Obtaining microdispersed iron-nickel powder in the process of electrochemical processing of VNZh type heavy tungsten alloys

The process of electrochemical processing of the VNZh type heavy tungsten alloy (wt. %: 80 W, 16 Ni, 4 Fe) under the action of direct and alternating current of industrial frequency in an ammonia-alkaline solution has been investigated. It was found, that the process is accompanied by the transition of tungsten from the alloy to the solution and the formation of a microdispersed powder, based on iron and nickel.

Study of the significance of the ph of the substrate of the biogas installation during treating it with a low-frequency electromagnetic field

The article considers the issue of studying the value of pH, substrate in the process of methane fermentation in the mesophilic regime and the influence of the electromagnetic field of industrial frequency. The aim is to investigate the influence of electromagnetic fields on the pH value of the substrate during fermentation. Different types of microorganisms are involved in the process of methanogenesis, and the decisive role in it is played by methane-forming archaea, which are most sensitive to pH and should be in the range of 6.5 - 8. Therefore, it is necessary to check the effect of low frequency electromagnetic field on substrate pH. The study was performed for 25 days on two substrates, one of which was exposed to a low-frequency electromagnetic field with an electromagnetic induction of 3.5 mT. The research results show that the pH value of the substrate exposed to the electromagnetic field during the methane fermentation process was within acceptable limits, and the second substrate decreased, that is, it was acidified. Key words: methane fermentation, substrate, pH value, electromagnetic field

Increasing the Efficiency of Production of Synthetic Cast Iron Castings

The main factor that determines the content of the development strategies of a modern foundry is the use of modern technological processes, especially melting technology. First of all, this applies to the production of iron castings, which make up 65% of the mass of all alloys. Since 2000, in Russia, there has been a sharp decrease in the amount of pig iron scrap, the cost of foundry and pig iron and the cost of their transportation have increased significantly. This led to an increase in material costs in the production of castings from synthetic iron, which was mainly obtained in crucible induction furnaces of industrial frequency (ICT). In addition, problems began to arise with the use of acidic lining as the cheapest and most durable, since an increased amount of steel scrap began to be used in the metal charge, and for this reason the melting temperature was raised above 1450 ° C. The durability of the lining has sharply decreased, and downtime associated with its replacement has increased. All this had a negative impact on the efficiency of the production of synthetic iron castings.

Removal of isopropyl alcohol by electrical discharge from an aqueous solution with microbubbles

The removal of isopropyl alcohol impurities with an initial volume concentration of 20 % in a cell with a working area volume of 831 cm 3 in a water flow with fine air bubbles with a solution flow rate of 2 m 3/h by a quasi-volume electric discharge obtained using a multi-electrode system of sectioned needle electrodes has been experimentally investigated. At an alternating voltage of an industrial frequency of 50 Hz, the creation of a finely dispersed phase with air bubbles in an electric discharge cell increases the efficiency of isopropyl alcohol removal from the water flow by 6 %.

THE PREVALENCE OF ENDOCRINE AND CARDIOVASCULAR PATHOLOGY AMONG WORKERS EXPOSED TO MAGNETIC FIELDS

The negative side of the high rate of development of the electric power industry is the increase in the influence of electromagnetic radiation on humans. Unlike an electric field, a magnetic field is not shielded by personal protective equipment. Personnel exposed to industrial frequency magnetic fields are exposed to the negative effects of radiation on the nervous, cardiovascular, immune, and endocrine systems. Objective: to study and analyze the prevalence of diseases of the endocrine and cardiovascular systems in workers employed in the electric power industry. Materials and methods: 598 employees of the electric power industry were examined. The analysis of the survey data was carried out on the basis of descriptive statistics (relative values (%), the number of cases (n)) using the Microsoft Office Excel 2016 software package. Results: out of 598 men, 29.8% were obese, 16.7% had cardiovascular diseases and 2.7% had type 2 diabetes. The structure of morbidity by seniority groups was also analyzed and the dependence of the prevalence of morbidity on the length of service was revealed. Conclusion: the analysis of the obtained data indicates a high prevalence of diseases of the cardiovascular system and obesity among employees of the electric power industry exposed to industrial frequency magnetic fields.

