Investigation of the state of the electric field of the atmosphere in the area of open pit mining

Introduction. Emissions from industrial enterprises, open pit mining, vehicles, etc. can change the electrical properties of the surface layer of the atmosphere and have undesirable environmental consequences for the environment and technical facilities. Studies of the electrical state of the atmosphere in clear weather were carried out in the area of the Mukulan quarry in the North Caucasus. In the course of the study, increased values of the electric field strength were observed, apparently due to the process of electrization of aerosol particles of different sizes, formed in the process of mechanical destruction and crushing of rock particles.

Materials and research methods. Measurements of the electric field strength of the atmosphere, which is one of the important parameters of atmospheric electricity, were carried out using a rotary type fluxmeter at an altitude of 2542 m. At the same time, special attention was paid to the reliability of the results obtained during these measurements. A technique was used for conducting atmospheric-electrical measurements, which excludes errors introduced by various factors, such as the method of placing the measuring equipment, the heterogeneity of the terrain, the weather conditions of the observation point, which was located in the layer of air mass exchange and turbulent diffusion.

Results of the study and their discussion. An analysis of the results obtained on days with undisturbed clear weather showed that the only factor influencing the unitary course of the field strength at such a height remains the open pit mining, where on such days there is constant intense dust formation and the associated electrization of aerosol particles of different sizes. If the processes of electrification proceed intensively and for a long time, then an excess space charge accumulates in the surface layer of the atmosphere, which contributes to the formation of increased values of the electric field near the earth’s surface. The average value of the electric field strength was 600-700 V/m, which exceeds by an order of magnitude the results of measurements carried out at such heights by other researchers in undisturbed weather conditions. Local changes in the field strength were also noted when approaching the measuring site, a visually observed cloud of dust, which manifested itself in synchronous changes in the field strength, at which its value decreases and sometimes reaches negative values and recovers after some time to its average values. Local changes in the field are caused by the action of a negative space charge concentrated in a dust cloud consisting of large particles, the average size of which was estimated from the settling rate of aerosol particles and amounted to about 30 μm. It was found that there is a direct relationship between the field strength and the concentration of aerosol particles formed during the mechanical destruction of rocks, as a result of which the particles are electrified.

Conclusions. Studies of the electrical state carried out in the area of the Mukulan quarry showed that in good weather conditions, electrization is observed in the surface layer of the atmosphere. Aerosol particles acquire a charge in the process of mechanical destruction of rock particles and disruption of contact between them. At the same time, selective charging and capture of light air ions, depending on their size, and macroseparation in the field of gravitational forces occur, on the one hand, the rapid settling of large particles charged negatively on the earth’s surface, and on the other hand, small particles that can be in suspension for days in the atmosphere, charged with a positive sign, which leads to a decrease in air conductivity and, accordingly, an increase in the field strength in the quarry area.

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