Sorption of Nanomaterials to Sandstone Rock

We investigated the interaction of silica nanostructured particles and sandstone rock using various experimental approaches, such as fluid compatibility, batch sorption and single-phase core-floods. Diol and polyethylenglycol (PEG) surface-modified nanostructured silica materials were tested using two brines differing in ionic strength and with the addition of sodium carbonate (Na2CO3). Berea and Keuper outcrop materials (core plug and crushed samples) were used. Core-flood effluents were analysed to define changes in concentration and a rock’s retention compared to a tracer. Field Flow Fractionation (FFF) and Dynamic Light Scattering (DLS) were performed to investigate changes in the effluent’s size distribution. Adsorption was evaluated using UV–visible spectroscopy and scanning electron microscopy (SEM). The highest adsorption was observed in brine with high ionic strength, whereas the use of alkali reduced the adsorption. The crushed material from Berea rock showed slightly higher adsorption compared to Keuper rock, whereas temperature had a minor effect on adsorption behaviour. In core-flood experiments, no effects on permeability have been observed. The used particles showed a delayed breakthrough compared to the tracer, and bigger particles passed the rock core faster. Nanoparticle recovery was significantly lower for PEG-modified nanomaterials in Berea compared to diol-modified nanomaterials, suggesting high adsorption. SEM images indicate that adsorption spots are defined via surface roughness rather than mineral type. Despite an excess of nanomaterials in the porous medium, monolayer adsorption was the prevailing type observed.

DETERMINATION OF DESIGN PARAMETERS OF A STEP DISK MILL

The calculation of the design parameters of a disc mill equipped with a feeder made in the form of a conical hopper is given. For shredders of the disintegrator type, it is very important to ensure the uniformity of loading of the crushed material of the working zone of active impact on particles. In addition, the most important factor is the throughput capacity of all sections of the grinding plant. The throughput should be determined by the design and technological parameters of the working chamber of the mill. Its overload can lead to a blockage of the working chamber, and insufficient throughput will negatively affect the intensity and effectiveness of the impact on the particles of the material. For example, insufficient concentration of particles in the secondary zone of the grinding chamber leads to a decrease in the efficiency of mutual abrasion. The article attempts to determine the design and technological parameters in the loading and accelerating parts of the disk mill. At the same time, it is necessary to coordinate the throughput of the disk spreader and the volumetric flow rate of the material particles flowing from the hopper. In this case, it is advisable to take into account that as a result of a rather high rotational speed and the size of the initial particles, with the wrong height of the radial blade of the spreader, material particles can roll over the radial blades, which leads to a delay of the material in the zone of the spreading disc. Therefore, it is necessary to determine the calculation formulas for finding the required height of the radial blade of the spreading disc, depending on the size of the initial particles. The formula demonstrates that the height of the separating blade depends on the particle size, the speed of rotation of the disks and the distance to the point of meeting of the particle with the radial blade.

DETERMINATION OF DESIGN PARAMETERS OF A STEP DISK MILL

The calculation of the design parameters of a disc mill equipped with a feeder made in the form of a conical hopper is given. For shredders of the disintegrator type, it is very important to ensure the uniformity of loading of the crushed material of the working zone of active impact on particles. In addition, the most important factor is the throughput capacity of all sections of the grinding plant. The throughput should be determined by the design and technological parameters of the working chamber of the mill. Its overload can lead to a blockage of the working chamber, and insufficient throughput will negatively affect the intensity and effectiveness of the impact on the particles of the material. For example, insufficient concentration of particles in the secondary zone of the grinding chamber leads to a decrease in the efficiency of mutual abrasion. The article attempts to determine the design and technological parameters in the loading and accelerating parts of the disk mill. At the same time, it is necessary to coordinate the throughput of the disk spreader and the volumetric flow rate of the material particles flowing from the hopper. In this case, it is advisable to take into account that as a result of a rather high rotational speed and the size of the initial particles, with the wrong height of the radial blade of the spreader, material particles can roll over the radial blades, which leads to a delay of the material in the zone of the spreading disc. Therefore, it is necessary to determine the calculation formulas for finding the required height of the radial blade of the spreading disc, depending on the size of the initial particles. The formula demonstrates that the height of the separating blade depends on the particle size, the speed of rotation of the disks and the distance to the point of meeting of the particle with the radial blade.

Combined activation technologies mineral raw materials

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.

Optimization of Conditions for Processing of Lead–Zinc Ores Enrichment Tailings of East Kazakhstan

This article presents the results of studies of a low-waste technology for processing enrichment tailings using a combined enrichment–hydrometallurgical method. After washing the enrichment tailings from harmful products and reducing their size, multi-stage flotation of the crushed material of the enrichment tailings was carried out. The use of a new reagent in the flotation process was studied in order to ensure the maximum recovery of the main valuable components from the enrichment tailings. A new collector of Aero 7249 (Shenyang Florrea Chemicals Co., Ltd., Shenyang, China) type was used for the flotation. The recovery of valuable components was as follows: Cu, 6.78%; Zn, 91.69%; Pb, 80.81%; Au, 95.90%; Ag, 82.50%; Fe, 78.78%. Tailings of the flotation were re-enriched using a fatty acid collector (sodium oleate). Additional (reverse) flotation resulted in obtaining a product corresponding to the composition of building sand in terms of the content of valuable components of the waste rock. The studies of the conditions for processing the enrichment tailings of lead–zinc ore indicate the possibility of its optimization in order to maximize the involvement of waste in the production.

