represent an important alternative in reducing emissions and energy consumption, whilst, at the same time, achieving a considerable mechanical performance. The results obtained from this study show that the geopolymers produced from crushed brick were characterized by good properties in terms of open porosity, water absorption, mechanical strength, and surface resistance values when compared to building materials produced using traditional technologies.

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