Non-Contact Methods for High-Voltage Insulation Equipment Diagnosis during Operation

The article describes a complex of non-contact methods for remote diagnosis of high-voltage insulators as well as the two-channel method for remote diagnostics of the operating state of high-voltage insulators, based on the registration of partial discharges by electromagnetic and acoustic sensors. The presented device allows visual inspection and searches for faulty high-voltage equipment and a remote non-contact method of recording high-intensity electric fields of industrial frequency and their spatial distribution based on the electro-optical effect. The scheme of using the system for monitoring and diagnosing the technical condition of high-voltage support insulators of open switchgear is described. The results of experimental studies confirm the possibility of industrial applicability of the proposed method for non-contact remote diagnostics of the state of high-voltage insulators under operating voltage.

SUBSTANTIATION OF APPLICATION FEATURES OF LIQUID MIXTURES FOR SCREENING OF ELECTROMAGNETIC FIELDS

The protective and rheological properties of composite materials based on water-dispersed paint and iron ore concentrate were studied. Features of liquid mixtures application for shielding of magnetic field of industrial frequency and electromagnetic field of ultrahigh frequency were substantiated. The study of the protective characteristics and rheological properties of composite materials based on water-dispersed paint and iron ore concentrate indicates the possibility of their use for shielding electromagnetic fields of a wide frequency range. It was found that the efficiency of the composite material (total shielding coefficient and reflection coefficient of electromagnetic waves) depends on the dispersion of the shielding filler, so the particle size analysis of iron ore concentrate was performed. The analysis shows that the predominant size of iron-containing particles is 23‒24 μm, which is quite acceptable for their uniform distribution in the body of the matrix. Shielding protective material was made of water-dispersion paint with the addition of iron ore concentrate in weight quantities of 15, 30, 45, 60%. The shielding coefficients of the electromagnetic field of industrial frequency and ultrahigh frequency with different filler content were measured. It was found that if the concentration of filler exceeds 30%, both the rheological characteristics of the mixture and the shielding coefficients of electromagnetic fields are unsatisfactory. A dramatic increase in shielding coefficients occurs at a filler concentration of 40%. This mixture has acceptable adhesive properties. It was established that the shielding coefficients could be enhanced if the dispersion of the filler is increased, which will contribute to the stability of the colloidal mixture and improve the rheological properties.

On Physical Modeling of the Current Measurements in a Jet of Fire Extinguishing Agent

In accordance with the current regulations for extinguishing a fire, including without disconnecting electric power supply of direct (alternating) current of industrial frequency, fire extinguishers are allowed with a leakage current in a jet of extinguishing agent of not more than 500 µA, which is measured with an applied potential difference of 36 kV. Therefore, the recommendations for preliminary disconnection of electric power supply do not cover fire extinguishers that are certified according to the level of safe leakage current. The article deals with fire extinguishing agents based on aqueous solutions. It is obvious that the development of such fire extinguishers requires additional analytical and experimental research. The purpose of this article is the computational and physical modeling of the current leakage process, and the justification of the requirements for the parameters of the extinguishing agent flow at the outlet of the exhaust nozzle. As a result of the conducted research, the calculation methodоlogy and a scheme of the physical model of a high-voltage test bench for measuring the leakage current were developed based on measuring the active resistance of fire extinguishing agent flow in a constant voltage field and the electric capacitance of the measuring space of the test bench. The developed methodology allows to increase the reliability of the calculated results and significantly reduce the cost of working out the nozzle design. Measured at an applied voltage of 36 kV of industrial frequency, the amount of current leakage in a jet of the extinguishing agent is satisfactorily consistent with the calculation. The obtained computational and experimental results allowed to determine the range of permissible values of the active resistance and the requirements to the length of the continuous section of the jet of the extinguishing agent, which ensure safe use of the fire extinguisher for fire-fighting, including without disconnecting the electric power supply of the constant (alternating) current of industrial frequency with a voltage up to 1000 V.

Recycling of Secondary cooper Waste

The process of dissolution of copper crumbs with nitric acid without superposition and with superposition of alternating current of industrial frequency is investigated. The main parameters of the process of copper dissolution by nitric acid in the absence of nitrogen dioxide formation are determined. The technology of electrolytic dissolution of copper with nitric acid is proposed.