Investigation on the Self-synchronization of Dual Steady States for a Vibrating System with Four Unbalanced Rotors

In the field of vibration utilization engineering, to achieve the maximum degree or the highest efficiency use of the excitation force is still a hotspot among researchers. Based on this, this paper has carried out a series of synchronous theoretical analysis on the four identical unbalanced rotors (IURs) symmetrically and circularly mounted on a rigid frame (RF) model, which is used to drive a cone crusher. The dimensionless coupling equations of the four IURs are established using the improved small parameter method. The analysis of the coupling dynamics characteristics of the system shows that the four motors of the system adjust the speed through the synchronous torque to achieve synchronization, and a parameter determination method for realizing offset self-synchronization to eccentric force was put forward under the steady state of ultra-resonance. Furthermore, the relationship between the equivalent stiffness of the crushed material and crushing force and compression coefficient is discussed, and the design method of the full-load crusher working under the steady state of sub-resonance is proposed. Finally, through a series of computer simulations, the correctness of the self-synchronization of dual steady states is verified.

THERMAL CONTROL OF MECHANOCHEMICAL REACTION

Mechanochemistry studies and explains the processes of chemical and physicochemical transformations that are generated by mechanical action on a substance. When carrying out deep mechanochemical transformations, as a rule, it is necessary to transfer to solid reagents a portion of energy comparable to the energy of interatomic bonds. For this, various machines and apparatus are used, such as extruders, in which mechanical energy is constantly transferred to the crushed material. The article discusses the interaction of two reagents in a simple chemical reaction in the state of a mixture of particles of two types, which occurs during compression of particles having a rough irregular shape, and colliding with each other, forming areas of contact. Significant stress concentrations and heating of the substance with the formation of a new phase arise in these regions. Thermal control of the mechanochemical reaction is to maintain an optimal balance of dissipative heat and heat from the coolant in the worm reactor so that the rate of flow and the final product of the reaction meet the specified specifications. The formulas provided in the article for calculating the coefficient of the rate of mechanochemical reaction, heat transfer between worm reactor and jacket channel, heat exchange between jacket and environment allows to calculate the balance conditions for thermal management. The block diagram of the technological line, which is presented in the article, is more economical in comparison with carrying out the same reaction in a solvent. The economic benefit lies in the elimination of the steps of introducing and removing the solvent from the reaction product. At the end, it is indicated that the mechanochemical reaction of the transformation of a mixture of two dispersed materials consisting of solid particles into a liquid can be realized in continuous conditions in a flow mode in a worm machine. And thermal control of the course of a mechanochemical reaction can be carried out using controlled heat exchange with a coolant in a jacket under conditions of turn-around spatial dispersion.

THE EFFECT OF THE WEAR DEGREE OF WORKING ELEMENTS IN A JAW CRUSHER ON THE OPERATING EFFECTIVENESS OF A TWO-STAGE GRANITE GRINDING SYSTEM

The article presents an analysis of the influence of the wear degree of working elements in a jaw crusher on the crushing process and on the quality of the crushed material. The evaluation of the operating effectiveness of a technological system comprising two crushers was based on the quality indicator of the crushed product, i.e. on the share of irregular grains for a fraction with a mean grain size of 31.5/63 mm at each of the two stages of crushing. The wear degree was monitored by performing microscopic observations of the plates in the fixed jaw and by measuring the critical geometric characteristics of the crusher, e.g., tooth height, jaw size, and discharge opening size, during the entire service life of the crusher.

Prospects for energy-saving methods of crushing brittle materials

Crushing machines are part of the charge departments of blast-furnace and steel-making shops of metallurgical enterprises. One of the main indicator of the crushing process is its energy efficiency. It is determined by the mass of crushed material when consuming a unit of electricity. The article considers various methods of crushing brittle materials and the design of crushing machines for their implementation. The analysis of the crushers has shown that impact crushers are the most energy-efficient. However, due to a significant drawback (the yield of a suitable product is very small), they are practically not used in the metallurgical industry, in which high requirements are imposed on the finished product fractional composition. In the metallurgical industry, compression crushers are widely used with approximately the same specific energy intensity, that is, with the same energy consumption for the destruction of a unit volume of material of equal strength. Compression fracture is the most energy intensive crushing method known. In single-roll crushers, a piece of material is fed into the gap between a roll and a solid, stationary plate. During the operation a complex stress state is generated in the destructed material. Compressive forces act on a piece of crushed material, causing normal compressive stresses in it, and an internal torque, causing shear stresses. This is achieved by the reduction in energy on crushing by 20 – 30 % in comparison with crushers operating in compression (all other things are equal). The authors describe the design of a crusher, in which the destruction of the processed material occurs due to the forces acting on the crushed piece in one plane towards each other. In this case, only shear stresses arise in the processed piece. The use of crushers, in which the destruction of the processed material occurs due to generation of only tangential stresses in a piece, can reduce the energy consumption per unit of finished product by almost a half. The design of such crushers is a promising direction in the development of machines intended for crushing.

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.